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Sample records for 4v eli alloy

  1. Notch effects on high-cycle fatigue properties of Ti 6Al 4V ELI alloy at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Yuri, T.; Ono, Y.; Ogata, T.

    2006-01-01

    Notch effects on the high-cycle fatigue properties of the forged Ti-6Al-4V ELI alloy at cryogenic temperatures were investigated. Also, the high-cycle fatigue data were compared with the rolled Ti-5Al-2.5Sn ELI alloy. The one million cycles fatigue strength (FS) of the smooth specimen for the forged Ti-6Al-4V ELI alloy increased with a decrease of test temperature. However, the FS of each notched specimen at 4 K were lower than those at 77 K. On the other hand, the FS of the smooth and the notched specimens for the forged Ti-6Al-4V ELI alloy at 4 K were lower than those for the rolled Ti-5Al-2.5Sn ELI alloy. This is considered to be the early initiation of the fatigue crack in the forged Ti-6Al-4V ELI alloy compares with the forged Ti-5Al-2.5Sn ELI.

  2. Tensile properties of cast titanium alloys: Titanium-6Al-4V ELI and Titanium-5Al-2.5Sn ELI

    NASA Technical Reports Server (NTRS)

    Billinghurst, E. E., Jr.

    1992-01-01

    This work was performed to determine the tensile properties of cast, hot isostatic pressed (HIP'ed), and annealed titanium alloys, Ti-6Al-4V ELI and Ti-5Al-2.5Sn ELI, that are candidate materials for the space transportation main engine (STME) liquid hydrogen turbopump impeller. Samples of the cast alloys were HIP'ed, annealed, and machined into tensile specimens. The specimens were tested in air at ambient temperature (70 F) and also at -423 F in liquid hydrogen. The Ti-6Al-4V alloy had an average ultimate strength of 129.1 ksi at 70 F and 212.2 ksi at -423 F. The Ti-5Al-2.5Sn alloy had an average ultimate strength of 108.4 ksi at 70 degrees F and 185.0 ksi at -423 F. The ductility, as measured by reduction of area, for the Ti-6Al-4V averaged 15.2 percent at 70 F and 8.7 percent at -423 F, whereas for the Ti-5Al-2.5Sn alloy average reduction of area was 24.6 percent at 70 F and 11.7 percent at -423 F.

  3. Effect of Test Frequency on Fatigue Crack Growth Rates of Ti-6Al-4V ELI Alloy at Cryogenic Temperature

    SciTech Connect

    Yuri, T.; Ono, Y.; Ogata, T.

    2006-03-31

    In order to clarify the effect of test frequency on the fatigue crack growth rates (da/dN) of Ti-6Al-4V ELI alloy have been investigated at cryogenic temperature. The fatigue crack growth tests were conducted using the test frequencies of 5 and 20 Hz, respectively. At 4 K, the effects of the test frequencies on the fatigue crack growth rates of Ti-6Al-4V ELI alloy were not clear or significant. The fatigue crack growth rates in the low propagation rate region at 4 K were smaller than those at 293 K. On the other hand, those in the high propagation rate region at 4 K were bigger than those at 293 K. The former is considered that the crack closure level was higher as compared to that at 293 K and the latter is due to the difference values of the fracture toughness at 4 and 293 K, respectively. The fracture surfaces of compact tension (CT) specimens in the high propagation rate regions at each test temperature revealed the striations, and furthermore accompanied with the flute fracture surface at 4 K. On the other hand, those of CT specimens in the low propagation rate region at 4 K were found facet-like fracture surfaces corresponding with almost the {alpha}-grain size.

  4. Evaluation of the stiffness and friction of Ti6Al4V ELI treated by glow discharge nitriding

    NASA Astrophysics Data System (ADS)

    Tavera, J. R.; Peña Ballesteros, D. Y.; Estupiñán Duran, H. A.

    2016-02-01

    In this study, an evaluation of the elastic-plastic surface hardening on Ti6Al4V ELI titanium nitride films obtained by glow discharge method was carried out by nanoindentation tests according to the standard ISO 14577. The nanotribological properties (metal-metal) were also evaluated using the pin-on-disc system Ti6Al4V surface deposition ELI with nitrogen, obtaining a correlation between the coefficient of friction of Ti6Al4V ELI treated by PVD and the Young's modulus of the respective substrate modified by PVD. To characterize the substrate for the characterization tests, scanning electron microscopy, atomic force microscopy and X-ray diffraction and contact angle were carried out. The results demonstrated that the substrates nitrided improved mechanical and tribological properties, hardness, Young's modulus and coefficient of friction, making the alloy Ti6Al4V ELI support axial loads in tension and compression.

  5. Effects of the microstructure and porosity on properties of Ti-6Al-4V ELI alloy fabricated by electron beam melting (EBM)

    DOE PAGESBeta

    Galarraga, Haize; Lados, Diana A.; Dehoff, Ryan R.; Kirka, Michael M.; Nandwana, Peeyush

    2016-01-01

    Electron Beam Melting (EBM) is a metal powder bed-based Additive Manufacturing (AM) technology that makes possible the fabrication of three dimensional near-net-shaped parts directly from computer models. EBM technology has been in continuously updating, obtaining optimized properties of the processed alloys. Ti-6Al-4V titanium alloy is the most widely used and studied alloy for this technology and is the focus of this work. Several research works have been completed to study the mechanisms of microstructure formation as well as its influence on mechanical properties. However, the relationship is not completely understood, and more systematic research work is necessary in order tomore » attain a better understanding of these features. In this work, samples fabricated at different locations, orientations, and distances from the build platform have been characterized, studying the relationship of these variables with the resulting material intrinsic characteristics and properties (surface topography, microstructure, porosity, micro-hardness and static mechanical properties). This study has revealed that porosity is the main factor controlling mechanical properties relative to the other studied variables. Therefore, in future process developments, decreasing of the porosity should be considered as the primary goal in order to improve mechanical properties.« less

  6. Effects of the microstructure and porosity on properties of Ti-6Al-4V ELI alloy fabricated by electron beam melting (EBM)

    SciTech Connect

    Galarraga, Haize; Lados, Diana A.; Dehoff, Ryan R.; Kirka, Michael M.; Nandwana, Peeyush

    2016-01-01

    Electron Beam Melting (EBM) is a metal powder bed-based Additive Manufacturing (AM) technology that makes possible the fabrication of three dimensional near-net-shaped parts directly from computer models. EBM technology has been in continuously updating, obtaining optimized properties of the processed alloys. Ti-6Al-4V titanium alloy is the most widely used and studied alloy for this technology and is the focus of this work. Several research works have been completed to study the mechanisms of microstructure formation as well as its influence on mechanical properties. However, the relationship is not completely understood, and more systematic research work is necessary in order to attain a better understanding of these features. In this work, samples fabricated at different locations, orientations, and distances from the build platform have been characterized, studying the relationship of these variables with the resulting material intrinsic characteristics and properties (surface topography, microstructure, porosity, micro-hardness and static mechanical properties). This study has revealed that porosity is the main factor controlling mechanical properties relative to the other studied variables. Therefore, in future process developments, decreasing of the porosity should be considered as the primary goal in order to improve mechanical properties.

  7. The design and production of Ti-6Al-4V ELI customized dental implants

    NASA Astrophysics Data System (ADS)

    Chahine, Gilbert; Koike, Mari; Okabe, Toru; Smith, Pauline; Kovacevic, Radovan

    2008-11-01

    This paper addresses the production of customized Ti-6Al-4V ELI dental implants via electron beam melting (EBM). The melting of Ti-6Al-4V ELI powder produces implants with great biocompatibility, fi ne mechanical performance, and a high bone ingrowth potential. The EBM technology is used to produce one-component dental implants that mimic the exact shape of the patient’s tooth, replacing the traditional, three-component, “screw-like” standardized dental implants currently used. The new generation of implants provides the possibility of simplifying pre-insertion procedures leading to faster healing time, and the potential of better and stronger osseointegration, specifi cally through incorporating lattice structure design.

  8. Surface Quality of Ti-6%Al-4%V ELI When Machined Using CVD-Carbide Tools at High Cutting Speed

    SciTech Connect

    Gusri, A. I.; Che Hassan, C. H.; Jaharah, A. G.; Yasir, A.; Zaid, Y.; Yanuar, B.

    2011-01-17

    Machining of Ti-6Al-4V ELI becomes more interested topic due to extremely weight-to-strength ratio and resistance to corrosion at elevated temperature. Quality of machined surface is presented by surface roughness, surface texture and damages of microstructure of titanium alloys. The turning parameters evaluated are cutting speed of 55-95 m/min, feed rate of 0.15-0.35 mm/rev, depth of cut of 0.10-0.20 mm and tool grade of CVD carbide tools. The results show the trend lines of surface roughness value are higher at the initial machining and the surface texture profile has a strong correlation with the feed rate. At the machining condition of cutting speed of 95 m/min, feed rate of 0.35 mm/rev and depth of cut of 0.10 mm produced the with layer with thickness of 2.0 {mu}m.

  9. Strain-based fatigue data for Ti-6Al-4V ELI under fully-reversed and mean strain loads.

    PubMed

    Carrion, Patricio E; Shamsaei, Nima

    2016-06-01

    This article presents the experimental data supporting the study to obtain the mean strain/stress effects on the fatigue behavior of Ti-6Al-4V ELI. A series of strain-controlled fatigue experiments on Ti-6Al-4V ELI were performed at four strain ratios (-1, -0.5, 0, and 0.5). Two types of data are included for each specimen. These are the hysteresis stress-strain responses for the cycle in a log10 increment, and the maximum and minimum stress-strain responses for each cycle. Fatigue lives are also reported for all the experiments. PMID:26952022

  10. Gene expression of human osteoblasts cells on chemically treated surfaces of Ti-6Al-4V-ELI.

    PubMed

    Oliveira, D P; Palmieri, A; Carinci, F; Bolfarini, C

    2015-06-01

    Surface modifications of titanium alloys are useful methods to enhance the biological stability of intraosseous implants and to promote a well succeeded osseointegration in the early stages of implantation. This work aims to investigate the influence of chemically modified surfaces of Ti-6Al-4V-ELI (extra-low interstitial) on the gene expression of human osteoblastic (HOb) cells. The surface treatments by acid etching or acid etching plus alkaline treatment were carried out to modify the topography, effective area, contact angle and chemical composition of the samples. The surface morphology was investigated using: scanning electron microscopy (SEM) and confocal laser-scanning microscope (CLSM). Roughness measurements and effective surface area were obtained using the CLSM. Surface composition was analysed by energy dispersive X-ray spectroscopy (EDX) and by X-Ray Diffraction (XRD). The expression levels of some bone related genes (ALPL, COL1A1, COL3A1, SPP1, RUNX2, and SPARC) were analysed using real-time Reverse Transcription Polymerase Chain Reaction (real-time RT-PCR). The results showed that all the chemical modifications studied in this work influenced the surface morphology, wettability, roughness, effective area and gene expression of human osteoblasts. Acid phosphoric combined to alkaline treatment presented a more accelerated gene expression after 7days while the only phosphoric etching or chloride etching combined to alkaline treatment presented more effective responses after 15days. PMID:25842132

  11. Laser Assisted Milling of Ti-6Al-4V ELI with the Analysis of Surface Integrity and its Economics

    NASA Astrophysics Data System (ADS)

    Hedberg, Gary K.; Shin, Yung C.

    2015-09-01

    This study presents the experimental evaluation of laser assisted milling (LAML) of Ti-6AL-4V ELI (Ti-64), which is used in the orthopedic industry, by using localized preheating of the workpiece via laser irradiation. Improvements to the machinability of this material with LAML are assessed while considering the surface integrity. Suitable laser heating conditions as well as machining conditions are determined based on temperature prediction modeling. Machinability improvements are shown in terms of tool wear, material removal rates and cutting force reduction. Systematic characterization of samples is shown to demonstrate that the machined sub-surfaces are not adversely affected during LAML by precisely controlling laser heating, via hardness measurements, scanning electron microscopy (SEM) for microstructure analysis, and X-ray diffraction (XRD) for residual stresses. An economic analysis shows that LAML provides the cost reduction over conventional machining.

  12. Wear Mechanism of Chemical Vapor Deposition (CVD) Carbide Insert in Orthogonal Cutting Ti-6Al-4V ELI at High Cutting Speed

    SciTech Connect

    Gusri, A. I.; Che Hassan, C. H.; Jaharah, A. G.

    2011-01-17

    The performance of Chemical Vapor Deposition (CVD) carbide insert with ISO designation of CCMT 12 04 04 LF, when turning titanium alloys was investigated. There were four layers of coating materials for this insert i.e.TiN-Al2O3-TiCN-TiN. The insert performance was evaluated based on the insert's edge resistant towards the machining parameters used at high cutting speed range of machining Ti-6Al-4V ELI. Detailed study on the wear mechanism at the cutting edge of CVD carbide tools was carried out at cutting speed of 55-95 m/min, feed rate of 0.15-0.35 mm/rev and depth of cut of 0.10-0.20 mm. Wear mechanisms such as abrasive and adhesive were observed on the flank face. Crater wear due to diffusion was also observed on the rake race. The abrasive wear occurred more at nose radius and the fracture on tool were found at the feed rate of 0.35 mm/rev and the depth of cut of 0.20 mm. The adhesion wear takes place after the removal of the coating or coating delaminating. Therefore, adhesion or welding of titanium alloy onto the flank and rake faces demonstrates a strong bond at the workpiece-tool interface.

  13. Fatigue crack growth of Ti-6Al-4V-0.1Ru (ELI grade) in ocean environments

    NASA Astrophysics Data System (ADS)

    Langoy, Morten Andre

    1999-11-01

    This study of fatigue crack growth rates found that Ti-6Al-4V-0.1Ru alloy seamless pipe in beta transformed/annealed condition is well suited for dynamically loaded risers, which transport the reservoir fluid (oil and gas) from the well to the vessel, and promises significant economic benefits can be realized by employing the material in this application. The tested ocean environments did not detrimentally affect crack growth rates. The material was studied in two conditions: as-received (i.e., the parent material) and cold rolled (simulating the effect of coiling and reeling). The effect of different combinations of loading and environment on fatigue crack growth rates of the parent and cold rolled materials were studied systematically using a design of experiments (DOE) approach. Different combinations of temperature, load frequency, R (sigmamin/sigmamax of the fatigue cycle), pre-strain (cold work), and environment (laboratory air and aerated and deaerated simulated ocean water) were used in the study. The observed fatigue crack growth rates ranged from 4 x 10 -10 to 1 x 10-6 m/cycle and the investigated DeltaK's (stress intensity ranges) ranged from 7 to 45 MPa√m. Fatigue crack growth rates are not substantially higher in ocean environments than in air, but the differences appear to be real. Cold work (5% reduction in thickness by rolling) reduces fatigue crack growth rates (compared to the parent material) at intermediate and high DeltaK by a factor of two. Microstructure, fracture surfaces, and crack path also were related to testing conditions. Fracture surfaces reveal a change of morphology from features associated with microstructure-sensitive crack propagation (cyclic cleavage) to features (striations) linked with structure-insensitive (continuum-mode) growth. Contrary to expectations based on anecdotal accounts, crack branching is observed at the center of the samples regardless of DeltaK or other parameters and also on the outer surfaces of the

  14. Microstructure and tribological behaviors of Ti6Al4V alloy treated by plasma Ni alloying

    NASA Astrophysics Data System (ADS)

    Wang, Zhenxia; He, Zhiyong; Wang, Yingqin; Liu, Xiaoping; Tang, Bin

    2011-09-01

    Ni modified layer was prepared on surface of the Ti6Al4V substrate by plasma surface alloying technique. Surface morphology, micro-structure, composition distribution, phase structure, and microhardness of the Ni modified layer were analyzed. Tribological performance of the Ni modified layer and Ti6Al4V substrate was investigated by using pin-on-disc tribometer. The results indicate that roughness of the Ni modified layer was increased due to formation of the micro-convex on the modified surface. The concentration of Ni gradually decreased from the surface to interior. The maximum content of Ni atoms was nearly 90%. The modified layer was composed of TiNi, Ti2Ni and Ti phases. The maximum microhardness of the Ni modified layer was about 677 HV0.025 which was increased about two-fold of microhardness of the control Ti6Al4V substrate. Wear resistance of the Ni modified layer was improved obviously, and showed micro-abrasion wearing. The strengthened mechanism of the as-treated Ti6Al4V alloy is discussed.

  15. Fatigue behavior of Ti-6Al-4V alloy in saline solution with the surface modified at a micro- and nanoscale by chemical treatment.

    PubMed

    Claros, Cesar Adolfo Escobar; Oliveira, Diego Pedreira; Campanelli, Leonardo Contri; Pereira da Silva, Paulo Sergio Carvalho; Bolfarini, Claudemiro

    2016-10-01

    This work evaluated the influence of the surface modification using acid etching combined with alkaline treatment on the fatigue strength of Ti-6Al-4V ELI alloy. The topography developed by chemical surface treatments (CST) was examined by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Increased roughness and effective surface area were investigated and compared with the Ti-6Al-4V samples without modification. Surface composition was analyzed by energy dispersive X-ray spectroscopy (EDS). Axial fatigue resistance of polished and modified surfaces was determined by stepwise load increase tests and staircase test method. Light microscopy and SEM were employed to examine the fracture surface of the tested specimens. According to the results, a similar fatigue behavior was found and a negligible difference in the fatigue crack nucleation was observed for the Ti-6Al-4V with CST in comparison to the samples without treatment. PMID:27287139

  16. Surface integrity after pickling and anodization of Ti-6Al-4V titanium alloy

    NASA Astrophysics Data System (ADS)

    Vermesse, Eric; Mabru, Catherine; Arurault, Laurent

    2013-11-01

    The surface integrity of Ti-6Al-4V titanium alloy was studied at different stages of surface treatments, especially pickling and compact anodization, through surface characteristics potentially worsening fatigue resistance.

  17. Ultrafine-grained structure formation in Ti-6Al-4V alloy via warm swaging

    NASA Astrophysics Data System (ADS)

    Klimova, M.; Boeva, M.; Zherebtsov, S.; Salishchev, G.

    2014-08-01

    The influence of warm swaging on the structure and properties of Ti-6Al-4V alloy was studied. Warm swaging of the alloy in the interval 680-500°C with the total strain of ɛ=2.66 was found to be resulted in the formation of a homogeneous globular microstructure with a grain size of 0.4 μm in both longitudinal and transversal sections. Room temperature tensile strength and tensile elongation of the swaged alloy was 1315MPa and 10.5%, respectively. Ultrafine-grained Ti-6Al-4V alloy produced by swaging exhibited good workability at 600-700 °C.

  18. Osteoblastic behavior to zirconium coating on Ti-6Al-4V alloy

    PubMed Central

    Lee, Bo-Ah; Kim, Hae-Jin; Xuan, Yun-Ze; Park, Yeong-Joon; Chung, Hyun-Ju

    2014-01-01

    PURPOSE The purpose of this study was to assess the surface characteristics and the biocompatibility of zirconium (Zr) coating on Ti-6Al-4V alloy surface by radio frequency (RF) magnetron sputtering method. MATERIALS AND METHODS The zirconium films were developed on Ti-6Al-4V discs using RF magnetron sputtering method. Surface profile, surface composition, surface roughness and surface energy were evaluated. Electrochemical test was performed to evaluate the corrosion behavior. Cell proliferation, alkaline phosphatase (ALP) activity and gene expression of mineralized matrix markers were measured. RESULTS SEM and EDS analysis showed that zirconium deposition was performed successfully on Ti-6Al-4V alloy substrate. Ti-6Al-4V group and Zr-coating group showed no significant difference in surface roughness (P>.05). Surface energy was significantly higher in Zr-coating group than in Ti-6Al-4V group (P<.05). No difference in cell morphology was observed between Ti-6Al-4V group and Zr-coating group. Cell proliferation was higher in Zr-coating group than Ti-6Al-4V group at 1, 3 and 5 days (P<.05). Zr-coating group showed higher ALP activity level than Ti-6Al-4V group (P<.05). The mRNA expressions of bone sialoprotein (BSP) and osteocalcin (OCN) on Zr-coating group increased approximately 1.2-fold and 2.1-fold respectively, compared to that of Ti-6Al-4V group. CONCLUSION These results suggest that zirconium coating on Ti-6Al-4V alloy could enhance the early osteoblast responses. This property could make non-toxic metal coatings on Ti-6Al-4V alloy suitable for orthopedic and dental implants. PMID:25551012

  19. Resistance spot welding of Ti-6A1-4V alloy

    SciTech Connect

    Jarboe, D.M.

    1980-06-01

    The effects of weld power, electrode force, electrode tip radius, and elapsed time between cleaning and welding on resistance spot welds in Ti-6Al-4V alloy were evaluated. The alloy is weldable by this technique, and a wide latitude can be taken in processing variables.

  20. Mechanical properties of cast Ti-6Al-4V-XCu alloys.

    PubMed

    Aoki, T; Okafor, I C I; Watanabe, I; Hattori, M; Oda, Y; Okabe, T

    2004-11-01

    The mechanical properties of Ti-6Al-4V-XCu (1, 4 and 10 wt% Cu) alloys were examined. The castings for each alloy were made in a centrifugal titanium casting machine. Two shapes of specimens were used: a dumbbell (20 mm gauge length x 2.8 mm diameter) for mechanical property studies, and a flat slab (2 mm x 10 mm x 10 mm) for metallography, microhardness determination and X-ray diffractometry. Tensile strength, yield strength, modulus of elasticity, elongation and microhardness were evaluated. After tensile testing, the fracture surfaces were observed using scanning electron microscopy. The tensile strengths of the quaternary alloys decreased from 1016 MPa for the 1% Cu alloy to 387 MPa for the 10% Cu alloy. Elongation decreased with an increase in the copper content. The 1% Cu alloy exhibited elongation similar to Ti-6Al-4V without copper (3.0%). The results also indicated that the copper additions increased the bulk hardness of the quaternary alloy. In particular, the 10% Cu alloy had the highest hardness and underwent the most brittle fracture. The mechanical properties of cast Ti-6Al-4V alloy with 1 and 4% Cu were well within the values for existing dental casting non-precious alloys. PMID:15525390

  1. Porous Ti6Al4V alloys with enhanced normalized fatigue strength for biomedical applications.

    PubMed

    Li, Fuping; Li, Jinshan; Kou, Hongchao; Zhou, Lian

    2016-03-01

    In this paper, porous Ti6Al4V alloys for biomedical applications were fabricated by diffusion bonding of alloy meshes. The compression-compression fatigue behavior was studied. It results that porous Ti6Al4V alloys show enhanced normalized fatigue strength which is in the range of 0.5-0.55 at 10(6)cycles. The porosity has some effect on the absolute S-N curves but minor effect on the normalized S-N curves. The relationship between strain per cycle and number of cycles shows three distinct stages and the value of strain per cycle is constant in stage II. The reasons for the higher normalized fatigue strength of porous Ti6Al4V alloys are discussed based on the fatigue crack initiation and propagation. PMID:26706555

  2. Corrosion behavior of cast Ti-6Al-4V alloyed with Cu.

    PubMed

    Koike, Marie; Cai, Zhuo; Oda, Yutaka; Hattori, Masayuki; Fujii, Hiroyuki; Okabe, Toru

    2005-05-01

    It has recently been found that alloying with copper improved the inherently poor grindability and wear resistance of titanium. This study characterized the corrosion behavior of cast Ti-6Al-4V alloyed with copper. Alloys (0.9 or 3.5 mass % Cu) were cast with the use of a magnesia-based investment in a centrifugal casting machine. Three specimen surfaces were tested: ground, sandblasted, and as cast. Commercially pure titanium and Ti-6Al-4V served as controls. Open-circuit potential measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air + 10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was conducted in the same medium deaerated by N(2) + 10% CO(2). Polarization resistance (R(p)), Tafel slopes, and corrosion current density (I(corr)) were determined. A passive region occurred for the alloy specimens with ground and sandblasted surfaces, as for CP Ti. However, no passivation was observed on the as-cast alloys or on CP Ti. There were significant differences among all metals tested for R(p) and I(corr) and significantly higher R(p) and lower I(corr) values for CP Ti compared to Ti-6Al-4V or the alloys with Cu. Alloying up to 3.5 mass % Cu to Ti-6Al-4V did not change the corrosion behavior. Specimens with ground or sandblasted surfaces were superior to specimens with as-cast surfaces. PMID:15744719

  3. New Powder Metallurgical Approach to Achieve High Fatigue Strength in Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Cao, Fei; Ravi Chandran, K. S.; Kumar, Pankaj; Sun, Pei; Zak Fang, Z.; Koopman, Mark

    2016-05-01

    Recently, manufacturing of titanium by sintering and dehydrogenation of hydride powders has generated a great deal of interest. An overarching concern regarding powder metallurgy (PM) titanium is that critical mechanical properties, especially the high-cycle fatigue strength, are lower than those of wrought titanium alloys. It is demonstrated here that PM Ti-6Al-4V alloy with mechanical properties comparable (in fatigue strength) and exceeding (in tensile properties) those of wrought Ti-6Al-4V can be produced from titanium hydride powder, through the hydrogen sintering and phase transformation process. Tensile and fatigue behavior, as well as fatigue fracture mechanisms, have been investigated under three processing conditions. It is shown that a reduction in the size of extreme-sized pores by changing the hydride particle size distribution can lead to improved fatigue strength. Further densification by pneumatic isostatic forging leads to a fatigue strength of ~550 MPa, comparable to the best of PM Ti-6Al-4V alloys prepared by other methods and approaching the fatigue strengths of wrought Ti-6Al-4V alloys. The microstructural factors that limit fatigue strength in PM titanium have been investigated, and pathways to achieve greater fatigue strengths in PM Ti-6Al-4V alloys have been identified.

  4. Lattice variations of Ti-6Al-4V alloy with hydrogen content

    SciTech Connect

    Zhu Tangkui Li, Miaoquan

    2011-07-15

    Effect of hydrogen content on the lattice parameter of Ti-6Al-4V alloy has been investigated by X-ray diffraction. The experimental results show that the solution of hydrogen in the Ti-6Al-4V alloy affects significantly on the lattice parameters of {alpha}, {beta} and {delta} phases, especially the {beta} phase. Furthermore, the critical hydrogen content of {delta} hydride formation for Ti-6Al-4V alloy is 0.385 wt.%. When the hydrogen content is lower than the critical hydrogen content, the {delta} hydride cannot precipitate and the lattice parameter ({alpha}) of {beta} phase linearly increases with the increasing of hydrogen content. When the hydrogen content is higher than the critical hydrogen content, the {delta} hydride precipitates and the lattice parameter ({alpha}) of {beta} phase varies inconspicuously with hydrogen content. In addition, the effects of lattice variations and {delta} hydride formation on microstructure are discussed. The {alpha}/{beta} interfaces of lamellar transformed {beta} phase become fuzzy with the increasing of hydrogen content because of the lattice expansion of {beta} phase. Compared with that of the Ti-6Al-4V alloy at low hydrogen content ({<=} 0.385 wt.%), the contrasts of primary {alpha} phase and transformed {beta} phase of Ti-6Al-4V alloy at high hydrogen content ({>=} 0.385 wt.%) were completely reversed due to the formation of {delta} hydride. - Research Highlights: {yields} A novel method for determining {delta} hydride in Ti-6Al-4V alloy is presented. {yields} The critical hydrogen content of {delta} hydride formation is 0.385 wt.%. {yields} The lattice parameter of {beta} phase can be expressed as follows: a=0.323(1+9.9x10{sup -2}C{sub H}) . {yields} Precipitation of {delta} hydride has a significant influence on the microstructure. {yields} The {alpha}/{beta} interfaces of transformed {beta} phase became fuzzy in the hydrogenated alloy.

  5. Enhanced superplasticity and strength in modified Ti-6Al-4V alloys

    SciTech Connect

    Wert, J.A.; Paton, N.E.

    1983-12-01

    Beta-stabilizing elements were added Ti-6Al-4V alloy with a view to lowering its optimum superplastic forming temperature. The alloys modified with 2 wt pct Fe, Co, and Ni produced values of flow stress, strain rate sensitivity, and total elongation at 1088 K approaching those of the base Ti-6Al-4V alloy at its standard superplastic forming temperature of 1200 K. In addition to lowering the superplastic forming temperature, the beta-stabilizing elements also increased room temperature strength levels above those normally found for Ti-6Al-4V. The addition of beta-stabilizing elements raised resistance to deformation at room temperature, while lowering it at elevated temperatures. This result is explained by considering the effects of high-diffusivity beta stabilizers on deformation processes at room and elevated temperatures. 23 references.

  6. Corrosion behavior of PIRAC nitrided Ti-6Al-4V surgical alloy.

    PubMed

    Starosvetsky, D; Shenhar, A; Gotman, I

    2001-02-01

    Hard titanium nitride (TiN) coatings were obtained on the surface of Ti-6Al-4V alloy using an original PIRAC nitriding method, based on annealing the samples under a low pressure of monatomic nitrogen created by selective diffusion of N from the atmosphere. PIRAC nitrided samples exhibited excellent corrosion resistance in Ringer's solution in both potentiodynamic and potentiostatic tests. The anodic current and metal ion release rate of PIRAC nitrided Ti-6Al-4V at the typical corrosion potential values were significantly lower than those of the untreated alloy. This, together with the excellent adhesion and high wear resistance of the TiN coatings, makes PIRAC nitriding an attractive surface treatment for Ti-6Al-4V alloy surgical implants. PMID:15348321

  7. Study on improved tribological properties by alloying copper to CP-Ti and Ti-6Al-4V alloy.

    PubMed

    Wang, Song; Ma, Zheng; Liao, Zhenhua; Song, Jian; Yang, Ke; Liu, Weiqiang

    2015-12-01

    Copper alloying to titanium and its alloys is believed to show an antibacterial performance. However, the tribological properties of Cu alloyed titanium alloys were seldom studied. Ti-5Cu and Ti-6Al-4V-5Cu alloys were fabricated in the present study in order to further study the friction and wear properties of titanium alloys with Cu additive. The microstructure, composition and hardness were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and hardness tester. The tribological behaviors were tested with ZrO2 counterface in 25% bovine serum using a ball-on-disc tribo-tester. The results revealed that precipitations of Ti2Cu intermetallic compounds appeared in both Ti-5Cu and Ti-6Al-4V-5Cu alloys. The tribological results showed an improvement in friction and wear resistance for both Ti-5Cu and Ti-6Al-4V-5Cu alloys due to the precipitation of Ti2Cu. The results also indicated that both CP-Ti and Ti-5Cu behaved better wear resistance than Ti-6Al-4V and Ti-6Al-4V-5Cu due to different wear mechanisms when articulated with hard zirconia. Both CP-Ti and Ti-5Cu revealed dominant adhesive wear with secondary abrasive wear mechanism while both Ti-6Al-4V and Ti-6Al-4V-5Cu showed severe abrasive wear and cracks with secondary adhesive wear mechanism due to different surface hardness integrated by their microstructures and material types. PMID:26354247

  8. Shot peening for Ti-6Al-4V alloy compressor blades

    NASA Technical Reports Server (NTRS)

    Carek, Gerald A.

    1987-01-01

    A text program was conducted to determine the effects of certain shot-peening parameters on the fatigue life of the Ti-6Al-4V alloys as well as the effect of a demarcation line on a test specimen. This demarcation line, caused by an abrupt change from untreated surface to shot-peened surface, was thought to have caused the failure of several blades in a multistage compressor at the NASA Lewis Research Center. The demarcation line had no detrimental effect upon bending fatigue specimens tested at room temperature. Procedures for shot peening Ti-6Al-4V compressor blades are recommended for future applications.

  9. Nanometer-scale surface modification of Ti6Al4V alloy for orthopedic applications.

    PubMed

    Xie, Jianhui; Luan, Ben Li

    2008-01-01

    This communication presents a novel technology to enhance the biocompatibility of bioinert Ti6Al4V alloy as implant materials for orthopaedic application. The surface of Ti6Al4V alloy was electrochemically activated in NaOH solution to create a porous structure with nanometer topographic features and an alkaline environment, thus promoting the formation of bone-like hydroxyapatite coating and enhancing the bonding strength of the coating. This innovative activation process was proved to be effective and essential. The activated surface was confirmed to be pure TiO2 and the formed coating was characterized of pure hydroxyapatite with a nanometer-scaled grain size structure by means of XPS, FESEM/SEM/EDX, XRD, and TEM techniques. PMID:17600328

  10. Ultrasonic cavitation erosion of gas nitrided Ti-6Al-4V alloys.

    PubMed

    Mitelea, I; Dimian, E; Bordeaşu, I; Crăciunescu, C

    2014-07-01

    Ultrasonic cavitation erosion experiments were performed on Ti-6Al-4V alloys samples in annealed, nitrided and nitrided and subsequently heat treated state. The protective oxide layer formed as a result of annealing and heat treatment after nitriding is eliminated after less than 30 min cavitation time, while the nitride layer lasts up to 90 min cavitation time. Once the protective layer is removed, the cavitation process develops by grain boundary erosion, leading to the expulsion of grains from the surface. The gas nitrided Ti-6Al-4V alloy, forming a TixN surface layer, proved to be a better solution to improve the cavitation erosion resistance, compared to the annealed and nitrided and heat treated state, respectively. The analysis of the mean depth of erosion rate at 165 min cavitation time showed an improvement of the cavitation erosion resistance of the nitrided samples of up to 77% higher compared to the one of the annealed samples. PMID:24500067

  11. Microstructure evolution and grain refinement of Ti-6Al-4V alloy by laser shock processing

    NASA Astrophysics Data System (ADS)

    Ren, X. D.; Zhou, W. F.; Liu, F. F.; Ren, Y. P.; Yuan, S. Q.; Ren, N. F.; Xu, S. D.; Yang, T.

    2016-02-01

    Microstructure evolution and grain refinement of Ti-6Al-4V alloy after laser shock processing (LSP) are systematically investigated in this paper. Laser shock waves were induced by a Q-switched Nd:YAG laser system operated with a wave-length of 1064 nm and 10 ns pulse width. The microstructures of LSP samples were characterized by scanning electron microscopy (SEM) and transmission electron microscope (TEM). Present results indicate that the surface hardness of samples subjected to LSP impacts has significantly improved. Multidirectional twin intersections and dislocation movements lead to grain subdivision in α phase with ultra-high plastic deformation. High-density dislocations are found in β phase. Multidirectional twin intersections and division of sub-grain boundaries play an important role in the grain refinement of Ti-6Al-4V alloy under LSP loading conditions.

  12. Effect of Thermodiffusion Nitriding on Cytocompatibility of Ti-6Al-4V Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Pohrelyuk, I. M.; Tkachuk, O. V.; Proskurnyak, R. V.; Boiko, N. M.; Kluchivska, O. Yu.; Stoika, R. S.

    2016-04-01

    The nitrided layer was formed on the surface of Ti-6Al-4V titanium alloy by the thermodiffusion saturation in nitrogen at the atmospheric pressure. The study of the vitality of pseudonormal human embryo kidney cells of the HEK293T line showed that their cultivation in the presence of the untreated alloy sample is accompanied by a statistically significant reduction in the number of living cells compared with the control sample (untreated cells), whereas their cultivation in the presence of the nitrided alloy sample does not change the cell number considerably. In addition, it was shown that cell behavior in the presence of the nitrided sample differs only slightly from the control sample, whereas the growth of cells in the presence of the untreated alloy differed significantly from that in the control sample, demonstrating small groups of cells instead of their big clusters.

  13. Fractographic observations of Ti-6Al-4V alloy fatigued in vacuum.

    NASA Technical Reports Server (NTRS)

    Ritter, D. L.; Wei, R. P.

    1971-01-01

    These observations were made as part of a study of the influence of temperature and chemical environment on fatigue-crack growth. The results obtained, along with additional fractographic results in other environments, suggest that the mechanism for fatigue-crack growth in the Ti-6Al-4V alloy is basically similar (striations are observed) for a wide range of environments. In addition to ?vacuum,' these environments include distilled water, ?dry' and ?wet' air, ?dry' hydrogen, and ?dry' and ?wet' argon.

  14. Microstructure-Tensile Properties Correlation for the Ti-6Al-4V Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Shi, Xiaohui; Zeng, Weidong; Sun, Yu; Han, Yuanfei; Zhao, Yongqing; Guo, Ping

    2015-04-01

    Finding the quantitative microstructure-tensile properties correlations is the key to achieve performance optimization for various materials. However, it is extremely difficult due to their non-linear and highly interactive interrelations. In the present investigation, the lamellar microstructure features-tensile properties correlations of the Ti-6Al-4V alloy are studied using an error back-propagation artificial neural network (ANN-BP) model. Forty-eight thermomechanical treatments were conducted to prepare the Ti-6Al-4V alloy with different lamellar microstructure features. In the proposed model, the input variables are microstructure features including the α platelet thickness, colony size, and β grain size, which were extracted using Image Pro Plus software. The output variables are the tensile properties, including ultimate tensile strength, yield strength, elongation, and reduction of area. Fourteen hidden-layer neurons which can make ANN-BP model present the most excellent performance were applied. The training results show that all the relative errors between the predicted and experimental values are within 6%, which means that the trained ANN-BP model is capable of providing precise prediction of the tensile properties for Ti-6Al-4V alloy. Based on the corresponding relations between the tensile properties predicted by ANN-BP model and the lamellar microstructure features, it can be found that the yield strength decreases with increasing α platelet thickness continuously. However, the α platelet thickness exerts influence on the elongation in a more complicated way. In addition, for a given α platelet thickness, the yield strength and the elongation both increase with decreasing β grain size and colony size. In general, the β grain size and colony size play a more important role in affecting the tensile properties of Ti-6Al-4V alloy than the α platelet thickness.

  15. Microstructure, mechanical and wear properties of laser surface melted Ti6Al4V alloy.

    PubMed

    Balla, Vamsi Krishna; Soderlind, Julie; Bose, Susmita; Bandyopadhyay, Amit

    2014-04-01

    Laser surface melting (LSM) of Ti6Al4V alloy was carried out with an aim to improve properties such as microstructure and wear for implant applications. The alloy substrate was melted at 250W and 400W at a scan velocity of 5mm/s, with input energy of 42J/mm(2) and 68J/mm(2), respectively. The results showed that equiaxed α+β microstructure of the substrate changes to mixture of acicular α in β matrix after LSM due to high cooling rates in the range of 2.25×10(-3)K/s and 1.41×10(-3)K/s during LSM. Increasing the energy input increased the thickness of remelted region from 779 to 802µm and 1173 to 1199µm. Similarly, as a result of slow cooling rates under present experimental conditions, the grain size of the alloy increased from 4.8μm to 154-199μm. However, the hardness of the Ti6Al4V alloy increased due to LSM melting and resulted in lowest in vitro wear rate of 3.38×10(-4)mm(3)/Nm compared to untreated substrate with a wear rate of 6.82×10(-4)mm(3)/Nm. PMID:24388220

  16. Tool wear in cryogenic turning of Ti-6Al-4V alloy

    NASA Astrophysics Data System (ADS)

    Venugopal, K. A.; Paul, S.; Chattopadhyay, A. B.

    2007-01-01

    Though titanium alloys are being increasingly sought in a wide variety of engineering and biomedical applications, their manufacturability, especially machining and grinding imposes lot of constraints. Rapid tool wear encountered in machining of titanium alloys is a challenge that needs to be overcome. Cryogenic machining with liquid nitrogen as coolant is being investigated by researchers to reduce the cutting zone temperatures and enhance the tool life. The effects of cryogenic cooling have been studied on growth and nature tool wear in the present investigation while turning Ti-6Al-4V alloy bars with microcrystalline uncoated carbide inserts under dry, wet and cryogenic cooling environments in the cutting velocity range of 70-100 m/min. Cryogenic cooling by liquid nitrogen jets enabled substantial improvement in tool life through reduction in adhesion-dissolution-diffusion tool wear through control of machining temperature desirably at the cutting zone.

  17. Permeation behavior of deuterium implanted into Ti sbnd 6Al sbnd 4V alloy

    NASA Astrophysics Data System (ADS)

    Arita, M.; Hayashi, T.; Okuno, K.; Hayashi, Y.

    1997-09-01

    Permeation of deuterium implanted into Ti sbnd 6Al sbnd 4V alloy has been studied using 0.5 keV D + ion beam in the temperature range of 323 to 753 K. Above 600 K, the ratio of steady state permeation flux/incident flux ranges from 3.3 × 10 -3 at 633 K to 4.8 × 10 -3 at 753 K. The activation energy of permeation is about 0.12 eV in this temperature range. At temperatures below 600 K, the permeation flux of deuterium decreases drastically. Deuterium implanted in the lower temperature range desorbed from the alloy by heating after implantation. Thus, the most of the implanted ions remain in the alloy at low temperatures.

  18. In vivo and in vitro response to electrochemically anodized Ti-6Al-4V alloy.

    PubMed

    Lee, Yu Mi; Lee, Eun Jung; Yee, Sung Tae; Kim, Byung Il; Choe, Eun Sang; Cho, Hyun Wook

    2008-05-01

    Tissues' reactions to metals depend on a variety of properties of the metal, most notably surface structure. Anodizing has been shown to alter the surface properties of metal, thus eliciting a change in the biocompatibility of the metal. In order to evaluate the biocompatibility of unoxidized titanium alloy (Ti-6Al-4V) and anodized titanium alloy samples, the samples were implanted in murine abdominal subcutaneous tissues, and maintained for 2 and 4 weeks. The reaction of the abdominal subcutaneous connective tissues to the samples was then assessed. Fibrous connective tissue capsules were observed around the vicinity of the sample, and these capsules were shown to harbor fibroblasts, fibrocytes, and other cells, including neutrophils, macrophages, and giant multinucleated cells. The average thickness of the fibrous capsules observed around the anodized alloy samples was less than that of the capsules seen around samples of the unoxidized titanium alloy. Blood was obtained from the tails of the experimental mice, and blood cell analyses were conducted in order to assess the levels of leukocytes, red blood cells, and thrombocytes. The blood analysis results of the unoxidized control group and treatment group were all within normal ranges. In addition, the biocompatibility of the titanium alloy samples was evaluated using cell culture techniques. The numbers of MG-63 cells cultured on oxidized samples tended to be greater than those in the controls; however, these increases were not statistically significant. The alkaline phosphatase activity of the sample oxidized at 310 V evidenced significantly higher activity than was observed in the control group. These results indicate that the anodized Ti-6Al-4V alloy will be of considerable utility in biomedical applications. PMID:17914611

  19. Reflection, re-emission and permeation of deuterium implanted in Ti6Al4V alloy

    NASA Astrophysics Data System (ADS)

    Bandourko, V.; Ohkoshi, K.; Yamaguchi, K.; Yamawaki, M.

    1997-02-01

    A Ti6Al4V alloy has been selected as the vacuum vessel structural material in the tokamak physics experiment (TPX) [1] and in the steady state tokamak JT-60 Super Upgrade (JT-60 SU) [2]. To determine the amount of hydrogen retained in titanium alloy during glow discharge cleaning and plasma operation the knowledge of the parameters such as a recombination coefficient K and a particles reflection coefficient RN is necessary. Presence of the non-metallic impurities on the surface strongly affects both the above mentioned parameters. In the present work, the permeation behavior of deuterium has been investigated for deuterium implanted into Ti6Al4V membrane with an incident ion energy 150-1500 eV/D. RN has been determined by means of the thermal desorption technique. The surface chemical composition was controlled in-situ by means of AES and SIMS analyses. Experimentally obtained values of RN are larger than computer simulation results for both the clean Ti6Al4V surface and the surface layer with the concentration of the chemical elements same as that experimentally observed. The calculated values of RN are not significantly different from one another. The amount of retained hydrogen was estimated for TPX condition taking into account the contribution of the reflected particles to the flux balance.

  20. Fatigue Properties of Ti-6Al-4V Alloy in Vacuum at Cryogenic Temperature

    NASA Astrophysics Data System (ADS)

    Dong, S. L.; Lu, G.; Zhang, L. Q.; Yang, D. Z.; He, S. Y.; Han, E. H.

    2009-01-01

    In the present study, the fatigue properties of a 720 ° C/1h annealed Ti-6Al-4V alloy have been evaluated under the following conditions: in air at room temperature (RT), in vacuum at RT and in vacuum at cryogenic temperature, using a vacuum-cryogenic electric fatigue machine. Fracture surfaces of the fatigued specimens and the microstructures in regions adjacent to fracture surface were examined by scanning election microscopy (SEM) and transmission election microscopy (TEM). The results showed that the fatigue strength of Ti-6Al-4V alloy decreased in the order of the following conditions: in vacuum at cryogenic temperature, in vacuum at RT and in air at RT. The longest fatigue life of the alloy could be obtained in vacuum at cryogenic temperature, while the shortest one in air at room temperature. Crack initiation site, crack prorogation path and rapid failure zone were distinguishable on the fractured surfaces of the specimens fatigued either in air or in vacuum at room and cryogenic temperatures. Generally, the fatigue cracks initiated at the surface of the specimens and many dimples could be found in the rapid failure zone. Dislocation slip was found to be the main deformation mode under the three testing conditions.

  1. Effect of plasma welding parameters on the flexural strength of Ti-6Al-4V alloy.

    PubMed

    Lyra e Silva, João Paulo; Fernandes Neto, Alfredo Júlio; Raposo, Luís Henrique Araújo; Novais, Veridiana Resende; de Araujo, Cleudmar Amaral; Cavalcante, Luisa de Andrade Lima; Simamoto Júnior, Paulo Cezar

    2012-01-01

    The aim of this study was to assess the effect of different plasma arc welding parameters on the flexural strength of titanium alloy beams (Ti-6Al-4V). Forty Ti-6Al-4V and 10 NiCr alloy beam specimens (40 mm long and 3.18 mm diameter) were prepared and divided into 5 groups (n=10). The titanium alloy beams for the control group were not sectioned or subjected to welding. Groups PL10, PL12, and PL14 contained titanium beams sectioned and welded at current 3 A for 10, 12 or 14 ms, respectively. Group NCB consisted of NiCr alloy beams welded using conventional torch brazing. After, the beams were subjected to a three-point bending test and the values obtained were analyzed to assess the flexural strength (MPa). Statistical analysis was carried out by one-way ANOVA and Tukey's HSD test at 0.05 confidence level. Significant difference was verified among the evaluated groups (p<0.001), with higher flexural strength for the control group (p<0.05). No significant differences was observed among the plasma welded groups (p>0.05). The NCB group showed the lowest flexural strength, although it was statistically similar to the PL 14 group (p>0.05). The weld depth penetration was not significantly different among the plasma welded groups (p=0.05). Three representative specimens were randomly selected to be evaluated under scanning electron microcopy. The composition of the welded regions was analyzed by energy dispersive X-ray spectroscopy. This study provides an initial set of parameters supporting the use of plasma welding during fabrication of titanium alloy dental frameworks. PMID:23338261

  2. Gas nitriding and subsequent oxidation of Ti-6Al-4V alloys

    PubMed Central

    2012-01-01

    Ti-6Al-4V alloys consisting of α-Ti grains and intergranular β-Ti islands were nitrided at 850°C for 1 to 12 h under a nitrogen pressure of 1 Pa. With increasing nitriding time, the Ti-N compound layer became thicker, and the α-Ti diffusion zone containing dissolved nitrogen became wider. In the Ti-N compound layer, the initially formed Ti2N became TiN as the nitriding progressed. The nitride layers were oxidized to rutile-TiO2 after oxidation at 700°C for 10 h in air. PMID:22221679

  3. Gas nitriding and subsequent oxidation of Ti-6Al-4V alloys.

    PubMed

    Lee, Dong Bok; Pohrelyuk, Iryna; Yaskiv, Oleh; Lee, Jae Chun

    2012-01-01

    Ti-6Al-4V alloys consisting of α-Ti grains and intergranular β-Ti islands were nitrided at 850°C for 1 to 12 h under a nitrogen pressure of 1 Pa. With increasing nitriding time, the Ti-N compound layer became thicker, and the α-Ti diffusion zone containing dissolved nitrogen became wider. In the Ti-N compound layer, the initially formed Ti2N became TiN as the nitriding progressed. The nitride layers were oxidized to rutile-TiO2 after oxidation at 700°C for 10 h in air. PMID:22221679

  4. A study of cumulative fatigue damage in titanium 6Al-4V alloy

    NASA Technical Reports Server (NTRS)

    Jeelani, S.; Ghebremedhin, S.; Musial, M.

    1986-01-01

    Experimental data were obtained using titanium 6Al-4V alloy under stress ratios of -1, 0, and negative infinity. A study of cumulative fatigue damage using Miner's (1945) and Kramer's (1974) equations for stress ratios of -1 and 0 for low-high, low-high mixed, high-low, and high-low mixed stress sequences has revealed close agreement between the theoretical and experimental values of fatigue damage and fatigue life. Kramer's equation predicts less conservative and more realistic cumulative fatigue damage than does the popularly used Miner's rule.

  5. Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

    NASA Astrophysics Data System (ADS)

    Klimenov, V. A.; Kurgan, K. A.; Chumaevskii, A. V.; Klopotov, A. A.; Gnyusov, S. F.

    2016-01-01

    The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

  6. Effect of Tricalcium Magnesium Silicate Coating on the Electrochemical and Biological Behavior of Ti-6Al-4V Alloys.

    PubMed

    Maleki-Ghaleh, Hossein; Hafezi, Masoud; Hadipour, Mohammadreza; Nadernezhad, Ali; Aghaie, Ermia; Behnamian, Yashar; Abu Osman, Noor Azuan

    2015-01-01

    In the current study, a sol-gel-synthesized tricalcium magnesium silicate powder was coated on Ti-6Al-4V alloys using plasma spray method. Composition of feed powder was evaluated by X-ray diffraction technique before and after the coating process. Scanning electron microscopy and atomic force microscopy were used to study the morphology of coated substrates. The corrosion behaviors of bare and coated Ti-6Al-4V alloys were examined using potentiodynamic polarization test and electrochemical impedance spectroscopy in stimulated body fluids. Moreover, bare and coated Ti-6Al-4V alloys were characterized in vitro by culturing osteoblast and mesenchymal stem cells for several days. Results demonstrated a meaningful improvement in the corrosion resistance of Ti-6Al-4V alloys coated with tricalcium magnesium silicate compared with the bare counterparts, by showing a decrease in corrosion current density from 1.84 μA/cm2 to 0.31 μA/cm2. Furthermore, the coating substantially improved the bioactivity of Ti-6Al-4Valloys. Our study on corrosion behavior and biological response of Ti-6Al-4V alloy coated by tricalcium magnesium silicate proved that the coating has considerably enhanced safety and applicability of Ti-6Al-4V alloys, suggesting its potential use in permanent implants and artificial joints. PMID:26383641

  7. Effect of Tricalcium Magnesium Silicate Coating on the Electrochemical and Biological Behavior of Ti-6Al-4V Alloys

    PubMed Central

    Hadipour, Mohammadreza; Nadernezhad, Ali; Aghaie, Ermia; Behnamian, Yashar; Abu Osman, Noor Azuan

    2015-01-01

    In the current study, a sol-gel-synthesized tricalcium magnesium silicate powder was coated on Ti-6Al-4V alloys using plasma spray method. Composition of feed powder was evaluated by X-ray diffraction technique before and after the coating process. Scanning electron microscopy and atomic force microscopy were used to study the morphology of coated substrates. The corrosion behaviors of bare and coated Ti-6Al-4V alloys were examined using potentiodynamic polarization test and electrochemical impedance spectroscopy in stimulated body fluids. Moreover, bare and coated Ti-6Al-4V alloys were characterized in vitro by culturing osteoblast and mesenchymal stem cells for several days. Results demonstrated a meaningful improvement in the corrosion resistance of Ti-6Al-4V alloys coated with tricalcium magnesium silicate compared with the bare counterparts, by showing a decrease in corrosion current density from 1.84 μA/cm2 to 0.31 μA/cm2. Furthermore, the coating substantially improved the bioactivity of Ti-6Al-4Valloys. Our study on corrosion behavior and biological response of Ti-6Al-4V alloy coated by tricalcium magnesium silicate proved that the coating has considerably enhanced safety and applicability of Ti-6Al-4V alloys, suggesting its potential use in permanent implants and artificial joints. PMID:26383641

  8. Surface nanocrystallization of Ti-6Al-4V alloy: microstructural and mechanical characterization.

    PubMed

    Pi, Y; Agoda-Tandjawa, G; Potiron, S; Demangel, C; Retraint, D; Benhayoune, H

    2012-06-01

    In this study, microstructural and mechanical properties of Ti-6Al-4V alloy, before and after the SMA treatment (SMAT) as well as the duplex SMAT/Nitriding process at different treatment conditions, were investigated in order to deepen the knowledge of these properties for biomedical devices. For that purpose, tribological (wear resistance, coefficient of friction) and mechanical (Vickers microhardness) tests were performed. To carry out the microstructural and surface topographical characterization of the samples, the scanning electron microscopy (SEM) and the 3D-SEM reconstruction from stereoscopic images have been used. By means of profiles deduced from the 3D images, the surface roughness has been calculated. The obtained results allowed to find an interesting SMAT condition which, followed by nitriding at low temperature, can greatly improve tribological and mechanical properties of Ti-6Al-4V alloy. It was also shown from SEM characterization and the original method of 3D-SEM reconstruction, that SMAT can reduce the machined grooves and consequently the roughness of the samples decreases. Moreover, we demonstrated, for the first time, that instead of usual etching method, the ionic polishing allowed to reveal the grains, the grain boundaries and the twins as well as the surface nanocrystalline layer generated by SMAT. Thus, the thickness of the SMATed layer decreases with the nitriding temperature, whereas the surface grain size increases. PMID:22905548

  9. Cell interaction with modified nanotubes formed on titanium alloy Ti-6Al-4V.

    PubMed

    Moravec, Hynek; Vandrovcova, Marta; Chotova, Katerina; Fojt, Jaroslav; Pruchova, Eva; Joska, Ludek; Bacakova, Lucie

    2016-08-01

    Nanotubes with diameters ranging from 40 to 60nm were prepared by electrochemical oxidation of the Ti-6Al-4V alloy in electrolyte containing ammonium sulphate and ammonium fluoride. The nanotubes were further modified with calcium and phosphate ions or were heat treated. Polished Ti-6Al-4V alloy served as a reference sample. The spreading of human osteoblast-like cells was similar on all nanotube samples but lower than on polished samples. The number of initially adhered cells was higher on non-modified nanotubes, but the final cell number was the highest on Ca-enriched nanotubes and the lowest on heat-treated nanotubes. However, these differences were relatively small and less pronounced than the differences in the concentration of specific molecular markers of cell adhesion and differentiation, estimated by their intensity of immunofluorescence staining. The concentration of vinculin, i.e. a protein of focal adhesion plaques, was the lowest on nanotubes modified with calcium. Collagen I, an early marker of osteogenic cell differentiation, was also the lowest on samples modified with calcium and was highest on polished samples. Alkaline phosphatase, a middle marker of osteogenic differentiation, was observed in lowest concentration on nanotubes modified with phosphorus and the highest on heat-treated samples. Osteocalcin concentrations, a late marker of osteogenic cell differentiation, were similar on all tested samples, although they tended to be the highest on heat-treated samples. Thus, osteogenic differentiation can be modulated by various additional treatments of nanotube coatings on Ti-6Al-4V implants. PMID:27157757

  10. Hydrogen peroxide treatment on Ti-6Al-4V alloy: A promising surface modification technique for orthopaedic application

    NASA Astrophysics Data System (ADS)

    Karthega, M.; Rajendran, N.

    2010-01-01

    Ti-6Al-4V alloy was treated with various concentrations (5 wt.%, 15 wt.% and 25 wt.%) of hydrogen peroxide (H 2O 2) and then heat treated to produce an anatase titania layer. The surface modified substrates were immersed in simulated body fluid (SBF) solution for the growth of an apatite layer on the surface and the formed apatite layer was characterized using various surface characterization techniques. The results revealed that titania layer with anatase nature was observed for all H 2O 2 treated Ti-6Al-4V alloy, irrespective of the H 2O 2 concentrations. Ti-6Al-4V alloy treated with 15 wt.% and 25 wt.% of H 2O 2 induced apatite formation, however 5 wt.% of H 2O 2 treated Ti-6Al-4V failed to form apatite layer on the surface. The electrochemical behaviour of H 2O 2 treated specimens in SBF solution was studied using potentiodynamic polarization and electrochemical impedance spectroscopy. Ti-6Al-4V alloy treated with 25 wt.% of H 2O 2 solution exhibited low current density and high charge transfer resistance values compared to specimens treated with other concentrations of H 2O 2 and untreated Ti-6Al-4V alloy.

  11. Viscoelastoplastic Deformation and Damage Response of Titanium Alloy, Ti-6Al-4V, at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Arnold, Steven M.; Lerch, Bradley A.; Saleeb, Atef F.; Kasemer, Matthew P.

    2013-01-01

    Time-dependent deformation and damage behavior can significantly affect the life of aerospace propulsion components. Consequently, one needs an accurate constitutive model that can represent both reversible and irreversible behavior under multiaxial loading conditions. This paper details the characterization and utilization of a multi-mechanism constitutive model of the GVIPS class (Generalized Viscoplastic with Potential Structure) that has been extended to describe the viscoelastoplastic deformation and damage of the titanium alloy Ti-6Al-4V. Associated material constants were characterized at five elevated temperatures where viscoelastoplastic behavior was observed, and at three elevated temperatures where damage (of both the stiffness reduction and strength reduction type) was incurred. Experimental data from a wide variety of uniaxial load cases were used to correlate and validate the proposed GVIPS model. Presented are the optimized material parameters, and the viscoelastoplastic deformation and damage responses at the various temperatures.

  12. Grain Refinement of Freeform Fabricated Ti-6Al-4V Alloy Using Beam/Arc Modulation

    NASA Technical Reports Server (NTRS)

    Mitzner, Scott; Liu, Stephen; Domack, Marcia S.; Hafley, Robert A.

    2012-01-01

    Grain refinement can significantly improve the mechanical properties of freeform-fabricated Ti-6Al-4V alloy, promoting increased strength and enhanced isotropy compared with coarser grained material. Large beta-grains can lead to a segregated microstructure, in regard to both alpha-phase morphology and alpha-lath orientation. Beam modulation, which has been used in conventional fusion welding to promote grain refinement, is explored in this study for use in additive manufacturing processes including electron beam freeform fabrication (EBF(sup 3)) and gas-tungsten arc (GTA) deposition to alter solidification behavior and produce a refined microstructure. The dynamic molten pool size induced by beam modulation causes rapid heat flow variance and results in a more competitive grain growth environment, reducing grain size. Consequently, improved isotropy and strength can be achieved with relatively small adjustments to deposition parameters.

  13. Problems Associated with Attaching Strain Gages to Titanium Alloy Ti-61-4V

    NASA Technical Reports Server (NTRS)

    Jenkins, J. M.; Lemcoe, M. M.

    1977-01-01

    Weldable strain gages have shown excellent high temperature characteristics for supersonic cruise aircraft application. The spotwelding attachment method, however, has resulted in serious reductions in the fatigue life of titanium alloy (Ti-6Al-4V) fatigue specimens. The reduction is so severe that the use of weldable strain gages on operational aircraft must be prohibited. The cause of the fatigue problem is thought to be a combination of the microstructure changes in the material caused by spotwelding and the presence of the flange of the stain gage. Brazing, plating, and plasma spraying were investigated as substitutes for spotwelding. The attachment of a flangeless gage by plasma spraying provided the most improvement in the fatigue life of the titanium.

  14. Influence of Initial Microstructure on Hot Workability of Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Yeom, Jong-Taek; Kim, Jeoung Han; Hong, Jae-Keun; Park, Nho-Kwang; Lee, Chong Soo

    Hot workability of Ti-6Al-4V alloy with different initial microstructures was investigated by considering processing maps and the dynamic material deformation behavior. The emphasis has been focused on the effect of initial microstructure (equiaxed versus bimodal structure). Process maps were generated using the dynamic material model (DMM), unifying the relationships between constitutive deformation behavior, hot workability and microstructures evolution. Also, the flow instability was investigated using the various flow instability criteria and microstructural analysis. To establish the processing maps with different initial microstructures, high temperature compression tests were carried out at various temperatures and strain rates up to a true strain of 0.7. Microstructural changes occurring during the deformation were analyzed in terms of high temperature deformation mechanisms. Finally the useful instability criterion for predicting the forming defects was suggested through the compression test results with different temperatures and strain rates.

  15. Influence of Grain Size on Electrically Assisted Tensile Behavior of Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Li, Xifeng; Ji, Boyu; Zhou, Qiang; Chen, Jun; Gao, Peng

    2016-08-01

    The effect of grain size and current density on deformation behavior during electrically assisted tension of Ti-6Al-4V alloy was investigated. The microstructural variations under different conditions were observed by optical microscope, SEM and TEM. The dislocation density was quantified by x-ray diffraction technique. The decrease in grain size could increase the elongation growth and stress reduction during electrically assisted tension. Fine grain size specimens can reach higher temperature than coarse grain specimens. With increasing current density, wider and deeper dimples on the fracture surfaces were observed, and less dislocation density and pileups were found in comparison with room-temperature tension without current. The dislocation density has a 62.1% reduction at 10.48 A/mm2 compared with room-temperature tension for 9.2 μm grain size specimens.

  16. Influence of Temperature on Nitrogen Ion Implantation of Ti6Al4V Alloy

    NASA Astrophysics Data System (ADS)

    Zhao, Qing; Zheng, Yong-zhen; Mo, Zhi-tao; Tang, De-li; Tong, Hong-hui; Geng, Man

    2001-04-01

    In order to achieve increased layer thickness, and wearing resistance, enhanced ion implantation with nitrogen has been carried out at temperatures of 100, 200, 400, and 600°C with a dose of 4×1018 ions cm-2. Using the Plasma Source Ion Implantation (PSII) device, specimens of Ti6Al4V alloy were implanted at elevated temperatures, using the ion flux as the heating source. Auger Electron Spectroscopy (AES), Scanning Electron Microscopy (SEM), x-ray Diffraction (XRD), micro-hardness measurements and pin-on-disk wearing tester were utilized to evaluate the surface property improvements. The thickness of the implanted layer increased by about an order of magnitude when the temperature was elevated from 100 to 600°C. Higher surface hardness and wearing resistance was also obtained in implantation under higher temperature. XRD image showed the presence of titanium nitrides on the implanted surface.

  17. Fatigue performance of medical Ti6Al4V alloy after mechanical surface treatments.

    PubMed

    Sonntag, Robert; Reinders, Jörn; Gibmeier, Jens; Kretzer, J Philippe

    2015-01-01

    Mechanical surface treatments have a long history in traditional engineering disciplines, such as the automotive or aerospace industries. Today, they are widely applied to metal components to increase the mechanical performance of these. However, their application in the medical field is rather rare. The present study aims to compare the potential of relevant mechanical surface treatments on the high cycle fatigue (R = 0.1 for a maximum of 10 million cycles) performance of a Ti6Al4V standard alloy for orthopedic, spinal, dental and trauma surgical implants: shot peening, deep rolling, ultrasonic shot peening and laser shock peening. Hour-glass shaped Ti6Al4V specimens were treated and analyzed with regard to the material's microstructure, microhardness, residual stress depth profiles and the mechanical behavior during fatigue testing. All treatments introduced substantial compressive residual stresses and exhibited considerable potential for increasing fatigue performance from 10% to 17.2% after laser shock peening compared to non-treated samples. It is assumed that final mechanical surface treatments may also increase fretting wear resistance in the modular connection of total hip and knee replacements. PMID:25823001

  18. Effect of cryogenic treatment on the plastic property of Ti-6Al-4V titanium alloy

    NASA Astrophysics Data System (ADS)

    Gu, K. X.; Wang, J. J.; Yuan, Z.; Zhang, H.; Li, Z. Q.; Zhao, B.

    2014-01-01

    The effect of cryogenic treatment on the plastic property of Ti-6Al-4V plate was studied in the present work. After cryogenic treatment, the low temperature temper at 180 ▭ was conducted in one of the groups and the results were compared with that of the untreated and cryotreated ones. The SLX series program controlled cryogenic equipment was used for the cryogenic treatment. The tensile tests were conducted by universal tensile testing machine and parameters of elongation and area reduction were used to evaluate plastic property. The scanning electron microscope was used to study the morphology of microstructure and fracture surface. The results show that after cryogenic treatment alone the elongation increased 10.6% and the area reduction increased 13.5% while the strength reduced to a small extent. Cryogenic treatment followed with low temperature temper increased the elongation and area reduction just by the extent of 4.7% and 9.5%. It means that the additional low temperature temper after cryogenic is not beneficial to the tensile properties of Ti-6Al-4V alloy. The examination of microstructure by scanning electron microscopy revealed that cryogenic treatment reduced the content of β phase particles which is the main reason for the improvement in plasticity.

  19. Effect of cryogenic treatment on the plastic property of Ti-6Al-4V titanium alloy

    SciTech Connect

    Gu, K. X.; Wang, J. J.; Yuan, Z.; Zhang, H.; Li, Z. Q.; Zhao, B.

    2014-01-27

    The effect of cryogenic treatment on the plastic property of Ti-6Al-4V plate was studied in the present work. After cryogenic treatment, the low temperature temper at 180 ▭ was conducted in one of the groups and the results were compared with that of the untreated and cryotreated ones. The SLX series program controlled cryogenic equipment was used for the cryogenic treatment. The tensile tests were conducted by universal tensile testing machine and parameters of elongation and area reduction were used to evaluate plastic property. The scanning electron microscope was used to study the morphology of microstructure and fracture surface. The results show that after cryogenic treatment alone the elongation increased 10.6% and the area reduction increased 13.5% while the strength reduced to a small extent. Cryogenic treatment followed with low temperature temper increased the elongation and area reduction just by the extent of 4.7% and 9.5%. It means that the additional low temperature temper after cryogenic is not beneficial to the tensile properties of Ti-6Al-4V alloy. The examination of microstructure by scanning electron microscopy revealed that cryogenic treatment reduced the content of β phase particles which is the main reason for the improvement in plasticity.

  20. Fatigue Performance of Medical Ti6Al4V Alloy after Mechanical Surface Treatments

    PubMed Central

    Sonntag, Robert; Reinders, Jörn; Gibmeier, Jens; Kretzer, J. Philippe

    2015-01-01

    Mechanical surface treatments have a long history in traditional engineering disciplines, such as the automotive or aerospace industries. Today, they are widely applied to metal components to increase the mechanical performance of these. However, their application in the medical field is rather rare. The present study aims to compare the potential of relevant mechanical surface treatments on the high cycle fatigue (R = 0.1 for a maximum of 10 million cycles) performance of a Ti6Al4V standard alloy for orthopedic, spinal, dental and trauma surgical implants: shot peening, deep rolling, ultrasonic shot peening and laser shock peening. Hour-glass shaped Ti6Al4V specimens were treated and analyzed with regard to the material’s microstructure, microhardness, residual stress depth profiles and the mechanical behavior during fatigue testing. All treatments introduced substantial compressive residual stresses and exhibited considerable potential for increasing fatigue performance from 10% to 17.2% after laser shock peening compared to non-treated samples. It is assumed that final mechanical surface treatments may also increase fretting wear resistance in the modular connection of total hip and knee replacements. PMID:25823001

  1. High-cycle fatigue behavior of Ti-5Al-2.5Sn ELI alloy forging at low temperatures

    SciTech Connect

    Ono, Yoshinori; Yuri, Tetsumi; Ogata, Toshio; Demura, Masahiko; Matsuoka, Saburo; Sunakawa, Hideo

    2014-01-27

    High-cycle fatigue properties of Ti-5Al-2.5Sn Extra Low Interstitial (ELI) alloy forging were investigated at low temperatures. The high-cycle fatigue strength at low temperatures of this alloy was relatively low compared with that at ambient temperature. The crystallographic orientation of a facet formed at a fatigue crack initiation site was determined by electron backscatter diffraction (EBSD) method in scanning electron microscope (SEM) to understand the fatigue crack initiation mechanism and discuss on the low fatigue strength at low temperature. Furthermore, in terms of the practical use of this alloy, the effect of the stress ratio (or mean stress) on the high-cycle fatigue properties was evaluated using the modified Goodman diagram.

  2. High-cycle fatigue behavior of Ti-5Al-2.5Sn ELI alloy forging at low temperatures

    NASA Astrophysics Data System (ADS)

    Ono, Yoshinori; Yuri, Tetsumi; Ogata, Toshio; Demura, Masahiko; Matsuoka, Saburo; Sunakawa, Hideo

    2014-01-01

    High-cycle fatigue properties of Ti-5Al-2.5Sn Extra Low Interstitial (ELI) alloy forging were investigated at low temperatures. The high-cycle fatigue strength at low temperatures of this alloy was relatively low compared with that at ambient temperature. The crystallographic orientation of a facet formed at a fatigue crack initiation site was determined by electron backscatter diffraction (EBSD) method in scanning electron microscope (SEM) to understand the fatigue crack initiation mechanism and discuss on the low fatigue strength at low temperature. Furthermore, in terms of the practical use of this alloy, the effect of the stress ratio (or mean stress) on the high-cycle fatigue properties was evaluated using the modified Goodman diagram.

  3. Surface Integrity of Titanium Alloy Ti-6Al-4 V in Ball end Milling

    NASA Astrophysics Data System (ADS)

    Mhamdi, M.-B.; Boujelbene, M.; Bayraktar, E.; Zghal, A.

    With the evolution of machine tools and the emergence of new cutting tools such as cermet, CBN; and in framework of the production of parts with complex geometry, the manufacturers were able to realize more and more parts of complex shape. The multi-axis machining is the main technique for achieving the free form; in fact the multi-axis milling with ball end tools attracts the interest of the aerospace industry and the mussel industry which continues to seek ways to improve the surface quality of finished parts. The titanium alloy is widely used in aerospace industry is the subject of this study in fact, the integrity of the surfaces of parts produced by multi-axis milling is an issue more relevant than ever for the aerospace industry. This paper aims to study the influence of the tool position and the parameters cutting precisely the speed feed Vf, the engagement of the tool on the roughness 3 D, micro-hardness and microstructure alteration created in sub-surface during the milling of concave surface of titanium alloy type Ti-6Al-4 V.

  4. Permanent mold casting of titanium alloy Ti-6Al-4V

    SciTech Connect

    Sadayappan, M.; Sahoo, M.; Lavender, C.; paul.jablonski, P.D.

    2008-01-01

    A literature review indicated that data on the effect of various casting defects, such as inclusions and porosity, on the properties of titanium alloy castings were not readily available. This information is required to reduce the cost of fabricating titanium castings for potential automotive applications. To this end, a research project was initiated to develop data on the as-cast properties of titanium alloy Ti-6Al-4V (Ti64). Step plate castings with 3.2, 6.3, 13, and 25 mm thick steps were produced in a high-density graphite mold following melting in an induction furnace with water-cooled copper hearth. The mechanical properties were determined in the as-cast condition and were found to be close to the values reported in standards. Few casting defects such as inclusions and porosity were observed, and the loss of strength due to these defects is not significant. It is shown that titanium castings with good mechanical properties can be produced in high-density graphite molds.

  5. Cryogenic turning of the Ti-6Al-4V alloy with modified cutting tool inserts

    NASA Astrophysics Data System (ADS)

    Dhananchezian, M.; Pradeep Kumar, M.

    2011-01-01

    Productivity in the machining of titanium alloys is adversely affected by rapid tool wear as a consequence of high cutting zone temperature. Conventional cutting fluids are ineffective in controlling the cutting temperature in the cutting zone. In this research work, an attempt has been made to investigate the effect of liquid nitrogen when it is applied to the rake surface, and the main and auxiliary flank surfaces through holes made in the cutting tool insert during the turning of the Ti-6Al-4V alloy. The cryogenic results of the cutting temperature, cutting forces, surface roughness and tool wear of the modified cutting tool insert have been compared with those of wet machining. It has been observed that in the cryogenic cooling method, the cutting temperature was reduced by 61-66% and the surface roughness was reduced to a maximum of 36% over wet machining. The cutting force was decreased by 35-42% and the flank wear was reduced by 27-39% in cryogenic cooling over that of wet machining. Cryogenic cooling enabled a substantial reduction in the geometry of tool wear through the control of the tool wear mechanisms. The application of liquid nitrogen to the heat generation zones through holes made in the cutting tool insert was considered to be more effective over conventional machining.

  6. Numerical Simulation and Superplastic Forming of Ti-6Al-4V Alloy for a Dental Prosthesis

    NASA Astrophysics Data System (ADS)

    Li, Xiaomei; Soo, Steven

    2011-04-01

    This article investigates superplastic forming (SPF) technique in conjunction with finite element (FE) simulation applied to dental repair. The superplasticity of Ti-6Al-4V alloys has been studied using a uniquely designed five-hole test with the aim of obtaining the modeled grain size and the flow stress parameters. The data from the five-hole test are subsequently put into the FE program for the simulation of a partial upper denture dental prosthesis (PUD4). The FE simulation of the PUD4 is carried out to set up appropriate input parameters for pressing due to the SPF process being fully automatic controlled. A variety of strain rates ranging from 2.4 × 10-5 to 1 × 10-3 s-1 are selected for the characterization of superplastic properties of the alloy. The Superflag FE program is used to generate an appropriate pressure-time profile and provide information on thickness, grain size, and grain growth rate distribution. Both membrane elements and solid elements have been adopted in the simulation and the results from both types of elements are compared. An evaluation of predicted parameters for the SPF of the prosthesis is presented.

  7. Characterization of disk-laser dissimilar welding of titanium alloy Ti-6Al-4V to aluminum alloy 2024

    NASA Astrophysics Data System (ADS)

    Caiazzo, Fabrizia; Alfieri, Vittorio; Cardaropoli, Francesco; Corrado, Gaetano; Sergi, Vincenzo

    2013-02-01

    Both technical and economic reasons suggest to join dissimilar metals, benefiting from the specific properties of each material in order to perform flexible design. Adhesive bonding and mechanical joining have been traditionally used although adhesives fail to be effective in high-temperature environments and mechanical joining are not adequate for leak-tight joints. Friction stir welding is a valid alternative, even being difficult to perform for specific joint geometries and thin plates. The attention has therefore been shifted to laser welding. Interest has been shown in welding titanium to aluminum, especially in the aviation industry, in order to benefit from both corrosive resistance and strength properties of the former, and low weight and cost of the latter. Titanium alloy Ti-6Al-4V and aluminum alloy 2024 are considered in this work, being them among the most common ones in aerospace and automotive industries. Laser welding is thought to be particularly useful in reducing the heat affected zones and providing deep penetrative beads. Nevertheless, many challenges arise in welding dissimilar metals and the aim is further complicated considering the specific features of the alloys in exam, being them susceptible to oxidation on the upper surface and porosity formation in the fused zone. As many variables are involved, a systematic approach is used to perform the process and to characterize the beads referring to their shape and mechanical features, since a mixture of phases and structures is formed in the fused zone after recrystallization.

  8. Characterization of the deformation texture after tensile test and cold rolling of a Ti-6Al-4V sheet alloy

    NASA Astrophysics Data System (ADS)

    Mehdi, B.; Azzeddine, H.; Badji, R.; Ji, V.; Alili, B.; Bradai, D.

    2015-04-01

    The deformation texture after cold rolling and tensile test of an industrial Ti-6Al-4V sheet alloy was studied using X-ray diffraction. The alloy was subjected to a cold rolling to different thickness reductions (from 20% to 60%) and then tensile tests have been carried out along three directions relatively to the rolling direction (0°, 45° and 90°). The experimental results were compared to the existing literature and discussed in terms of active plastic deformation mechanisms.

  9. Macroscopic and microscopic investigations on uniaxial ratchetting of two-phase Ti–6Al–4V alloy

    SciTech Connect

    Kang, Guozheng; Dong, Yawei; Liu, Yujie; Jiang, Han

    2014-06-01

    The uniaxial ratchetting of Ti–6Al–4V alloy with two phases (i.e., primary hexagonal close packed (HCP) α and secondary body-centered cubic (BCC) β phases) was investigated by macroscopic and microscopic experiments at room temperature. Firstly, the effects of cyclic softening/hardening feature, applied mean stress and stress amplitude on the uniaxial ratchetting of the alloy were discussed. The macroscopic investigation of Ti–6Al–4V alloy presents obvious strain-amplitude-dependent cyclic softening, as well as a three-staged evolution curve with regard to the ratchetting strain rate. The ratchetting depends greatly on the applied mean stress and stress amplitude while the ratchetting strain increases with the increasing applied mean stress and stress amplitude. Then, the evolution of dislocation patterns and deformation twinning during the uniaxial ratchetting of two-phase Ti–6Al–4V alloy were observed using transmission electron microscopy (TEM). The microscopic observation shows that deformation twinning occurs in the primary α phase and its amount increases gradually during the uniaxial ratchetting. Simultaneously, the planar dislocation evolves from discrete lines to some dislocation nets and parallel lines with the increasing number of cycles. The deformation twinning in the primary α phase is one of main contributions to the uniaxial ratchetting of Ti–6Al–4V alloy, and should be considered in the construction of corresponding constitutive model. - Highlights: • A three-staged ratchetting occurs in the stress-controlled cyclic tests of Ti–6Al–4V alloy. • Dislocation patterns change from discrete lines to nets and parallel lines. • Deformation twinning occurs during the uniaxial ratchetting. • Both dislocation slipping and twinning are the causes of ratchetting.

  10. Study for Corrosion and Hydrogen Evolution Behavior of Ti-6Al-4V Alloy in Simulated Acid Rain Water

    NASA Astrophysics Data System (ADS)

    Tammam, R. H.; Fekry, A. M.

    2014-03-01

    The electrochemical behavior of Ti-6Al-4V alloy was investigated using electrochemical impedance spectroscopy (EIS) measurements at the open circuit potentials and potentiodynamic polarization measurements in a simulated acid rain containing inorganic additives. The ac circuit model for Ti-6Al-4V alloy at corrosion interface in simulated acid rain containing inorganic additives was proposed, which was based on two time constants equivalent circuit. Ti-6Al-4V alloy in a simulated acid rain of pH 1.5 containing inorganic additives showed a characteristic of a capacitive behavior. The effect of different concentrations of the inorganic additives (iodate, dichromate, phosphate, and nitrate) on the corrosion of the alloy in acid rain water (ARW) was also studied. It was found that the corrosion rate decreases drastically in the solution containing iodate, dichromate, and phosphate anions; however, nitrate anions increase the corrosion rate of the alloy. The investigated inorganic additives had inhibiting effect on the corrosion of the alloy in ARW, and their efficiency decreases according to the order: iodate > dichromate > phosphate > blank > nitrate. Polarization data results are in good agreement with EIS.

  11. Friction Stir-Welded Titanium Alloy Ti-6Al-4V: Microstructure, Mechanical and Fracture Properties

    NASA Astrophysics Data System (ADS)

    Sanders, D. G.; Edwards, P.; Cantrell, A. M.; Gangwar, K.; Ramulu, M.

    2015-05-01

    Friction stir welding (FSW) has been refined to create butt welds from two sheets of Ti-6Al-4V alloy to have an ultra-fine grain size. Weld specimen testing was completed for three different FSW process conditions: As welded, stress relieved, stress relieved and machined, and for the un-welded base material. The investigation includes macrostructure, microstructure, microhardness, tensile property testing, notched bar impact testing, and fracture toughness evaluations. All experiments were conducted in accordance with industry standard testing specifications. The microstructure in the weld nugget was found to consist of refined and distorted grains of alpha in a matrix of transformed beta containing acicular alpha. The enhanced fracture toughness of the welds is a result of increased hardness, which is attributed to an increase in alpha phase, increase in transformed beta in acicular alpha, and grain refinement during the weld process. The noted general trend in mechanical properties from as welded, to stress relieved, to stress relieved and machined conditions exhibited a decrease in ultimate tensile strength, and yield strength with a small increase in ductility and a significant increase in fracture toughness.

  12. Effect of SiC interlayer between Ti6Al4V alloy and hydroxyapatite films.

    PubMed

    Azem, Funda Ak; Birlik, Isil; Braic, Viorel; Toparli, Mustafa; Celik, Erdal; Parau, Anca; Kiss, Adrian; Titorencu, Irina; Vladescu, Alina

    2015-04-01

    Bioactive coatings are frequently used to improve the osseointegration of the metallic implants used in dentistry or orthopaedics. Among different types of bioactive coatings, hydroxyapatite (Ca10(PO4)6(OH)2) is one of the most extensively used due to its chemical similarities to the components of bones and teeth. In this article, production and characterization of hydroxyapatite films deposited on Ti6Al4V alloy prepared by magnetron sputtering were reported. Besides, SiC was deposited on substrate surface to study the interlayer effect. Obtained coatings were annealed at 600 °C for 30 and 120 min in a mixed atmosphere of N2 + H2O vapours with the heating rate of 12 °C min(-1). The effects of SiC interlayer and heat treatment parameters on the structural, mechanical and corrosion properties were investigated. After heat treatment process, the crystalline hydroxyapatite was obtained. Additionally, cell viability tests were performed. The results show that the presence of the SiC interlayer contributes a decrease in surface roughness and improves the mechanical properties and corrosion performance of the hydroxyapatite coatings. Biological properties were not affected by the presence of the SiC interlayer. PMID:25934259

  13. Are new TiNbZr alloys potential substitutes of the Ti6Al4V alloy for dental applications? An electrochemical corrosion study.

    PubMed

    Ribeiro, Ana Lúcia Roselino; Hammer, Peter; Vaz, Luís Geraldo; Rocha, Luís Augusto

    2013-12-01

    The main aim of this work was to assess the electrochemical behavior of new Ti35Nb5Zr and Ti35Nb10Zr alloys in artificial saliva at 37 °C to verify if they are indicated to be used as biomaterials in dentistry as alternatives to Ti6Al4V alloys in terms of corrosion protection efficiency of the material. Electrochemical impedance spectroscopy (EIS) experiments were carried out for different periods of time (0.5-216 h) in a three-electrode cell, where the working electrode (Ti alloys) was exposed to artificial saliva at 37 °C. The near-surface region of the alloys was investigated using x-ray photoelectron spectroscopy (XPS). All alloys exhibited an increase in corrosion potential with the immersion time, indicating the growth and stabilization of the passive film. Ti35Nb5Zr and Ti6Al4V alloys had their EIS results interpreted by a double-layer circuit, while the Ti35Nb10Zr alloy was modeled by a one-layer circuit. In general, the new TiNbZr alloys showed similar behavior to that observed for the Ti6Al4V. XPS results suggest, in the case of the TiNbZr alloys, the presence of a thicker passive layer containing a lower fraction of TiO2 phase than that of Ti6Al4V. After long-term immersion, all alloys develop a calcium phosphate phase on the surface. The new TiNbZr alloys appear as potential candidates to be used as a substitute to Ti6Al4V in the manufacturing of dental implant-abutment sets. PMID:24280708

  14. Effect of creep in titanium alloy Ti-6Al-4V at elevated temperature on aircraft design and flight test

    NASA Technical Reports Server (NTRS)

    Jenkins, J. M.

    1984-01-01

    Short-term compressive creep tests were conducted on three titanium alloy Ti-6Al-4V coupons at three different stress levels at a temperature of 714 K (825 F). The test data were compared to several creep laws developed from tensile creep tests of available literature. The short-term creep test data did not correlate well with any of the creep laws obtained from available literature. The creep laws themselves did not correlate well with each other. Short-term creep does not appear to be very predictable for titanium alloy Ti-6Al-4V. Aircraft events that result in extreme, but short-term temperature and stress excursions for this alloy should be approached cautiously. Extrapolations of test data and creep laws suggest a convergence toward predictability in the longer-term situation.

  15. Kinetic Study of the Solid-State Transformation of Vacuum-Plasma-Sprayed Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Salimijazi, H. R.; Mousavi, Z. A.; Golozar, M. A.; Mostaghimi, J.; Coyle, T.

    2014-01-01

    Because of the nature of the plasma spraying process, the physical and mechanical properties of vacuum-plasma-sprayed structures of Ti-6Al-4V alloy are completely different from those of conventionally manufactured alloys such as bulk materials from casting and forging. To obtain desired mechanical and physical properties, vacancy and internal defects must be reduced, splat boundaries must be eliminated, and optimal phase compositions should be obtained through postdeposition heat treatments. To determine appropriate heat treatment processes, one needs to study the kinetic behavior of the as-sprayed microstructure at elevated temperatures. In the current study, the kinetics of the solid transformations found in Ti-6Al-4V alloys produced during the vacuum plasma spraying process was studied based on the Johnson-Mehl-Avrami theory. For the kinetic behavior of this alloy, the nonconstant temperature dependence of the transformation rate constant exhibits an irregularity at 900 °C, marking a change in the transformation mechanism. For the lower-temperature (<900 °C) curves, the constant gradient indicates a lack of change in the transformation mechanism, including homogeneous nucleation, with growth of α phase. For higher temperatures (>900 °C), a gradient change indicates a change in the transformation mechanism. The first mechanism was the formation of α-phase grain boundary, and the second mechanism was α-plate nucleation and growth from grain boundaries. The value of the transformation rate constant in the kinetics study of as-sprayed Ti-6Al-4V alloy was much higher than for material produced by the casting method. Using the results obtained from the kinetics of the phase transformation at different constant temperatures, a time-temperature-transformation (TTT) diagram for as-sprayed Ti-6Al-4V alloy was developed.

  16. Biomimetic Hydroxyapatite Growth on Functionalized Surfaces of Ti-6Al-4V and Ti-Zr-Nb Alloys

    NASA Astrophysics Data System (ADS)

    Pylypchuk, Ie V.; Petranovskaya, A. L.; Gorbyk, P. P.; Korduban, A. M.; Markovsky, P. E.; Ivasishin, O. M.

    2015-08-01

    A biomimetic approach for coating titanium-containing alloys with hydroxyapatite (HA) is reported in the article. Two types of Ti-containing alloys were chosen as an object for coating: Ti-6Al-4V (recommended for orthopedic application) and a novel highly biocompatible Ti-Zr-Nb alloy, with good mechanical compatibility due to a modulus that is more close to that of human bones (E ≈ 50 GPa instead of 110 GPa in Ti-6Al-4V). Coating process was carried out in a 10×-concentrated simulated body fluid (SBF)—synthetic analog of human body plasma. The effect of oxidized and carboxylated alloy surface on formation of biomimetic hydroxyapatite has been studied. By XRD, we found influence of thermal conditions on HA crystal formation and size. SEM images and Fourier transform infrared confirmed that hydroxyapatite with different morphology, crystallinity, and Ca/P ratio formed on metallic surfaces. X-ray photoelectron spectroscopy showed that in the Ti-6AL-4V sample the observed Ca/P ratio reach 0.97, whereas in the Ti-Zr-Nb sample the observed Ca/P ratio reach 1.15.

  17. Biomimetic Hydroxyapatite Growth on Functionalized Surfaces of Ti-6Al-4V and Ti-Zr-Nb Alloys.

    PubMed

    Pylypchuk, Ie V; Petranovskaya, A L; Gorbyk, P P; Korduban, A M; Markovsky, P E; Ivasishin, O M

    2015-12-01

    A biomimetic approach for coating titanium-containing alloys with hydroxyapatite (HA) is reported in the article. Two types of Ti-containing alloys were chosen as an object for coating: Ti-6Al-4V (recommended for orthopedic application) and a novel highly biocompatible Ti-Zr-Nb alloy, with good mechanical compatibility due to a modulus that is more close to that of human bones (E ≈ 50 GPa instead of 110 GPa in Ti-6Al-4V). Coating process was carried out in a 10×-concentrated simulated body fluid (SBF)-synthetic analog of human body plasma. The effect of oxidized and carboxylated alloy surface on formation of biomimetic hydroxyapatite has been studied. By XRD, we found influence of thermal conditions on HA crystal formation and size. SEM images and Fourier transform infrared confirmed that hydroxyapatite with different morphology, crystallinity, and Ca/P ratio formed on metallic surfaces. X-ray photoelectron spectroscopy showed that in the Ti-6AL-4V sample the observed Ca/P ratio reach 0.97, whereas in the Ti-Zr-Nb sample the observed Ca/P ratio reach 1.15. PMID:26297184

  18. Investigation of the HA film deposited on the porous Ti6Al4V alloy prepared via additive manufacturing

    NASA Astrophysics Data System (ADS)

    Surmeneva, M.; Chudinova, E.; Syrtanov, M.; Koptioug, A.; Surmenev, R.

    2015-11-01

    This study is focused on the use of radio frequency magnetron sputtering to modify the surface of porous Ti6Al4V alloy fabricated via additive manufacturing technology. The hydroxyapatite (HA) coated porous Ti6Al4V alloy was studied in respect with its chemical and phase composition, surface morphology, water contact angle and hysteresis, and surface free energy. Thin nanocrystalline HA film was deposited while its structure with diamond-shaped cells remained unchanged. Hysteresis and water contact angle measurements revealed an effect of the deposited HA films, namely an increased water contact angle and contact angle hysteresis. The increase of the contact angle of the coating-substrate system compared to the uncoated substrate was attributed to the multiscale structure of the resulted surfaces.

  19. Sustained load crack growth design data for Ti-6Al-4V titanium alloy tanks containing hydrazine

    NASA Technical Reports Server (NTRS)

    Lewis, J. C.; Kenny, J. T.

    1976-01-01

    Sustained load crack growth data for Ti-6Al-4V titanium alloy in hydrazine per MIL-P-26536 and refined hydrazine are presented. Fracture mechanics data on crack growth thresholds for heat-treated forgings, aged and unaged welds, and aged and unaged heat-affected zones are reported. Fracture mechanics design curves of crack growth threshold stress intensity versus temperature are generated from 40 to 71 C.

  20. Study on the Hot Processing Parameters-Impact Toughness Correlation of Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Shi, Xiaohui; Zeng, Weidong; Sun, Yu; Han, Yuanfei; Zhao, Yongqing

    2016-05-01

    In this research, the hot processing parameters-impact toughness correlation of Ti-6Al-4V titanium alloy is studied. Fifty-four groups of hot processing treatments with different forging temperatures (930, 950, 970 °C), deformation degrees (20, 50, 80%), annealing temperatures (600, 700, 800 °C), and annealing time (1 and 5 h) were conducted. The orthogonal design was used to find the primary hot processing parameters influencing the impact toughness of Ti-6Al-4V alloy. The results show that the annealing temperature can exert the biggest influence on impact toughness. Low annealing temperature is essential to achieve high impact toughness value. In addition, the BP neural network was used to describe the quantitative correlation between hot processing parameters and impact toughness. The results show that the BP neural network exhibits good performance in predicting the impact toughness of Ti-6Al-4V alloy. The prediction error is within 5%. The BP neural network and the orthogonal design method are mutually confirmed in the present work. Finally, based on the microstructure analysis, the reasons responsible for above experimental results are explained.

  1. Study on the Hot Processing Parameters-Impact Toughness Correlation of Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Shi, Xiaohui; Zeng, Weidong; Sun, Yu; Han, Yuanfei; Zhao, Yongqing

    2016-04-01

    In this research, the hot processing parameters-impact toughness correlation of Ti-6Al-4V titanium alloy is studied. Fifty-four groups of hot processing treatments with different forging temperatures (930, 950, 970 °C), deformation degrees (20, 50, 80%), annealing temperatures (600, 700, 800 °C), and annealing time (1 and 5 h) were conducted. The orthogonal design was used to find the primary hot processing parameters influencing the impact toughness of Ti-6Al-4V alloy. The results show that the annealing temperature can exert the biggest influence on impact toughness. Low annealing temperature is essential to achieve high impact toughness value. In addition, the BP neural network was used to describe the quantitative correlation between hot processing parameters and impact toughness. The results show that the BP neural network exhibits good performance in predicting the impact toughness of Ti-6Al-4V alloy. The prediction error is within 5%. The BP neural network and the orthogonal design method are mutually confirmed in the present work. Finally, based on the microstructure analysis, the reasons responsible for above experimental results are explained.

  2. The influence of temperature on fatigue crack growth in a mill annealed Ti-6Al-4V alloy.

    NASA Technical Reports Server (NTRS)

    Wei, R. P.; Ritter, D. L.

    1972-01-01

    To study the influence of temperature on the rate of fatigue crack growth in high strength metal alloys, constant load amplitude fatigue crack growth experiments were carried out using a .25-in.-thick mill annealed Ti-6Al-4V alloy plate. The rates of fatigue crack growth were determined as a function of temperature, ranging from room temperature to about 290 C, and as a function of the crack tip stress intensity factor in a dehumidified high purity argon environment. Limited correlative experiments were carried out in distilled water, dehumidified oxygen and hydrogen, and in vacuum. The results indicate that the rate of fatigue crack growth is essentially independent of test temperature in this alloy, and is affected by residual moisture in very small concentrations. Companion fractographic examinations suggest that the mechanims for fatigue crack growth in the various environments are essentially the same.

  3. Effects of cutting parameters on tool insert wear in end milling of titanium alloy Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Luo, Ming; Wang, Jing; Wu, Baohai; Zhang, Dinghua

    2016-06-01

    Titanium alloy is a kind of typical hard-to-cut material due to its low thermal conductivity and high strength at elevated temperatures, this contributes to the fast tool wear in the milling of titanium alloys. The influence of cutting conditions on tool wear has been focused on the turning process, and their influence on tool wear in milling process as well as the influence of tool wear on cutting force coefficients has not been investigated comprehensively. To fully understand the tool wear behavior in milling process with inserts, the influence of cutting parameters on tool wear in the milling of titanium alloys Ti6Al4V by using indexable cutters is investigated. The tool wear rate and trends under different feed per tooth, cutting speed, axial depth of cut and radial depth of cut are analyzed. The results show that the feed rate per tooth and the radial depth of cut have a large influence on tool wear in milling Ti6Al4V with coated insert. To reduce tool wear, cutting parameters for coated inserts under experimental cutting conditions are set as: feed rate per tooth less than 0.07 mm, radial depth of cut less than 1.0 mm, and cutting speed sets between 60 and 150 m/min. Investigation on the relationship between tool wear and cutting force coefficients shows that tangential edge constant increases with tool wear and cutter edge chipping can lead to a great variety of tangential cutting force coefficient. The proposed research provides the basic data for evaluating the machinability of milling Ti6Al4V alloy with coated inserts, and the recommend cutting parameters can be immediately applied in practical production.

  4. Surface modification of additive manufactured Ti6Al4V alloy with Ag nanoparticles: wettability and surface morphology study

    NASA Astrophysics Data System (ADS)

    Chudinova, E.; Surmeneva, M.; Koptioug, A.; Sharonova, A.; Loza, K.; Surmenev, R.

    2016-02-01

    In this work, the use of electrophoretic deposition to modify the surface of Ti6Al4V alloy fabricated via additive manufacturing technology is reported. Poly(vinylpyrrolidone) (PVP)-stabilized silver nanoparticles (AgNPs) had a spherical shape with a diameter of the metallic core of 100±20 nm and ζ -potential -15 mV. The AgNPs- coated Ti6Al4V alloy was studied in respect with its chemical composition and surface morphology, water contact angle, hysteresis, and surface free energy. The results of SEM microphotography analysis showed that the AgNPs were homogeneously distributed over the surface. Hysteresis and water contact angle measurements revealed the effect of the deposited AgNPs layer, namely an increased water contact angle and decreased contact angle hysteresis. However, the average water contact angle was 125° for PVP-stabilized-AgNPs-coated surface, whereas ethylene glycol gave the average contact angle of 17°. A higher surface energy is observed for AgNPs-coated Ti6Al4V surface (70.17 mN/m) compared with the uncoated surface (49.07 mN/m).

  5. Osseointegration of Ti6Al4V alloy implants coated with titanium nitride by a new method.

    PubMed

    Sovak, G; Weiss, A; Gotman, I

    2000-03-01

    Coating titanium alloy implants with titanium nitride (TiN) by the method of Powder Immersion Reaction Assisted Coating (PIRAC) produces a stable layer on their surface. We have examined the ability of the new TiN coating to undergo osseointegration. We implanted TiN-coated and uncoated Ti6Al4V alloy pins into the femora of six-month-old female Wistar rats. SEM after two months showed a bone collar around both TiN-coated and uncoated implants. Morphometrical analysis revealed no significant differences between the percentage of the implant-bone contact and the area and volume of the bone around TiN-coated compared with uncoated implants. Electron-probe microanalysis indicated the presence of calcium and phosphorus at the implant-bone interface. Mineralisation around the implants was also confirmed by labelling with oxytetracycline. Strong activity of alkaline phosphatase and weak activity of tartrate-resistant acid phosphatase were shown histochemically. Very few macrophages were detected by the non-specific esterase reaction at the site of implantation. Our findings indicate good biocompatibility and bone-bonding properties of the new PIRAC TiN coatings which are comparable to those of uncoated Ti6Al4V alloy implants. PMID:10755443

  6. Electrochemical investigation of chromium oxide-coated Ti-6Al-4V and Co-Cr-Mo alloy substrates.

    PubMed

    Swaminathan, Viswanathan; Zeng, Haitong; Lawrynowicz, Daniel; Zhang, Zongtao; Gilbert, Jeremy L

    2011-08-01

    Hard coatings for articulating surfaces of total joint replacements may improve the overall wear resistance. However, any coating approach must take account of changes in corrosion behavior. This preliminary assessment analyzes the corrosion kinetics, impedance and mechanical-electrochemical stability of 100 μm thick plasma sprayed chromium oxide (Cr₂O₃) coatings on bearing surfaces in comparison to the native alloy oxide films on Co-Cr-Mo and Ti-6Al-6V. Cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, and mechanical abrasion under potentiostatic conditions were performed on coated and substrate surfaces in physiological saline. SEM analysis characterized the coating morphology. The results showed that the corrosion current density values of chromium oxide coatings (0.4-1.2 μA/cm²) were of the same order of magnitude as Ti-6Al-4V alloy. Mechanical abrasion did not increase corrosion rates of chromium oxide coatings but did for uncoated Co-Cr-Mo and Ti-6Al-4V. The impedance response of chromium oxide coatings was very different than Co-Cr-Mo and Ti-6Al-4V native oxides characterized by a defected coating model. More of a frequency-independent purely resistive response was seen in mid-frequency range for the coatings (CPE(coat) : 40-280 nF/cm² (rad/s)(1-α) , α: 0.67-0.83) whereas a more capacitive character is seen for Co-Cr-Mo and Ti-6Al-4V (CPE(ox) around 20 μF/cm² (rad/s)(1-α) , α around 0.9). Pores, interparticle gaps and incomplete fusion typical for thermal spray coatings were present in these oxides which could have influenced corrosion resistance. The coating microstructure could have allowed some fluid penetration. Overall, these coatings appear to have suitable corrosion properties for wear surfaces. PMID:21648063

  7. Effects of combined plasma chromizing and shot peening on the fatigue properties of a Ti6Al4V alloy

    NASA Astrophysics Data System (ADS)

    Yu, Shouming; Liu, Daoxin; Zhang, Xiaohua; Du, Dongxing

    2015-10-01

    A plasma chromizing treatment was conducted on Ti6Al4V samples by employing the recently developed double glow plasma surface alloying technology. The Cr-alloyed layer consisted of four sub-layers, namely the Cr deposition, Cr2Ti, CrTi4, and Cr-Ti solid-solution layers. The local hardness and moduli were determined via nanoindentation. In addition, the fatigue properties of the samples were evaluated by using a rotating-bending fatigue machine under a given load. The results showed that the hardness or elastic moduli of the adjacent sub-layers differed significantly and the fatigue properties of the Ti6Al4V alloy deteriorated with the plasma chromizing treatment. This deterioration stemmed mainly from cracks initiated at the interfaces between the sub-layers and the microstructural changes of the substrate; these changes were induced by the high temperature used in the plasma chromizing process. However, the fatigue life of the plasma-chromized samples was increased by a shot peening post-treatment. The fatigue life of the samples resulting from this combination of treatments was slightly higher than that of the single-shot-peened Ti6Al4V substrate. In fact, the sample retaining only the Cr-Ti solid-solution layer (that is, the first three sub-layers were removed), when shot-peened, exhibited the highest fatigue life among all the tested samples; this was attributed to that sample having the highest residual compressive stress, the significant work hardening, and the good hardness to toughness balance.

  8. Effect of cryogenic treatment on wear resistance of Ti-6Al-4V alloy for biomedical applications.

    PubMed

    Gu, Kaixuan; Wang, Junjie; Zhou, Yuan

    2014-02-01

    The effect of cryogenic treatment on wear resistance of Ti-6Al-4V alloy for biomedical applications was experimentally investigated in this paper. Cryogenic treatments with the same soaking time of 24h at different temperatures of -80°C, -140°C and -196°C were conducted and the treatments at the same temperature of -196°C were then further given different soaking time of 3h, 48h and 72h to be investigated. After cryogenic treatment, the Vickers hardness of specimens was measured. Wear resistance of Ti-6Al-4V alloy was measured by pin-on-disk wear test under dry sliding condition. The results demonstrated that the Vickers hardness increased slightly with the reduction of temperature while it increased obviously with the elongation of soaking time at -196°C. The friction coefficients of specimens cryo-treated at -196°C were lower than those of untreated and of cryo-treated at -80°C and -140°C. And the longer the soaking time is during the cryogenic treatment, the higher the friction coefficient reduction can be achieved. The obvious reduction of mass loss can be obtained at -196°C with 72h soaking. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to detect the microstructure and worn surface of specimens. By cryogenic treatment, the plowing in the worn surface was smoothed and shallowed, and the degree of plastic deformation in the subsurface was decreased. There was no obvious phase transformation which can be detected in the microstructure after cryogenic treatment. However, the tendency of refinement in grain size can be detected by XRD which improved the wear resistance of Ti-6Al-4V alloy. PMID:24287307

  9. Tribocorrosion mechanisms of Ti6Al4V biomedical alloys in artificial saliva with different pHs

    NASA Astrophysics Data System (ADS)

    Licausi, M. P.; Igual Muñoz, A.; Amigó Borrás, V.

    2013-10-01

    Titanium and its alloys has been widely used for the design of dental implants because of its biocompatibility, mechanical properties and corrosion resistance. The powder-metallurgy process is a promising alternative to the casting fabrication process of titanium alloys for bone implants design as the porous structure mimics the natural bone structures, allowing the bone to grow into the pores which results in a better fixation of the artificial implant. However, under in vivo conditions the implants are subjected to tribocorrosion phenomenon, which consists in the degradation mechanisms due to the combined effect of wear and corrosion. The aim of this study is to evaluate the tribocorrosion behaviour of cast and sintered Ti6Al4V biomedical alloy for dental applications using the cast material as reference. Titanium samples were tested in artificial human saliva solution with three different pHs (3, 6, 9) and in an acidic saliva with 1000 ppm fluorides (AS-3-1000F-) by different electrochemical techniques (potentiodynamic curves, potentiostatic tests and tribo-electrochemical tests). Cast and sintered titanium alloys exhibit the same tribocorrosion mechanisms in AS independently of the pH which consists in plastic deformation with passive dissolution, but the addition of fluorides to the acidified solution changes the degradation mechanism towards active dissolution of the titanium alloys.

  10. Observation of Etch-Pits and LAGB Configurations During Ambient Creep of Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Kumar, Jalaj; Singh, A. K.; Raman, S. Ganesh Sundara; Kumar, Vikas

    2016-06-01

    The present work describes the microstructural features of alloy Ti-6Al-4V during constant stress creep at ambient temperature. Samples tested at 800 and 900 MPa stress levels exhibit the presence of etch-pits and/or voids. The ambient creep strain increases with an increase in applied stress due to higher strain rate sensitivity at higher stresses. A high density of low-angle grain boundaries is noticed in and around etch-pits in the creep-tested specimens due to occurrence of slip. The inverse pole figure obtained by EBSD indicates prismatic texture as the main deformation component in the creep-tested specimens.

  11. Observation of Etch-Pits and LAGB Configurations During Ambient Creep of Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Kumar, Jalaj; Singh, A. K.; Raman, S. Ganesh Sundara; Kumar, Vikas

    2016-03-01

    The present work describes the microstructural features of alloy Ti-6Al-4V during constant stress creep at ambient temperature. Samples tested at 800 and 900 MPa stress levels exhibit the presence of etch-pits and/or voids. The ambient creep strain increases with an increase in applied stress due to higher strain rate sensitivity at higher stresses. A high density of low-angle grain boundaries is noticed in and around etch-pits in the creep-tested specimens due to occurrence of slip. The inverse pole figure obtained by EBSD indicates prismatic texture as the main deformation component in the creep-tested specimens.

  12. Crack-closure and crack-growth measurements in surface-flawed titanium alloy Ti6Al-4V

    NASA Technical Reports Server (NTRS)

    Elber, W.

    1975-01-01

    The crack-closure and crack-growth characteristics of the titanium alloy Ti-6Al-4V were determined experimentally on surface-flawed plate specimens. Under cyclic loading from zero to tension, cracks deeper than 1 mm opened at approximately 50 percent of the maximum load. Cracks shallower than 1 mm opened at higher loads. The correlation between crack-growth rate and the total stress-intensity range showed a lower threshold behavior. This behavior was attributed to the high crack-opening loads at short cracks because the lower threshold was much less evident in correlations between the crack-growth rates and the effective stress-intensity range.

  13. The influence of temperature on fatigue-crack growth in a mill-annealed Ti-6Al-4V alloy

    NASA Technical Reports Server (NTRS)

    Wei, R. P.; Ritter, D. L.

    1971-01-01

    To understand the influence of temperature on the rate of fatigue crack growth in high strength metal alloys, constant load amplitude fatigue crack growth experiments were carried out using a 1/4 inch thick (6.35 mm) mill-annealed Ti-6Al-4V alloy plate as a model material. The rates of fatigue crack growth were determined as a function of temperature, ranging from room temperature to about 290 C and as a function of the crack tip, stress intensity factor K, in dehumidified high purity argon environment. The dependence of the rate of fatigue crack growth on K appears to be separable into two regions. The transition correlates with changes in both the microscopic and macroscopic appearances of the fracture surfaces, and suggests a change in the mechanism and the influence of microstructure on fatigue crack growth.

  14. Mechanism of surface modification of the Ti-6Al-4V alloy using a gas tungsten arc heat source

    SciTech Connect

    Labudovic, M.; Kovacevic, R.; Kmecko, I.; Khan, T.I.; Blecic, D.; Blecic, Z.

    1999-06-01

    The surface modification of a Ti-6Al-4V alloy using a gas tungsten arc, as a heat source, was studied. The experimental results show that the titanium alloy surface can be melted and nitrided using pure nitrogen or a nitrogen/argon mixture shielding atmosphere. The resolidified surfaces are 0.9 to 1.2-mm thick and contain titanium nitride dendrites, {alpha}-titanium, and {alpha}{double_prime}-titanium (martensite). The average dendrite arm spacing is influenced by the electrode speed. Small titanium nitride dendrites are homogeneously distributed in the resolidified surfaces. The microstructure and phase constitution in the resolidified surfaces were determined and analyzed, and the mechanism of the formation of titanium nitrides is discussed. The results show that the nitriding kinetics obey parabolic laws and are, therefore, controlled by nitrogen diffusion. The nitrogen-concentration depth profiles, calculated using Fick`s second law of diffusion, are compared to experimental nitrogen depth profiles, showing satisfactory agreement.

  15. Effects of hydrogen on ELI titanium alloy Ti-5Al-2.5Sn

    NASA Technical Reports Server (NTRS)

    Chandler, W. T.; Hensley, W. E.

    1970-01-01

    Tensile tests on titanium alloy, following abrasion under hydrogen and temperature cycling, reveal lowered tensile strength, increased ductility, and no embrittlement. Fretting the metal on itself in flowing hydrogen or abrading with an iron file in flowing hydrogen produces titanium hydride.

  16. Compressive mechanical compatibility of anisotropic porous Ti6Al4V alloys in the range of physiological strain rate for cortical bone implant applications.

    PubMed

    Li, Fuping; Li, Jinshan; Kou, Hongchao; Huang, Tingting; Zhou, Lian

    2015-09-01

    Porous titanium and its alloys are believed to be promising materials for bone implant applications, since they can reduce the "stress shielding" effect by tailoring porosity and improve fixation of implant through bone ingrowth. In the present work, porous Ti6Al4V alloys for biomedical application were fabricated by diffusion bonding of alloy meshes. Compressive mechanical behavior and compatibility in the range of physiological strain rate were studied under quasi-static and dynamic conditions. The results show that porous Ti6Al4V alloys possess anisotropic structure with elongated pores in the out-of-plane direction. For porous Ti6Al4V alloys with 60-70 % porosity, more than 40 % pores are in the range of 200-500 μm which is the optimum pore size suited for bone ingrowth. Quasi-static Young's modulus and yield stress of porous Ti6Al4V alloys with 30-70 % relative density are in the range of 6-40 GPa and 100-500 MPa, respectively. Quasi-static compressive properties can be quantitatively tailored by porosity to match those of cortical bone. Strain rate sensitivity of porous Ti6Al4V alloys is related to porosity. Porous Ti6Al4V alloys with porosity higher than 50 % show enhanced strain rate sensitivity, which is originated from that of base materials and micro-inertia effect. Porous Ti6Al4V alloys with 60-70 % porosity show superior compressive mechanical compatibility in the range of physiological strain rate for cortical bone implant applications. PMID:26384823

  17. Improved wear resistance of functional diamond like carbon coated Ti-6Al-4V alloys in an edge loading conditions.

    PubMed

    Choudhury, Dipankar; Lackner, Jürgen M; Major, Lukasz; Morita, Takehiro; Sawae, Yoshinori; Bin Mamat, Azuddin; Stavness, Ian; Roy, Chanchal K; Krupka, Ivan

    2016-06-01

    This study investigates the durability of functional diamond-like carbon (DLC) coated titanium alloy (Ti-6Al-4V) under edge loading conditions for application in artificial hip joints. The multilayered (ML) functional DLC coatings consist of three key layers, each of these layers were designed for specific functions such as increasing fracture strength, adapting stress generation and enhancing wear resistance. A 'ball-on-disk' multi-directional wear tester was used in the durability test. Prior to the wear testing, surface hardness, modulus elasticity and Raman intensity were measured. The results revealed a significant wear reduction to the DLC coated Ti-6Al-4V disks compared to that of non-coated Ti-6Al-4V disks. Remarkably, the counterpart Silicon Nitride (Si3N4) balls also yielded lowered specific wear rate while rubbed against the coated disks. Hence, the pairing of a functional multilayered DLC and Si3N4 could be a potential candidate to orthopedics implants, which would perform a longer life-cycle against wear caused by edge loading. PMID:27085502

  18. A novel constitutive model for hot deformation behaviors of Ti-6Al-4V alloy based on probabilistic method

    NASA Astrophysics Data System (ADS)

    Lin, Y. C.; Zhao, Chun-Yang; Chen, Ming-Song; Chen, Dong-Dong

    2016-08-01

    The flow behaviors of Ti-6Al-4V alloy are studied by isothermal compressive experiments at the deformation temperature from 850 to 950 °C and strain rate from 0.001 to 1 s-1. To analyze the uncertainties induced by material itself and testing procedure, repetitive compressive tests are conducted under each experimental condition. It is found that the uncertainties of flow behaviors are too great to be ignored. The innovation of the study is that the probability theory is introduced to model flow behaviors. 312 (=531,441) sets of flow curves are created by the resampling method, in which 10,000 sets are used to determine the material parameters of constitutive equations. Therefore, the probability densities of material parameters can be easily obtained. It is found that the probability density functions of the most material parameters are similar to the normal distribution. The values of material parameters with the maximum probability density are selected for the established constitutive model. The advantage of the established constitutive model is that it can describe the most probable flow characteristics of Ti-6Al-4V alloy.

  19. Strain localization during tensile Hopkinson bar testing of commercially pure titanium and Ti6Al4V titanium alloy

    NASA Astrophysics Data System (ADS)

    Moćko, Wojciech; Kruszka, Leopold; Brodecki, Adam

    2015-09-01

    The goal of the analysis was to determine the strain localization for various specimen shapes (type A and type B according to PN-EN ISO 26203-1 standard) and different loading conditions, i.e. quasi- static and dynamic. Commercially pure titanium (Grade 2) and titanium alloy Ti6Al4V (Grade 5) were selected for the tests. Tensile loadings were applied out using servo-hydraulic testing machine and tensile Hopkinson bar with pre-tension. The results were recorded using ARAMIS system cameras and fast camera Phantom V1210, respectively at quasi-static and dynamic loading conditions. Further, specimens outline was determined on the basis of video data using TEMA MOTION software. The strain distribution on the specimen surface was estimated using digital image correlation method. The larger radius present in the specimen of type B in comparison to specimen of type A, results in slight increase of the elongation for commercially pure titanium at both quasi-static and dynamic loading conditions. However this effect disappears for Ti6Al4V alloy. The increase of the elongation corresponds to the stronger necking effect. Material softening due to increase of temperature induced by plastic work was observed at dynamic loading conditions. Moreover lower elongation at fracture point was found at high strain rates for both materials.

  20. FEM Simulation and Experimental Validation of LBW Under Conduction Regime of Ti6Al4V Alloy

    NASA Astrophysics Data System (ADS)

    Churiaque, C.; Amaya-Vazquez, M. R.; Botana, F. J.; Sánchez-Amaya, J. M.

    2016-07-01

    Laser Beam Welding (LBW) is an advanced process to join materials with a laser beam of high energy density. LBW is especially suitable to join titanium alloys, as it allows high localization and low size of the melting pool, reducing considerably the energy of the process, in comparison with other welding technologies. Among the two widely known welding regimes, conduction and keyhole, the former is claimed to be a viable alternative to keyhole, mainly because it is a very stable process, provides high-quality welds free of defects, and involves lower laser cost. In the present work, a Finite Element Method (FEM) has been developed to simulate the LBW of Ti6Al4V alloy under conduction regime. The "Goldak double ellipsoid model" has been taken for the first time to simulate this LBW conduction process. In order to refine and validate the model, experimental conduction welding tests were performed on Ti6Al4V pieces with a high-power diode laser. Microstructural analyses and hardness measurements were also performed on the laser weld beads to identify the generated phases. Distortion and residual stresses were also obtained from the FEM simulations. An excellent agreement between the simulation and experimental results was found regarding the bead morphology and phase transformations.

  1. Sustained load crack growth design data for Ti-6Al-4V titanium alloy tanks containing hydrazine

    NASA Technical Reports Server (NTRS)

    Lewis, J. C.; Kenny, J. T.

    1976-01-01

    Results are presented for an experimental study intended to provide sustained load crack growth (SLCG) data for Ti-6Al-4V titanium alloy tanks containing MIL-P-26536 hydrazine and refined hydrazine. Fracture mechanics data on crack growth threshold for heat-treated forgings, aged and unaged welds, and aged and unaged heat-affected zones (HAZ) are presented. All tests were made on uniaxially loaded fracture mechanics specimens involving part-through cracks, and an electrical discharge machined notch was used to start the crack. Fracture mechanics design curves of crack growth threshold stress intensity versus temperature are obtained for the temperature range 40-71 C. Major conclusions are that extreme susceptibility to SLCG in hydrazine is a universal property of unaged weld metal in Ti-6Al-4V titanium alloy of normal interstitial content, and that aging both weld metal and HAZ at 510 C for 4 hr after welding completely removes all susceptibility to SLCG induced by hydrazine, with less susceptibility to SLCG in refined hydrazine.

  2. Further Investigation Into the Use of Laser Surface Preparation of Ti-6Al-4V Alloy for Adhesive Bonding

    NASA Technical Reports Server (NTRS)

    Palmieri, Frank L.; Crow, Allison; Zetterberg, Anna; Hopkins, John; Wohl, Christopher J.; Connell, John W.; Belcher, Tony; Blohowiak, Kay Y.

    2014-01-01

    Adhesive bonding offers many advantages over mechanical fastening, but requires robust materials and processing methodologies before it can be incorporated in primary structures for aerospace applications. Surface preparation is widely recognized as one of the key steps to producing robust and predictable bonds. This report documents an ongoing investigation of a surface preparation technique based on Nd:YAG laser ablation as a replacement for the chemical etch and/or abrasive processes currently applied to Ti-6Al-4V alloys. Laser ablation imparts both topographical and chemical changes to a surface that can lead to increased bond durability. A laser based process provides an alternative to chemical-immersion, manual abrasion, and grit blast process steps which are expensive, hazardous, environmentally unfriendly, and less precise. In addition, laser ablation is amenable to process automation, which can improve reproducibility to meet quality standards for surface preparation. An update on work involving adhesive property testing, surface characterization, surface stability, and the effect of laser surface treatment on fatigue behavior is presented. Based on the tests conducted, laser surface treatment is a viable replacement for the immersion chemical surface treatment processes. Testing also showed that the fatigue behavior of the Ti-6Al-4V alloy is comparable for surfaces treated with either laser ablation or chemical surface treatment.

  3. The comparison of phosphate-titanate-silicate layers on the titanium and Ti6Al4V alloy base.

    PubMed

    Rokita, M

    2011-08-15

    The studied layers were composed of two parts: titanate-silicate underlayer for better adhesion and titanate-phosphate-silicate layers for potential bioparameters. The layers with different amounts of hydroxyapatite were deposited on titanium and Ti6Al4V alloy substrates using dipping sol-gel method and electrophoresis. The selection of sol/suspension composition, deposition time and heat treatment conditions have the decisive influence on the layers parameters. The obtained layers should be very thin and almost amorphous. The specific nature of ceramic layers on the metal substrates excludes the use of some measurements methods or makes it difficult to interpret the measurement results. All the obtained samples were compared using XRD analysis data (GID technique), SEM with EDX measurements and FTIR spectroscopy (transmission and reflection techniques) before and after soaking in simulated body fluid. FTIR spectroscopy with mathematical treatment of the spectra (BIO-RAD Win-IR program, Arithmetic-subtract function) was used to detect the increase or decrease of any phosphate phases during SBF soaking. Based on the FTIR results the processes of hydroxyapatite (HAp) growth or layer dissolution were estimated. The layers deposited on titanium substrate are more crystalline then the ones deposited on Ti6Al4V. During SBF soaking process the growth of small amount of microcrystalline carbonate hydroxyapatite was observed on titanium substrate. The layer on Ti6Al4V base contained amorphous carbonate apatite. During heating treatment above about 870-920 K this apatite transforms into carbonate hydroxyapatite. The Ti6Al4V substrate seems to be more advantageous in context of potentially bioactive materials obtaining. PMID:20864390

  4. Microstructural characterisation of nanocomposite nc-MeC/a-C coatings on oxygen hardened Ti-6Al-4V alloy

    SciTech Connect

    Moskalewicz, T.; Wendler, B.; Czyrska-Filemonowicz, A.

    2010-10-15

    Nanocomposite coatings are novel, important systems composed of two or more nanocrystalline, or nanocrystalline and amorphous, phases. Such coatings offer a possibility of tailoring the coating microstructure and achieving new improved properties of coated materials. In this work a duplex surface treatment, consisting of an oxygen diffusion treatment and deposition of low friction nanocomposite nc-MeC/a-C (Me = transition metal, Ti, W or Cr) coatings, was applied for improvement of the Ti-6Al-4V alloy properties. The coatings composed of nanocrystallites of transition metal carbides (TiC or Cr{sub x}C{sub y} or WC) embedded in hydrogen-free amorphous carbon (a-C) matrix were deposited onto the surface of an oxygen hardened Ti-6Al-4 V alloy substrate by means of a simple DC magnetron sputtering. A nano/microstructure of the substrate material and coatings has been examined by scanning- and transmission electron microscopy complemented with the results of X-ray diffraction analyses. It was found that the nanocomposite coatings are composed of different carbide nanocrystals (with sizes of a few nanometres) embedded in an amorphous carbon matrix. The results of qualitative and quantitative analyses of the nanocrystalline phase in the coatings with use of high-resolution transmission electron microscopy combined with image analysis are given in the paper. An effect of the nano/microstructure parameters of the coated alloy onto its micro-mechanical (nanohardness and Young's modulus) and tribological properties (wear resistance and friction coefficient) is discussed in the paper.

  5. Electrochemical behavior of 45S5 bioactive ceramic coating on Ti6Al4V alloy for dental applications

    NASA Astrophysics Data System (ADS)

    Machado López, M. M.; Espitia Cabrera, M. I.; Faure, J.; Contreras García, M. E.

    2016-04-01

    Titanium and its alloys are widely used as implant materials because of their mechanical properties and non-toxic behavior. Unfortunately, they are not bioinert, which means that they can release ions and can only fix the bone by mechanical anchorage, this can lead to the encapsulation of dense fibrous tissue in the body. The bone fixation is required in clinical conditions treated by orthopedic and dental medicine. The proposal is to coat metallic implants with bioactive materials to establish good interfacial bonds between the metal substrate and bone by increasing bioactivity. Bioactive glasses, ceramics specifically 45 S5 Bioglass, have drawn attention as a serious functional biomaterial because osseointegration capacity. The EPD method of bioglass gel precursor was proposed in the present work as a new method to obtain 45S5/Ti6A14V for dental applications. The coatings, were thermally treated at 700 and 800°C and presented the 45 S5 bioglass characteristic phases showing morphology and uniformity with no defects, quantification percentages by EDS of Si, Ca, Na, P and O elements in the coating scratched powders, showed a good proportional relationship demonstrating the obtention of the 45S5 bioglass. The corrosion tests were carried out in Hank's solution. By Tafel extrapolation, Ti6Al4V alloy showed good corrosion resistance in Hank's solution media, by the formation of a passivation layer on the metal surface, however, in the system 45S5/Ti6Al4V there was an increase in the corrosion resistance; icon-, Ecorr and corrosion rate decreased, the mass loss and the rate of release of ions, were lower in this system than in the titanium alloy without coating.

  6. Degradation of Ti-6Al-4V alloy under cyclic loading in a simulated body environment with cell culturing.

    PubMed

    Doi, Kotaro; Miyabe, Sayaka; Tsuchiya, Hiroaki; Fujimoto, Shinji

    2016-03-01

    The present study reports the corrosion fatigue of the Ti-6Al-4V alloy using cyclic deformation test in a simulated body fluid under cell culturing for the first time. Cyclic deformation tests were carried out using three types of specimens to reveal the effects of proteins and cells on the corrosion fatigue of the alloy. For the 1-day-immersed and 1-week-immersed specimens, tensile specimens were soaked in a simulated body fluid for 1 day and 1 week, respectively, before cyclic deformation test, whereas for the cell-cultured specimen, MC3T3-E1 osteoblast-like cells were seeded and then cultured on tensile specimens for 1 week. The incubation period for crack initiation was longer for the cell-cultured and 1-week-immersed specimens compared to that for the 1-day-immersed specimen. On the other hand, crack propagation period for the cell-cultured and 1-week-immersed specimens was shorter than that for the 1-day-immersed specimen. These results indicate that proteins and cells adhered on the alloy surface inhibit metal dissolution at newly created surface emerged by cyclic deformation to suppress crack initiation, whereas they accelerate crack propagation because dissolution at crack tip is accelerated in the occluded space formed under proteins and cells. PMID:26651063

  7. Electrochemical Evaluation of Nanocrystalline Diamond Thin Films on Ti-6Al-4V Implant Alloy

    NASA Astrophysics Data System (ADS)

    Fries, Marc; Venugopalan, Ramakrishna; Vohra, Yogesh

    2002-03-01

    Some 186,000 hip replacement surgeries are peformed every year in the United States alone. About 10surgeries are revision operations to replace an implant that has most likely failed through mechanical-electrochemical interactions resulting in implant wear. The ability to enhance the resistance to such mechanical-electrochemical interaction and thereby reduce wear could result in significantly increased device lifespan. Nanocrystalline diamond (NCD) thin films were deposited on Ti-6Al-4V disk samples (processed per ASTM F86 standard for medical implant surface conditions) using microwave plasma chemical vapor deposition (MPCVD). As a first step, these samples (n=3/test per group) were subjected to electrochemical evaluation in inorganic neutral salt solution at 37 C. The electrochemical evaluation involved both impedence spectroscopy (per ASTM G106) and polarization testing (per ASTM G5). The impedence spectroscopy data indicated a significantly higher charge transfer resistance at the interface due to the protective NCD as compared to the bare or uncoated substrate. The polarization test data confirmed that this increased charge transfer resistance resulted in a decreased current density measurement. This decreased current density measurement resulted in an order of magnitude lower calculated static corrosion rate from the NCD coated samples as opposed to the uncoated controls. Future studies will focus on investigations that will facilitate transfer of these static electrochemical resistance results to a more relevant mechanical-electrochemical interaction milieu.

  8. Finite Element Simulation of Machining of Ti6Al4V Alloy

    SciTech Connect

    Rizzuti, S.; Umbrello, D.

    2011-05-04

    Titanium and its alloys are an important class of materials, especially for aerospace applications, due to their excellent combination of strength and fracture toughness as well as low density. However, these materials are generally regarded as difficult to machine because of their low thermal conductivity and high chemical reactivity with cutting tool materials. Moreover, the low thermal conductivity of Titanium inhibits dissipation of heat within the workpiece causing an higher temperature at the cutting edge and generating for higher cutting speed a rapid chipping at the cutting edge which leads to catastrophic failure. In addition, chip morphology significantly influences the thermo-mechanical behaviour at the workpiece/tool interface, which also affects the tool life.In this paper a finite element analysis of machining of TiAl6V4 is presented. In particular, cutting force, chip morphology and segmentation are taken into account due to their predominant roles to determine machinability and tool wear during the machining of these alloys. Results in terms of residual stresses are also presented. Moreover, the numerical results are compared with experimental ones.

  9. Ultrafine Grain Formation in a Ti-6Al-4V Alloy by Thermomechanical Processing of a Martensitic Microstructure

    NASA Astrophysics Data System (ADS)

    Chao, Qi; Hodgson, Peter D.; Beladi, Hossein

    2014-05-01

    In the current study, ultrafine equiaxed grains with a size of 150 to 800 nm were successfully produced in a Ti-6Al-4V alloy through thermomechanical processing of a martensitic starting microstructure. This was achieved through a novel mechanism of grain refinement consisting of several concurrent processes. This involves the development of substructure in the lath interiors at an early stage of deformation, which progressed into small high-angle segments with increasing strain. Consequently, the microstructure was gradually transformed to an equiaxed ultrafine grained structure, mostly surrounded by high-angle grain boundaries, through continuous dynamic recrystallization. Simultaneously, the supersaturated martensite was decomposed during deformation, leading to the progressive formation of beta phase, mainly nucleated on the intervariant lath boundaries.

  10. Effect of n-implantation on the corrosive-wear properties of surgical Ti-6Al-4V alloy

    SciTech Connect

    Williams, J.M.; Beardsley, G.M.; Buchanan, R.A.; Bacon, R.K.

    1984-01-01

    The effects of N-ion implantation on the corrosive-wear properties of Ti-6Al-4V, an alloy used for construction of the femoral component of artificial hip joints in humans, were tested. In corrosive-wear tests designed to simulate pertinent hip-joint parameters, electrochemical corrosion currents were measured for cylindrical samples in saline electrolyte in an arrangement which allowed the samples to be rotated between loaded polyethylene pads simultaneously with the current measurement. To further quantify material removal, Zr markers were ion-implanted into some samples so that, by use of Rutherford backscattering, material removal could be detected by changes in position of the marker relative to the surface. Corrosion currents were greatly reduced by implantation of approximately 20 at. % N, but even implantation of the Zr markers also reduced corrosion currents. The marker experiments confirmed the low rate of material removal for the implanted samples. 10 references, 5 figures, 1 table.

  11. Formation mechanism of linear friction welded Ti-6Al-4V alloy joint based on microstructure observation

    SciTech Connect

    Ma Tiejun; Chen Tao Li Wenya; Wang Shiwei; Yang Siqian

    2011-01-15

    The microstructure of the linear friction welded Ti-6Al-4V titanium alloy joint was investigated by optical microscope, scanning electronic microscope and transmission electron microscope. Results show that the dynamic recovery and recrystallization resulting from the intensive plastic deformation and fast heating and cooling processes during linear friction welding account for the superfine {alpha} + {beta} grains in the weld center. Fine {alpha} grains distribute in the {beta} matrix or at the boundaries of {beta} grains. A mass of dislocations networks and metastructures present within the {alpha} and {beta} grains. - Research Highlights: {yields} TEM is employed in the analysis. {yields} The dynamic recovery is the main mechanism in thermal deformation of TC4. {yields} Superfine grains in the weld result from dynamic recovery and dynamic recrystallizaion, but the recrystallization is inadequate.

  12. Preparation, corrosion resistance and hemocompatibility of the superhydrophobic TiO2 coatings on biomedical Ti-6Al-4V alloys

    NASA Astrophysics Data System (ADS)

    Jiang, J. Y.; Xu, J. L.; Liu, Z. H.; Deng, L.; Sun, B.; Liu, S. D.; Wang, L.; Liu, H. Y.

    2015-08-01

    In this paper the micro-arc oxidation (MAO) technique and subsequent superhydrophobic treatment were applied to fabricate the superhydrophobic TiO2 coatings on biomedical Ti-6Al-4V alloys. The surface morphology, surface roughness, water contact angle, corrosion resistance and hemocompatibility of the MAO and superhydrophobic samples were investigated. The results showed that the single anatase TiO2 coating was formed on the surface Ti-6Al-4V alloy with rough and porous micrometer-scale structure. The low surface energy film was grafted on the surface of the TiO2 coating by self-assembling reaction during the hydrophobic treatment process, which resulted in the formation of superhydrophobic surfaces with the water contact angle of 153.39°. It was found that the corrosion resistance of the superhydrophobic samples increased by one order of magnitude compared to those of the uncoated Ti-6Al-4V alloys. The hemolysis ratio and platelets adhesion characteristics of the Ti-6Al-4V alloys were also improved greatly through the MAO treatment and subsequent superhydrophobic treatment. Especially, no platelet could be observed on the surface of the superhydrophobic samples. Therefore, the superhydrophobic TiO2 coatings of Ti-6Al-4V alloys with higher hemocompatibility would show great promise in their potential blood-contacting applications.

  13. Corrosion kinetics and topography analysis of Ti-6Al-4V alloy subjected to different mouthwash solutions.

    PubMed

    Faverani, Leonardo Perez; Barao, Valentim Adelino Ricardo; Pires, Maria Flávia Araújo; Yuan, Judy Chia-Chun; Sukotjo, Cortino; Mathew, Mathew T; Assunção, Wirley Gonçalves

    2014-10-01

    This study evaluated the corrosion kinetics and surface topography of Ti-6Al-4V alloy exposed to mouthwash solutions (0.12% chlorhexidine digluconate, 0.053% cetylpyridinium chloride and 3% hydrogen peroxide) compared to artificial saliva (pH6.5) (control). Twenty Ti-6Al-4V alloy disks were used and divided into 4 groups (n=5). For the electrochemical assay, standard tests as open circuit potential and electrochemical impedance spectroscopy (EIS) were applied at baseline, 7 and 14days after immersion in the solutions. Scanning electron microscopy, atomic force microscopy and profilometry (average roughness - Ra) were used for surface characterization. Total weight loss of disks was calculated. Data were analyzed by ANOVA and Bonferroni's test (α=0.05). Hydrogen peroxide generated the lowest polarization resistance (Rp) values for all periods (P<0.05). For the capacitance (Cdl), similar results were observed among groups at baseline (P=0.098). For the 7 and 14-day periods, hydrogen peroxide promoted the highest Cdl values (P<0.0001). Hydrogen peroxide promoted expressive superficial changes and greater Ra values than the others (P<0.0001). It could be concluded that solutions containing cetylpyridinium chloride and chlorhexidine digluconate might be the mouthwashes of choice during the post-operatory period of dental implants. However, hydrogen peroxide is counter-indicated in these situations. Further studies evaluating the dynamics of these solutions (tribocorrosion) and immersing the disks in daily cycles (two or three times a day) to mimic a clinical situation closest to the application of mouthwashes in the oral cavity are warranted to prove our results. PMID:25175181

  14. Effect of heat treatment on microstructures and mechanical properties of a Ti-6Al-4V alloy rod prepared by powder compact extrusion

    NASA Astrophysics Data System (ADS)

    Yang, Fei; Gabbitas, Brian

    2015-03-01

    In this paper, Ti-6Al-4V alloy rods were manufactured by the powder compact extrusion of a powder mixture of hydride-dehydride (HDH) titanium powder, elemental aluminum powder and master alloy powder. Extrusions were carried out at 1300°C and with a holding time of 5 min in an argon atmosphere. The effects of different heat treatments (HT1: 960°C/1 h, water quenching, HT2: 960°C/1 h, water quenching + 500°C/6 h, air cooling, HT3: 850°C/2 h, furnace cooling to 540°C, then air cooling) on the microstructure and mechanical properties of as-extruded Ti-6Al-4V alloy rods were investigated. The results showed that a homogeneous microstructure, composed of a lamellar structure with a grain size range of 40-60 μm, was produced by powder compact extrusion of a powder mixture. The mechanical properties achieved were an ultimate tensile strength (UTS) of 1254 MPa, a yield strength (YS) of 1216 MPa and 8% ductility. After quenching at 960°C and with a holding time of 1 h, the UTS and YS of the heat treated Ti-6Al-4V alloy rod were increased to 1324 MPa and 1290 MPa, and the ductility was increased to 12%. After HT2, the UTS and YS of the heat treated Ti-6Al-4V alloy rod were significantly increased to 1436 MPa and 1400 MPa, but the ductility decreased to 4%. After HT3, the mechanical properties of the heat treated Ti-6Al-4V alloy rod were slightly decreased to give a UTS of 1213 MPa and a YS of 1180 MPa, with an increase in ductility to 11%. The microstructural changes of as-extruded Ti-6Al-4V alloy rods were also investigated for the different heat treatments.

  15. Sol gel derived hydroxyapatite coatings on titanium and its alloy Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Stoch, A.; Jastrzebski, W.; Długoń, E.; Lejda, W.; Trybalska, B.; Stoch, G. J.; Adamczyk, A.

    2005-06-01

    Titanium has been used for many medical and dental applications; however, its joining to a living bone is not satisfactorily good or the implant integration with bone tissue takes several months.The aim of this work is to produce hydroxyapatite (HAP) coatings on titanium and its alloy for facilitating and shortening the processes towards osseointegration. HAP coatings were obtained by sol-gel method with sol solutions prepared from calcium nitrate tetrahydrate and triammonium phosphate trihydrate as the calcium and phosphorous sources. Two types of gelatine were added to the sol: agar-agar or animals gelatine. Both were found to enhance the formation and stability of amorphous HAP using soluble salts as the sources of calcium and phosphate. HAP coatings were deposited from HAP-GEL sol using dip-withdrawal technique, then the plates were dried and annealed at temperatures 460-750 °C. FTIR spectroscopy and XRD analysis were used to study the phase composition of phosphate coatings. Morphology and chemical analysis of HAP layers was performed using a scanning electron microscope equipped with an energy dispersive X-ray analyser (SEM+EDX). The biological activity of sol-gel phosphate coatings was observed during thermostatic held in simulated body fluid (SBF). It was found that chemical composition and structure of HAP coatings depends on pH and final thermal treatment of the layer.

  16. Preparation of conversion coating on Ti-6Al-4V alloy in mixed solution of phytic acid and ammonium fluoride through chemical modification

    NASA Astrophysics Data System (ADS)

    Li, Lanlan; He, Jian; Yang, Xu

    2016-05-01

    Conversion coatings on Ti-6Al-4V alloy was prepared through chemical modification in phytic acid and ammonium fluoride mixed solution. The influences of pH, time and the composition of solution on the microstructure of alloy surface were investigated. Scanning electron microscopy was used to observe the microstructure. The chemical composition of alloy surface before and after modification was investigated by energy dispersive X-ray spectroscopy. The results indicated that a conversion coating could be formed on the Ti-6Al-4V alloy in a mixed solution of phytic acid and ammonium fluoride, the growth and microstructure of the conversion coatings were critically dependent on the pH, time and concentration of phytic acid and ammonium fluoride. In 100 mg/ml phytic acid containing 125 mg/ml ammonium fluoride solution with a pH of 6, a compact conversion coating with the thickness of about 4.7 μm formed after 30 min immersion on Ti-6Al-4V alloy surface. The preliminary evaluation of bioactivity of conversion coating was performed by in vitro cell experiments. The results showed that this chemical modification method is a promising surface modification technique for Ti-6Al-4V alloy inplants.

  17. Study on Variants of Solution Treatment and Aging Cycle of Titanium Alloy Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Kumar, V. Anil; Chhangani, Sumit

    2016-04-01

    Ti6Al4V with two different chemical compositions, one rich and the other lean in α-stabilizer oxygen were selected to study the effect of quench severity during solution treatment and their aging response. These two coupons were taken from two differently processed wrought products viz. rolled ring and closed die forging. The coupons were then subjected to solution treatment followed by employing different cooling rates to vary the quench severity and different aging treatments by changing the aging temperature and time. The microstructure and mechanical properties thus obtained are correlated with respect to the heat treatment conditions. It is noted that there is a significant increase in strength of the alloy retaining the ductility when it is aged in the aging temperature regime of 550-650 °C and time of 8 h. Role of higher oxygen content is noted, which is more pronounced with higher severity of quench (by water quenching). Specimens representative of different heat treatment conditions were characterized using optical microscope, electron back-scattered diffraction, and electron microscope. The presence of martensitic (α') structure along with uniform distribution of fine primary α, secondary α precipitates and refined β-grains, twins in the microstructure helps in improving the strength of the material. Also, during high temperature aging of 700 °C, which incidentally falls in the range of annealing temperature of the alloy, overaging occurs which is similar to effect of annealing and hence retains the ductility as well.

  18. Fracture assessment for electron beam welded damage tolerant Ti-6Al-4V alloy by the FITNET procedure

    NASA Astrophysics Data System (ADS)

    Lu, Wei; Shi, Yaowu; Li, Xiaoyan; Lei, Yongping

    2013-09-01

    Fracture assessment of the cracked structures is essential to avoiding fracture failure. A number of fracture assessment procedures have been proposed for various steel structures. However, the studies about the application of available procedures for titanium alloy structures are scarcely reported. Fracture assessment for the electron beam(EB) welded thick-walled damage tolerant Ti-6Al-4V(TC4-DT) alloy is performed by the fitness-for-service(FFS) FITNET procedure. Uniaxial tensile tests and fracture assessment tests of the base metal and weld metal are carried out to obtain the input information of assessment. The standard options and advanced options of FITNET FFS procedure are used to the fracture assessment of the present material. Moreover, the predicted maximum loads of compact tensile specimen using FITNET FFS procedure are verified with the experimental data of fracture assessment tests. As a result, it is shown that the mechanical properties of weld metal are inhomogeneous along the weld depth. The mismatch ratio M is less than 10% at the weld top and middle, whereas more than 10% at the weld bottom. Failure assessment lines of standard options are close to that of advanced option, which means that the standard options are suitable for fracture assessment of the present welds. The accurate estimation of the maximum loads has been obtained by fracture assessment of standard options with error less than 6%. Furthermore, there are no potential advantages of applying higher options or mismatch options. Thus, the present welded joints can be treated as homogeneous material during the fracture assessment, and standard option 1 can be used to achieve accurate enough results. This research provides the engineering treatment methods for the fracture assessment of titanium alloy and its EB welds.

  19. Data Sheet Program and Mechanical Properties of Ti-5Al-2.5Sn ELI and Alloy 718 at Cryogenic Temperatures

    SciTech Connect

    Ogata, T.; Yuri, T.; Sumiyoshi, H.; Ono, Y.; Matsuoka, S.; Okita, K.

    2004-06-28

    In the development of Japan's self-developed H-IIA launch vehicle, it is important to sufficiently comprehend the properties of materials under conditions in which the materials are used in the system for its design and the improvement of its reliability. Through the process of failure analysis of the LE-7 engine of H-II No. 8 in 1999, detailed materials data and photographs of the fracture surface were required as reference data to determine in terms of fracture morphology and to analyze the fracture stress. A series of mechanical properties tests, such as tensile tests, impact tests, fracture toughness tests, and fatigue tests, on Ti-5Al-2.5Sn ELI and Alloy 718 at room temperature to 4K were mainly conducted by NIMS and NASDA. The obtained tensile and fracture toughness properties were a little bit smaller than those reported by NASA and NRIM, however, the fatigue properties were relatively lower than the data reported so far. Data resulting from the tests were reviewed in detail and published in the form of data sheets. This paper will introduce the data sheet program on space use materials and discuss an effect of microstructure of Ti-5Al-2.5Sn ELI and Alloy 718 on their mechanical properties at cryogenic temperatures.

  20. Data Sheet Program and Mechanical Properties of Ti-5Al-2.5Sn ELI and Alloy 718 at Cryogenic Temperatures

    NASA Astrophysics Data System (ADS)

    Ogata, T.; Yuri, T.; Sumiyoshi, H.; Ono, Y.; Matsuoka, S.; Okita, K.

    2004-06-01

    In the development of Japan's self-developed H-IIA launch vehicle, it is important to sufficiently comprehend the properties of materials under conditions in which the materials are used in the system for its design and the improvement of its reliability. Through the process of failure analysis of the LE-7 engine of H-II No. 8 in 1999, detailed materials data and photographs of the fracture surface were required as reference data to determine in terms of fracture morphology and to analyze the fracture stress. A series of mechanical properties tests, such as tensile tests, impact tests, fracture toughness tests, and fatigue tests, on Ti-5Al-2.5Sn ELI and Alloy 718 at room temperature to 4K were mainly conducted by NIMS and NASDA. The obtained tensile and fracture toughness properties were a little bit smaller than those reported by NASA and NRIM, however, the fatigue properties were relatively lower than the data reported so far. Data resulting from the tests were reviewed in detail and published in the form of data sheets. This paper will introduce the data sheet program on space use materials and discuss an effect of microstructure of Ti-5Al-2.5Sn ELI and Alloy 718 on their mechanical properties at cryogenic temperatures.

  1. Effect of laser power on the microstructural behaviour and strength of modified laser deposited Ti6Al4V+Cu alloy for medical application

    NASA Astrophysics Data System (ADS)

    Erinosho, Mutiu F.; Akinlabi, Esther T.

    2016-03-01

    The excellent biocompatibility property of Grade 5 titanium alloy has made its desirability largely increasing in the field of biomedical. The titanium alloy (Ti6Al4V) was modified with the addition of 3 weight percent (wt %) copper via a laser deposition process using the Ytterbium fiber laser with a wavelength of 1.047 μm. Therefore, this paper presents the effect of laser power on the microstructural behaviour and strength of the modified Ti6Al4V+Cu alloy. The laser powers were varied between 600 W and 1600 W respectively while all other parameters such as the scanning speed, powder flow rates and gas flow rates were kept constant. The melt pool and width of the deposited alloy increases as the laser power was increased. The α-lamella was observed to be finer at low laser power, and towards the fusion zone, Widmanstettan structures were fused and become smaller; and showing an evidence of α-martensite phases. The strength of the modified alloy was derived from the hardness values. The strength was observed to increase initially to a point as the laser power increases and afterwards decreased as the laser power was further increased. The improved Ti6Al4V+Cu alloy can be anticipated for biomedical application.

  2. Study of aging effects in a Ti-6AL-4V alloy with Widmanstätten and equiaxed microstructures by non-destructive means

    SciTech Connect

    Carreon, Hector; Ruiz, Alberto; Santoveña, Bayron

    2014-02-18

    When the Ti-6Al-4V alloy is over-aged at 500-600°C, nanometer-sized α{sub 2} (Ti{sub 3}Al) phases can be homogeneously precipitated inside α phases, thereby leading to the additional improvement of mechanical properties. The present study was concerned with the effects of over-aging on thermoelectric power (TEP) measurements in a Ti-6Al-4V alloy. Widmanstätten and equiaxed microstructures containing fine and agr{sub 2} (Ti{sub 3}Al) particles were obtaining by over-aging a Ti-6Al-4V alloy. Over-aging heat treatments were conducted at 515°C, 545°C and 575°C for different aging times. In order to find out the factors affecting the variation in the TEP, the over-aging samples were examined by optical microscopy (OM) and (SEM) scanning electron microscopy. In particular, we studied the behavior of the physical material property hardness, an important parameter of the Ti-6Al-4V alloy mechanical properties, with respect to the variation in the aging time and temperature. It was found that the TEP measurements reveal an increase in the magnitude of the absolute TEP value of the over-aged Widmanstätten and equiaxed microstructures with regards to the unaged condition for different aging times, with a somewhat higher value at 515°C.

  3. Study of aging effects in a Ti-6AL-4V alloy with Widmanstätten and equiaxed microstructures by non-destructive means

    NASA Astrophysics Data System (ADS)

    Carreon, Hector; Ruiz, Alberto; Santoveña, Bayron

    2014-02-01

    When the Ti-6Al-4V alloy is over-aged at 500-600°C, nanometer-sized α2 (Ti3Al) phases can be homogeneously precipitated inside α phases, thereby leading to the additional improvement of mechanical properties. The present study was concerned with the effects of over-aging on thermoelectric power (TEP) measurements in a Ti-6Al-4V alloy. Widmanstätten and equiaxed microstructures containing fine &agr2 (Ti3Al) particles were obtaining by over-aging a Ti-6Al-4V alloy. Over-aging heat treatments were conducted at 515°C, 545°C and 575°C for different aging times. In order to find out the factors affecting the variation in the TEP, the over-aging samples were examined by optical microscopy (OM) and (SEM) scanning electron microscopy. In particular, we studied the behavior of the physical material property hardness, an important parameter of the Ti-6Al-4V alloy mechanical properties, with respect to the variation in the aging time and temperature. It was found that the TEP measurements reveal an increase in the magnitude of the absolute TEP value of the over-aged Widmanstätten and equiaxed microstructures with regards to the unaged condition for different aging times, with a somewhat higher value at 515°C.

  4. Fatigue Performance of Powder Metallurgy (PM) Ti-6Al-4V Alloy: A Critical Analysis of Current Fatigue Data and Metallurgical Approaches for Improving Fatigue Strength

    NASA Astrophysics Data System (ADS)

    Cao, Fei; Ravi Chandran, K. S.

    2016-03-01

    A comprehensive assessment of fatigue performance of powder metallurgy (PM) Ti-6Al-4V alloy, manufactured using various powder-based processing approaches to-date, is performed in this work. The focus is on PM processes that use either blended element (BE) or pre-alloyed (PA) powder as feedstock. Porosity and the microstructure condition have been found to be the two most dominant material variables that control the fatigue strength. The evaluation reveals that the fatigue performance of PM Ti-6Al-4V, in the as-sintered state, is far lower than that in the wrought condition. This is largely caused by residual porosity, even if it is present in small amounts, or, by the coarse lamellar colony microstructure. The fatigue strength is significantly improved by the closure of pores, and it approaches the levels of wrought Ti-6Al-4V alloys, after hot-isostatic-pressing (HIPing). Further thermo-mechanical and heat treatments lead to additional increases in fatigue strength-in one case, a high fatigue strength level, exceeding that of the mill-annealed condition, was achieved. The work identifies the powder, process and microstructure improvements that are necessary for achieving high fatigue strength in powder metallurgical Ti-6Al-4V alloys in order for them to effectively compete with wrought forms. The present findings, gathered from the traditional titanium powder metallurgy, are also directly applicable to additively manufactured titanium, because of the similarities in pores, defects, and microstructures between the two manufacturing processes.

  5. Nanostructured Ti6Al4V alloy fabricated using modified alkali-heat treatment: Characterization and cell adhesion.

    PubMed

    Su, Yingmin; Komasa, Satoshi; Sekino, Tohru; Nishizaki, Hiroshi; Okazaki, Joji

    2016-02-01

    In order to optimize the creation of a nanostructured surface on Ti6Al4V titanium alloy, an alkali treatment was performed using a 10-M NaOH solution at various temperatures (30, 40, 50, and 60°C) so as to determine the optimal temperature. This was combined with subsequent heat treatments (200, 400, 600, and 800°C) in air. The effects of different temperatures for the latter treatments on the nanostructure surface and the initial cell adhesion were evaluated, and the optimal temperature of the alkali solution was found to be 30°C. Further, the nanotopography, surface chemistry, and surface roughness of the nanoporous structure were retained after heat treatments performed at 200, 400, and 600°C, and only the phase structure was altered. The amorphous sodium titanate phase, the content of which increased with increased heat-treatment temperature, may have played a role in promoting cell adhesion on the nanoporous surface. However, heat treatment at 800°C did not enhance the cell-surface attachment. Rather, the nanostructure degraded significantly with the reappearance of Al and V. PMID:26652415

  6. Effects of Recrystallization on Microstructure and Texture Evolution of Cold-Rolled Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Jiang, Haitao; Dong, Peng; Zeng, Shangwu; Wu, Bo

    2016-04-01

    The effects of recrystallization during annealing process on microstructure and texture evolution of cold-rolled Ti-6Al-4V alloy plates were investigated. The plates after cold rolling with a thickness reduction of 5, 10, and 15% were annealed under different conditions of 750 °C for 1 h, 800 °C for 1 h, and 800 °C for 1.5 h, respectively. It was found out that the recrystallization temperature decreased with increasing rolling reduction due to higher storage energy, while the extension of annealing time caused grain growth. For the cold-rolled plate with a reduction of 10%, the resulting microstructure showed more equal-axis grains after annealing at 800 °C for 1 h, among different conditions. Moreover, the XRD results showed that the cold-rolled plate composed mainly of {0001} <10-10> basal texture, {10-11} <1-210> and {01-12} <10-10> pyramidal textures, and {01-10} <10-10> prismatic texture, and that the weak {10-11} <1-210> texture was transformed to components {01-12} <10-10> and {01-10} <10-10>, which were expected to improve formability. Electron back-scattered diffraction results ascertained that two mechanisms, i.e., recrystallization sites of preferred orientations and favorable grain growth both played important roles in static recrystallization.

  7. Characterization of laser peening-induced effects on a biomedical Ti6Al4V alloy by thermoelectric means

    NASA Astrophysics Data System (ADS)

    Carreón, Hector; Barriuso, Sandra; Porro, Juan Antonio; González-Carrasco, Jose Luis; Ocaña, José Luis

    2014-12-01

    Laser peening has recently emerged as a useful technique to overcome detrimental effects associated with other well-known surface modification processes such as shot peening or grit blasting used in the biomedical field. It is worthwhile to notice that besides the primary residual stress effect, thermally induced effects might also cause subtle surface and subsurface microstructural changes that might influence corrosion resistance and fatigue strength of structural components. In this work, plates of Ti-6Al-4V alloy of 7 mm in thickness were modified by laser peening without using a sacrificial outer layer. Irradiation by a Q-switched Nd-YAG laser (9.4-ns pulse length) working at the fundamental 1064-nm wavelength at 2.8 J/pulse and with water as a confining medium was used. Laser pulses with a 1.5-mm diameter at an equivalent overlapping density of 5000 cm-2 were applied. Attempts to analyze the global-induced effects after laser peening were addressed by using the contacting and noncontacting thermoelectric power techniques.

  8. Self-assembled monolayers of alendronate on Ti6Al4V alloy surfaces enhance osteogenesis in mesenchymal stem cells

    NASA Astrophysics Data System (ADS)

    Rojo, Luis; Gharibi, Borzo; McLister, Robert; Meenan, Brian J.; Deb, Sanjukta

    2016-07-01

    Phosphonates have emerged as an alternative for functionalization of titanium surfaces by the formation of homogeneous self-assembled monolayers (SAMs) via Ti-O-P linkages. This study presents results from an investigation of the modification of Ti6Al4V alloy by chemisorption of osseoinductive alendronate using a simple, effective and clean methodology. The modified surfaces showed a tailored topography and surface chemistry as determined by SEM microscopy and RAMAN spectroscopy. X-ray photoelectron spectroscopy revealed that an effective mode of bonding is created between the metal oxide surface and the phosphate residue of alendronate, leading to formation of homogenous drug distribution along the surface. In-vitro studies showed that alendronate SAMs induce differentiation of hMSC to a bone cell phenotype and promote bone formation on modified surfaces. Here we show that this novel method for the preparation of functional coatings on titanium-based medical devices provides osseoinductive bioactive molecules to promote enhanced integration at the site of implantation.

  9. Adhesion study of thermoplastic polyimides with Ti-6Al-4V alloy and PEEK-graphite composites

    SciTech Connect

    Yoon Taeho.

    1991-01-01

    High glass transition (e.g. 360C) melt processable thermoplastic polyimide homopolymers and poly(imide-siloxane) segmented copolymers were prepared from a number of diamines and dianhydrides via solution imidization, polydimethylsilxane segment incorporation and molecular weight control with non-reactive phthalimide end-groups. The adhesive bond performance of these polyimides was investigated as a function of molecular weight, siloxane incorporation, residual solvent, test temperature, and polyimide structure via single-lap shear samples prepared from treated Ti-6Al-4V alloy adherends and compression-molded film adhesives of scrim-cloth adhesives. The adhesive bond strengths increased greatly with siloxane-segment incorporation at 10, 20 and 30 wt% and decreased slightly with total polymer molecular weight. As the test temperature was increased, adhesive bond strength increased, decreased or showed a maximum at some temperatures depending on the polyimide structure and siloxane content. The poly(imide-30% siloxane) segmented copolymer and a miscible poly(ether-imide) also demonstrated excellent adhesive bond strength with poly(arylene ether ketone) PEEK{reg sign}-graphite composites.

  10. Microstructural characterization of Ti-6Al-4V alloy subjected to the duplex SMAT/plasma nitriding.

    PubMed

    Pi, Y; Faure, J; Agoda-Tandjawa, G; Andreazza, C; Potiron, S; Levesque, A; Demangel, C; Retraint, D; Benhayoune, H

    2013-09-01

    In this study, microstructural characterization of Ti-6Al-4V alloy, subjected to the duplex surface mechanical attrition treatment (SMAT)/nitriding treatment, leading to improve its mechanical properties, was carried out through novel and original samples preparation methods. Instead of acid etching which is limited for morphological characterization by scanning electron microscopy (SEM), an original ion polishing method was developed. Moreover, for structural characterization by transmission electron microscopy (TEM), an ion milling method based with the use of two ions guns was also carried out for cross-section preparation. To demonstrate the efficiency of the two developed methods, morphological investigations were done by traditional SEM and field emission gun SEM. This was followed by structural investigations through selected area electron diffraction (SAED) coupled with TEM and X-ray diffraction techniques. The results demonstrated that ionic polishing allowed to reveal a variation of the microstructure according to the surface treatment that could not be observed by acid etching preparation. TEM associated to SAED and X-ray diffraction provided information regarding the nanostructure compositional changes induced by the duplex SMAT/nitriding process. PMID:23766242

  11. Behavior of surface and corner cracks subjected to tensile and bending loads in Ti-6Al-4V alloy

    NASA Technical Reports Server (NTRS)

    Forman, Royce G.; Mettu, Sambi R.

    1990-01-01

    The behavior of part-through flaws with regard to failure under monotonic loading and their growth under fatigue loading was studied experimentally and analytically. Comparisons are made of experimental values of toughness obtained using surface and corner cracked specimens with those obtained using standard test specimens, and also experimental growth cycles were compared with numerical predictions using the NASA/FLAGRO computer program. Tests were conducted on various types of surface and corner cracks under tensile and bending loads. Room temperature lab air provided the test environment. The material used in this study was the Ti-6Al-4V alloy in the solution treated and aged (STA) and stress relieved condition. Detailed tabulation of the fracture toughness data and results of life prediction using the NASA/FLAGRO program are presented. Fatigue crack growth rates for the part-through cracked specimens are compared with a base curve fitted from the data obtained using standard specimens. The fatigue loading used in the crack growth testing was constant-amplitude sinusoidal type.

  12. A Modified Johnson-Cook Constitutive Equation to Predict Hot Deformation Behavior of Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Cai, Jun; Wang, Kuaishe; Zhai, Peng; Li, Fuguo; Yang, Jie

    2014-09-01

    A modified Johnson-Cook constitutive equation of Ti-6Al-4V alloy is proposed based on hot compression tests performed in the temperature range of 1073-1323 K and strain rate 0.001-1 s-1. The experimental stress-strain data were employed to develop the modified Johnson-Cook constitutive equation of different phase regimes (α + β and β phase). The predicted flow stresses using the developed equation were compared with experimental data. Correlation coefficient (R) and average absolute relative error (AARE) were introduced to verify the validity of the constitutive equation. The values of R and AARE for α + β phase were 0.990 and 7.81%, respectively. And in β phase region, the values of R and AARE were 0.985 and 10.36%, respectively. Meanwhile, the accuracy, the number of material constants involved, and the computational time required of the constitutive equation were evaluated by comparing with a strain-compensated Arrhenius-type constitutive equation. The results indicate that accuracy of modified Johnson-Cook constitutive equation is higher than that of compensated Arrhenius-type model at α + β phase, while lower at single β phase region. Meanwhile, the time required for evaluating the material constants of modified Johnson-Cook constitutive equation is much shorter than that of the strain-compensated Arrhenius type ones.

  13. A Modified Johnson-Cook Constitutive Equation to Predict Hot Deformation Behavior of Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Cai, Jun; Wang, Kuaishe; Zhai, Peng; Li, Fuguo; Yang, Jie

    2015-01-01

    A modified Johnson-Cook constitutive equation of Ti-6Al-4V alloy is proposed based on hot compression tests performed in the temperature range of 1073-1323 K and strain rate 0.001-1 s-1. The experimental stress-strain data were employed to develop the modified Johnson-Cook constitutive equation of different phase regimes (α + β and β phase). The predicted flow stresses using the developed equation were compared with experimental data. Correlation coefficient ( R) and average absolute relative error (AARE) were introduced to verify the validity of the constitutive equation. The values of R and AARE for α + β phase were 0.990 and 7.81%, respectively. And in β phase region, the values of R and AARE were 0.985 and 10.36%, respectively. Meanwhile, the accuracy, the number of material constants involved, and the computational time required of the constitutive equation were evaluated by comparing with a strain-compensated Arrhenius-type constitutive equation. The results indicate that accuracy of modified Johnson-Cook constitutive equation is higher than that of compensated Arrhenius-type model at α + β phase, while lower at single β phase region. Meanwhile, the time required for evaluating the material constants of modified Johnson-Cook constitutive equation is much shorter than that of the strain-compensated Arrhenius type ones.

  14. Study on load relaxation based on hot bending and sizing of Ti6Al4V alloy sheet

    NASA Astrophysics Data System (ADS)

    Po, Liu; Yingying, Zong; Debin, Shan; Bin, Guo

    2013-05-01

    The mechanism of hot sizing following sheet thermal forming of titanium alloy is considered as stress relaxation based on creep flow. A certain amount of internal stress in sheet metal parts can be relaxed during hot-sizing stage and hence the springback can be markedly reduced. Hot v-bending of Ti6Al4V sheet were carried out to study the behavior of load relaxation and springback in specimens after hot sizing, also known as shape retention. Experimental results reveal that load relaxation occurs during hot sizing following sheet v-bending. Reduction of springback angle obtained using hot sizing is obviously larger than that obtained without hot sizing under the same thermal environment. During hot sizing, springback angle decreases with increase in temperature and time, respectively. Load relaxation behavior is affected by loading method, namely constant velocity and two step loading. The linear relation between creep rate and load relaxation rate was deduced in hot-sizing stage. The calculated ratio shows good agreement with experimental data obtained by two-step loading. V-bending and sizing together with appropriate loading method are demonstrated as a good approach for stress relaxation analysis.

  15. Effect of Variants of Thermomechanical Working and Annealing Treatment on Titanium Alloy Ti6Al4V Closed Die Forgings

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Kumar, V. Anil; Kumar, P. Ram

    2016-06-01

    Performance of titanium alloy Ti6Al4V pressure vessels made of closed die forged domes of route `B' (multiple step forged and mill annealed) is reported to be better than route `A' (single/two step forged and mill annealed). Analysis revealed that forgings processed through route `B' have uniformity in microstructure and yield strength at various locations within the forging, as compared to that of route `A.' It is attributed to in-process recrystallization (dynamic as well as static) of route `B' forgings as compared to limited recrystallization of route `A' forgings. Further, post-forging recrystallization annealing (RA) effect is found to be more significant for route `A' forgings in achieving uniform microstructure and mechanical properties, since route `B' forgings have already undergone similar phenomenon during the thermomechanical working process itself. Considering prime importance of yield strength, statistical scatter in yield strength values within the forgings have been evaluated for forgings of both the routes. Standard deviation in the yield strength of route `B' forgings was lower (<10 MPa) as compared to route `A' (>15 MPa), which later became lower (~10 MPa) after RA with a minor decrease in yield strength. The present work discusses these variants of thermomechanical processing along with annealing to achieve better uniformity in properties and microstructure.

  16. Void shrinking process and mechanisms of the diffusion bonded Ti-6Al-4V alloy with different surface roughness

    NASA Astrophysics Data System (ADS)

    Li, H.; Li, M. Q.; Kang, P. J.

    2016-01-01

    The diffusion bonding of Ti-6Al-4V alloy with different surface roughness was performed at 5 and 10 MPa. The influence of surface roughness on the void shrinking process and mechanisms was investigated. The average void size increases as the R a increases from 0.33 to 0.44 μm, while it decreases as the R a increases to 0.46 μm because of the decreasing of R λq. The void shrinking mechanisms were analyzed by using the dynamic model of void shrinking. Power-law creep is a dominant mechanism on void shrinking, of which the contribution decreases as the R a increases from 0.33 to 0.44 μm, while it increases as the R a increases to 0.46 μm. The influence of surface roughness on the contribution of plastic deformation and surface source mechanism on void shrinking is not significant while that on the contribution of interface source mechanism is dependent on the imposing pressure. The optimizing surface roughness is with a R a of 0.33 μm and R λq of 5.38 μm in this study.

  17. Self-assembled monolayers of alendronate on Ti6Al4V alloy surfaces enhance osteogenesis in mesenchymal stem cells.

    PubMed

    Rojo, Luis; Gharibi, Borzo; McLister, Robert; Meenan, Brian J; Deb, Sanjukta

    2016-01-01

    Phosphonates have emerged as an alternative for functionalization of titanium surfaces by the formation of homogeneous self-assembled monolayers (SAMs) via Ti-O-P linkages. This study presents results from an investigation of the modification of Ti6Al4V alloy by chemisorption of osseoinductive alendronate using a simple, effective and clean methodology. The modified surfaces showed a tailored topography and surface chemistry as determined by SEM microscopy and RAMAN spectroscopy. X-ray photoelectron spectroscopy revealed that an effective mode of bonding is created between the metal oxide surface and the phosphate residue of alendronate, leading to formation of homogenous drug distribution along the surface. In-vitro studies showed that alendronate SAMs induce differentiation of hMSC to a bone cell phenotype and promote bone formation on modified surfaces. Here we show that this novel method for the preparation of functional coatings on titanium-based medical devices provides osseoinductive bioactive molecules to promote enhanced integration at the site of implantation. PMID:27468811

  18. Effect of Wire-EDM cutting parameters on material removal rate of titanium alloy (Ti6Al4V)

    NASA Astrophysics Data System (ADS)

    Azam, N.; Afendi, M.

    2016-07-01

    In this study, titanium alloy (Ti6Al4V) which is also known as difficult to cut material is used as workpiece. Seven main parameters namely pulse duration (A), pulse interval (B), servo voltage (C), ignition pulse current (D), wire tension (E), wire speed (F) and dielectric pressure (G) have been experimentally studied by using Taguchi method as well as the determination of optimum parameters for material removal rate (MRR). Analysis of variance (ANOVA) has been used for recognizing the level of significant of WEDM cutting parameter for optimizing MRR and the result found that pulse duration and servo voltage give significant effect on MRR. While according to Signal to Noise (S/N) ratio response table for MRR, the parameters combination of A3B3C3D3E1F3G3 give the optimum value for MRR. It is also observed that the predicted results agree with the experimental values within an error of 4.6 %.

  19. Self-assembled monolayers of alendronate on Ti6Al4V alloy surfaces enhance osteogenesis in mesenchymal stem cells

    PubMed Central

    Rojo, Luis; Gharibi, Borzo; McLister, Robert; Meenan, Brian J.; Deb, Sanjukta

    2016-01-01

    Phosphonates have emerged as an alternative for functionalization of titanium surfaces by the formation of homogeneous self-assembled monolayers (SAMs) via Ti-O-P linkages. This study presents results from an investigation of the modification of Ti6Al4V alloy by chemisorption of osseoinductive alendronate using a simple, effective and clean methodology. The modified surfaces showed a tailored topography and surface chemistry as determined by SEM microscopy and RAMAN spectroscopy. X-ray photoelectron spectroscopy revealed that an effective mode of bonding is created between the metal oxide surface and the phosphate residue of alendronate, leading to formation of homogenous drug distribution along the surface. In-vitro studies showed that alendronate SAMs induce differentiation of hMSC to a bone cell phenotype and promote bone formation on modified surfaces. Here we show that this novel method for the preparation of functional coatings on titanium-based medical devices provides osseoinductive bioactive molecules to promote enhanced integration at the site of implantation. PMID:27468811

  20. Effects of Recrystallization on Microstructure and Texture Evolution of Cold-Rolled Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Jiang, Haitao; Dong, Peng; Zeng, Shangwu; Wu, Bo

    2016-05-01

    The effects of recrystallization during annealing process on microstructure and texture evolution of cold-rolled Ti-6Al-4V alloy plates were investigated. The plates after cold rolling with a thickness reduction of 5, 10, and 15% were annealed under different conditions of 750 °C for 1 h, 800 °C for 1 h, and 800 °C for 1.5 h, respectively. It was found out that the recrystallization temperature decreased with increasing rolling reduction due to higher storage energy, while the extension of annealing time caused grain growth. For the cold-rolled plate with a reduction of 10%, the resulting microstructure showed more equal-axis grains after annealing at 800 °C for 1 h, among different conditions. Moreover, the XRD results showed that the cold-rolled plate composed mainly of {0001} <10-10> basal texture, {10-11} <1-210> and {01-12} <10-10> pyramidal textures, and {01-10} <10-10> prismatic texture, and that the weak {10-11} <1-210> texture was transformed to components {01-12} <10-10> and {01-10} <10-10>, which were expected to improve formability. Electron back-scattered diffraction results ascertained that two mechanisms, i.e., recrystallization sites of preferred orientations and favorable grain growth both played important roles in static recrystallization.

  1. Behavior of surface and corner cracks subjected to tensile and bending loads in a Ti-6Al-4V alloy

    NASA Technical Reports Server (NTRS)

    Forman, Royce G.; Mettu, Sambi R.

    1992-01-01

    The behavior of part-through flaws with regard to failure under monotonic loading and their growth under fatigue loading was investigated experimentally and analytically. The objective of this paper is to present comparisons of experimental values of toughness obtained using surface- and corner-cracked specimens with those obtained using standard test specimens, and also to compare experimental growth cycles with numerical predictions using the NASA/FLAGRO computer program. Tests were conducted on various types of surface and corner cracks under tensile and bending loads. Room temperature laboratory air provided the test environment. The material used in this investigation was the Ti-6Al-4V alloy in the solution treated and aged (STA) and stress-relieved condition. Detailed tabulation of the fracture toughness data and results of life prediction using the NASA/FLAGRO program are presented. Fatigue crack growth rates for the part-through-cracked specimens are compared with a base curve fitted from the data obtained using standard specimens. The fatigue loading used in the crack growth testing was of constant-amplitude sinusoidal type.

  2. Commercially pure titanium (cp-Ti) versus titanium alloy (Ti6Al4V) materials as bone anchored implants - Is one truly better than the other?

    PubMed

    Shah, Furqan A; Trobos, Margarita; Thomsen, Peter; Palmquist, Anders

    2016-05-01

    Commercially pure titanium (cp-Ti) and titanium alloys (typically Ti6Al4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally, influenced material selection for different clinical applications: predominantly Ti6Al4V in orthopaedics while cp-Ti in dentistry. This paper attempts to address three important questions: (i) To what extent do the surface properties differ when cp-Ti and Ti6Al4V materials are manufactured with the same processing technique?, (ii) Does bone tissue respond differently to the two materials, and (iii) Do bacteria responsible for causing biomaterial-associated infections respond differently to the two materials? It is concluded that: (i) Machined cp-Ti and Ti6Al4V exhibit similar surface morphology, topography, phase composition and chemistry, (ii) Under experimental conditions, cp-Ti and Ti6Al4V demonstrate similar osseointegration and biomechanical anchorage, and (iii) Experiments in vitro fail to disclose differences between cp-Ti and Ti6Al4V to harbour Staphylococcus epidermidis growth. No clinical comparative studies exist which could determine if long-term, clinical differences exist between the two types of bulk materials. It is debatable whether cp-Ti or Ti6Al4V exhibit superiority over the other, and further comparative studies, particularly in a clinical setting, are required. PMID:26952502

  3. Investigation of the Workability and Response of Ti-6Al-4V Titanium alloys at Lower Elevated Temperature and Higher Strain Rate

    SciTech Connect

    Huang, Cindy Xiaohui; Lim, Chao Voon; Castagne, Sylvie

    2011-05-04

    Titanium and its alloys have a wide range of applications in various industries such as aerospace, medical, automotive and even commercial products. However, formability of titanium alloys has always been an issue. This study presents the results of an investigation on the workability and response of Ti-6Al-4V deformed at different strain rates and lower elevated temperatures with different initial microstructures. Compression tests of cylindrical specimens were performed at various temperatures (300 deg. C, 400 deg. C, 450 deg. C, 500 deg. C) and at different strain rates (0.001 s{sup -1}, 0.02 s{sup -1} and 0.1 s{sup -1}). The effects of strain rate, temperature and initial microstructure on the workability of the Ti alloy were investigated. Based on these experimental results, workability maps for the respective initial microstructures were developed. Results showed that temperature played an important role in the formability of Ti-6Al-4V titanium alloys unlike strain rate. In addition, feasibility study on Multi-Directional Forging (MDF) was performed and positive results were obtained. It was demonstrated that Ti-6Al-4V titanium alloys can undergo severe plastic deformation at lower elevated temperature (400-500 deg. C) and at a higher strain rate of 0.1 s{sup -1}.

  4. Development of Ti-6Al-4V and Ti-1Al-8V-5Fe Alloys Using Low-Cost TiH2 Powder Feedstock

    SciTech Connect

    Joshi, Vineet V.; Lavender, Curt; Moxon, Vladimir; Duz, Vlad; Nyberg, Eric; Weil, K. Scott

    2012-09-25

    Thermo-mechanical processing was performed on two titanium alloy billets, a beta-titanium alloy (Ti1Al8V5Fe) and an alpha-beta titanium alloy (Ti6Al4V), which had been produced using a novel low-cost powder metallurgy process that relies on the use of TiH2 powder as a feedstock material. The thermomechanical processing was performed in the beta region of the respective alloys to form 16-mm diameter bars. The hot working followed by the heat treatment processes not only eliminated the porosity within the materials but also developed the preferred microstructures. Tensile testing and rotating beam fatigue tests were conducted on the as-rolled and heat-treated materials to evaluate their mechanical properties. The mechanical properties of these alloys matched well with those produced by the conventional ingot processing route.

  5. Constitutive modeling for Ti-6Al-4V alloy machining based on the SHPB tests and simulation

    NASA Astrophysics Data System (ADS)

    Chen, Guang; Ke, Zhihong; Ren, Chengzu; Li, Jun

    2016-06-01

    A constitutive model is critical for the prediction accuracy of a metal cutting simulation. The highest strain rate involved in the cutting process can be in the range of 104-106 s-1. Flow stresses at high strain rates are close to that of cutting are difficult to test via experiments. Split Hopkinson compression bar (SHPB) technology is used to study the deformation behavior of Ti-6Al-4V alloy at strain rates of 10-4-104s-1. The Johnson Cook (JC) model was applied to characterize the flow stresses of the SHPB tests at various conditions. The parameters of the JC model are optimized by using a genetic algorithm technology. The JC plastic model and the energy density-based ductile failure criteria are adopted in the proposed SHPB finite element simulation model. The simulated flow stresses and the failure characteristics, such as the cracks along the adiabatic shear bands agree well with the experimental results. Afterwards, the SHPB simulation is used to simulate higher strain rate(approximately 3×104 s-1) conditions by minimizing the size of the specimen. The JC model parameters covering higher strain rate conditions which are close to the deformation condition in cutting were calculated based on the flow stresses obtained by using the SHPB tests (10-4-104 s-1) and simulation (up to 3×104 s-1). The cutting simulation using the constitutive parameters is validated by the measured forces and chip morphology. The constitutive model and parameters for high strain rate conditions that are identical to those of cutting were obtained based on the SHPB tests and simulation.

  6. 3D finite element simulation of microstructure evolution in blade forging of Ti-6Al-4V alloy based on the internal state variable models

    NASA Astrophysics Data System (ADS)

    Luo, Jiao; Wu, Bin; Li, Miao-Quan

    2012-02-01

    The physically-based internal state variable (ISV) models were used to describe the changes of dislocation density, grain size, and flow stress in the high temperature deformation of titanium alloys in this study. The constants of the present models could be identified based on experimental results, which were conducted at deformation temperatures ranging from 1093 K to 1303 K, height reductions ranging from 20% to 60%, and the strain rates of 0.001, 0.01, 0.1, 1.0, and 10.0 s-1. The physically-based internal state variable models were implemented into the commercial finite element (FE) code. Then, a three-dimensional (3D) FE simulation system coupling of deformation, heat transfer, and microstructure evolution was developed for the blade forging of Ti-6Al-4V alloy. FE analysis was carried out to simulate the microstructure evolution in the blade forging of Ti-6Al-4V alloy. Finally, the blade forging tests of Ti-6Al-4V alloy were performed to validate the results of FE simulation. According to the tensile tests, it is seen that the mechanical properties, such as tensile strength and elongation, satisfy the application requirements well. The maximum and minimum differences between the calculated and experimental grain size of primary α phase are 11.71% and 4.23%, respectively. Thus, the industrial trials show a good agreement with FE simulation of blade forging.

  7. The Nature of Tensile Ductility as Controlled by Extreme-Sized Pores in Powder Metallurgy Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Ravi Chandran, K. S.; Cao, F.; Koopman, M.; Fang, Z. Zak

    2016-05-01

    Tensile properties of Ti-6Al-4V titanium alloy, sintered by a new process (sintering, phase transformation, and dehydrogenation of titanium hydride compacts, termed HSPT process), were investigated to determine how the sintering pores influence the tensile strength and ductility. It was found that the ductility in the sintered alloy is severely affected by the size of the largest pore, referred here as extreme-sized pore, even when the average volume fraction of porosity is nearly constant between a large number of samples. It is shown that the rapid decrease in ductility, with an increase in the extreme pore size, is caused by strain localization around the extreme-sized pore and early crack initiation. This crack initiation leads to fracture of the plane containing the pore thereby limiting the extent of uniform plastic strain that can be attained before fracture. Interestingly, the strength properties are, however, found to be independent of the size of the extreme-sized pore. The results are explained on the basis of stress concentration and strain localization around the extreme-sized pores. The work also reveals that if the extreme-sized pores are eliminated, PM Ti-6Al-4V alloy with high strength (~1100 MPa) and good ductility (~12 pct), which is easily comparable to a wrought Ti-6Al-4V alloy, can be achieved even at oxygen levels up to 0.4 wt pct.

  8. Effects of Dextrose and Lipopolysaccharide on the Corrosion Behavior of a Ti-6Al-4V Alloy with a Smooth Surface or Treated with Double-Acid-Etching

    PubMed Central

    Faverani, Leonardo P.; Assunção, Wirley G.; de Carvalho, Paulo Sérgio P.; Yuan, Judy Chia-Chun; Sukotjo, Cortino; Mathew, Mathew T.; Barao, Valentim A.

    2014-01-01

    Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (α = 0.05). In the corrosion parameters, there was a strong lipopolysaccharide correlation with the Ipass (passivation current density), Cdl (double-layer capacitance), and Rp (polarization resistance) values (p<0.05) for the Ti-6Al-4V alloy with surface treatment by double-acid-etching. The combination of dextrose and lipopolysaccharide was correlated with the Icorr (corrosion current density) and Ipass (p<0.05). The acid-treated groups showed a significant increase in Cdl values and reduced Rp values (p<0.05, t-test). According to the topography, there was an increase in surface roughness (R2 = 0.726, p<0.0001 for the smooth surface; R2 = 0.405, p = 0.036 for the double-acid-etching-treated surface). The microhardness of the smooth Ti-6Al-4V alloy decreased (p<0.05) and that of the treated Ti-6Al-4V alloy increased (p<0.0001). Atomic force microscopy showed changes in the microstructure of the Ti-6Al-4V alloy by increasing the surface thickness mainly in the group associated with dextrose and lipopolysaccharide. The combination of dextrose and lipopolysaccharide affected the corrosion behavior of the Ti-6Al-4V alloy surface treated with double-acid-etching. However, no

  9. Electrodeposition of HAp coatings on Ti6Al4V alloy and its electrochemical behavior in simulated body fluid solution

    NASA Astrophysics Data System (ADS)

    Thanh Dinh, Thi Mai; Thom Nguyen, Thi; Pham, Thi Nam; Phuong Nguyen, Thu; Thu Trang Nguyen, Thi; Hoang, Thai; Grossin, David; Bertrand, Ghislaine; Drouet, Christophe

    2016-06-01

    Hydroxyapatite (HAp) coatings were prepared on Ti6Al4V substrate by electrodeposition method from electrolyte solution containing Ca(NO3)2, NH4H2PO4 and NaNO3. The results show that the HAp coatings were single phase crystals of HAp. Scanning electron microscope (SEM) images present that HAp/Ti6Al4V have flake shapes which arrange to form like-coral agglomerates. In vitro test of the Ti6Al4V and HAp/Ti6Al4V in simulated body fluid (SBF) solution was investigated with different immersion times. pH of SBF solution decreased and the mass of materials increased. SEM images prove the formation of apatite on the surface of Ti6Al4V and HAp/Ti6Al4V. The corrosion current density during immersion time of substrate is always higher than the one of HAp/Ti6Al4V because the deposited HAp can protect well for the substrate.

  10. Stress-corrosion crack-growth study of titanium alloy Ti-6Al-4V exposed to freon PCA and nitrogen tetroxide MON-1

    NASA Technical Reports Server (NTRS)

    Bjorklund, R. A.

    1983-01-01

    An experimental fracture mechanics program was performed to determine the stress corrosion crack growth sensitivity of the propellant tank material, titanium alloy Ti-6Al-4V, for aerospace satellite applications involving long term exposure to Freon PCA and nitrogen tetroxide MON-1. Sustained load tests were made at a 49 C (120 F) constant temperature using thin gauge tensile test specimens containing semielliptical surface flaws. Test specimen types included parent metal, center of weld, and weld heat affected zone. It was concluded that Ti-6Al-4V alloy is not adversely affected in a stress environment when exposed to Freon PCA for 1000 hours followed by exposure to nitrogen tetroxide MON-1 for 2000 hours at stress levels up to 80% of the experimental critical plane strain stress intensity factor.

  11. Study of Tool Wear Mechanisms and Mathematical Modeling of Flank Wear During Machining of Ti Alloy (Ti6Al4V)

    NASA Astrophysics Data System (ADS)

    Chetan; Narasimhulu, A.; Ghosh, S.; Rao, P. V.

    2014-12-01

    Machinability of titanium is poor due to its low thermal conductivity and high chemical affinity. Lower thermal conductivity of titanium alloy is undesirable on the part of cutting tool causing extensive tool wear. The main task of this work is to predict the various wear mechanisms involved during machining of Ti alloy (Ti6Al4V) and to formulate an analytical mathematical tool wear model for the same. It has been found from various experiments that adhesive and diffusion wear are the dominating wear during machining of Ti alloy with PVD coated tungsten carbide tool. It is also clear from the experiments that the tool wear increases with the increase in cutting parameters like speed, feed and depth of cut. The wear model was validated by carrying out dry machining of Ti alloy at suitable cutting conditions. It has been found that the wear model is able to predict the flank wear suitably under gentle cutting conditions.

  12. INFLUENCE OF THE FINAL TEMPERATURE OF INVESTMENT HEALTING ON THE TENSILE STRENGTH AND VICKERS HARDNESS OF CP TI AND TI-6AL-4V ALLOY

    PubMed Central

    Oliveira, Pedro César Garcia; Adabo, Gelson Luis; Ribeiro, Ricardo Faria; da Rocha, Sicknan Soares; Ávila, Fabiano Araújo; do Valle, Accácio Lins

    2007-01-01

    The aim of the work was to evaluate the influence of the temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy casting. Were obtained for the tensile strength test dumbbell rods that were invested in the Rematitan Plus investment and casting in the Discovery machine cast. Thirty specimens were obtained, fiftten to the CP Titanium and fifteen to the Ti-6Al-4V alloy, five samples to each an of the three temperatures of investment: 430°C (control group), 480°C and 530°C. The tensile test was measured by means of a universal testing machine, MTS model 810, at a strain of 1.0 mm/min. After the tensile strenght test the specimens were secctioned, embedded and polished to hardness measurements, using a Vickers tester, Micromet 2100. The means values to tensile tests to the temperatures 430°C, 480 and 530: CP Ti (486.1 – 501.16 – 498.14 –mean 495.30 MPa) and Ti-6Al-4V alloy (961.33 – 958.26 – 1005.80 – mean 975.13 MPa) while for the Vickers hardness the values were (198.06, 197.85, 202.58 – mean 199.50) and (352.95, 339.36, 344.76 – mean 345.69), respectively. The values were submitted to Analysis of Variance (ANOVA) and Tukey,s Test that indicate differences significant only between the materials, but not between the temperature, for both the materias. It was conclued that increase of the temperature of investment its not chance the tensile strength and the Vickers hardness of the CP Titanium and Ti-6Al-4V alloy. PMID:19089099

  13. Thermal Modeling and Simulation of Electron Beam Melting for Rapid Prototyping on Ti6Al4V Alloys

    NASA Astrophysics Data System (ADS)

    Neira Arce, Alderson

    To be a viable solution for contemporary engineering challenges, the use of titanium alloys in a wider range of applications requires the development of new techniques and processes that are able to decrease production cost and delivery times. As a result, the use of material consolidation in a near-net-shape fashion, using dynamic techniques like additive manufacturing by electron beam selective melting EBSM represents a promising method for part manufacturing. However, a new product material development can be cost prohibitive, requiring the use of computer modeling and simulation as a way to decrease turnaround time. To ensure a proper representation of the EBSM process, a thermophysical material characterization and comparison was first performed on two Ti6Al4V powder feedstock materials prepared by plasma (PREP) and gas atomized (GA) processes. This evaluation comprises an evaluation on particle size distribution, density and powder surface area, collectively with the temperature dependence on properties such as heat capacity, thermal diffusivity, thermal conductivity and surface emissivity. Multiple techniques were employed in this evaluation, including high temperature differential scanning calorimetry (HT-DSC), laser flash analysis (LFA), infrared remote temperature analysis (IR-Thermography), laser diffraction, liquid and gas pycnometry using mercury and krypton adsorption respectively. This study was followed by the review of complementary strategies to simulate the temperature evolution during the EBSM process, using a finite element analysis package called COMSOL Multiphysics. Two alternatives dedicated to representing a moving heat source (electron beam) and the powder bed were developed using a step-by-step approximation initiative. The first method consisted of the depiction of a powder bed discretized on an array of domains, each one representing a static melt pool, where the moving heat source was illustrated by a series of time dependant selective

  14. Electrochemical characterization of MC3T3-E1 cells cultured on γTiAl and Ti-6Al-4V alloys.

    PubMed

    Bueno-Vera, J A; Torres-Zapata, I; Sundaram, P A; Diffoot-Carlo, N; Vega-Olivencia, C A

    2015-12-01

    Electrochemical impedance spectroscopy (EIS) was used to study the behavior of MC3T3-E1 cells cultured in an αMEM+FBS solution on two Ti-based alloys (Ti-6Al-4V and γTiAl) for 4, 7 and 14 days. EIS measurements were carried out at an open-circuit potential in a 1 mHz to 100 kHz frequency range. Results indicate a general increase in impedance on the Ti alloy surfaces with cells as a function of time. Bode plots indicate changes corresponding to the passive oxide film, adsorption of proteins and cell tissue on surfaces with the passage of time. Normal cellular activity based on the polygonal morphology, with long and fine cytoplasmic prolongations of the cells on Ti-6Al-4V and γTiAl was observed from SEM images. Similarly, mineralization nodules corresponding to cell differentiation associated with the osseogenetic process were observed confirmed by Alizarin Red S staining. Immunofluorescence analysis to detect the presence of collagen Type I showed an increase in the segregation of collagen as a function of time. The impedance values obtained from EIS testing are indicative of the corrosion protection offered to the Ti alloy substrates by the cell layer. This study shows that γTiAl has better corrosion resistance than that of Ti-6Al-4V in the αMEM+FBS environment in the presence of MC3T3-E1 cells. PMID:26145813

  15. Novel artificial hip joint: A layer of alumina on Ti-6Al-4V alloy formed by micro-arc oxidation.

    PubMed

    Khanna, Rohit; Kokubo, Tadashi; Matsushita, Tomiharu; Nomura, Yuuji; Nose, Norihiro; Oomori, Yoshiyuki; Yoshida, Takuya; Wakita, Koichi; Takadama, Hiroaki

    2015-10-01

    In many hip replacement surgeries, monolithic alumina is used as a femoral head due to its high wear resistance. However, it is liable to fracture under load bearing operations in artificial joints. We propose a promising way to overcome this limitation by forming a dense alumina layer onto a relatively tough substrate such as Ti-6Al-4V alloy to obtain high wear resistance on a material that can sustain relatively high toughness. For this purpose, Al metal powders were deposited onto Ti-6Al-4V alloy by cold spraying in N2 atmosphere. Interfacial adhesion between Al and the Ti alloy was improved by the formation of a reaction layer of Al3Ti between them by heating at 640 °C for 1h in air. Subsequently, micro-arc oxidation treatment was performed to oxidize Al. The oxidized layer was composed of an outer porous layer of γ-alumina and inner-most dense layer of α-alumina. The α-alumina layer was almost fully densified and exhibited high Vickers hardness almost equal to that of alumina ceramics used as the femoral head. Thus, the newly developed dense alumina/Ti alloy can be potentially used to produce the reliable bearing surfaces of artificial hip joint. PMID:26117770

  16. Increasing Ti-6Al-4V brazed joint strength equal to the base metal by Ti and Zr amorphous filler alloys

    SciTech Connect

    Ganjeh, E.; Sarkhosh, H.; Bajgholi, M.E.; Khorsand, H.; Ghaffari, M.

    2012-09-15

    Microstructural features developed along with mechanical properties in furnace brazing of Ti-6Al-4V alloy using STEMET 1228 (Ti-26.8Zr-13Ni-13.9Cu, wt.%) and STEMET 1406 (Zr-9.7Ti-12.4Ni-11.2Cu, wt.%) amorphous filler alloys. Brazing temperatures employed were 900-950 Degree-Sign C for the titanium-based filler and 900-990 Degree-Sign C for the zirconium-based filler alloys, respectively. The brazing time durations were 600, 1200 and 1800 s. The brazed joints were evaluated by ultrasonic test, and their microstructures and phase constitutions analyzed by metallography, scanning electron microscopy and X-ray diffraction analysis. Since microstructural evolution across the furnace brazed joints primarily depends on their alloying elements such as Cu, Ni and Zr along the joint. Accordingly, existence of Zr{sub 2}Cu, Ti{sub 2}Cu and (Ti,Zr){sub 2}Ni intermetallic compounds was identified in the brazed joints. The chemical composition of segregation region in the center of brazed joints was identical to virgin filler alloy content which greatly deteriorated the shear strength of the joints. Adequate brazing time (1800 s) and/or temperature (950 Degree-Sign C for Ti-based and 990 Degree-Sign C for Zr-based) resulted in an acicular Widmanstaetten microstructure throughout the entire joint section due to eutectoid reaction. This microstructure increased the shear strength of the brazed joints up to the Ti-6Al-4V tensile strength level. Consequently, Ti-6Al-4V can be furnace brazed by Ti and Zr base foils produced excellent joint strengths. - Highlights: Black-Right-Pointing-Pointer Temperature or time was the main factors of controlling braze joint strength. Black-Right-Pointing-Pointer Developing a Widmanstaetten microstructure generates equal strength to base metal. Black-Right-Pointing-Pointer Brittle intermetallic compounds like (Ti,Zr){sub 2}Ni/Cu deteriorate shear strength. Black-Right-Pointing-Pointer Ti and Zr base filler alloys were the best choice for brazing Ti

  17. In situ synthesized TiB-TiN reinforced Ti6Al4V alloy composite coatings: microstructure, tribological and in-vitro biocompatibility.

    PubMed

    Das, Mitun; Bhattacharya, Kaushik; Dittrick, Stanley A; Mandal, Chitra; Balla, Vamsi Krishna; Sampath Kumar, T S; Bandyopadhyay, Amit; Manna, Indranil

    2014-01-01

    Wear resistant TiB-TiN reinforced Ti6Al4V alloy composite coatings were deposited on Ti substrate using laser based additive manufacturing technology. Ti6Al4V alloy powder premixed with 5wt% and 15wt% of boron nitride (BN) powder was used to synthesize TiB-TiN reinforcements in situ during laser deposition. Influences of laser power, scanning speed and concentration of BN on the microstructure, mechanical, in vitro tribological and biological properties of the coatings were investigated. Microstructural analysis of the composite coatings showed that the high temperature generated due to laser interaction with Ti6Al4V alloy and BN results in situ formation of TiB and TiN phases. With increasing BN concentration, from 5wt% to 15wt%, the Young's modulus of the composite coatings, measured by nanoindentation, increased from 170±5GPa to 204±14GPa. In vitro tribological tests showed significant increase in the wear resistance with increasing BN concentration. Under identical test conditions TiB-TiN composite coatings with 15wt% BN exhibited an order of magnitude less wear rate than CoCrMo alloy-a common material for articulating surfaces of orthopedic implants. Average top surface hardness of the composite coatings increased from 543±21HV to 877±75HV with increase in the BN concentration. In vitro biocompatibility and flow cytometry study showed that these composite coatings were non-toxic, exhibit similar cell-materials interactions and biocompatibility as that of commercially pure titanium (CP-Ti) samples. In summary, excellent in vitro wear resistance, high stiffness and suitable biocompatibility make these composite coatings as a potential material for load-bearing articulating surfaces towards orthopaedic implants. PMID:24121827

  18. Cytocompatibility of Ti-6Al-4V and Ti-5Al-2.5Fe alloys according to three surface treatments, using human fibroblasts and osteoblasts.

    PubMed

    Bordji, K; Jouzeau, J Y; Mainard, D; Payan, E; Netter, P; Rie, K T; Stucky, T; Hage-Ali, M

    1996-05-01

    Titanium alloys are well known for their superior mechanical properties as well as for their good biocompatibility, making them desirable as surgical implant materials. However, these alloys have been proven to behave poorly in friction since wear particles were often detected in tissues and organs associated with titanium implants. In this paper, three surface treatments were investigated in order to improve the wear resistance and the hardness of Ti-6Al-4V and Ti-5Al-2.5Fe: (a) glow discharge nitrogen implantation (10(17) atoms cm-2), (b) plasma nitriding by plasma diffusion treatment (PDT) and (c) deposition of TiN layer by plasma-assisted chemical vapour deposition (PACVD) additionally to PDT. Surface characterization after the different treatments showed considerable improvement in surface hardness, especially after the two nitriding processes. Moreover, the good corrosion resistance of untreated alloys was maintained. A cell culture model using human cells was chosen to study the effect of such treatments on the cytocompatibility of these materials. The results showed that Ti-5Al-2.5Fe alloy was as cytocompatible as the Ti-6Al-4V alloy and the same surface treatment led to identical biological consequences on both alloys. Nitrogen implantation did not modify at all the cellular behaviour observed on untreated samples. After the two nitriding treatments, cell proliferation and viability appeared to be significantly reduced and the scanning electron microscopy study revealed somewhat irregular surface states. However, osteoblast phenotype expression and protein synthesis capacity were not affected. PDT and PACVD may be interesting alternatives to the physical vapour deposition technique. PMID:8718939

  19. A comparison of corrosion, tribocorrosion and electrochemical impedance properties of pure Ti and Ti6Al4V alloy treated by micro-arc oxidation process

    NASA Astrophysics Data System (ADS)

    Fazel, M.; Salimijazi, H. R.; Golozar, M. A.; Garsivaz jazi, M. R.

    2015-01-01

    In this paper, the micro-arc oxidation (MAO) coatings were performed on pure Ti and Ti6Al4V samples at 180 V. The results indicated that unlike the volcanic morphology of oxide layer on pure Ti, a cortex-like morphology with irregular vermiform slots was seen on MAO/Ti6Al4V sample. According to polarization curves, the corrosion resistance of untreated samples was significantly increased by MAO process. The electrochemical impedance spectroscopy analysis showed a lower capacitance of barrier layer (led to higher resistance) for MAO/Ti specimens. This indicates that corrosive ions diffusion throughout the oxide film would be more difficult resulted in a higher corrosion resistance. Tribocorrosion results illustrated that the potential of untreated samples was dropped sharply to very low negative values. However, the lower wear volume loss was achieved for Ti6Al4V alloy. SEM images of worn surfaces demonstrated the local detachment of oxide layer within the wear track of MAO/Ti sample. Conversely, no delamination was detected in MAO/Ti6Al4V and a mild abrasive wear was the dominant mechanism.

  20. A comparison in mechanical properties of cermets of calcium silicate with Ti-55Ni and Ti-6Al-4V alloys for hard tissues replacement.

    PubMed

    Ataollahi Oshkour, Azim; Pramanik, Sumit; Shirazi, Seyed Farid Seyed; Mehrali, Mehdi; Yau, Yat-Huang; Abu Osman, Noor Azuan

    2014-01-01

    This study investigated the impact of calcium silicate (CS) content on composition, compressive mechanical properties, and hardness of CS cermets with Ti-55Ni and Ti-6Al-4V alloys sintered at 1200°C. The powder metallurgy route was exploited to prepare the cermets. New phases of materials of Ni16Ti6Si7, CaTiO3, and Ni31Si12 appeared in cermet of Ti-55Ni with CS and in cermet of Ti-6Al-4V with CS, the new phases Ti5Si3, Ti2O, and CaTiO3, which were emerged during sintering at different CS content (wt%). The minimum shrinkage and density were observed in both groups of cermets for the 50 and 100 wt% CS content, respectively. The cermets with 40 wt% of CS had minimum compressive Young's modulus. The minimum of compressive strength and strain percentage at maximum load were revealed in cermets with 50 and 40 wt% of CS with Ti-55Ni and Ti-6Al-4V cermets, respectively. The cermets with 80 and 90 wt% of CS showed more plasticity than the pure CS. It concluded that the composition and mechanical properties of sintered cermets of Ti-55Ni and Ti-6Al-4V with CS significantly depend on the CS content in raw cermet materials. Thus, the different mechanical properties of the cermets can be used as potential materials for different hard tissues replacements. PMID:25538954

  1. Microstructures and Properties of Plasma Electrolytic Oxidized Ti Alloy (Ti-6Al-4V) for Bio-implant Application

    NASA Astrophysics Data System (ADS)

    Kumari, Renu; Blawert, Carsten; Majumdar, J. Dutta

    2016-02-01

    In the present study, plasma electrolytic oxidation (PEO) of Ti6Al4V has been performed in an electrolyte containing 20 g/L of Na2SiO3, 10 g/L of Na3PO4, 2 g/L of KOH, and 5 g/L of hydroxyapatite at an optimum constant potential of 430 V for 10 minutes. Followed by PEO treatment, surface roughness was measured using non-contact optical profilometer. A detailed characterization of microstructure, composition and phase analysis was carried out using scanning electron microscopy, energy-dispersive X-ray spectroscopic analysis, Fourier-transform infrared, and X-ray diffraction study. The mechanical properties of the surface have been evaluated by measuring nano-hardness and wear resistance. The effect of surface modification on corrosion resistance property has also been evaluated in Hank's solution. Finally, wettability and bioactivity test have been also performed. PEO developed a thick (150 μm) porous (35 pct) oxide film on the surface of Ti-6Al-4V consisting of anatase, rutile, and SiO2. The nano-hardness of the PEO-treated surface is increased to 8 ± 0.5 GPa as compared to 2 ± 0.4 GPa of the as-received Ti-6Al-4V. Wear and corrosion resistance were improved following oxidation. There is an improvement in wettability in terms of decrease in contact angle from 60 ± 1.5 to 45 ± 1 deg. Total surface energy and its polar component were also increased significantly on PEO-treated surface as compared to the as-received Ti6Al4V.

  2. Oxynitrided Surface Layer Produced On Ti6Al4V Titanium Alloy Under Low Temperature Glow Discharge Conditions For Medical Applications

    NASA Astrophysics Data System (ADS)

    Wierzchon, T.; Ossowski, M.; Borowski, T.; Morgiel, J.; Czarnowska, E.

    2011-01-01

    In spite that titanium oxides increase biocompatibility of titanium implants but their functional life is limited due to the problems arising from brittles and metalosis. Therefore technology, that allow to produce composite surface layer with controlled microstructure, chemical and phase composition and surface morphology on titanium alloy and eliminates the oxides disadvantages has been existing till now is searched. The requirements of titanium and its alloys implants can be fulfill by the low—temperature glow discharge assisted oxynitriding. The paper describes the surface layer of TiO2+TiN+Ti2N+αTi(N) type produced at temperature 680° C that preserves mechanical properties of titanium alloy Ti6Al4V. Characteristics of produced diffusion multi-phase surface layers in range of phase composition, microstructure (SEM, TEM, XRD) and its properties, such as frictional wear resistance are presented. The biological properties in dependency to the applied sterilization method are also analyzed. Properties of produced surface layers are discussed with reference to titanium alloy. The obtained data show that produced surface layers improves titanium alloy properties both frictional wear and biological. Preliminary in vitro examinations show good biocompatibility and antithrombogenic properties.

  3. Oxynitrided Surface Layer Produced On Ti6Al4V Titanium Alloy Under Low Temperature Glow Discharge Conditions For Medical Applications

    SciTech Connect

    Wierzchon, T.; Ossowski, M.; Borowski, T.; Morgiel, J.; Czarnowska, E.

    2011-01-17

    In spite that titanium oxides increase biocompatibility of titanium implants but their functional life is limited due to the problems arising from brittles and metalosis. Therefore technology, that allow to produce composite surface layer with controlled microstructure, chemical and phase composition and surface morphology on titanium alloy and eliminates the oxides disadvantages has been existing till now is searched. The requirements of titanium and its alloys implants can be fulfill by the low-temperature glow discharge assisted oxynitriding.The paper describes the surface layer of TiO{sub 2}+TiN+Ti{sub 2}N+{alpha}Ti(N) type produced at temperature 680 deg. C that preserves mechanical properties of titanium alloy Ti6Al4V. Characteristics of produced diffusion multi-phase surface layers in range of phase composition, microstructure (SEM, TEM, XRD) and its properties, such as frictional wear resistance are presented. The biological properties in dependency to the applied sterilization method are also analyzed.Properties of produced surface layers are discussed with reference to titanium alloy. The obtained data show that produced surface layers improves titanium alloy properties both frictional wear and biological. Preliminary in vitro examinations show good biocompatibility and antithrombogenic properties.

  4. Microstructure and Texture Evolution During Sub-Transus Thermomechanical Processing of Ti-6Al-4V-0.1B Alloy: Part I. Hot Rolling in (α + β) Phase Field

    NASA Astrophysics Data System (ADS)

    Roy, Shibayan; Suwas, Satyam

    2013-07-01

    In the current study, the evolution of microstructure and texture has been studied for Ti-6Al-4V-0.1B alloy during sub-transus thermomechanical processing. This part of the work deals with the deformation response of the alloy by rolling in the (α + β) phase field. The (α + β) annealing behavior of the rolled specimen is communicated in part II. Rolled microstructures of the alloys exhibit either kinked or straight α colonies depending on their orientations with respect to the principal rolling directions. The Ti-6Al-4V-0.1B alloy shows an improved rolling response compared with the alloy Ti-6Al-4V because of smaller α lamellae size, coherency of α/β interfaces, and multiple slip due to orientation factors. Accelerated dynamic globularization for this alloy is similarly caused by the intralamellar transverse boundary formation via multiple slip and strain accumulation at TiB particles. The (0002)α pole figures of rolled Ti-6Al-4V alloy shows "TD splitting" at lower rolling temperatures because of strong initial texture. Substantial β phase mitigates the effect of starting texture at higher temperature so that "RD splitting" characterizes the basal pole figure. Weak starting texture and easy slip transfer for Ti-6Al-4V-0.1B alloy produce simultaneous TD and RD splittings in basal pole figures at all rolling temperatures.

  5. Wear studies on plasma-sprayed Al2O3 and 8mole% of Yttrium-stabilized ZrO2 composite coating on biomedical Ti-6Al-4V alloy for orthopedic joint application

    PubMed Central

    Ganapathy, Perumal; Manivasagam, Geetha; Rajamanickam, Asokamani; Natarajan, Alagumurthi

    2015-01-01

    This paper presents the wear characteristics of the composite ceramic coating made with Al2O3-40wt%8YSZ on the biomedical grade Ti-6Al-4V alloy (grade 5) used for total joint prosthetic components, with the aim of improving their tribological behavior. The coatings were deposited using a plasma spraying technique, and optimization of plasma parameters was performed using response surface methodology to obtain dense coating. The tribological behaviors of the coated and uncoated substrates were evaluated using a ball-on-plate sliding wear tester at 37°C in simulated body-fluid conditions. The microstructure of both the titanium alloy and coated specimen were examined using an optical microscope and scanning electron microscope. The hardness of the plasma-sprayed alumina–zirconia composite coatings was 2.5 times higher than that of the Ti-6Al-4V alloy, while the wear rate of Ti-6Al-4V alloy was 253 times higher than that of the composite-coated Ti-6Al-4V alloy. The superior wear resistance of the alumina–zirconia coated alloy is attributed to its enhanced hardness and intersplat bonding strength. Wear-track examination showed that the predominant wear mechanism of Ti-6Al-4V alloy was abrasive and adhesive wear, whereas, in the case of alumina–zirconia composite coated alloy, the wear was dominated by microchipping and microcracking. PMID:26491323

  6. Theoretical Assessment on the Phase Transformation Kinetic Pathways of Multi-component Ti Alloys: Application to Ti-6Al-4V

    DOE PAGESBeta

    Ji, Yanzhou; Heo, Tae Wook; Zhang, Fan; Chen, Long-Qing

    2015-12-21

    Here we present our theoretical assessment of the kinetic pathways during phase transformations of multi-component Ti alloys. Employing the graphical thermodynamic approach and an integrated free energy function based on the realistic thermodynamic database and assuming that a displacive structural transformation occurs much faster than long-range diffusional processes, we analyze the phase stabilities of Ti-6Al-4V (Ti-6wt.%Al-4wt.%V). Our systematic analyses predict a variety of possible kinetic pathways for β to (α + β) transformations leading to different types of microstructures under various heat treatment conditions. In addition, the possibility of unconventional kinetic pathways is discussed. Lastly, we also briefly discuss themore » application of our approach to general multicomponent/multiphase alloy systems.« less

  7. The effect of nitric acid exposure on Galileo spacecraft titanium alloy Ti-6Al-4V propellant tanks

    NASA Technical Reports Server (NTRS)

    Hsieh, Cheng; O'Donnell, Tim; Yavrouian, Andre

    1990-01-01

    The Ti-6Al-4V-constructed retropropulsion-module tanks of the Galileo spacecraft were purged with nitrogen tetroxide in order to wait out a major launch rescheduling; nitric acid is among the residual products of such an operation. A test program was conducted on representative samples to ascertain the fracture toughness and stress corrosion threshold of the tanks' material, in view of Space Shuttle safety and mission-reliability requirements. It was found that the tanks' structural integrity was not degraded by nitric acid exposure.

  8. Brazing ZrO{sub 2} ceramic to Ti–6Al–4V alloy using NiCrSiB amorphous filler foil: Interfacial microstructure and joint properties

    SciTech Connect

    Cao, J.; Song, X.G.; Li, C.; Zhao, L.Y.; Feng, J.C.

    2013-07-15

    Reliable brazing of ZrO{sub 2} ceramic and Ti–6Al–4V alloy was achieved using NiCrSiB amorphous filler foil. The interfacial microstructure of ZrO{sub 2}/Ti–6Al–4V joints was characterized by scanning electron microscope, energy dispersive spectrometer and micro-focused X-ray diffractometer. The effects of brazing temperature on the interfacial microstructure and joining properties of brazed joints were investigated in detail. Active Ti of Ti–6Al–4V alloy dissolved into molten filler metal and reacted with ZrO{sub 2} ceramic to form a continuous TiO reaction layer, which played an important role in brazing. Various reaction phases including Ti{sub 2}Ni, Ti{sub 5}Si{sub 3} and β-Ti were formed in brazed joints. With an increasing of brazing temperature, the TiO layer thickened gradually while the Ti{sub 2}Ni amount reduced. Shear test indicated that brazed joints tend to fracture at the interface between ZrO{sub 2} ceramic and brazing seam or Ti{sub 2}Ni intermetallic layer. The maximum average shear strength reached 284.6 MPa when brazed at 1025 °C for 10 min. - Graphical Abstract: Interfacial microstructure of ZrO{sub 2}/TC4 joint brazed using NiCrSiB amorphous filler foil was: ZrO{sub 2}/TiO/Ti{sub 2}Ni + β-Ti + Ti{sub 5}Si{sub 3}/β-Ti/Widmanstätten structure/TC4. - Highlights: • Brazing of ZrO{sub 2} ceramic and Ti-6Al-4V alloy was achieved. • Interfacial microstructure was TiO/Ti{sub 2}Ni + β + Ti{sub 5}Si{sub 3}/β/Widmanstätten structure. • The formation of TiO produced the darkening effect of ZrO{sub 2} ceramic. • The highest joining strength of 284.6MPa was obtained.

  9. Effect of micro shot peening on the mechanical properties and corrosion behavior of two microstructure Ti-6Al-4V alloy

    NASA Astrophysics Data System (ADS)

    Ahmed, Aymen A.; Mhaede, Mansour; Wollmann, Manfred; Wagner, Lothar

    2016-02-01

    Titanium alloys continue to be used extensively for the fabrication of surgical implants due to their excellent mechanical, physical and biological performance. The surface modification is the main technique to maintain a relatively good mechanical properties and biocompatibility. In this study, a surface modification through micro shot peening (SP) using different ceramic shot (850, 450 and 125-250 μm) at 0.22 mmA have been done on two microstructures Ti-6Al-4V alloy. The effect of this treatment on the corrosion behavior, surface roughness, microhardness profiles, and residual stresses were investigated. In addition, the corrosion behavior of the ultra-fine grain of Ti-6Al-4V materials produced by rotary swaging (RS) deformation has been investigated and compared with the duplex (DU) and globular (GL) microstructures. The corrosion behavior was studied using potentiodynamic polarization and electro impedance spectroscopy techniques. The electrochemical tests were performed in Ringer's solution at 37 °C. The results show that shot peening resulted in near-surface maximum hardness and residual stresses values. Increasing the shot size led to a lower surface roughness and an improved corrosion resistance. However, SP reduces the corrosion resistance compared with the untreated materials. The globular microstructure shows high corrosion rate compared with the duplex and nanostructured materials.

  10. Accurate Descriptions of Hot Flow Behaviors Across β Transus of Ti-6Al-4V Alloy by Intelligence Algorithm GA-SVR

    NASA Astrophysics Data System (ADS)

    Wang, Li-yong; Li, Le; Zhang, Zhi-hua

    2016-07-01

    Hot compression tests of Ti-6Al-4V alloy in a wide temperature range of 1023-1323 K and strain rate range of 0.01-10 s-1 were conducted by a servo-hydraulic and computer-controlled Gleeble-3500 machine. In order to accurately and effectively characterize the highly nonlinear flow behaviors, support vector regression (SVR) which is a machine learning method was combined with genetic algorithm (GA) for characterizing the flow behaviors, namely, the GA-SVR. The prominent character of GA-SVR is that it with identical training parameters will keep training accuracy and prediction accuracy at a stable level in different attempts for a certain dataset. The learning abilities, generalization abilities, and modeling efficiencies of the mathematical regression model, ANN, and GA-SVR for Ti-6Al-4V alloy were detailedly compared. Comparison results show that the learning ability of the GA-SVR is stronger than the mathematical regression model. The generalization abilities and modeling efficiencies of these models were shown as follows in ascending order: the mathematical regression model < ANN < GA-SVR. The stress-strain data outside experimental conditions were predicted by the well-trained GA-SVR, which improved simulation accuracy of the load-stroke curve and can further improve the related research fields where stress-strain data play important roles, such as speculating work hardening and dynamic recovery, characterizing dynamic recrystallization evolution, and improving processing maps.

  11. Characteristics of Ti(C, N)/TiB composite layer on Ti-6Al-4V alloy produced by laser surface melting

    NASA Astrophysics Data System (ADS)

    Zeng, Xian; Yamaguchi, Tomiko; Nishio, Kazumasa

    2016-06-01

    A Ti(C, N)/TiB reinforced titanium matrix composite layer was successfully in-situ synthesized by laser melting on Ti-6Al-4V alloy surface with Ti-BN-C mixed powder, aiming at improving the wear resistance. The microstructure, chemical composition, hardness and wear behavior were analyzed. The results showed that, the cross sectional microstructure can be clearly divided into three parts, which were the laser melted layer, heat affected zone and non-affected zone. The reinforcements in laser melted layer consisted of dendritic TiC0.3N0.7 phases and fine-structure TiB phases. The matrix in laser melted layer was in a two-phase structure, being composed of platelet α titanium and intergranular β titanium. The hardness was increased from 320 HV in the substrate to 450-550 HV in the modified layer. The wear resistance was improved that, the wear volume loss of the laser treated sample was approximately half of the as received Ti-6Al-4V alloy after 8 h wear test.

  12. Effects of high-energy electro-pulsing treatment on microstructure, mechanical properties and corrosion behavior of Ti-6Al-4V alloy.

    PubMed

    Ye, Xiaoxin; Wang, Lingsheng; Tse, Zion T H; Tang, Guoyi; Song, Guolin

    2015-04-01

    The effect of electro-pulsing treatment (EPT) on the microstructure, mechanical properties and corrosion behavior of cold-rolled Ti-6Al-4V alloy strips was investigated in this paper. It was found that the elongation to failure of materials obtains a noticeable enhancement with increased EPT processing time while slightly sacrificing strength. Fine recrystallized grains and the relative highest elongation to failure (32.5%) appear in the 11second-EPT samples. Grain coarsening and decreased ductility were brought in with longer EPT duration time. Fracture surface analysis shows that transition from intergranular brittle facture to transgranular dimple fracture takes place with an increase in processing time of EPT. Meanwhile, corrosion behavior of titanium alloys is greatly improved with increased EPT processing time, which is presented by polarization test and surface observation with the beneficial effect of forming a protective anatase-TiO2 film on the surface of alloys. The rapid recrystallization behavior and oxide formation of the titanium alloy strip under EPTs are attributed to the enhancement of nucleation rate, atomic diffusion and oxygen migration resulting from the coupling of the thermal and athermal effects. PMID:25687017

  13. Enhanced compatibility and initial stability of Ti6Al4V alloy orthodontic miniscrews subjected to anodization, cyclic precalcification, and heat treatment

    PubMed Central

    Oh, Eun-Ju; Nguyen, Thuy-Duong T.; Lee, Seung-Youp; Jeon, Young-Mi; Bae, Tae-Sung

    2014-01-01

    Objective To evaluate the bioactivity, and the biomechanical and bone-regenerative properties of Ti6Al4V miniscrews subjected to anodization, cyclic precalcification, and heat treatment (APH treatment) and their potential clinical use. Methods The surfaces of Ti6Al4V alloys were modified by APH treatment. Bioactivity was assessed after immersion in simulated body fluid for 3 days. The hydrophilicity and the roughness of APH-treated surfaces were compared with those of untreated (UT) and anodized and heat-treated (AH) samples. For in vivo tests, 32 miniscrews (16 UT and 16 APH) were inserted into 16 Wistar rats, one UT and one APH-treated miniscrew in either tibia. The miniscrews were extracted after 3 and 6 weeks and their osseointegration (n = 8 for each time point and group) was investigated by surface and histological analyses and removal torque measurements. Results APH treatment formed a dense surface array of nanotubular TiO2 layer covered with a compact apatite-like film. APH-treated samples showed better bioactivity and biocompatibility compared with UT and AH samples. In vivo, APH-treated miniscrews showed higher removal torque and bone-to-implant contact than did UT miniscrews, after both 3 and 6 weeks (p < 0.05). Also, early deposition of densely mineralized bone around APH-treated miniscrews was observed, implying good bonding to the treated surface. Conclusions APH treatment enhanced the bioactivity, and the biomechanical and bone regenerative properties of the Ti6Al4V alloy miniscrews. The enhanced initial stability afforded should be valuable in orthodontic applications. PMID:25309864

  14. A Comparison in Mechanical Properties of Cermets of Calcium Silicate with Ti-55Ni and Ti-6Al-4V Alloys for Hard Tissues Replacement

    PubMed Central

    Pramanik, Sumit; Shirazi, Seyed Farid Seyed; Mehrali, Mehdi; Yau, Yat-Huang; Abu Osman, Noor Azuan

    2014-01-01

    This study investigated the impact of calcium silicate (CS) content on composition, compressive mechanical properties, and hardness of CS cermets with Ti-55Ni and Ti-6Al-4V alloys sintered at 1200°C. The powder metallurgy route was exploited to prepare the cermets. New phases of materials of Ni16Ti6Si7, CaTiO3, and Ni31Si12 appeared in cermet of Ti-55Ni with CS and in cermet of Ti-6Al-4V with CS, the new phases Ti5Si3, Ti2O, and CaTiO3, which were emerged during sintering at different CS content (wt%). The minimum shrinkage and density were observed in both groups of cermets for the 50 and 100 wt% CS content, respectively. The cermets with 40 wt% of CS had minimum compressive Young's modulus. The minimum of compressive strength and strain percentage at maximum load were revealed in cermets with 50 and 40 wt% of CS with Ti-55Ni and Ti-6Al-4V cermets, respectively. The cermets with 80 and 90 wt% of CS showed more plasticity than the pure CS. It concluded that the composition and mechanical properties of sintered cermets of Ti-55Ni and Ti-6Al-4V with CS significantly depend on the CS content in raw cermet materials. Thus, the different mechanical properties of the cermets can be used as potential materials for different hard tissues replacements. PMID:25538954

  15. Determination of Specific Forces and Tool Deflections in Micro-milling of Ti-6Al-4V alloy using Finite Element Simulations and Analysis

    SciTech Connect

    Farina, Simone; Ceretti, Elisabetta; Thepsonti, Thanongsak; Oezel, Tugrul

    2011-05-04

    Titanium alloys offer superb properties in strength, corrosion resistance and biocompatibility and are commonly utilized in medical devices and implants. Micro-end milling process is a direct and rapid fabrication method for manufacturing medical devices and implants in titanium alloys. Process performance and quality depend upon an understanding of the relationship between cutting parameters and forces and resultant tool deflections to avoid tool breakage. For this purpose, FE simulations of chip formation during micro-end milling of Ti-6Al-4V alloy with an ultra-fine grain solid carbide two-flute micro-end mill are investigated using DEFORM software.At first, specific forces in tangential and radial directions of cutting during micro-end milling for varying feed advance and rotational speeds have been determined using designed FE simulations for chip formation process. Later, these forces are applied to the micro-end mill geometry along the axial depth of cut in 3D analysis of ABAQUS. Consequently, 3D distributions for tool deflections and von Misses stress are determined. These analyses will yield in establishing integrated multi-physics process models for high performance micro-end milling and a leap-forward to process improvements.

  16. Fabrication of dense α-alumina layer on Ti-6Al-4V alloy hybrid for bearing surfaces of artificial hip joint.

    PubMed

    Khanna, Rohit; Kokubo, Tadashi; Matsushita, Tomiharu; Takadama, Hiroaki

    2016-12-01

    Recent advances in hip replacements are focused towards producing reliable bearing surfaces to enhance their longevity. In this perspective, progressive attempts have been made to improve the wear resistance of polyethylene to eliminate osteolysis and mechanical reliability of brittle alumina ceramics, but in vain. It is proposed that both high wear resistance and mechanical reliability can be retained if a thin layer of dense alumina is formed onto high toughness Ti-6Al-4V alloy. For this purpose, we devised a unique methodology in which a layer of Al metal was deposited onto the Ti alloy substrate by cold spraying (CS), followed by a heat treatment to form Al3Ti reaction layer at their interface to improve adhesion and subsequent micro-arc oxidation (MAO) treatment to transform Al to alumina layer. An optimal MAO treatment of cold sprayed Al formed an adherent and dense α-alumina layer with high Vickers hardness matching with that of sintered alumina used as a femoral head. Structure-phase-property relationships in dense α-alumina layer have been revealed and discussed in the light of our research findings. The designed alumina/Ti alloy hybrid might be a potential candidate for reliable bearing surfaces of artificial hip joint. PMID:27612821

  17. Microstructure and Texture Evolution During Symmetric and Asymmetric Rolling of a Martensitic Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Chao, Qi; Hodgson, Peter D.; Beladi, Hossein

    2016-01-01

    In the current study, the effect of deformation mode ( i.e., symmetric vs asymmetric rolling) on the extent of grain refinement and texture development in Ti-6Al-4V was examined through warm rolling of a martensitic starting microstructure. During rolling, the initial martensitic lath structure was progressively fragmented, primarily through continuous dynamic recrystallization. This eventually led to an ultrafine-grained (UFG) microstructure composed of equiaxed grains with a mean size of 180 to 230 nm, mostly surrounded by high-angle grain boundaries. Depending on the rolling reduction and deformation mode (symmetric and asymmetric), the rolled specimens displayed different layer morphologies throughout the specimen thickness: a fully UFG surface layer, a partial UFG transition layer, and a partially fragmented lath interior layer. Due to a higher level of effective strain and continuous rotation of the principle axis, asymmetric rolling resulted in a greater extent of grain refinement compared with symmetric rolling at a given thermomechanical condition. A bulk UFG structure was successfully obtained using 70 pct asymmetric rolling. In addition, the rolling texture exhibited various characteristics throughout the thickness due to a different combination of shear and compressive strains. Principally, the basal texture component was displaced from the normal toward rolling direction during asymmetric rolling, differing from the symmetric rolling textures.

  18. Microstructure and Texture Evolution in Double-Cone Samples of Ti-6Al-4V Alloy with Colony Preform Microstructure

    NASA Astrophysics Data System (ADS)

    Yang, Kun Vanna; Lim, Chao Voon Samuel; Zhang, Kai; Sun, Jifeng; Yang, Xiaoguang; Huang, Aijun; Wu, Xinhua; Davies, Christopher H.

    2015-12-01

    Heat-treated Ti-6Al-4V forged bar with colony microstructure was machined into double-cone-shaped samples for a series of isothermal uniaxial compression test at 1223 K (950 °C) with varying constant crosshead speeds of 12.5, 1.25, and 0.125 mms-1 to a height reduction of 70 pct. Another set of samples deformed under the same conditions were heat treated at 1173 K (900 °C) for an hour followed by water quench. Finite element modeling was used to provide the strains, strain rates, and temperature profiles of the hot compression samples, and the microstructure and texture evolution was examined at four positions on each sample, representative of different strain ranges. Lamellae fragmentation and kinking are the dominant microstructural features at lower strain range up to a maximum of 2.0, whereas globularization dominates at strains above 2.0 for the as-deformed samples. The globularization fraction generally increases with strain, or by post-deformation heat treatment, but fluctuates at lower strain. The grain size of the globular α is almost constant with strain and maximizes for samples with the lowest crosshead speed due to the longer deformation time. The globular α grain also coarsens because of post-deformation heat treatment, with its size increasing with strain level. With respect to texture evolution, a basal transverse ring and another component 30 deg from ND is determined for samples deformed at 12.5 mms-1, which is consistent with the temperature increase to close to β-transus from simulation results. The texture type remains unchanged with its intensity increased and spreads with increasing strain.

  19. In vitro apatite formation on nano-crystalline titania layer aligned parallel to Ti6Al4V alloy substrates with sub-millimeter gap.

    PubMed

    Hayakawa, Satoshi; Matsumoto, Yuko; Uetsuki, Keita; Shirosaki, Yuki; Osaka, Akiyoshi

    2015-06-01

    Pure titanium substrates were chemically oxidized with H2O2 and subsequent thermally oxidized at 400 °C in air to form anatase-type titania layer on their surface. The chemically and thermally oxidized titanium substrate (CHT) was aligned parallel to the counter specimen such as commercially pure titanium (cpTi), titanium alloy (Ti6Al4V) popularly used as implant materials or Al substrate with 0.3-mm gap. Then, they were soaked in Kokubo's simulated body fluid (SBF, pH 7.4, 36.5 °C) for 7 days. XRD and SEM analysis showed that the in vitro apatite-forming ability of the contact surface of the CHT specimen decreased in the order: cpTi > Ti6Al4V > Al. EDX and XPS surface analysis showed that aluminum species were present on the contact surface of the CHT specimen aligned parallel to the counter specimen such as Ti6Al4V and Al. This result indicated that Ti6Al4V or Al specimens released the aluminum species into the SBF under the spatial gap. The released aluminum species might be positively or negatively charged in the SBF and thus can interact with calcium or phosphate species as well as titania layer, causing the suppression of the primary heterogeneous nucleation and growth of apatite on the contact surface of the CHT specimen under the spatial gap. The diffusion and adsorption of aluminum species derived from the half-sized counter specimen under the spatial gap resulted in two dimensionally area-selective deposition of apatite particles on the contact surfaces of the CHT specimen. PMID:25989935

  20. Faster methods for estimating arc centre position during VAR and results from Ti-6Al-4V and INCONEL 718 alloys

    NASA Astrophysics Data System (ADS)

    Nair, B. G.; Winter, N.; Daniel, B.; Ward, R. M.

    2016-07-01

    Direct measurement of the flow of electric current during VAR is extremely difficult due to the aggressive environment as the arc process itself controls the distribution of current. In previous studies the technique of “magnetic source tomography” was presented; this was shown to be effective but it used a computationally intensive iterative method to analyse the distribution of arc centre position. In this paper we present faster computational methods requiring less numerical optimisation to determine the centre position of a single distributed arc both numerically and experimentally. Numerical validation of the algorithms were done on models and experimental validation on measurements based on titanium and nickel alloys (Ti6Al4V and INCONEL 718). The results are used to comment on the effects of process parameters on arc behaviour during VAR.

  1. A study of calcium carbonate/multiwalled-carbon nanotubes/chitosan composite coatings on Ti-6Al-4V alloy for orthopedic implants

    NASA Astrophysics Data System (ADS)

    Ahmed, Rasha A.; Fekry, Amany M.; Farghali, R. A.

    2013-11-01

    In an attempt to increase the stability, bioactivity and corrosion resistance of Ti-6Al-4V alloy, chitosan (CS) biocomposite coatings reinforced with multiwalled-carbon nanotubes (MWCNTs), and calcium carbonate (CaCO3) for surface modification were utilized by electroless deposition. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) reveals the formation of a compact and highly crosslinked coatings. Electrochemical techniques were used to investigate the coats stability and resistivity for orthopedic implants in simulated body fluid (SBF). The results show that Est value is more positive in the following order: CaCO3/MWCNTs/CS > CS/MWCNTs > CS > MWCNTs. The calculated icorr was 0.02 nA cm-2 for CaCO3/MWCNTs/CS which suggested a high corrosion resistance.

  2. Multilayered TiAlN films on Ti6Al4V alloy for biomedical applications by closed field unbalanced magnetron sputter ion plating process.

    PubMed

    Yi, Peiyun; Peng, Linfa; Huang, Jiaqiang

    2016-02-01

    Ti6Al4V alloy has been widely used as a suitable material for surgical implants such as artificial hip joints. In this study, a series of multilayered gradient TiAlN coatings were deposited on Ti6Al4V substrate using closed field unbalanced magnetron sputter ion plating (CFUBMSIP) process. Taguchi design of experiment approach was used to reveal the influence of depositing parameters to the film composition and performance of TiAlN coatings. The phase structure and chemical composition of the TiAlN films were characterized by X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). Mechanical properties, including hardness, Young's modulus, friction coefficient, wear rate and adhesion strength were systematically evaluated. Potentiodynamic tests were conducted to evaluate the corrosion resistance of the coated samples in Ringer's solution at 37°C to simulate human body environment. Comprehensive performance of TiAlN films was evaluated by assigning different weight according to the application environment. S8, deposited by Ti target current of 8A, Al target current of 6A, bias voltage of -60V and nitrogen content with OEM (optical emission monitor) value of 45%, was found to achieve best performance in orthogonal experiments. Depositing parameters of S8 might be practically applied for commercialization of surgical implants. PMID:26652421

  3. Synthesis of High-Temperature Self-lubricating Wear Resistant Composite Coating on Ti6Al4V Alloy by Laser Deposition

    NASA Astrophysics Data System (ADS)

    Luo, Jian; Liu, Xiu-Bo; Xiang, Zhan-Feng; Shi, Shi-Hong; Chen, Yao; Shi, Gao-Lian; Wu, Shao-Hua; Wu, Yu-Nan

    2015-05-01

    Laser deposition was adopted to prepare novel Ni-based solid solution (γ-NiCrAlTi)/ TiC/α-Ti/CaF2 high-temperature self-lubricating wear resistant composite coating on Ti6Al4V alloy. Microstructure, micro-hardness, wear behavior, and counter-body effect of the coating were investigated systematically. It can be seen that the coating mainly consists of γ-NiCrAlTi, TiC, α-Ti, and small fine CaF2 particles. Average micro-hardness of the coating is 1023 HV0.3, which is about three-factor higher than that of Ti6Al4V substrate (380 HV0.3). The friction coefficient and wear rate of the coating decrease at all test temperatures to different extents with respect to the substrate. The improvement in wear resistance is believed to be the combined effects of the γ-NiCrAlTi solid solution, the dominating anti-wear capabilities of the reinforced TiC carbides, and the self-lubricating property of CaF2.

  4. Influence of damping coefficient from permanent magnets on chatter formation during end milling of titanium alloy (Ti-6Al-4V)

    NASA Astrophysics Data System (ADS)

    Sulaiman, S. A.; Amin, A. N.

    2015-12-01

    In machining operations, chatter is undesirable due to its adverse effects on the product quality, operation cost, machining accuracy and machine tool life. It is also responsible for reducing output. Chatter is a self-excitation phenomenon occurring in machine tools, in which the cutting process tends to lower the damping capacity of the machine structural components ending in an unstable behavior of the system. Chatter arises due to resonance when the vibrations of the instability of chip formation and the natural vibration modes of the machine-system components coincide. This paper focuses on the influence of damping coefficient from permanent magnets on chip serration frequency as an approach of minimizing chatter in end milling of Titanium alloy (Ti6Al4V). The method consists of two ferrite permanent magnet bars (dimensions: 1" × 6" × 3"), mounted 5mm from the cutting tool using a specially designed fixture which provided a uniform magnetic field of 2500-2700 Gausses. A titanium alloy Ti6Al4V block was then end milled using uncoated WC-Co inserts. A sequence of 15 experimental runs was conducted based on a small Central Composite Design (CCD) model in Response Surface Methodology (RSM). The primary (independent) parameters were: cutting speed, feed, and depth of cut. The data acquisition system comprised a vibration sensor (accelerometer) and a signal conditioning unit was used to measure the vibration data. The resultant vibrations were then analyzed using the DASYLab 5.6 software. Machining tests were conducted for two different conditions - with and without the application of magnets. Scanning Electron Microscope (SEM) was used to measure the chip segmentations. The SEM analysis of chip serrations demonstrated that the chip serration frequency were more stable while cutting under the presence of permanent magnets due to lower intensity of chatter.

  5. Identification of Stable Processing Parameters in Ti-6Al-4V Alloy from a Wide Temperature Range Across β Transus and a Large Strain Rate Range

    NASA Astrophysics Data System (ADS)

    Quan, Guo-Zheng; Wen, Hai-Rong; Pu, Shi-Ao; Zou, Zhen-Yu; Wu, Dong-Sen

    2015-11-01

    The hot workability of Ti-6Al-4V alloy was investigated according to the measured stress-strain data and their derived forms from a series of hot compressions at the temperatures of 1,023-1,323 K and strain rates of 0.01-10 s-1 with a height reduction of 60%. As the true strain was 0.3, 0.5, 0.7 and 0.9, respectively, the response maps of strain rate sensitivity (m-value), power dissipation efficiency (η-value) and instability parameter (ξ-value) to temperature and strain rate were developed on the basis of dynamic material model (DMM). Then the processing map was obtained by superimposition of the power dissipation and the instability maps. According to the processing map, the stable regions (η > 0 and ξ > 0) and unstable regions (η < 0 or ξ < 0) were clarified clearly. Further, the stable regions (temperatures of 1,198-1,248 K and strain rates of 0.01-0.1 s-1) with higher η value (> 0.3) corresponding to the ideal deformation mechanisms involving globularization and superplasticity were identified and recommended. The microstructures of the deformed samples were then observed by microscopy. And homogeneous microstructures with refined grains were found in the recommended parameter domains. The optimal working parameter domains identified by processing map and validated by microstructure observations contribute to the design in reasonable hot forming process of Ti-6Al-4V alloy without resorting to expensive and time-consuming trial-and-error methods.

  6. Innovative surface modification of Ti-6Al-4V alloy with a positive effect on osteoblast proliferation and fatigue performance.

    PubMed

    Havlikova, Jana; Strasky, Josef; Vandrovcova, Marta; Harcuba, Petr; Mhaede, Mansour; Janecek, Milos; Bacakova, Lucie

    2014-06-01

    A novel approach of surface treatment of orthopaedic implants combining electric discharge machining (EDM), chemical milling (etching) and shot peening is presented in this study. Each of the three techniques have been used or proposed to be used as a favourable surface treatment of biomedical titanium alloys. But to our knowledge, the three techniques have not yet been used in combination. Surface morphology and chemistry were studied by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Fatigue life of the material was determined and finally several in-vitro biocompatibility tests have been performed. EDM and subsequent chemical milling leads to a significant improvement of osteoblast proliferation and viability thanks to favourable surface morphology and increased oxygen content on the surface. Subsequent shot-peening significantly improves the fatigue endurance of the material. Material after proposed combined surface treatment possesses favourable mechanical properties and enhanced osteoblast proliferation. EDM treatment and EDM with shot peening also supported early osteogenic cell differentiation, manifested by a higher expression of collagen type I. The combined surface treatment is therefore promising for a range of applications in orthopaedics. PMID:24863238

  7. Effects of surface-treated cpTi and Ti6Al4V alloy on the initial attachment of human osteoblast cells.

    PubMed

    Oji, M O; Wood, J V; Downes, S

    1999-12-01

    This study concerns the effect of simple surface treatments on the nature of the oxide layer, of commercially pure titanium (cpTi) and Ti6Al4V alloy substrates and their effect on human osteoblast cells (HOBS). After treatment the surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) in order to identify the surface groups responsible for the cell attachment process. The assessment of cell attachment was monitored by the Alamar blue assay (AB), measuring cell activity, in three types of media: phosphate-buffered saline (PBS), serum containing and serum-free Dulbecco's modified Eagle's cell culture medium (SER+ and SERF respectively). XPS analysis of the treated surfaces revealed consistent peaks representative of TiO2 on all surfaces and Ti(0) and Ti2O3 on the non-heat-treated surfaces. The cell activity assays indicated that there were no significant differences in cellular activity caused by surface treatments, but the cellular activity compared between the three types of medium was greatest in the PBS over the initial stages of attachment. PMID:15347967

  8. Evaluation of physicochemical properties of surface modified Ti6Al4V and Ti6Al7Nb alloys used for orthopedic implants.

    PubMed

    Basiaga, Marcin; Kajzer, Wojciech; Walke, Witold; Kajzer, Anita; Kaczmarek, Marcin

    2016-11-01

    The paper presents the results of selected functional properties of TiO2 layers deposited by ALD method on the surface of Ti6Al4V and Ti6Al7Nb alloys intended for implants in bone surgery. TiO2 layer was applied at the constant temperature of the ALD process at T=200°C at a variable number of cycles, which resulted in a different layer thickness. Different process cycles of 500, 1250, and 2500 were analyzed. The application of experimental methods (AFM, SEM, wettability, potentiodynamic test, EIS, scratch test, nanohardness and layer thickness) enabled to select the optimal number of cycles, and thus the thickness of the TiO2 layer of the most favorable functional properties. The obtained results clearly showed that regardless of the type of titanium substrate, the TiO2 layer applied in a 2500cycle ALD process has the best physicochemical and electrochemical properties. These properties have major impact on biocompatibility, and therefore the quality of the final product. The information obtained can be useful for manufacturers of medical devices involved in the production of implants used in reconstructive surgery of skeletal system. PMID:27524088

  9. Pore Geometry Optimization of Titanium (Ti6Al4V) Alloy, for Its Application in the Fabrication of Customized Hip Implants

    PubMed Central

    Roy, Sandipan; Panda, Debojyoti; Khutia, Niloy; Chowdhury, Amit Roy

    2014-01-01

    The present study investigates the mechanical response of representative volume elements of porous Ti-6Al-4V alloy, to arrive at a desired range of pore geometries that would optimize the reduction in stiffness necessary for biocompatibility with the stress concentration arising around the pore periphery, under physiological loading conditions with respect to orthopedic hip implants. A comparative study of the two is performed with the aid of a newly defined optimizing parameter called pore efficiency that takes into consideration both the stiffness quantity and the stress localization around pores. To perform a detailed analysis of the response of the porous structure over the entire spectrum of loading conditions that a hip implant is subjected to in vivo, the mechanical responses of 3D finite element models of cubic and rectangular parallelepiped geometries, with porosities varying over a range of 10% to 60%, are simulated under representative compressive, flexural as well as combined loading conditions. The results that are obtained are used to suggest a range of pore diameters that lower the effective stiffness and modulus of the implant to around 60% of the stiffness and modulus of dense solid implants while keeping the stress levels within permissible limits. PMID:25400663

  10. Comparative assessment of structural and biological properties of biomimetically coated hydroxyapatite on alumina (alpha-Al2O3) and titanium (Ti-6Al-4V) alloy substrates.

    PubMed

    Kapoor, Renu; Sistla, Pavana Goury; Kumar, Jerald Mahesh; Raj, T Avinash; Srinivas, G; Chakraborty, Jui; Sinha, Mithlesh K; Basu, Debabrata; Pande, Gopal

    2010-09-01

    Previous reports have shown the use of hydroxyapatite (HAp) and related calcium phosphate coatings on metal and nonmetal substrates for preparing tissue-engineering scaffolds, especially for osteogenic differentiation. These studies have revealed that the structural properties of coated substrates are dependent significantly on the method and conditions used for coating and also whether the substrates had been modified prior to the coating. In this article, we have done a comparative evaluation of the structural features of the HAp coatings, prepared by using simulated body fluid (SBF) at 25 degrees C for various time periods, on a nonporous metal substrate titanium-aluminium-vanadium (Ti-6Al-4V) alloy and a bioinert ceramic substrate alpha-alumina (alpha-Al(2)O(3)), with and without their prior treatment with the globular protein bovine serum albumin (BSA). Our analysis of these substrates by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectrometry showed significant and consistent differences in the quantitative and qualitative properties of the coatings. Interestingly, the bioactivity of these substrates in terms of supporting in vitro cell adhesion and spreading, and in vivo effects of implanted substrates, showed a predictable pattern, thus indicating that some coated substrates prepared under our conditions could be more suitable for biological/biomedical applications. PMID:20730928

  11. Fatigue Life and Short Crack Behavior in Ti-6Al-4V Alloy; Interactions of Foreign Object Damage, Stress, and Temperature

    NASA Astrophysics Data System (ADS)

    Majidi, Behzad

    2008-04-01

    High-cycle fatigue (HCF) failures associated with foreign object damage (FOD) in turbine engines of military aircrafts have been of major concern for the aeronautic industry in recent years. The present work is focused on characterizing the effects of FOD on crack initiation and small crack growth of a Ti-6Al-4V alloy at ambient and also elevated temperatures. Results show that the preferred crack initiation site depends on applied stress and temperature as maximum fractions of cracks emanating from the simulated damage site, and naturally initiated cracks are observed at 25 °C under the maximum stress of 700 MPa and at 300 °C under the maximum stress of 300 MPa. The fatigue crack growth rate is influenced by increasing temperature, and the FCG rate at 300 °C is higher than that at room temperature under the same Δ K, whereas this effect for FOD-site initiated cracks is not so remarkable. This observation seems to be due to the effect of stress relaxation at 300 °C. Results also indicate that fatigue crack initiation life ( N i ) and fatigue life ( N f ) are expressed by three-parameter Weibull distribution function.

  12. Weld heat-affected zone in Ti-6Al-4V alloy. Part 2: Modeling and experimental simulation of growth and phase transformations

    SciTech Connect

    Shah, A.K.; Kulkarni, S.D.; Gopinathan, V.; Krishnan, R.

    1995-10-01

    The work carried out involved development of theoretical models to predict the {alpha} + {beta} {R_arrow} {beta} transformation during heating, grain growth, and subsequent transformation of {beta} on cooling in the Ti-6Al-4V alloy. The data for correlation of microstructure to mechanical properties have been generated experimentally using simulated HAZ (heat-affected zone) specimens. The overall effect of the weld variables on the HAZ microstructure can be visualized from the HAZ microstructure diagram which depicts various phase transformations occurring during the weld thermal cycle in t{sub 8/5}-T{sub p} space. The results of computer modeling indicate that due to the rapid heating and cooling cycles encountered in welding, the shift in {beta} transus may be hundreds of degrees. Also, in the near-HAZ region, the grains can grow an order of magnitude larger than the original grain size. The formation of lamellar {alpha} can be minimized by reducing the t{sub 8/5} parameter. The experimental simulation results confirm excessive grain growth in the HAZ region. The hardness values do not show any significant trend, but the fracture toughness is found to deteriorate in the HAZ.

  13. Experimental and numerical investigation of temperature distribution and melt pool geometry during pulsed laser welding of Ti6Al4V alloy

    NASA Astrophysics Data System (ADS)

    Akbari, Mohammad; Saedodin, Seyfolah; Toghraie, Davood; Shoja-Razavi, Reza; Kowsari, Farshad

    2014-07-01

    This paper reports on a numerical and experimental investigation of laser welding of titanium alloy (Ti6Al4V) for modeling the temperature distribution to predict the heat affected zone (HAZ), depth and width of the molten pool. This is a transient three-dimensional problem in which, because of simplicity, the weld pool surface is considered flat. The complex physical phenomenon causing the formation of keyhole has not been considered. The temperature histories of welding process were studied. It was observed that the finite volume thermal model was in good agreement with the experimental data. Also, we predicted the temperature as a function of distance at different laser welding speeds and saw that at each welding speed, the temperature profile was decreased sharply in points close to the laser beam center, and then decreased slightly in the far region from the laser beam center. The model prediction error was found to be in the 2-17% range with most numerical values falling within 7% of the experimental values.

  14. A Comparative Study on Johnson Cook, Modified Zerilli-Armstrong and Arrhenius-Type Constitutive Models to Predict High-Temperature Flow Behavior of Ti-6Al-4V Alloy in α + β Phase

    NASA Astrophysics Data System (ADS)

    Cai, Jun; Wang, Kuaishe; Han, Yingying

    2016-03-01

    True stress and true strain values obtained from isothermal compression tests over a wide temperature range from 1,073 to 1,323 K and a strain rate range from 0.001 to 1 s-1 were employed to establish the constitutive equations based on Johnson Cook, modified Zerilli-Armstrong (ZA) and strain-compensated Arrhenius-type models, respectively, to predict the high-temperature flow behavior of Ti-6Al-4V alloy in α + β phase. Furthermore, a comparative study has been made on the capability of the three models to represent the elevated temperature flow behavior of Ti-6Al-4V alloy. Suitability of the three models was evaluated by comparing both the correlation coefficient R and the average absolute relative error (AARE). The results showed that the Johnson Cook model is inadequate to provide good description of flow behavior of Ti-6Al-4V alloy in α + β phase domain, while the predicted values of modified ZA model and the strain-compensated Arrhenius-type model could agree well with the experimental values except under some deformation conditions. Meanwhile, the modified ZA model could track the deformation behavior more accurately than other model throughout the entire temperature and strain rate range.

  15. Characterization of titanium alloys for cryogenic applications

    NASA Astrophysics Data System (ADS)

    Reytier, M.; Kircher, F.; Levesy, B.

    2002-05-01

    Titanium alloys are employed in the design of superconducting magnet support systems for their high mechanical strength associated with their low thermal conductivity. But their use requires a careful attention to their crack tolerance at cryogenic temperature. Measurements have been performed on two extra low interstitial materials (Ti-5Al-2.5Sn ELI and Ti-6Al-4V ELI) with different thickness and manufacturing process. The investigation includes the tensile properties at room and liquid helium temperatures using smooth and notched samples. Moreover, the fracture toughness has been determined at 4.2 K using Compact Tension specimens. The microstructure of the different alloys and the various fracture surfaces have also been studied. After a detailed description of the experimental procedures, practical engineering characteristics are given and a comparison of the different titanium alloys is proposed for cryogenic applications.

  16. The diameter of nanotubes formed on Ti-6Al-4V alloy controls the adhesion and differentiation of Saos-2 cells.

    PubMed

    Filova, Elena; Fojt, Jaroslav; Kryslova, Marketa; Moravec, Hynek; Joska, Ludek; Bacakova, Lucie

    2015-01-01

    Ti-6Al-4V-based nanotubes were prepared on a Ti-6Al-4V surface by anodic oxidation on 10 V, 20 V, and 30 V samples. The 10 V, 20 V, and 30 V samples and a control smooth Ti-6Al-4V sample were evaluated in terms of their chemical composition, diameter distribution, and cellular response. The surfaces of the 10 V, 20 V, and 30 V samples consisted of nanotubes of a relatively wide range of diameters that increased with the voltage. Saos-2 cells had a similar initial adhesion on all nanotube samples to the control Ti-6Al-4V sample, but it was lower than on glass. On day 3, the highest concentrations of both vinculin and talin measured by enzyme-linked immunosorbent assay and intensity of immunofluorescence staining were on 30 V nanotubes. On the other hand, the highest concentrations of ALP, type I collagen, and osteopontin were found on 10 V and 20 V samples. The final cellular densities on 10 V, 20 V, and 30 V samples were higher than on glass. Therefore, the controlled anodization of Ti-6Al-4V seems to be a useful tool for preparing nanostructured materials with desirable biological properties. PMID:26648719

  17. Interfacial reaction of intermetallic compounds of ultrasonic-assisted brazed joints between dissimilar alloys of Ti6Al4V and Al4Cu1Mg.

    PubMed

    Ma, Zhipeng; Zhao, Weiwei; Yan, Jiuchun; Li, Dacheng

    2011-09-01

    Ultrasonic-assisted brazing of Al4Cu1Mg and Ti6Al4V using Zn-based filler metal (without and with Si) has been investigated. Before brazing, the Ti6Al4V samples were pre-treated by hot-dip aluminizing and ultrasonic dipping in a molten filler metal bath in order to control the formation of intermetallic compounds between the Ti6Al4V samples and the filler metal. The results show that the TiAl(3) phase was formed in the interface between the Ti6Al4V substrate and the aluminized coating. For the Zn-based filler metal without Si, the Ti6Al4V interfacial area of the brazed joint did not change under the effect of the ultrasonic wave, and only consisted of the TiAl(3) phase. For the Zn-based filler metal with Si, the TiAl(3) phase disappeared and a Ti(7)Al(5)Si(12) phase was formed at the interfacial area of the brazed joints under the effect of the ultrasonic wave. Due to the TiAl(3) phase completely changing to a Ti(7)Al(5)Si(12) phase, the morphology of the intermetallic compounds changed from a block-like shape into a lamellar-like structure. The highest shear strength of 138MPa was obtained from the brazed joint free of the block-like TiAl(3) phase. PMID:21489846

  18. The diameter of nanotubes formed on Ti-6Al-4V alloy controls the adhesion and differentiation of Saos-2 cells

    PubMed Central

    Filova, Elena; Fojt, Jaroslav; Kryslova, Marketa; Moravec, Hynek; Joska, Ludek; Bacakova, Lucie

    2015-01-01

    Ti-6Al-4V-based nanotubes were prepared on a Ti-6Al-4V surface by anodic oxidation on 10 V, 20 V, and 30 V samples. The 10 V, 20 V, and 30 V samples and a control smooth Ti-6Al-4V sample were evaluated in terms of their chemical composition, diameter distribution, and cellular response. The surfaces of the 10 V, 20 V, and 30 V samples consisted of nanotubes of a relatively wide range of diameters that increased with the voltage. Saos-2 cells had a similar initial adhesion on all nanotube samples to the control Ti-6Al-4V sample, but it was lower than on glass. On day 3, the highest concentrations of both vinculin and talin measured by enzyme-linked immunosorbent assay and intensity of immunofluorescence staining were on 30 V nanotubes. On the other hand, the highest concentrations of ALP, type I collagen, and osteopontin were found on 10 V and 20 V samples. The final cellular densities on 10 V, 20 V, and 30 V samples were higher than on glass. Therefore, the controlled anodization of Ti-6Al-4V seems to be a useful tool for preparing nanostructured materials with desirable biological properties. PMID:26648719

  19. Development of Laser Fabricated Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    deGroh, Henry C., III

    2006-01-01

    Laser Engineered Net Shaping (LENS) depositions with Ti-6Al-4V gas-atomized powder were accomplished at five different temperatures, ranging from 30 to 400 C, imposed on the base plate. These base plate temperatures were employed in an effort to relieve stresses which develop during the deposition. Warpage of the base plate was monitored. Only a slight decline in warpage was observed as the base plate temperature was increased. Results indicate that substrate temperatures closer to the stress relief minimum of 480 C would relieve deposition stresses, though process parameters would likely need to be modified to compensate for the higher base plate temperature. The compositions of the as-received powder and the LENS deposited material were chemically analyzed. The oxygen content of the LENS material was 0.154 wt.% which is less than the maximum impurity limit of 0.2 percent for commercial Ti-6Al-4V alloys, but is over the limit allowed in ELI grade (0.13 percent). The level of oxygen in the commercial base plate used was only 0.0635 percent. Tensile specimens were machined from the LENS deposited material and tested in tension at room temperature. The ultimate and yield tensile stresses of the LENS material were about 1200 and 1150 MPa respectively, which is about 20 percent higher than the strengths of wrought Ti-6Al-4V. The higher strength of the LENS material was due to its fine structure and high oxygen content. The LENS deposits were not fully dense; voids were frequent at the interfaces between deposited layers. These dispersed sheets of voids were parallel to the longitudinal axis of the resulting tensile specimens. Apparently there was sufficient continuous, fully dense material longitudinally to enable the high strengths. Ductility was low in the LENS material. Percent elongation at failure in the LENS material was near 4 percent, which is less than half of what is usually expected from Ti-6Al-4V. The low ductility was caused by high oxygen levels, and the

  20. Fatigue Life of Titanium Alloys Fabricated by Additive Layer Manufacturing Techniques for Dental Implants

    NASA Astrophysics Data System (ADS)

    Chan, Kwai S.; Koike, Marie; Mason, Robert L.; Okabe, Toru

    2013-02-01

    Additive layer deposition techniques such as electron beam melting (EBM) and laser beam melting (LBM) have been utilized to fabricate rectangular plates of Ti-6Al-4V with extra low interstitial (ELI) contents. The layer-by-layer deposition techniques resulted in plates that have different surface finishes which can impact significantly on the fatigue life by providing potential sites for fatigue cracks to initiate. The fatigue life of Ti-6Al-4V ELI alloys fabricated by EBM and LBM deposition techniques was investigated by three-point testing of rectangular beams of as-fabricated and electro-discharge machined surfaces under stress-controlled conditions at 10 Hz until complete fracture. Fatigue life tests were also performed on rolled plates of Ti-6Al-4V ELI, regular Ti-6Al-4V, and CP Ti as controls. Fatigue surfaces were characterized by scanning electron microscopy to identify the crack initiation site in the various types of specimen surfaces. The fatigue life data were analyzed statistically using both analysis of variance techniques and the Kaplan-Meier survival analysis method with the Gehan-Breslow test. The results indicate that the LBM Ti-6Al-4V ELI material exhibits a longer fatigue life than the EBM counterpart and CP Ti, but a shorter fatigue life compared to rolled Ti-6Al-4V ELI. The difference in the fatigue life behavior may be largely attributed to the presence of rough surface features that act as fatigue crack initiation sites in the EBM material.

  1. Microscopic Morphology and Microstructure of Ti-N and Ti-Ni Phase Between the Dilution Zone and the Clad Zone in Laser Remelting NiCrBSi/TiN Layer on Ti-6Al-4V Alloy Surface

    NASA Astrophysics Data System (ADS)

    Liu, Rongxiang; Guo, Lixin; Lei, Tingquan

    The microscopic morphology and microstructure of Ti-N and Ti-Ni phase between the dilution zone and the clad zone in laser remelting NiCrBSi/TiN layer on a Ti-6Al-4V alloy were characterized using TEM and SEM. The experimental results showed that during laser irradiation heating, TiN particles were partially dissolved into the melted Ni-base alloy, and the dissolved Ti and N atoms were precipitated in the form of TiN, TiN0.3. Ti exhibits height activity, it combines with Ni forming Ti2Ni, TiNi matrix intermetallic during laser remelting, faults exist in the Ti2Ni and TiNi phase, and crystal lattice of TiNi phase is superlattice. Lastly, the cause of the formation of the Ti-N and Ti-Ni phase is discussed.

  2. Determination of structural, mechanical and corrosion properties of Nb2O5 and (NbyCu 1-y)Ox thin films deposited on Ti6Al4V alloy substrates for dental implant applications.

    PubMed

    Mazur, M; Kalisz, M; Wojcieszak, D; Grobelny, M; Mazur, P; Kaczmarek, D; Domaradzki, J

    2015-02-01

    In this paper comparative studies on the structural, mechanical and corrosion properties of Nb2O5/Ti and (NbyCu1-y)Ox/Ti alloy systems have been investigated. Pure layers of niobia and niobia with a copper addition were deposited on a Ti6Al4V titanium alloy surface using the magnetron sputtering method. The physicochemical properties of the prepared thin films were examined with the aid of XRD, XPS SEM and AFM measurements. The mechanical properties (i.e., nanohardness, Young's modulus and abrasion resistance) were performed using nanoindentation and a steel wool test. The corrosion properties of the coatings were determined by analysis of the voltammetric curves. The deposited coatings were crack free, exhibited good adherence to the substrate, no discontinuity of the thin film was observed and the surface morphology was homogeneous. The hardness of pure niobium pentoxide was ca. 8.64GPa. The obtained results showed that the addition of copper into pure niobia resulted in the preparation of a layer with a lower hardness of ca. 7.79 GPa (for niobia with 17 at.% Cu) and 7.75 GPa (for niobia with 25 at.% Cu). The corrosion properties of the tested thin films deposited on the surface of titanium alloy depended on the composition of the thin layer. The addition of copper (i.e. a noble metal) to Nb2O5 film increased the corrosion resistance followed by a significant decrease in the value of corrosion currents and, in case of the highest Cu content, the shift of corrosion potential towards the noble direction. The best corrosion properties were obtained from a sample of Ti6Al4V coated with (Nb0.75Cu0.25)Ox thin film. It seems that the tested materials could be used in the future as protection coatings for Ti alloys in biomedical applications such as implants. PMID:25492191

  3. Microstructure and high-temperature oxidation resistance of TiN/Ti3Al intermetallic matrix composite coatings on Ti6Al4V alloy surface by laser cladding

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaowei; Liu, Hongxi; Wang, Chuanqi; Zeng, Weihua; Jiang, Yehua

    2010-11-01

    A high-temperature oxidation resistant TiN embedded in Ti3Al intermetallic matrix composite coating was fabricated on titanium alloy Ti6Al4V surface by 6kW transverse-flow CO2 laser apparatus. The composition, morphology and microstructure of the laser clad TiN/Ti3Al intermetallic matrix composite coating were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high-temperature oxidation resistance of the composite coatings and the titanium alloy substrate, isothermal oxidation test was performed in a conventional high-temperature resistance furnace at 600°C and 800°C respectively. The result shows that the laser clad intermetallic composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like, and dendrites), and uniformly distributed in the Ti3Al matrix. It indicates that a physical and chemical reaction between the Ti powder and AlN powder occurred completely under the laser irradiation. In addition, the microhardness of the TiN/Ti3Al intermetallic matrix composite coating is 844HV0.2, 3.4 times higher than that of the titanium alloy substrate. The high-temperature oxidation resistance test reveals that TiN/Ti3Al intermetallic matrix composite coating results in the better modification of high-temperature oxidation behavior than the titanium substrate. The excellent high-temperature oxidation resistance of the laser cladding layer is attributed to the formation of the reinforced phase TiN and Al2O3, TiO2 hybrid oxide. Therefore, the laser cladding TiN/Ti3Al intermetallic matrix composite coating is anticipated to be a promising oxidation resistance surface modification technique for Ti6Al4V alloy.

  4. Growth of aluminum-free porous oxide layers on titanium and its alloys Ti-6Al-4V and Ti-6Al-7Nb by micro-arc oxidation.

    PubMed

    Duarte, Laís T; Bolfarini, Claudemiro; Biaggio, Sonia R; Rocha-Filho, Romeu C; Nascente, Pedro A P

    2014-08-01

    The growth of oxides on the surfaces of pure Ti and two of its ternary alloys, Ti-6Al-4V and Ti-6Al-7Nb, by micro-arc oxidation (MAO) in a pH 5 phosphate buffer was investigated. The primary aim was to form thick, porous, and aluminum-free oxide layers, because these characteristics favor bonding between bone and metal when the latter is implanted in the human body. On Ti, Ti-6Al-4 V, and Ti-6Al-7Nb, the oxides exhibited breakdown potentials of about 200 V, 130 V, and 140 V, respectively, indicating that the oxide formed on the pure metal is the most stable. The use of the MAO procedure led to the formation of highly porous oxides, with a uniform distribution of pores; the pores varied in size, depending on the anodizing applied voltage and time. Irrespective of the material being anodized, Raman analyses allowed us to determine that the oxide films consisted mainly of the anatase phase of TiO2, and XPS results indicated that this oxide is free of Al and any other alloying element. PMID:24907769

  5. Osseointegration of Ti-6Al-4V alloy implants with a titanium nitride coating produced by a PIRAC nitriding technique: a long-term time course study in the rat.

    PubMed

    Sovak, Guy; Gotman, Irena; Weiss, Anna

    2015-02-01

    This study examined bone tissue responses to Ti-6Al-4V alloy implants with a hard TiN coating applied by an original powder immersion reaction-assisted coating (PIRAC) nitriding method. Progression of implant fixation in the distal epiphysis and within the medullary cavity of the rat femur was evaluated between 3 days and 6 months postimplantation by scanning electron microscopy, oxytetracycline incorporation, and histochemistry. After 6 months, successful osseointegration was achieved in both epiphyseal and diaphyseal sites. Throughout, implant portions located within the epiphysis remained in close contact with bone trabeculae that gradually engulfed the implant forming a bone collar continuous with the trabecular network of the epiphysis. In the diaphysis, woven bone was first formed within the marrow cavity around the implant and later was replaced by a shell of compact bone around the implant. In general, higher osseointegration rates were measured for TiN-coated versus the uncoated implants, both in the epiphysis and in the diaphysis. In conclusion, our findings indicate an excellent long-term biocompatibility of TiN coatings applied by the PIRAC nitriding technique and superior osteoinductive ability in comparison with uncoated Ti-6Al-4V alloy. Such coatings can, therefore, be considered for improving the corrosion and wear resistance of titanium-based orthopedic implants. PMID:25482093

  6. Drotrecogin alfa Eli Lilly.

    PubMed

    de Jonge, E

    2002-04-01

    Drotrecogin alfa (Xigris, recombinant activated protein C) is an anticoagulant developed and launched by Eli Lilly & Co for the treatment of sepsis [333781], [339372], [430133], [436271]. The FDA and the EMEA accepted the brand name Xigris for drotrecogin alfa in June 2001. This trade name had been proposed by Lilly in place of the previous brand name, Zovant, which was deemed unacceptable by the EMEA due to concerns that the name could be confused with hospital-based drugs [412512]. Filings for sepsis were made in the US, EU and Australia in February 2001 [398514], [447870] and in March 2001, the US FDA assigned drotrecogin alfa Priority Review status [403435]. The FDA extended the action date from July 27 to October 27, 2001 for completion of its review of the biologics license application (BLA) for drotrecogin alfa to assess further supplementary data submitted by Lilly [412512]. At the October 16, 2001 meeting (postponed from September 12), the FDA Advisory Committee on Anti-Infective Drugs split 10 to 10 over whether to recommend approval [425873], [425940]. In late October 2001, Lilly received an approvable letter from the FDA for the treatment of severe sepsis. Approval was contingent upon successful negotiation of labeling, agreement on post-approval clinical trials, and successful completion of manufacturing inspections [427301]. In November 2001, the FDA approved drotrecogin alfa for the reduction of mortality in adult patients with severe sepsis who have a high risk of death [430133]; the product was launched onto the US market days later [436271]. Following the FDA committee's split decision in October 2001, Credit Suisse First Boston, which expected mid-2002 approval but with restrictive labeling, revised its predictions from $1.265 billion in 2004 sharply downwards to $543 million [425929]. PMID:15565519

  7. Pemetrexed disodium (Eli Lilly).

    PubMed

    Norman, P

    2001-11-01

    Pemetrexed, a thymidylate synthase (TS) and transferase inhibitor, is in phase III trials with Eli Lilly as a potential treatment for several common solid tumors, including non-small cell lung cancer (NSCLC) and mesothelioma [321789], [410731]. Studies on pemetrexed have concluded that not only is the compound a TS inhibitor but also a potent inhibitor of human dihydrofolate reductase (DHFR). The results suggest that pemetrexed acts upon multiple intracellular targets and that the antitumor effect may be derived from its simultaneous inhibition of multiple folate-requiring enzymes [203662]: this compound has been designated as a multitargeted antifolate (MTA) [386680]. The drug also causes concentration- and time-dependent apoptosis [284380]. Other studies in which the 4-oxo group of the pyrimidine ring portion of pemetrexed was replaced with a hydrogen atom, demonstrated that the resulting analogs were potent DHFR inhibitors with very little activity against the enzymes glycinamide ribonucleotide formyltransferase (GARFT) and TS [310674]. In phase II European studies in 64 patients with advanced breast cancer, encouraging responses were seen in anthracycline-failure (23%) and anthracycline-refractory (19%) patients. Responses were observed in 28% of patients who had been previously treated with a taxane [326097]. Data from a phase II trial of pemetrexed (500 mg/m2 once every 21 days as a 10 min i.v. infusion) as a salvage therapy in advanced breast cancer showed that supplementation of the treatment regime with folic acid (FA) and vitamin B12 reduced its already manageable and tolerable toxicities [408821], [409650]. At doses of 500 mg/m2, the drug was also safely administered to 35 patients with impaired renal function [409953]. Phase I and II trials have shown that the main side effects include neutropenia, thrombocytopenia, mucositis, nausea and vomiting [203666], [272241]. Princeton University holds the patent rights to this drug under EP-00432677. In June

  8. Characterization of Ti-6%Al-4%V and VascoMax C-350

    SciTech Connect

    Sunwoo, A J

    2005-02-07

    The {alpha}-{beta} Ti-6% Al-4% V (Ti64) alloy can be heat treated to meet the specified requirements of the applications. The as-received material from SLAC was given a solution heat treatment (SHT) to have a good strength and ductility combination. The SHT was done at 200 C below the Beta transus of 990 C for 15 min and air-cooled to 20 C. The designed microstructure consists of {beta} phase precipitates within the {alpha} phase matrix. The characterization of the as-received Ti64 alloy sheet microstructure reveals equiaxed, 10 {micro}m-sized grains on the flat surface and finer, 8 {micro}m-sized grains in the through thickness. Figures 1 and 2 show the microstructure of the alloy. The typical Ti64 microstructure is lamellar structure, consisting of alternating {alpha} and {beta} phases. In order for the alloy to have the micron sized, equiaxed grains, it had to undergo extensive wrought processing. The Vicker's microhardness numbers (VHN) showed that the slightly larger grained flat surface had a higher averaged value than the through thickness; 33 kg/mm{sup 2} vs. 30 kg/mm{sup 2}. The residual effect of wrought processing is still present even after the SHT to cause the small difference in the hardness values. The results of tensile tests conducted at LLNL and at BNL are given in Tables 2 and 1 in Appendices 1 and 2, respectively. The effects of the irradiation dosage damage on the tensile properties of the Ti64 are presented in Appendix 2. The as-received tensile specimens are not the standard specimens for testing. As shown in Attachment, Figure 1, only the 6 mm length is used in the reduced gage section of the specimens. As a result, a small change in the gage length will translate to a higher percentage change in elongation, giving higher elongation values than using the 30 mm length of the specimen. Since most of the deformation is concentrated in the reduced gage section, the present results are more accurate measurement of ductility. The Ti64 specimens

  9. Effect of Surface Modifications of Ti40Zr10Cu38Pd12 Bulk Metallic Glass and Ti-6Al-4V Alloy on Human Osteoblasts In Vitro Biocompatibility

    PubMed Central

    Blanquer, Andreu; Hynowska, Anna; Nogués, Carme; Ibáñez, Elena; Sort, Jordi; Baró, Maria Dolors; Özkale, Berna; Pané, Salvador; Pellicer, Eva

    2016-01-01

    The use of biocompatible materials, including bulk metallic glasses (BMGs), for tissue regeneration and transplantation is increasing. The good mechanical and corrosion properties of Ti40Zr10Cu38Pd12 BMG and its previously described biocompatibility makes it a potential candidate for medical applications. However, it is known that surface properties like topography might play an important role in regulating cell adhesion, proliferation and differentiation. Thus, in the present study, Ti40Zr10Cu38Pd12 BMG and Ti6-Al-4V alloy were surface-modified electrochemically (nanomesh) or physically (microscratched) to investigate the effect of material topography on human osteoblasts cells (Saos-2) adhesion, proliferation and differentiation. For comparative purposes, the effect of mirror-like polished surfaces was also studied. Electrochemical treatments led to a highly interconnected hierarchical porous structure rich in oxides, which have been described to improve corrosion resistance, whereas microscratched surfaces showed a groove pattern with parallel trenches. Cell viability was higher than 96% for the three topographies tested and for both alloy compositions. In all cases, cells were able to adhere, proliferate and differentiate on the alloys, hence indicating that surface topography plays a minor role on these processes, although a clear cell orientation was observed on microscratched surfaces. Overall, our results provide further evidence that Ti40Zr10Cu38Pd12 BMG is an excellent candidate, in the present two topographies, for bone repair purposes. PMID:27243628

  10. Characterization and friction behavior of LST/PEO duplex-treated Ti6Al4V alloy with burnished MoS2 film

    NASA Astrophysics Data System (ADS)

    Qin, Yongkun; Xiong, Dangsheng; Li, Jianliang

    2015-08-01

    Laser surface-textured Ti6Al4V substrate was treated by plasma electrolytic oxidation process to prepare an oxide ceramic coating and then burnished with a thin MoS2 film. The area densities of textured dimples and the surface roughness of oxide ceramic underlay which affected the longevity of MoS2 films were thoroughly investigated. The results showed that a mixed surface pattern combining large textured dimples (diameter 150 μm) with small discharged dimples (diameter 5-17 μm) was fabricated by the LST/PEO duplex treatment and it contributed to prolonging the lubricating life of MoS2 film in comparison to the LST or PEO treatment. Wherein, the mixed dimples acted as lubricant reservoirs and the hard oxide coatings provided high load supports for the lubricating films. A much longer life of low friction was provided by the LST/PEO/MoS2 coatings with higher density of textured dimples (S = 55%) and lower roughness of LST/PEO surface (Ra = 1.0 μm).

  11. In situ strain profiling of elastoplastic bending in Ti-6Al-4V alloy by synchrotron energy dispersive x-ray diffraction

    SciTech Connect

    Croft, M.; Shukla, V.; Akdogan, E. K.; Sadangi, R.; Ignatov, A.; Balarinni, L.; Tsakalakos, T.; Jisrawi, N.; Zhong, Z.; Horvath, K.

    2009-05-01

    Elastic and plastic strain evolution under four-point bending has been studied by synchrotron energy dispersive x-ray diffraction. Measured strain profiles across the specimen thickness showed an increasing linear elastic strain gradient under increasing four-point bending load up to approx2 kN. The bulk elastic modulus of Ti-6Al-4V was determined as 118 GPa. The onset of plastic deformation was found to set in at a total in-plane strain of approx0.008, both under tension and compression. Plastic deformation under bending is initiated in the vicinity of the surface and at a stress of 1100 MPa, and propagates inward, while a finite core region remains elastically deformed up to 3.67 kN loading. The onset of the plastic regime and the plastic regime itself has been verified by monitoring the line broadening of the (100) peak of alpha-Ti. The effective compression/tension stress-strain curve has been obtained from the scaling collapse of strain profile data taken at seven external load levels. A similar multiple load scaling collapse of the plastic strain variation has also been obtained. The level of precision in strain measurement reported herein was evaluated and found to be 1.5x10{sup -5} or better.

  12. Direct Observations of Phase Transitions in Ti-6Al-4V Alloy Transient Welds using Time Resolved X-Ray Diffraction

    SciTech Connect

    Elmer, J W; Palmer, T A; Babu, S S; Zhang, W; Debroy, T

    2003-11-11

    Time Resolved X-Ray Diffraction (TRXRD) experiments were used to directly observe phase transformations occurring during gas tungsten arc spot welding of Ti-6Al-4V. These in-situ x-ray diffraction experiments tracked the evolution of the {alpha} {yields} {beta} {yields} L {yields} {beta} {yields} {alpha}/{alpha}{prime} phase transformation sequence in real time during rapid weld heating and cooling. Three different weld locations were examined, providing kinetic information about phase transformations in the fusion zone (FZ) and heat affected zone (HAZ) under different heating and cooling rates and at different temperatures. The TRXRD data were further coupled with the results of thermodynamic calculations of phase equilibria and numerical modeling to compute the weld temperatures. The results suggest that significant superheat is required above the {beta} transus temperature to complete the {alpha} {yields} {beta} transformation at all locations during weld heating, and that the amount of superheat decreases with distance from the center of the weld where the heating rates are lower. Johnson-Mehl-Avrami modeling of the weld heating kinetics produced a set of parameters that allowed the prediction of the {alpha} {yields} {beta} phase transformation rate at each location, but were not successful in determining a definitive mechanism for the transformation. The {beta} {yields} {alpha} transformation during weld cooling in the HAZ was shown to initiate at the {beta} transus temperature and reach completion below the Ms temperature, producing substantial {alpha}{prime}martensite. In the FZ, the {beta} {yields} {alpha} transformation during weld cooling was shown to initiate below the Ms temperature, and to completely transform the microstructure to {alpha}{prime} martensite.

  13. 78 FR 49723 - Humboldt-Toiyabe National Forests; Ely Ranger District; Ely Westside Rangeland Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-15

    ... Forest Service Humboldt-Toiyabe National Forests; Ely Ranger District; Ely Westside Rangeland Project... of the Ely Westside Rangeland Project began in 2006 with the original Notice of Intent published in... and conditions) on the allotments in the Ely Westside Rangeland Project area. The objection...

  14. In vitro biocompatibility, mechanical properties, and corrosion resistance of Ti-Zr-Nb-Ta-Pd and Ti-Sn-Nb-Ta-Pd alloys.

    PubMed

    Ito, A; Okazaki, Y; Tateishi, T; Ito, Y

    1995-07-01

    There is much discussion about the toxic effect of vanadium and aluminum contained in Ti-6Al-4V alloy for prosthetic implants. The goal of the present investigation was to develop new titanium alloys with sufficient mechanical properties using more biocompatible alloying elements: zirconium, tin, niobium, tantalum, and palladium. The relative growth rates of L929 and MC3T3-E1 cells were significantly higher when cultured with the extraction of Ti-10Zr-8Nb-2Ta-0.2Pd or Ti-15Zr-4Nb-2Ta-0.2Pd alloys than when cultured with the extraction of Ti-6Al-4AV ELI alloy. The tensile strength, elongation, and reduction of area for Ti-15Sn-4Nb-2Ta-0.2Pd alloy were 989 MPa, 14.4%, and 49.3%, respectively, surpassing Ti-6Al-4V ELI alloy. (ASTM F138-84); those for Ti-15Zr-4Nb-2Ta-0.2Pd alloy were 725 MPa, 23.6% and 54.9%, respectively. More than 15% addition of tin as well as zirconium deteriorated the tensile properties. Titanium release into a 5% hydrochloric acid solution from the new titanium alloys was 20-50 micrograms/cm2 per day, though that from Ti-6Al-4V ELI alloy was 1300 micrograms/cm2 per day. The optimum alloy compositions are Ti-15Zr-4Nb-2Ta-0.2Pd and Ti-15Sn-4Nb-2Ta-0.2Pd, judging from cytocompatibility, corrosion resistance, and mechanical properties. The former is characterized by its higher level cytocompatibility and corrosion resistance, while the latter is characterized by mechanical properties. PMID:7593029

  15. In vitro biological response of plasma electrolytically oxidized and plasma-sprayed hydroxyapatite coatings on Ti-6Al-4V alloy.

    PubMed

    Yeung, Wing Kiu; Reilly, Gwendolen C; Matthews, Allan; Yerokhin, Aleksey

    2013-08-01

    Plasma electrolytic oxidation (PEO) is a relatively new surface modification process that may be used as an alternative to plasma spraying methods to confer bioactivity to Ti alloy implants. The aim of this study was to compare physical, chemical and biological surface characteristics of two coatings applied by PEO processes, containing different calcium phosphate (CaP) and titanium dioxide phases, with a plasma-sprayed hydroxyapatite (HA) coating. Coating characteristics were examined by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, surface profilometry, and wettability tests. The biological properties were determined using the human osteoblastic cell line MG-63 to assess cell viability, calcium and collagen synthesis. The tests showed that PEO coatings are significantly more hydrophilic (6%) and have 78% lower surface roughness (Ra) than the plasma-sprayed coatings. Cell behavior was demonstrated to be strongly dependent on the phase composition and surface distribution of elements in the PEO coating. MG-63 viability for the TiO2 -based PEO coating containing amorphous CaPs was significantly lower than that for the PEO coating containing crystalline HA and the plasma-sprayed coating. However, collagen synthesis on both the CaP and the TiO2 PEO coatings was significantly higher (92% and 71%, respectively) than on the plasma-sprayed coating after 14 days. PEO has been demonstrated to be a promising method for coating of orthopedic implant surfaces. PMID:23529912

  16. Shock Response of Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Dandekar, Dattatraya P.; Spletzer, Stephen V.

    1999-06-01

    The properties of titanium alloys make them viable candidate materials for use in military ground vehicle systems. Ti-6Al-4V is an alloy that is currently used in aircraft/aerospace applications. However, to successfully make the transition to widespread use in the combat theater, the production and fabrication costs of this alloy must be reduced. Efforts to meet this goal have resulted in a new Ti-6Al-4V alloy material. This material was produced from 32% Ti sponge and 62% Ti-6Al-4V turnings. An ingot was formed by electron beam melting in a cold, water-cooled, copper hearth furnace. The motivation of this work is to characterize the shock response of the new alloy. Shock experiments were performed to obtain information pertaining to the shock, release, shock-reshock, and tensile behavior of the material.

  17. Materials data handbook. Titanium 6Al-4V

    NASA Technical Reports Server (NTRS)

    Muraca, R. F.; Whittick, J. S.

    1972-01-01

    A summary of the materials property information for Titanium 6Al-4V alloy is presented. The scope of the information includes physical and mechanical properties at cryogenic, ambient, and elevated temperatures. Information on material procurement, metallurgy of the alloy, corrosion, environmental effects, fabrication, and bonding is developed.

  18. Effect of the surface oxidization and nitridation on the normal spectral emissivity of titanium alloys Ti-6Al-4V at 800-1100 K at a wavelength of 1.5 μm

    NASA Astrophysics Data System (ADS)

    Zhu, Wenjie; Shi, Deheng; Zhu, Zunlue; Sun, Jinfeng

    2016-05-01

    This work strived to model the effect of surface oxidization and nitridation on the normal spectral emissivity of Ti-6Al-4V alloys at a temperature range of 800-1100 K and a wavelength of 1.5 μm. In experiments, the detector was as close to perpendicular to the surface of the specimens as possible so that only the normal spectral emissivity was measured. Two thermocouples were symmetrically welded near the measuring area for accurate measuring and monitoring of the temperature at the surface of the specimen. The specimens were heated for 6 h at a certain temperature. During this period, the normal spectral emissivity values were measured once every 1 min during the initial 180 min, and once every 2 min thereafter. The measurements were made at certain temperatures from 800 to 1100 K in intervals of 20 K. One strong oscillation in the normal spectral emissivity was observed at each temperature. The oscillations were formed by the interference between the radiation stemming from the oxidization and nitridation layer on the specimen surface and radiation from the substrate. The uncertainty in the normal spectral emissivity caused only by the surface oxidization and nitridation was found to be approximately 9.5-22.8%, and the corresponding uncertainty in the temperature generated only by the surface oxidization and nitridation was approximately 6.9-15.5 K. The model can reproduce well the normal spectral emissivity, including the strong oscillation that occurred during the initial heating period.

  19. Effect of outdoor exposure at ambient and elevated temperatures on fatigue life of Ti-6Al-4V titanium alloy sheet in the annealed and the solution treated and aged condition

    NASA Technical Reports Server (NTRS)

    Phillips, E. P.

    1974-01-01

    Specimens of Ti-6Al-4V titanium alloy sheet in the annealed and the solution-treated and aged heat-treatment condition were exposed outdoors at ambient and 560 K (550 F) temperatures to determine the effect of outdoor exposure on fatigue life. Effects of exposure were determined by comparing fatigue lives of exposed specimens to those of unexpected specimens. Two procedures for fatigue testing the exposed specimens were evaluated: (1) fatigue tests conducted outdoors by applying 1200 load cycles per week until failure occurred and (2) conventional fatigue tests (continuous cycling until failure occurred) conducted indoors after outdoor exposure under static load. The exposure period ranged from 9 to 28 months for the outdoor fatigue-test group and was 24 months for the static-load group. All fatigue tests were constant-amplitude bending of specimens containing a drilled hole (stress concentration factor of 1.6). The results of the tests indicate that the fatigue lives of solution-treated and aged specimens were significantly reduced by the outdoor exposure at 560 K but not by the exposure at ambient temperature. Fatigue lives of the annealed specimens were essentially unaffected by the outdoor exposure at either temperature. The two test procedures - outdoor fatigue test and indoor fatigue test after outdoor exposure - led to the same conclusions about exposure effects.

  20. Electrophoretic deposition of porous CaO-MgO-SiO2 glass-ceramic coatings with B2O3 as additive on Ti-6Al-4V alloy.

    PubMed

    Zhang, Wei; Chen, Xianchun; Liao, Xiaoming; Huang, Zhongbing; Dan, Xiuli; Yin, Guangfu

    2011-10-01

    The sub-micron glass-ceramic powders in CaO-MgO-SiO(2) system with 10 wt% B(2)O(3) additive were synthesized by sol-gel process. Then bioactive porous CaO-MgO-SiO(2) glass-ceramic coatings on Ti-6Al-4V alloy substrates were fabricated using electrophoretic deposition (EPD) technique. After being calcined at 850°C, the above coatings with thickness of 10-150 μm were uniform and crack-free, possessing porous structure with sub-micron and micron size connected pores. Ethanol was employed as the most suitable solvent to prepare the suspension for EPD. The coating porous appearance and porosity distribution could be controlled by adjusting the suspension concentration, applied voltage and deposition time. The heat-treated coatings possessed high crystalline and was mainly composed of diopside, akermanite, merwinite, calcium silicate and calcium borate silicate. Bonelike apatite was formed on the coatings after 7 days of soaking in simulated body fluid (SBF). The bonding strength of the coatings was needed to be further improved. PMID:21858723

  1. Mechanical properties and quality of diamond films synthesized on Ti{endash}6Al{endash}4V alloy using the microwave plasmas of CH{sub 4}/H{sub 2} and CO/H{sub 2} systems

    SciTech Connect

    Catledge, S.A.; Vohra, Y.K.

    1998-01-01

    Microwave plasma-enhanced chemical vapor deposition was used to grow diamond films on Ti{endash}6Al{endash}4V alloy using various gas phase precursors. The results of four types of experiments with different gas mixtures are compared: (1) 2{percent} CH{sub 4} in H{sub 2}; (2) initial saturation of 5{percent} CH{sub 4} in H{sub 2} followed by 2{percent} CH{sub 4} in H{sub 2}; (3) a CO-rich mixture with a CO:H{sub 2} ratio of 8; and (4) a hybrid mixture of 2{percent} CH{sub 4} in H{sub 2} followed by a CO:H{sub 2} ratio of 8. The substrate temperature during deposition with CH{sub 4}/H{sub 2} mixtures was between 715 and 810{degree}C, and was between 550 and 600{degree}C when CO/H{sub 2} mixtures were used. Optical emission spectroscopy was used to monitor the excited gas-phase species in the plasma. The films were characterized by micro-Raman spectroscopy, glancing-angle x-ray diffraction, and nanoindentation. The films grown with the type (1) mixture often exhibited good quality with high hardness (70 GPa) but suffered from poor adhesion to the substrate. The films grown with the type (2) mixture were of slightly lower quality and hardness (58 GPa) but exhibited better adhesion. The films produced from the type (3) mixture were adhered, but exhibited very low growth rates and low hardness (18 GPa). Finally, the films produced from the hybrid type (4) mixture were of poor quality and suffered from poor adhesion to the substrate. The differences in interfacial phases and mechanical properties for each film are discussed and the usefulness of each gas mixture for the diamond growth is evaluated. {copyright} {ital 1998 American Institute of Physics.}

  2. Local zone wise elastic and plastic properties of electron beam welded Ti-6Al-4V alloy using digital image correlation technique: A comparative study between uniform stress and virtual fields method

    NASA Astrophysics Data System (ADS)

    Saranath, K. M.; Ramji, M.

    2015-05-01

    Joining of materials using welding results in the formation of material zones with varying microstructure across the weld. Extraction of the mechanical properties of those individual heterogeneous zones are important in designing components and structures comprised of welds. In this study, the zone wise local extraction of the elastic and plastic properties of an electron beam welded Ti-6Al-4V titanium alloy has been carried out using both the uniform stress method (USM) and the virtual fields method (VFM) involving digital image correlation (DIC) technique. The surface strain field obtained using DIC technique from a transverse weld specimen tensile testing is used for extracting the zone wise strain evolution. Initially, using uniform stress assumption, zone wise full range stress-strain curves are extracted. In USM methodology, the elastic and plastic material models are fitted to the zone wise stress-strain curves and required parameters are extracted from it. But inherent disadvantage is lot of images need to be processed for the parameter extraction. Recently, VFM is gaining lot of popularity in characterization domain as it is robust, accurate and faster. VFM is based on the principle of virtual work where, the weak form of local equilibrium equations and kinematically admissible virtual displacement fields are utilized for parameter extraction. Hollomon's power law is used here as the hardening rule. Young's modulus, Poisson's ratio, yield stress, strength coefficient and strain hardening exponent are the parameters extracted zone wise using both USM and VFM. A Vicker's microhardness measurement is also conducted across the weld zone towards mapping the strength behavior. Fusion zone has reported higher yield strength, strength coefficient and Poisson's ratio. Young's modulus value is found decreasing from base metal towards the fusion zone. The trend observed in parameter variation across the weld zone obtained by both USM and VFM compares very well. Due

  3. Investigation on Tool Life and Surface Integrity when Drilling Ti-6Al-4V and Ti-5Al-4V-Mo/Fe

    NASA Astrophysics Data System (ADS)

    Rahim, Erween Abd.; Sharif, Safian

    Machinability study on the drilling of two alpha beta titanium alloy series, Ti-6Al-4V and Ti-5Al-4V-0.6Mo-0.4Fe were conducted using an uncoated carbide drill. The effect of cutting speed on tool life, tool failure mode, cutting force and surface integrity of the drilled surface were discussed. Results showed that Ti-6Al-4V exhibited a more superior machinability property when compared to the Ti-5Al-4V-Mo/Fe alloy system. The tool wear progression when drilling Ti-6Al-4V was lower than that of Ti-5Al-4V-Mo/Fe. The tool experienced similar failure mechanisms which were non uniform wear and chipping when drilling both alloys. At high cutting speed and after prolonged machining, excessive plastic deformation was observed on the subsurface layer of the drilled surface which resulted in increase in the hardness value.

  4. Powder metallurgy titanium 6A1-4V plate

    SciTech Connect

    Geisendorfer, R.F.

    1980-01-01

    A powder metallurgical approach has been combined with controlled mill processing to produce a highly uniform plate material suitable for structural applications. Prealloyed ELI Titanium 6A1-4V powder produced by the rotating electrode process was consolidated into billet by hot isostatic pressing. The resulting billet of uniform composition and random texture was then hot cross-rolled to 3 cm thick plate. Following rolling, the plate was given a beta annealing heat treatment to maximize damage tolerance. The plate was characterized with respect to metallurgical structure, composition, texture, and room temperature mechanical properties. The results of the study show that a powder metallurgy titanium mill product possessing uniform macro- and microstructure is technically feasible and exhibits tensile and fatigue properties equivalent to those of conventionally produced ingot-source wrought plate.

  5. Materials data handbook on titanium 6Al-4V

    NASA Technical Reports Server (NTRS)

    Muraca, R. F.; Whittick, J. S.

    1973-01-01

    Handbook has been prepared which describes latest property information on titanium 6Al-4V. Scope of information presented includes physical- and mechanical-property data at cryogenic, ambient, and elevated temperatures, supplemented with useful information in such areas as material procurement,metallurgy of alloy, corrosion, environmental effects, fabrication, and joining technology.

  6. On the fatigue behavior of medical Ti6Al4V roughened by grit blasting and abrasiveless waterjet peening.

    PubMed

    Lieblich, M; Barriuso, S; Ibáñez, J; Ruiz-de-Lara, L; Díaz, M; Ocaña, J L; Alberdi, A; González-Carrasco, J L

    2016-10-01

    Flat fatigue specimens of biomedical Ti6Al4V ELI alloy were surface-processed by high pressure waterjet peening (WJP) without abrasive particles using moderate to severe conditions that yield roughness values in the range of those obtained by commercial grit blasting (BL) with alumina particles. Fatigue behavior of WJP and BL specimens was characterized under cyclical uniaxial tension tests (R=0.1). The emphasis was put on a comparative analysis of the surface and subsurface induced effects and in their relevance on fatigue behavior. Within the experimental setup of this investigation it resulted that blasting with alumina particles was less harmful for fatigue resistance than abrasiveless WJP. BL specimens resulted in higher subsurface hardening and compressive residual stresses. Specimens treated with more severe WJP parameters presented much higher mass loss and lower compressive residual stresses. From the analysis performed in this work, it follows that, in addition to roughness, waviness emerges as another important topographic parameter to be taken into account to try to predict fatigue behavior. It is envisaged that optimization of WJP parameters with the aim of reducing waviness and mass loss should lead to an improvement of fatigue resistance. PMID:27454525

  7. "ELI"--The Educational Futures Game.

    ERIC Educational Resources Information Center

    Mahoney, V. L. Mike; Grantham, Lex

    This report describes ELI, a computer-based educational game that gives participants, as citizens of fictitious cities, the opportunity to examine a variety of typical community issues relating to education within the context of broader city and regional problems. After a brief introduction, the game structure is described, including the setting…

  8. Synthesis and characterization of Ni60-hBN high temperature self-lubricating anti-wear composite coatings on Ti6Al4V alloy by laser cladding

    NASA Astrophysics Data System (ADS)

    Lu, Xiao-Long; Liu, Xiu-Bo; Yu, Peng-Cheng; Qiao, Shi-Jie; Zhai, Yong-Jie; Wang, Ming-Di; Chen, Yao; Xu, Dong

    2016-04-01

    Ni60-hBN composite coatings with varying hBN content were prepared on Ti6Al4V substrates by laser cladding. The composite coatings with no cracks and few pores are bonded metallurgically with the substrates. The phase composition and microstructure of the composite coatings were investigated. The tribological properties of the composite coatings were evaluated under dry sliding wear test conditions at 20 °C, 300 °C and 600 °C, respectively. The microhardness gradually increased from the bottom to the top of the coating and increased with increasing of hBN content. The laser clad Ni60-10%hBN coating exhibits excellent tribological behavior at high temperatures (300 °C and 600 °C).

  9. Gamma beam system at ELI-NP

    SciTech Connect

    Ur, Calin Alexandru

    2015-02-24

    The Gamma Beam System of ELI-NP will produce brilliant, quasi-monochromatic gamma-ray beams via Inverse Compton Scattering of short laser pulses on relativistic electron beam pulses. The scattered radiation is Doppler upshifted by more than 1,000,000 times and is forward focused in a narrow, polarized, tunable, laser-like beam. The gamma-ray beam at ELI-NP will be characterized by large spectral density of about 10{sup 4} photons/s/eV, narrow bandwidth (< 0.5%) and tunable energy from 200 keV up to about 20 MeV. The Gamma Beam System is a state-of-the-art equipment employing techniques and technologies at the limits of the present-day's knowledge.

  10. Electronic Lab Information Exchange (ELIE) in Saudi Arabia.

    PubMed

    Al Saleem, Nouf; El Metwally, Ashraf; Househ, Mowafa

    2014-01-01

    The purpose of this paper is to discuss the Saudi experience in implementing Electronic Lab Information Exchange (ELIE) within healthcare organizations in Saudi Arabia. This paper reviews the benefits, challenges and achievements that Saudi Arabia has gone through over the last five years in implementing ELIE. Data sources included academic literature, websites, and informant interviews. Results show that various Saudi healthcare organizations are participating in ELIE and improvements in laboratory department workflow and patient care have been reported. Future work includes projects to be implemented in different laboratories within the Kingdom to link the various laboratory information systems to Electronic Health Records. Various challenges stand in the way of implementing ELIE including weakness of the information infrastructure, staff resistance, recruiting qualified staff to develop and implement ELIE, producing clear policy and procedures to ensure staff compliance with the data entry, ensuring the privacy and integrity of patient data, and the lack of awareness on the importance of ELIE. PMID:25000034

  11. Weld heat-affected zone in Ti-6Al-4V alloys. Part 1: Computer simulation of the effect of weld variables on the thermal cycles in the HAZ

    SciTech Connect

    Shah, A.K.; Kulkarni, S.D.; Gopinathan, V.; Krishnan, R.

    1995-09-01

    The weld thermal cycles encountered in the HAZ of titanium alloys have been characterized using modified Rosenthal equations. The results are shown in the form of axonometric plots depicting the effect of two weld variables keeping the other variables fixed. Computer simulation results show that the heat input and the plate thickness are the major variables affecting the thermal cycles in the HAZ. The effects of changes in welding speed are reflecting in the variation in the heat input. The electrode radius has minimal effect and can be termed as the minor variable. Preheat or interpass temperatures have an intermediate effect. An increase in electrode radius or decrease in plate thickness requires large apparent displacement of the heat source above the plate surface to be incorporated in the analytical solutions. The melt pool width increases sharply with an increase in the heat input (a/v) or a decrease in plate thickness (d); however, preheat temperature (T{sub 0}) has negligible effect. The effect of weld variables on the effective heat input is also similar. The t{sub 8/5} parameter increases sharply with reducing plate thickness or increasing heat input.

  12. Elie Metchnikoff, the Man and the Myth.

    PubMed

    Gordon, Siamon

    2016-01-01

    The year 2016 marks the centenary of the death of Elie Metchnikoff, the father of innate immunity and discoverer of the significance of phagocytosis in development, homeostasis and disease. Through a series of intravital experiments on invertebrates and vertebrates, he described the role of specialised phagocytic cells, macrophages and microphages, subsequently renamed neutrophils and polymorphonuclear leucocytes, in the host response to injury, inflammation, infection and tissue repair. As a vigorous proponent of cellular immunity, he championed its importance versus humoral immunity in the so-called antibody wars. By 1908, when the Nobel Prize was awarded to Elie Metchnikoff and Paul Ehrlich, this debate was not yet resolved. Even earlier, Metchnikoff had turned his research interests to the process of ageing and the possible link to intestinal auto-intoxication, giving rise to the current interest in the microbiome of the gut and the use of probiotics to promote health and longevity. During the past century, Metchnikoff's reputation has waxed and waned, as lymphocyte heterogeneity, specificity and memory began to dominate the field of adaptive immunity, yet his benign visage continues to provide an iconic presence for specialists in innate immunology, whose studies have made a striking comeback in the past decade. In this review, I shall consider the nature of his studies and the person as well as the legendary description of his Eureka experience in Messina in 1882, a story loved by students and investigators alike, that marked, in his own words, his transformation from zoologist to pathologist. PMID:26836137

  13. Laser remelting of Ti6AL4V using high power diode laser

    NASA Astrophysics Data System (ADS)

    Amaya-Vázquez, M. R.; Sánchez-Amaya, J. M.; Boukha, Z.; El Amrani, K.; Botana, F. J.

    2012-04-01

    Titanium alloys present excellent mechanical and corrosion properties, being widely employed in different industries such as medical, aerospace, automotive, petrochemical, nuclear and power generation, etc. Ti6Al4V is the α-β alloy most employed in industry. The modification of its properties can be achieved with convectional heat treatments and/or with laser processing. Laser remelting (LR) is a technology applied to Ti6Al4V by other authors with excimer and Nd-Yag laser with pure argon shielding gas to prevent risk of oxidation. In the present contribution, laser remelting has been applied for the first time to Ti6Al4V with a high power diode laser (with pure argon as shielding gas). Results showed that remelted samples (with medium energy densities) have higher microhardness and better corrosion resistance than Ti6Al4V base metal.

  14. Water droplet erosion mechanisms of Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Kamkar Zahmatkesh, Niloofar

    Water impingement erosion of materials can be a life-limiting phenomenon for the components in many erosive environments. For example, aircraft body exposed to rain, steam turbine blade, and recently in gas turbine coupled with inlet fogging system. The last is the focus of this study. Inlet fogging system is the most common method used to augment gas turbine output during hot days; high ambient temperature causes strong deterioration of the engine performance. Micro-scaled droplets introduced into the inlet airflow allow the cooling of entering air as well as intercooling the compressor (overspray) and thus optimizes the output power. However, erosion damage of the compressor blades in overspray stage is one of the major concerns associated with the inlet fogging system. The main objective of this research work (CRIAQ MANU419 project) is to understand the erosion induced by water droplets on Titanium alloy to eventually optimize the erosion resistance of the Ti-based compressor blade. Therefore, characterization of the water droplet erosion damage on Ti-6Al-4V receives the major importance. The influence of base material microstructure and impact parameters were considered in erosion evaluation in present study. This work covers the characterization of the erosion damage on Ti-6Al-4V alloy in two parts: - The water droplet erosion damage through a novel experimental approach. The collected data were processed both qualitatively and quantitatively for multi-aspects damage study. - The influence of impact velocity on erosion in an attempt to represent the in-service conditions.

  15. Characterization and analysis of surface notches on Ti-alloy plates fabricated by additive manufacturing techniques

    NASA Astrophysics Data System (ADS)

    Chan, Kwai S.

    2015-12-01

    Rectangular plates of Ti-6Al-4V with extra low interstitial (ELI) were fabricated by layer-by-layer deposition techniques that included electron beam melting (EBM) and laser beam melting (LBM). The surface conditions of these plates were characterized using x-ray micro-computed tomography. The depth and radius of surface notch-like features on the LBM and EBM plates were measured from sectional images of individual virtual slices of the rectangular plates. The stress concentration factors of individual surface notches were computed and analyzed statistically to determine the appropriate distributions for the notch depth, notch radius, and stress concentration factor. These results were correlated with the fatigue life of the Ti-6Al-4V ELI alloys from an earlier investigation. A surface notch analysis was performed to assess the debit in the fatigue strength due to the surface notches. The assessment revealed that the fatigue lives of the additively manufactured plates with rough surface topographies and notch-like features are dominated by the fatigue crack growth of large cracks for both the LBM and EBM materials. The fatigue strength reduction due to the surface notches can be as large as 60%-75%. It is concluded that for better fatigue performance, the surface notches on EBM and LBM materials need to be removed by machining and the surface roughness be improved to a surface finish of about 1 μm.

  16. Influence of surface modification on corrosion and biocompatibility of titanium alloys

    NASA Astrophysics Data System (ADS)

    Rahman, Zia Ur

    Titanium alloys are playing a vital role in the field of biomaterials due to their excellent corrosion resistance and biocompatibility. These alloys enhance the quality and longevity of human life by replacing or treating various parts of the body. However, as these materials are in constant contact with the aggressive body fluids, corrosion leads to metal ions dissolution. These ions leach to the adjacent tissues and causes adverse reactions. Surface modifications are used to improve corrosion resistance and biological activity without changing their bulk properties. In this investigation, electropolishing, magnetoelectropolishing, titanium coating and hydroxiapatitecoating were carried out on commercially pure titanium (CPTi), Ti6Al4V and Ti6Al4V-ELI (Extra Low Interstitials). These surface modifications are known to effect surface charge, chemistry, morphology; wettability, corrosion resistance and biocompatibility of these materials. In vitro cyclic potentiodynamic polarization tests were conducted in phosphate buffer saline in compliance with ASTM standard. The surface morphology, roughness and wettability of these alloys were studied using scanning electron microscope, atomic force microscope and contact angle meter, respectively. Moreover, biocompatibility of titanium alloys was assessed by growing MC3T3 pre-osteoblast cells on their surfaces

  17. Additive manufactured Ti6Al4V scaffolds with the RF- magnetron sputter deposited hydroxyapatite coating

    NASA Astrophysics Data System (ADS)

    Chudinova, E.; Surmeneva, M.; Koptioug, A.; Scoglund, P.; Surmenev, R.

    2016-01-01

    Present paper reports on the results of surface modification of the additively manufactured porous Ti6Al4V scaffolds. Radio frequency (RF) magnetron sputtering was used to modify the surface of the alloy via deposition of the biocompatible hydroxyapatite (HA) coating. The surface morphology, chemical and phase composition of the HA-coated alloy were studied. It was revealed that RF magnetron sputtering allows preparing a homogeneous HA coating onto the entire surface of scaffolds.

  18. 76 FR 53898 - Proposed Administrative Settlement Agreement and Order on Consent; In Re: Ely Copper Mine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-30

    ... AGENCY Proposed Administrative Settlement Agreement and Order on Consent; In Re: Ely Copper Mine... concerning the Ely Copper Mine Superfund Site in Vershire, Vermont with the following settling party: Ely... e-mail at gardner.ann@epa.gov . Additional information on the Ely Copper Mine Superfund Site can...

  19. Processing and properties of Ti-6Al-4V hollow sphere foams from hydride powder

    NASA Astrophysics Data System (ADS)

    Hardwicke, Canan Uslu

    Honeycomb structures currently used in aerospace systems are expensive to manufacture, limited to sheet form, and present joining problems and mechanical anisotropy that promotes shear failure at low stresses. Metallic foams produced by point contact bonding of monosized hollow spheres offer an alternative if they can be processed into strong, light-weight, and reasonably priced structural materials. In this work, technology has been established for fabricating good quality, Ti-6Al-4V hollow sphere foams using the coaxial nozzle powder slurry technique. It was shown that hydride form of Ti-ELI can be used as the starting precursor powder and processed into fine particles of 1-10 mum size range without increasing the impurity levels. Hydride dispersion in acetone was provided by the addition of polyester/polyamine copolymers through electrosteric stabilization. Addition of PMMA to the pseudoplastically dispersed organic slurries helped bind hydride powder spherical shells. Furthermore, monosized Ti-6Al-4V hollow spheres were sintered to 98% dense cell walls in Ar and point-contact bonded into closed-cell foams through solid-state diffusion. These findings suggest that near-net shape Ti-6Al-4V structures may be produced with isotropic properties, strength, toughness, and densities as low as 10% of the bulk. Findings concerning the optimum processing parameters and implications for future research are discussed.

  20. Crystallographic variant selection in Ti-6Al-4V

    SciTech Connect

    Stanford, N.; Bate, P.S. . E-mail: pete.bate@man.ac.uk

    2004-10-04

    Transformation textures in the two-phase alloy Ti-6Al-4V have been studied. Samples were heated into the fully {beta} phase condition and then slow cooled to allow diffusional transformation to {alpha}. This produced a microstructure of grain boundary {alpha} encircling colonies of Widmanstaetten {alpha}. Electron backscattered diffraction (EBSD) texture measurements showed that the {alpha} texture was markedly sharper than that calculated on a basis of equal variant probability, indicating that significant variant selection was occurring during diffusional transformation. Investigation of the {alpha} variants produced across prior {beta} grain boundaries has shown that the selection of variants during transformation is highly dependant on the crystallography of those boundaries. The effect of this crystallographic variant selection on the transformation texture has been modelled.

  1. Effect of UV irradiation on the surface Gibbs energy of Ti6Al4V and thermally oxidized Ti6Al4V.

    PubMed

    Pacha-Olivenza, M A; Gallardo-Moreno, A M; Méndez-Vilas, A; Bruque, J M; González-Carrasco, J L; González-Martín, M L

    2008-04-01

    Thermal oxidation of Ti6Al4V increases the thickness, modifies the structure, and changes the amount of alloying elements of the surface titanium dioxide layer with respect to the spontaneous passive layer of Ti6Al4V. The effects on the surface properties of Ti6Al4V and thermally oxidized Ti6Al4V after different periods of UV irradiation have been studied by measurement of water, formamide, and diiodomethane contact angles. The rate of modification of the water contact angle with the irradiation time is dependent on the surface treatment, but the water adhesion work, after an initial energetic step, follows a similar trend for both. Application of the Young equation together with the van Oss approach allowed evaluation of the surface Gibbs energy of the alloys. Similar to the water adhesion work, the surface Gibbs energy dependence on the irradiation time follows a similar trend for both samples and it is due to the change of the electron-donor parameter of the acid-base component. Also, a linear relationship common for both samples has been obtained between the cosines of the water contact angle and the formamide or diiodomethane contact angle. These facts indicate that the surface modification continuously produced by the UV irradiation is similar all along the process and similar for both samples after an energetic threshold for the thermally oxidized sample. It has been also tested that the hydrophilic-hydrophobic conversion is reversible for Ti6Al4V and Ti6Al4V thermally treated. PMID:18221751

  2. Treating orthopedic prosthesis with diamond-like carbon: minimizing debris in Ti6Al4V.

    PubMed

    Oliveira, Luciane Y S; Kuromoto, Neide K; Siqueira, Carlos J M

    2014-10-01

    Prostheses are subject to various forms of failing mechanisms, including wear from ordinary patient motion. Superficial treatments can improve tribological properties of the contact pair, minimizing wear and increasing prostheses lifetime. One possibility is the diamond-like carbon (DLC) coating, where Carbon is deposited with variable ratio of sp(2)/sp(3) structures, leading to an increase in surface hardness. So in this research Ti6Al4V samples were coated with DLC using sputtering process to evaluate the debris release. The Ti6Al4V and Ti6Al4V plus DLC coating surfaces were analyzed using Raman spectroscopy and instrumented indentation (hardness). The wear behavior was tested using a reciprocating linear tribometer. The wear rate was smaller in the coated samples, producing less debris than the untreated Ti6Al4V alloy. Debris morphology was also evaluated, using scanning electronic microscopy, and it was observed that debris size from the coated samples were bigger than those observed from the uncoated Ti6Al4V alloy, above the size that generally triggers biological response from the host. PMID:24948374

  3. Laser Processed TiN Reinforced Ti6Al4V Composite Coatings

    PubMed Central

    Balla, Vamsi Krishna; Bhat, Abhimanyu; Bose, Susmita; Bandyopadhyay, Amit

    2011-01-01

    The purpose of this first generation investigation is to evaluate fabrication, in vitro cytotoxicity, cell-materials interactions and tribological performance of TiN particle reinforced Ti6Al4V composite coatings for potential wear resistant load bearing implant applications. The microstructural analysis of the composites was performed using scanning electron microscope and phase analysis was done with X-ray diffraction. In vitro cell-materials interactions, using human fetal osteoblast cell line, have been assessed on these composite coatings and compared with Ti6Al4V alloy control samples. The tribological performance of the coatings were evaluated, in simulated body fluids, up to 1000 m sliding distance under 10N normal load. The results show that the composite coatings contain distinct TiN particles embedded in α + β phase matrix. The average top surface hardness of Ti6Al4V alloy increased from 394 ± 8 HV to 1138 ± 61 HV with 40 wt.% TiN reinforcement. Among the composite coatings, the coatings reinforced with 40 wt. % TiN exhibited the highest wear resistance of 3.74 × 10-6 mm3/Nm, which is lower than the wear rate, 1.04 × 10-5 mm3/Nm, of laser processed CoCrMo alloy tested under identical experimental conditions. In vitro biocompatibility study showed that these composite coatings were non-toxic and provides superior cell-material interactions compared to Ti6Al4V control, as a result of their high surface energy. In summary, excellent in vitro wear resistance and biocompatibility of present laser processed TiN reinforced Ti6Al4V alloy composite coatings clearly show their potential as wear resistant contact surfaces for load bearing implant applications. PMID:22301169

  4. Isentropic Compression Driven by High-Explosive Application to TI-6AL-4V

    NASA Astrophysics Data System (ADS)

    Voltz, C.; Sollier, A.; Maillet, J.-B.; Bouyer, V.

    2009-12-01

    We report on an isentropic compression experiment of Ti-6Al-4V alloy based on the use of the release of detonation products from a high-explosive to generate a ramp wave compression in a multisteps target. VISAR and DLI measurements of the rear free surface velocities of the different steps allow computing the sound velocity of the material during its compression, which is characteristic of the EOS of the material. The experimental device is described and the sound velocity measurements are analyzed. We obtain Ti-6Al-4V strength along the compression up to 15 GPa. The results are compared with two dimensional elastic-plastic simulations.

  5. Crystallographic Structure of Ti-6Al-4V, Ti-HP and Ti-CP Under High Pressure

    SciTech Connect

    Halevy, I.; Zamir, G; Winterrose, M; Ghose, S; Grandini, C; Moreno-Gobbi, A

    2010-01-01

    The phase stability of a commercial purity (Ti-CP), high purity (Ti-HP) and Ti-6Al-4V alloy were investigated in a diamond anvil cell up to 32 GPa and 298 K using a polychromatic X-ray beam. The Ti-CP and Ti-HP shown the same HCP (c/a {approx} 0.632) to Hexagonal (c/a {approx} 1.63) non reversible martensitic transition at about 9 GPa. The as received Ti-6Al-4V shows a very low relative volume fraction {beta}-Ti/{alpha}-Ti. No phase changes were observed in the Ti-6Al-4V alloy in the pressure range of this study. The {alpha} phase of the Ti-6Al-4V shows monotonic volume cell pressure dependence. This volume change is reversible and non-hysteretic. The cell of the a phase recovered its original volume when the pressure was released.

  6. Assessing Eli Broad's Assault on Public School System Leadership

    ERIC Educational Resources Information Center

    English, Fenwick W.; Crowder, Zan

    2012-01-01

    Eli Broad's approach to reforming urban public education does not recognize his own self-interest in promoting changes within such educational systems, a classic problem of misrecognition. The Broad agenda is an assault on the notion of the mission of public education as a service instead of a for-profit enterprise concerned with making money for…

  7. 52. GENERAL VIEW OF ELI WINDMILL ON STEEL TOWER IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. GENERAL VIEW OF ELI WINDMILL ON STEEL TOWER IN PASTURE LOCATED ABOUT 6-8 MILES SOUTH OF NEBRASKA CITY ABOUT ONE 1 MILE WEST OF NEBRASKA HIGHWAY 75. - Kregel Windmill Company Factory, 1416 Central Avenue, Nebraska City, Otoe County, NE

  8. 1. Historic American Buildings Survey Eli Lilly Company Photographic Department ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Historic American Buildings Survey Eli Lilly Company Photographic Department - About 1937-1938 Gift courtesy of Edward D. James, FAIA, Preservation Officer GENERAL VIEW OF TRADING POST (LEFT) AND CABIN OF WILLIAM CONNER (RIGHT) AFTER RESTORATION - William Conner Trading Post, State Highway 234, Noblesville, Hamilton County, IN

  9. Investigation of Ti6Al4V Orthogonal Cutting Numerical Simulations using Different Material Models

    SciTech Connect

    Alvarez, Roberto

    2010-06-15

    Titanium alloys are materials considered as extremely difficult to cut and titanium alloy Ti6Al4V is a reference in machining of titanium. The segmented (saw toothed) chip morphology has attracted great interest in researchers because the understanding of the saw-toothed chip morphology helps to understand the chip formation mechanisms. In this study, the effect of different constitutive models on the saw-toothed chip morphology is examined in machining Ti6Al4V. The paper presents the influence of eight material constitutive modelling in the simulation of segmented chip formation. A critical comparison of outstanding process outputs as cutting force, temperature and measurable parameters for segmented chips is carried out to compare and discuss the performance of the eight different material models to each other and with experimental data.

  10. Fatigue behavior of SiC reinforced Ti/6Al-4V/ at 650 C

    NASA Technical Reports Server (NTRS)

    Bhatt, R. T.; Grimes, H. H.

    1982-01-01

    Axial, low cycle fatigue properties of 25 and 44 fiber vol pct SiC/Ti(6Al-4V) composites, measured at 650 C, were compared with the fatigue properties of unreinforced Ti(6Al-4V) at the same temperature. A prior study of the fatigue behavior of this composite system at room temperature indicated that the SiC fiber reinforcement did not provide the anticipated improvement of fatigue resistance of this alloy. At 650 C, the composite fatigue properties degraded somewhat from those at room temperature. However, these properties degraded more for the unreinforced matrix at 650 C with the result that the composite fatigue strength was two to three times the fatigue strength of the matrix alloy. The reasons for this reversal are discussed in terms of crack initiation at broken fibers and residual matrix stresses.

  11. Static High Pressure X-Ray Diffraction of TI-6AL-4V

    NASA Astrophysics Data System (ADS)

    Chesnut, Gary N.; Velisavljevic, Nenad; Sanchez, Lilliana

    2007-12-01

    Ti-6Al-4V was examined under static-high pressure conditions using a diamond anvil cell. The angle-dispersive x-ray diffraction experiments were performed at the Advanced Photon Source, Argonne National Laboratory. Radial and axial geometry were used to examine multiple samples. The purpose of the experiment was to generate pressure-volume data at room temperature (which is non-existent in literature) and to examine deviatoric stress effects on such a hard alloy.

  12. Delivery of Antibiotics from Cementless Titanium-Alloy Cubes May Be a Novel Way to Control Postoperative Infections

    PubMed Central

    Bezuidenhout, Martin B.; van Staden, Anton D.; Oosthuizen, Gert A.; Dimitrov, Dimitar M.; Dicks, Leon M. T.

    2015-01-01

    Bacterial colonisation and biofilm formation onto orthopaedic devices are difficult to eradicate. In most cases infection is treated by surgical removal of the implant and cleaning of the infected area, followed by extensive treatment with broad-spectrum antibiotics. Such treatment causes great discomfort, is expensive, and is not always successful. In this study we report on the release of vancomycin through polyethersulfone membranes from channels in cementless titanium-alloy cubes. The cubes were constructed with LaserCUSING from Ti6Al4V ELI powder. Vancomycin was released by non-Fickian anomalous (constraint) diffusion. Approximately 50% of the vancomycin was released within the first 17 h. However, sustained delivery of vancomycin for 100 h was possible by reinjecting the channels. Refillable implants may be a novel way to control postoperative infections. PMID:25861649

  13. Electrochemical & osteoblast adhesion study of engineered TiO2 nanotubular surfaces on titanium alloys.

    PubMed

    Rahman, Zia Ur; Haider, Waseem; Pompa, Luis; Deen, K M

    2016-01-01

    TiO2 nanotubes were grafted on the surface of cpTi, Ti6Al4V and Ti6Al4V-ELI with the aim to provide a new podium for human pre-osteoblast cell (MC3T3) adhesion and proliferation. The surface morphology and chemistry of these alloys were examined with scanning electron microscopy and energy dispersive x-ray spectroscopy. TiO2 nanotubes were further characterized by cyclic potentiodynamic polarization tests and electrochemical impedance spectroscopy. The vertically aligned nanotubes were subjected to pre-osteoblast cell proliferation in order to better understand cell-material interaction. The study demonstrated that these cells interact differently with nanotubes of different titanium alloys. The significant acceleration in the growth rate of pre-osteoblast cell adhesion and proliferation is also witnessed. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium-based bio-assay, MTS. Each group of data was operated for p<0.05, concluded one way ANOVA to investigate the significance difference. PMID:26478299

  14. Ceramics to Ti6Al4V by Ni-Based Interlayers

    NASA Astrophysics Data System (ADS)

    Valenza, F.; Artini, C.; Passerone, A.; Cirillo, P.; Muolo, M. L.

    2014-05-01

    Pure ZrB2 and ZrB2-SiC composites were joined to Ti6Al4V at 1100 °C using B-Ni50 (at.%) as a filler alloy. The brazing medium and the processing parameters were chosen on the basis of specific wetting tests which showed the good adhesion properties of the B-Ni alloy with both the ceramic and the Ti alloy; interfacial reactions were foreseen and interpreted by phase diagram analysis. A multilayer metal-ceramic interfacial structure was observed in the joints and a key role was played by Ti coming from Ti6Al4V: it worked as the active element enhancing the adhesion of the liquid to the ceramic and segregated at the interface forming TiB. A satisfactory mechanical performance was obtained for ZrB2-SiC/Ti6Al4V joints, which exhibited a room temperature shear strength of 74 MPa.

  15. Corrosion Behavior of Friction Stir-Processed and Gas Tungsten Arc-Welded Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Atapour, Masoud; Pilchak, Adam L.; Frankel, G. S.; Williams, James C.

    2010-09-01

    The corrosion behavior of the investment-cast Ti-6Al-4V alloy in 5-pct HCl solution was investigated after gas tungsten arc welding and friction stir (FS) processing. The FS-processed samples exhibited superior corrosion behavior compared with the base metal and the arc-welded samples. The inferior corrosion resistance of the arc weldment was attributed to the acicular α and β microstructure and the alloying element partitioning between the phases. This was confirmed by scanning electron microscopy evaluations of the surface of specimens that had been immersed 50 hours in 20-pct HCl at 308 K (35 °C). In addition, the results indicated that vanadium as an alloying element has a detrimental effect on the corrosion performance of Ti-6Al-4V alloy in an HCl solution.

  16. Functionally graded Ti6Al4V and Inconel 625 by Laser Metal Deposition

    NASA Astrophysics Data System (ADS)

    Pulugurtha, Syamala R.

    The objective of the current work was to fabricate a crack-free functionally graded Ti6Al4V and Inconel 625 thin wall structure by Laser Metal Deposition (LMD). One potential application for the current material system is the ability to fabricate a functionally graded alloy that can be used in a space heat exchanger. The two alloys, Inconel 625 and Ti6Al4V are currently used for aerospace applications. They were chosen as candidates for grading because functionally grading those combines the properties of high strength/weight ratio of Ti6Al4V and high temperature oxidation resistance of Inconel 625 into one multifunctional material for the end application. However, there were challenges associated with the presence of Ni-Ti intermetallic phases (IMPs). The study focused on several critical areas such as (1) understanding microstructural evolution, (2) reducing macroscopic cracking, and (3) reducing mixing between graded layers. Finite element analysis (FEA) was performed to understand the effect of process conditions on multilayer claddings for simplified material systems such as SS316L and Inconel 625 where complex microstructures did not form. The thermo-mechanical models were developed using Abaqus(TM) (and some of them experimentally verified) to predict temperature-gradients; remelt layer depths and residual stresses. Microstructure evolution along the functionally graded Ti6Al4V and Inconel 625 was studied under different processing and grading conditions. Thermodynamic modeling using Factsage (v 6.1) was used to construct phase diagrams and predict the possible equilibrium major/minor phases (verified experimentally by XRD) that may be present along the functionally graded Ti6Al4V and Inconel 625 thin wall structures.

  17. Improving the osteointegration of Ti6Al4V by zeolite MFI coating.

    PubMed

    Li, Yong; Jiao, Yilai; Li, Xiaokang; Guo, Zheng

    2015-05-01

    Osteointegration is crucial for success in orthopedic implantation. In recent decades, there have been numerous studies aiming to modify titanium alloys, which are the most widely used materials in orthopedics. Zeolites are solid aluminosilicates whose application in the biomedical field has recently been explored. To this end, MFI zeolites have been developed as titanium alloy coatings and tested in vitro. Nevertheless, the effect of the MFI coating of biomaterials in vivo has not yet been addressed. The aim of the present work is to evaluate the effects of MFI-coated Ti6Al4V implants in vitro and in vivo. After surface modification, the surface was investigated using field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). No difference was observed regarding the proliferation of MC3T3-E1 cells on the Ti6Al4V (Ti) and MFI-coated Ti6Al4V (M-Ti) (p > 0.05). However, the attachment of MC3T3-E1 cells was found to be better in the M-Ti group. Additionally, ALP staining and activity assays and quantitative real-time RT-PCR indicated that MC3T3-E1 cells grown on the M-Ti displayed high levels of osteogenic differentiation markers. Moreover, Van-Gieson staining of histological sections demonstrated that the MFI coating on Ti6Al4V scaffolds significantly enhanced osteointegration and promoted bone regeneration after implantation in rabbit femoral condylar defects at 4 and 12 weeks. Therefore, this study provides a method for modifying Ti6Al4V to achieve improved osteointegration and osteogenesis. PMID:25757911

  18. Nitric acid passivation of Ti6Al4V reduces thickness of surface oxide layer and increases trace element release.

    PubMed

    Callen, B W; Lowenberg, B F; Lugowski, S; Sodhi, R N; Davies, J E

    1995-03-01

    Passivation of Ti6Al4V and cpTi implants using methods based on the ASTM-F86 nitric acid protocol are used with the intention of reducing their surface reactivity, and consequently the corrosion potential, in the highly corrosive biologic milieu. The ASTM-F86 passivation protocol was originally developed for surgical implants made of stainless steel and chrome cobalt alloy. Using X-ray photoelectron spectroscopy (XPS) to examine the effect of nitric acid passivation on the surface oxide layer of mill-annealed Ti6Al4V and cpTi, we have found that such treatment actually reduced the oxide thickness on the alloy while having no significant effect on the pure metal. These results correlated with observations obtained using graphite furnace atomic absorption spectrophotometry (GFAAS) to detect trace element release from solid, mill-annealed, Ti6Al4V and cpTi into serum-containing culture medium. We detected significantly greater levels of Ti, Al, and V in the presence of passivated compared to nonpassivated Ti6Al4V. In contrast, nitric acid passivation did not influence Ti release from mill-annealed cpTi. These results, derived from two mill-annealed Ti-based metals, would indicate that re-examination of ASTM-F86-based passivation protocols with respect to Ti6Al4V should be considered in view of the widespread use of this alloy for biomedical devices. PMID:7615579

  19. Extreme Light Infrastructure - Nuclear Physics Eli-Np Project

    NASA Astrophysics Data System (ADS)

    Gales, S.

    2015-06-01

    The development of high power lasers and the combination of such novel devices with accelerator technology has enlarged the science reach of many research fields, in particular High energy, Nuclear and Astrophysics as well as societal applications in Material Science, Nuclear Energy and Medicine. The European Strategic Forum for Research Infrastructures (ESFRI) has selected a proposal based on these new premises called "ELI" for Extreme Light Infrastructure. ELI will be built as a network of three complementary pillars at the frontier of laser technologies. The ELI-NP pillar (NP for Nuclear Physics) is under construction near Bucharest (Romania) and will develop a scientific program using two 10 PW class lasers and a Back Compton Scattering High Brilliance and Intense Low Energy Gamma Beam , a marriage of Laser and Accelerator technology at the frontier of knowledge. In the present paper, the technical description of the facility, the present status of the project as well as the science, applications and future perspectives will be discussed.

  20. Microstructure and Properties of the Ti6Al4V/Inconel 625 Bimetal Obtained by Explosive Joining

    NASA Astrophysics Data System (ADS)

    Topolski, Krzysztof; Szulc, Zygmunt; Garbacz, Halina

    2016-04-01

    The study is concerned with the bimetallic plate composed of the Ti6Al4V and Inconel 625 alloys. The alloys were joined together using the explosive method with the aim to produce a bimetallic joint. The structure and the mechanical properties of the as-received raw Ti6Al4V and Inconel 625 alloys, the Ti6Al4V/Inconel 625 joint, and the joint after annealing (600 °C for 1 h) were examined. The samples observations were performed using a light microscope and a scanning electron microscope. The mechanical properties were estimated by microhardness measurements, tensile tests, and three-point bending tests. Moreover, the deformation strengthening of the metals and the strength of the joint were analyzed. The explosive process resulted in a good quality bimetallic joint. Both sheets were deformed plastically and the joint surface between the alloys had a wavy shape. In the area of the joint surface, the hardness was increased. For example, the annealing at 600 °C for 1 h resulted in changes of the microhardness in the entire volume of the samples and in changes of the morphology of the joint surface. In three-point bending tests, the samples were examined in two opposite positions (Ti6Al4V on the top or Inconel 625 on the top). The results indicated to depend on the position in which the sample was tested.

  1. Potential and frequency effects on fretting corrosion of Ti6Al4V and CoCrMo surfaces.

    PubMed

    Swaminathan, Viswanathan; Gilbert, Jeremy L

    2013-09-01

    Fretting corrosion has been reported at the metal-metal interfaces of a wide range of medical devices, including total joint replacements, spinal devices, and overlapping cardiovascular stents. Currently, the fretting corrosion phenomenon associated with metal-on-metal contacts is not fully understood. This study investigated the effect of potential and fretting frequency on the fretting corrosion performance of Ti6Al4V/Ti6Al4V, Ti6Al4V/CoCrMo, and CoCrMo/CoCrMo alloy combinations at fixed normal load and displacement conditions using a custom built fretting corrosion test system. The results showed that the fretting current densities increased with increases in potential and were highest for Ti6Al4V/Ti6Al4V couple (1.5 mA/cm(2) at 0 V vs. Ag/AgCl). The coefficient of friction varied with potential and was about two times higher for Ti6Al4V/Ti6Al4V (0.71 V at 0 V vs. Ag/AgCl). In most of the potential range tested, the fretting corrosion behavior of CoCrMo/Ti6Al4V and CoCrMo/CoCrMo was similar and dominated by the CoCrMo surface. Increase in applied fretting frequency linearly increased the fretting current densities in the regions where the passive film is stable. Also, the model-based fretting current densities were in excellent agreement with the experimental results. Overall, Ti6Al4V/Ti6Al4V couple was more susceptible to fretting corrosion compared with other couples. However, the effects of these processes on the biological system were not assessed. PMID:23404905

  2. Anodic polarization behavior of Ti-Ni and Ti-6A1-4V in simulated physiological solutions.

    PubMed

    Speck, K M; Fraker, A C

    1980-10-01

    Anodic polarization measurements made in Hanks' physiological solution at 37 degrees C and a pH of 7.4 show titanium materials to be the most passive of the following metals: titanium, Ti-6A1-4V, Ti-Ni (memory alloy), MP35N (Co-Ni-Cr-Mo), Co-Cr-Mo, 316L stainless steel, and nickel. The influence of the amino acids, cysteine, and tryptophan on the corrosion behavior of Ti-Ni and Ti-6A1-4V was studied. Cysteine caused a lower breakdown potential for Ti-Ni, but it did not affect the breakdown of Ti-6A1-4V, although an increase in current density for Ti-6A1-4V was observed. Tryptophan produced no significant effects. PMID:6932415

  3. Cyclic deformation fatigue behaviour of Ti6Al4V thermochemically nitrided for articular prostheses.

    PubMed

    Gil, F J; Manero, J M; Rodriguez, D; Planell, J A

    2003-01-01

    Titanium and its alloys have many attractive properties including high specific strength, low density, and excellent corrosion resistance. Titanium and the Ti6Al4V alloy have long been recognized as materials with high biocompatibility. These properties have led to the use of these materials in biomedical applications. Despite these advantages, the lack of good wear resistance makes the use of titanium and Ti6Al4V difficult in some biomedical applications, for example, articulating components of prostheses. To overcome this limitation, nitriding has been investigated as a surface-hardening method for titanium. Although nitriding greatly improves the wear resistance, this method reduces the fatigue strength. Low cycle fatigue performance in air of nitrided Ti6Al4V at different deformation amplitudes has been studied. Results show a reduction of low cycle fatigue life of up to 10% compared to the non-treated material. Studies suggest it is not related to the titanium nitride surface layer, but to microstructural changes caused by the high temperature treatment. (Journal of Applied Biomaterial & Biomechanics 2003; 1: 43-7). PMID:20803471

  4. Influence of Porosity on Mechanical Properties and In vivo Response of Ti6Al4V Implants

    PubMed Central

    Bandyopadhyay, Amit; Espana, Felix; Balla, Vamsi Krishna; Bose, Susmita; Ohgami, Yusuke; Davies, Neal M

    2009-01-01

    Metallic biomaterials are widely used to restore the lost structure and functions of human bone. Due to the large number of joint replacements, there is a growing demand for new and improved orthopedic implants. More specifically, there is a need for novel load bearing metallic implants with low effective modulus matching to that of bone in order to reduce stress shielding and consequent increase in the in vivo life-span of the implant. In this study, we have fabricated porous Ti6Al4V alloy structures, using Laser Engineered Net Shaping (LENS™) to demonstrate that advanced manufacturing techniques such as LENS™ can be used to fabricate low-modulus, tailored porosity implants with a wide variety of metals/alloys, where the porosity can be designed in areas based on the patient's need to enhance biological fixation and achieve long-term in vivo stability. The effective modulus of Ti6Al4V alloy structures has been tailored between 7 and 60 GPa and porous Ti alloy structures containing 23 to 32 vol. % porosity showed modulus equivalent to human cortical bone. In vivo behavior of porous Ti6Al4V alloy samples in male Sprague-Dawley rats for 16 weeks demonstrated significant increase in calcium within the implants indicating excellent biological tissue ingrowth through interconnected porosity. In vivo results also showed that total amount of porosity plays an important role in tissue ingrowth. PMID:19913643

  5. Comparison of bio-mineralization behavior of Ti-6Al-4V-1Nb and Zr-1Nb nano-tubes formed by anodization

    NASA Astrophysics Data System (ADS)

    Choi, Yong; Hong, Sun I.

    2014-12-01

    Nano-tubes of titanium and zirconium alloys like Ti-6Al-4V-1Nb and Zr-1Nb were prepared by anodization followed by coating with hydroxylapatite (HA) and their bio-mineralization behaviors were compared to develop a bio-compatible material for implants in orthopedics, dentistry and cardiology. Ti-6Al-4V-1Nb weight gain in a simulated body solution increased gradually. The bigger tube diameter was, the heavier HA was deposited. Surface roughness of both alloys increased highly with the increasing diameter of nano-tube. Their surface roughness decreased by HA deposition due to the removal of the empty space of the nano-tubes. Zr-1Nb alloy had faster growth of nano-tubes layers more than Ti-6Al-4V-1Nb alloy.

  6. Fretting corrosion of CoCrMo and Ti6Al4V interfaces.

    PubMed

    Swaminathan, Viswanathan; Gilbert, Jeremy L

    2012-08-01

    Mechanically assisted corrosion (fretting corrosion, tribocorrosion etc.,) of metallic biomaterials is a primary concern for numerous implant applications, particularly in the performance of highly-loaded medical devices. While the basic underlying concepts of fretting corrosion or tribocorrosion and fretting crevice corrosion are well known, there remains a need to develop an integrated systematic method for the analysis of fretting corrosion involving metal-on-metal contacts. Such a method can provide detailed and quantitative information on the processes present and explore variations in surfaces, alloys, voltages, loadings, motion and solution conditions. This study reports on development of a fretting corrosion test system and presents elements of an in-depth theoretical fretting corrosion model that incorporates both the mechanical and the electrochemical aspects of fretting corrosion. To demonstrate the capabilities of the new system and validate the proposed model, experiments were performed to understand the effect of applied normal load on fretting corrosion performance of Ti6Al4V/Ti6Al4V, CoCrMo/Ti6Al4V, and CoCrMo/CoCrMo material couples under potentiostatic conditions with a fixed starting surface roughness. The results of this study show that fretting corrosion is affected by material couples, normal load and the motion conditions at the interface. In particular, fretting currents and coefficient of friction (COF) vary with load and are higher for Ti6Al4V/Ti6Al4V couple reaching 3 mA/cm(2) and 0.63 at about 73 MPa nominal contact stress, respectively. Ti6Al4V coupled with CoCrMo displayed lower currents (0.6 mA/cm(2)) and COF (0.3), and the fretting corrosion behavior was comparable to CoCrMo/CoCrMo couple (1.2 mA/cm(2) and 0.3, respectively). Information on the mechanical energy dissipated at the interface, the sticking behavior, and the load dependence of the inter-asperity distance calculated using the model elucidated the influence of

  7. Texture Dependency of High Strain Rate Properties of Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Wielewski, Euan; Siviour, Clive; Petrinic, Nik

    2009-06-01

    Over the last few decades the characterisation of Titanium alloys has become increasingly important, mainly due to the requirement for better understanding of lightweight structural materials in aerospace applications. This trend is further strengthened by the emergence of new manufacturing and processing technologies promising Titanium alloys at a lower price, placing them within the range of automotive and consumer product manufacturers. A key aspect of fully understanding the behaviour of Titanium alloys is to determine how varying microstructure affects high strain rate properties. This paper reports the data from high strain rate characterisation tests that have been carried out on four Ti-6Al-4V plates with differing microstructures in both tension (longitudinal, transverse directions) and compression (longitudinal, transverse, through thickness directions). Tension and compression Split-Hopkinson Pressure Bars were used to achieve strain rates of 10^3 s-1. The data from these characterisation tests can then be used to evaluate the affect of microstructure on the anisotropic properties of Ti-6Al-4V.

  8. Perspectives for photonuclear research at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility

    NASA Astrophysics Data System (ADS)

    Filipescu, D.; Anzalone, A.; Balabanski, D. L.; Belyshev, S. S.; Camera, F.; La Cognata, M.; Constantin, P.; Csige, L.; Cuong, P. V.; Cwiok, M.; Derya, V.; Dominik, W.; Gai, M.; Gales, S.; Gheorghe, I.; Ishkhanov, B. S.; Krasznahorkay, A.; Kuznetsov, A. A.; Mazzocchi, C.; Orlin, V. N.; Pietralla, N.; Sin, M.; Spitaleri, C.; Stopani, K. A.; Tesileanu, O.; Ur, C. A.; Ursu, I.; Utsunomiya, H.; Varlamov, V. V.; Weller, H. R.; Zamfir, N. V.; Zilges, A.

    2015-12-01

    The perspectives for photonuclear experiments at the new Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility are discussed in view of the need to accumulate novel and more precise nuclear data. The parameters of the ELI-NP gamma beam system are presented. The emerging experimental program, which will be realized at ELI-NP, is presented. Examples of day-one experiments with the nuclear resonance fluorescence technique, photonuclear reaction measurements, photofission experiments and studies of nuclear collective excitation modes and competition between various decay channels are discussed. The advantages which ELI-NP provides for all these experiments compared to the existing facilities are discussed.

  9. ELIMED, MEDical and multidisciplinary applications at ELI-Beamlines

    NASA Astrophysics Data System (ADS)

    Schillaci, F.; Anzalone, A.; Cirrone, G. A. P.; Carpinelli, M.; Cuttone, G.; Cutroneo, M.; De Martinis, C.; Giove, D.; Korn, G.; Maggiore, M.; Manti, L.; Margarone, D.; Musumarra, A.; Perozziello, F. M.; Petrovic, I.; Pisciotta, P.; Renis, M.; Ristic-Fira, A.; Romano, F.; Romano, F. P.; Schettino, G.; Scuderi, V.; Torrisi, L.; Tramontana, A.; Tudisco, S.

    2014-04-01

    ELI-Beamlines is one of the pillars of the pan-European project ELI (Extreme Light Infrastructure). It will be an ultra high-intensity, high repetition-rate, femtosecond laser facility whose main goal is generation and applications of high-brightness X-ray sources and accelerated charged particles in different fields. Particular care will be devoted to the potential applicability of laser-driven ion beams for medical treatments of tumors. Indeed, such kind of beams show very interesting peculiarities and, moreover, laser-driven based accelerators can really represent a competitive alternative to conventional machines since they are expected to be more compact in size and less expensive. The ELIMED project was launched thanks to a collaboration established between FZU-ASCR (ELI-Beamlines) and INFN-LNS researchers. Several European institutes have already shown a great interest in the project aiming to explore the possibility to use laser-driven ion (mostly proton) beams for several applications with a particular regard for medical ones. To reach the project goal several tasks need to be fulfilled, starting from the optimization of laser-target interaction to dosimetric studies at the irradiation point at the end of a proper designed transport beam-line. Researchers from LNS have already developed and successfully tested a high-dispersive power Thomson Parabola Spectrometer, which is the first prototype of a more performing device to be used within the ELIMED project. Also a Magnetic Selection System able to produce a small pencil beam out of a wide energy distribution of ions produced in laser-target interaction has been realized and some preliminary work for its testing and characterization is in progress. In this contribution the status of the project will be reported together with a short description of the of the features of device recently developed.

  10. Simulation of photofission experiments at the ELI-NP facility

    NASA Astrophysics Data System (ADS)

    Constantin, P.; Balabanski, D. L.; Cuong, P. V.

    2016-04-01

    An extensive experimental program for the study of photofission will take place at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility, where different actinide targets will be exposed to a brilliant gamma beam to produce fission fragments. We report on the implementation within the Geant4 simulation toolkit of the photofission process, of related background processes, and of extended ionic charge parameterization. These developments are used to evaluate the production rates of photofission fragments and their release efficiency from the actinide targets.

  11. 1. Historic American Buildings Survey Eli Lilly Company Photographic Department ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Historic American Buildings Survey Eli Lilly Company Photographic Department - About 1937-1938 Gift courtesy of Edward D. James, FAIA, Preservation Officer SKETCH PLAN OF FARM Legend: (1) William Conner House; (2) Still house; (3) Milk house; (4) Museum; (5) Loom house; (6) Modern barns, grain and implement storage; (7) Three-eighths of a mile north or here on the river bank, William Conner lived in a double cabin trading post; (8) Trading post; (9) Conner cabin; (10) Pioneer barn - William Conner Prairie Farm, State Highway 234, Noblesville, Hamilton County, IN

  12. Improving the osteointegration of Ti6Al4V by zeolite MFI coating

    SciTech Connect

    Li, Yong; Jiao, Yilai; Li, Xiaokang; Guo, Zheng

    2015-05-01

    Osteointegration is crucial for success in orthopedic implantation. In recent decades, there have been numerous studies aiming to modify titanium alloys, which are the most widely used materials in orthopedics. Zeolites are solid aluminosilicates whose application in the biomedical field has recently been explored. To this end, MFI zeolites have been developed as titanium alloy coatings and tested in vitro. Nevertheless, the effect of the MFI coating of biomaterials in vivo has not yet been addressed. The aim of the present work is to evaluate the effects of MFI-coated Ti6Al4V implants in vitro and in vivo. After surface modification, the surface was investigated using field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). No difference was observed regarding the proliferation of MC3T3-E1 cells on the Ti6Al4V (Ti) and MFI-coated Ti6Al4V (M−Ti) (p > 0.05). However, the attachment of MC3T3-E1 cells was found to be better in the M−Ti group. Additionally, ALP staining and activity assays and quantitative real-time RT-PCR indicated that MC3T3-E1 cells grown on the M−Ti displayed high levels of osteogenic differentiation markers. Moreover, Van-Gieson staining of histological sections demonstrated that the MFI coating on Ti6Al4V scaffolds significantly enhanced osteointegration and promoted bone regeneration after implantation in rabbit femoral condylar defects at 4 and 12 weeks. Therefore, this study provides a method for modifying Ti6Al4V to achieve improved osteointegration and osteogenesis. - Highlights: • Osteointegration is a crucial factor for orthopedic implants. • We coated MFI zeolite on Ti6Al4V substrates and investigated the effects in vitro and in vivo. • The MFI coating displayed good biocompatibility and promoted osteogenic differentiation in vitro. • The MFI coating promoted osteointegration and osteogenesis peri-implant in vivo.

  13. Procedures for determining MATMOD-4V material constants

    SciTech Connect

    Lowe, T.C.

    1993-11-01

    The MATMOD-4V constitutive relations were developed from the original MATMOD model to extend the range of nonelastic deformation behaviors represented to include transient phenomena such as strain softening. Improvements in MATMOD-4V increased the number of independent material constants and the difficulty in determining their values. Though the constitutive relations are conceptually simple, their form and procedures for obtaining their constants can be complex. This paper reviews in detail the experiments, numerical procedures, and assumptions that have been used to determine a complete set of MATMOD-4V constants for high purity aluminum.

  14. High-Temperature Galling Characteristics of Ti-6Al-4V with and without Surface Treatments

    SciTech Connect

    Blau, Peter Julian; ERDMAN III, DONALD L; Ohriner, Evan Keith; Jolly, Brian C

    2011-01-01

    Galling is a severe form of surface damage in metals and alloys that typically arises under relatively high normal force, low-sliding speed, and in the absence of effective lubrication. It can lead to macroscopic surface roughening and seizure. The occurrence of galling can be especially problematic in high-temperature applications like diesel engine exhaust gas recirculation system components and adjustable turbocharger vanes, because suitable lubricants may not be available, moisture desorption promotes increased adhesion, and the yield strength of metals decreases with temperature. Oxidation can counteract these effects to some extent by forming lubricative oxide films. Two methods to improve the galling resistance of titanium alloy Ti-6Al-4V were investigated: (a) applying an oxygen diffusion treatment, and (b) creating a metal-matrix composite with TiB2 using a high-intensity infrared heating source. A new, oscillating three-pin-on-flat, high-temperature test method was developed and used to characterize galling behavior relative to a cobalt-based alloy (Stellite 6B ). The magnitude of the oscillating torque, the surface roughness, and observations of surface damage were used as measures of galling resistance. Owing to the formation of lubricative oxide films, the galling resistance of the Ti-alloy at 485o C, even non-treated, was considerably better than it was at room temperature. The IR-formed composite displayed reduced surface damage and lower torque than the substrate titanium alloy.

  15. Combination of laser keyhole and conduction welding: Dissimilar laser welding of niobium and Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Torkamany, M. J.; Malek Ghaini, F.; Poursalehi, R.; Kaplan, A. F. H.

    2016-04-01

    Pulsed Nd:YAG laser welding of pure niobium plate to titanium alloy Ti-6Al-4V sheet in butt joint is studied regarding the laser/metal interaction modes. To obtain the optimized process parameters in dissimilar welding of Ti-6Al-4V/Nb, the melting ratio of laser beam energy for each weld counterpart is evaluated experimentally. Different laser welding modes of keyhole and conduction are predicted regarding the absorbed energy from the similar laser pulses on each weld counterpart. Laser keyhole and conduction welding were observed simultaneously through direct visualization of laser interaction with dissimilar metals using High Speed Imaging (HSI) system.

  16. An Experimental and Theoretical Study of Ti-6Al-4V to Multi-mbar Pressures

    SciTech Connect

    MacLeod, S G; Tegner, B E; Cynn, H; Evans, W J; Proctor, J; McMahon, M I; Ackland, G J

    2012-03-14

    We report results from an experimental and theoretical study of the ternary alloy Ti-6Al-4V to 221 GPa. We observe a phase transition to the hexagonal {omega}-phase at approximately 30 GPa, and then a further transition to the cubic {beta}-phase starting at 94-99 GPa. We do not observe the orthorhombic {gamma} and {delta} phases reported previously in pure Ti. Computational studies show that this sequence is possible only if there is significant local atomic ordering during the compression process, yet insufficient atomic diffusion to reach the phase separated thermodynamic equilibrium state.

  17. Producing Ti-6Al-4V plate from single-melt EBCHM ingot

    NASA Astrophysics Data System (ADS)

    Wood, J. R.

    2002-02-01

    The study reviewed in this paper was initiated to produce low-cost, aerospace-quality Ti-6Al-4V alloy plate directly from single melt, electron beam cold hearth melted slab ingots. This study is one of the programs of the Metals Affordability Initiative Consortium under the direction of the U.S. Air Force Research Laboratory’s Materials and Manufacturing Directorate. The main objective of this program is to achieve significant cost savings for titanium plate production while accelerating the implementation time. This article discusses the progress to date in this multi-year program.

  18. The ELI-NP facility for nuclear physics

    NASA Astrophysics Data System (ADS)

    Ur, C. A.; Balabanski, D.; Cata-Danil, G.; Gales, S.; Morjan, I.; Tesileanu, O.; Ursescu, D.; Ursu, I.; Zamfir, N. V.

    2015-07-01

    Extreme Light Infrastructure-Nuclear Physics (ELI-NP) is aiming to use extreme electromagnetic fields for nuclear physics research. The facility, currently under construction at Magurele-Bucharest, will comprise a high power laser system and a very brilliant gamma beam system. The technology involved in the construction of both systems is at the limits of the present-day's technological capabilities. The high power laser system will consist of two 10 PW lasers and it will produce intensities of up to 1023-1024 W/cm2. The gamma beam, produced via Compton backscattering of a laser beam on a relativistic electron beam, will be characterized by a narrow bandwidth (<0.5%) and tunable energy of up to almost 20 MeV. The research program of the facility covers a broad range of key topics in frontier fundamental physics and new nuclear physics. A particular attention is given to the development of innovative applications. In the present paper an overview of the project status and the overall performance characteristics of the main research equipment will be given. The main fundamental physics and applied research topics proposed to be studied at ELI-NP will also be briefly reviewed.

  19. Microwave-assisted fabrication of strontium doped apatite coating on Ti6Al4V.

    PubMed

    Zhou, Huan; Kong, Shiqin; Pan, Yan; Zhang, Zhiguo; Deng, Linhong

    2015-11-01

    Strontium has been shown to be a beneficial dopant to calcium phosphates when incorporated at nontoxic level. In the present work we studied the possibility of solution derived doping strontium into calcium phosphate coatings on titanium alloy Ti6Al4V based implants by a recently reported microwave-assisted method. By using this method strontium doped calcium phosphate nuclei were deposited to pretreated titanium alloy surface dot by dot to compose a crack-free coating layer. The presence of strontium in solution led to reduced roughness of the coating and finer nucleus size formed. In vitro study found that proliferation and differentiation of osteoblast cells seeded on the coating were influenced by strontium content in coatings, showing an increasing followed by a decreasing behavior with increasing substitution of calcium by strontium. It is suggested that this new microwave-assisted strontium doped calcium phosphate coatings may have great potential in implant modification. PMID:26249578

  20. Specific heat treatment of selective laser melted Ti-6Al-4V for biomedical applications

    NASA Astrophysics Data System (ADS)

    Huang, Qianli; Liu, Xujie; Yang, Xing; Zhang, Ranran; Shen, Zhijian; Feng, Qingling

    2015-12-01

    The ductility of as-fabricated Ti-6Al-4V falls far short of the requirements for biomedical titanium alloy implants and the heat treatment remains the only applicable option for improvement of their mechanical properties. In the present study, the decomposition of as-fabricated martensite was investigated to provide a general understanding on the kinetics of its phase transformation. The decomposition of asfabricated martensite was found to be slower than that of water-quenched martensite. It indicates that specific heat treatment strategy is needed to be explored for as-fabricated Ti-6Al-4V. Three strategies of heat treatment were proposed based on different phase transformation mechanisms and classified as subtransus treatment, supersolvus treatment and mixed treatment. These specific heat treatments were conducted on selective laser melted samples to investigate the evolutions of microstructure and mechanical properties. The subtransus treatment leaded to a basket-weave structure without changing the morphology of columnar prior β grains. The supersolvus treatment resulted in a lamellar structure and equiaxed β grains. The mixed treatment yielded a microstructure that combines both features of the subtransus treatment and supersolvus treatment. The subtransus treatment is found to be the best choice among these three strategies for as-fabricated Ti-6Al-4V to be used as biomedical implants.

  1. An experimental study of the (Ti-6Al-4V)-xH phase diagram using in situ synchrotron XRD and TGA/DSC techniques.

    SciTech Connect

    Sun, Pei; Fang, Z. Zak; Koopman, Mark; Paramore, James D.; Chandran, K. S. Ravi; Ren, Yang; Lu, Jun

    2015-02-01

    Hydrogen has been investigated for decades as a temporary alloying element to refine the microstructure of Ti-6Al-4V, and is now being used in a novel powder metallurgy method known as "hydrogen sintering and phase transformation". Pseudo-binary phase diagrams of (Ti-6Al-4V)-xH have been studied and developed, but are not well established due to methodological limitations. In this paper, in situ studies of phase transformations during hydrogenation and dehydrogenation of (Ti-6Al-4V)-xH alloys were conducted using high-energy synchrotron X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The eutectoid phase transformation of β ↔ α + δ was observed in the (Ti-6Al-4V)-xH alloy via in situ synchrotron XRD at 211 °C with a hydrogen concentration of 37.5 at.% (measured using TGA-DSC). The relationships of hydrogen composition to partial pressure and temperature were investigated in the temperature range 450-900°C. Based on these results, a partial pseudo-binary phase diagram of (Ti-6Al-4V)-xH is proposed for hydrogen compositions up to 60 at.% in the temperature range 100-900°C. Using the data collected in real time under controlled parameters of temperature, composition and hydrogen partial pressure, this work characterizes relevant phase transformations and microstructural evolution for practical titanium-hydrogen technologies of Ti-6Al-4V.

  2. Effect of hydroxyapatite thickness on metal ion release from Ti6Al4V substrates.

    PubMed

    Sousa, S R; Barbosa, M A

    1996-02-01

    The electrochemical dissolution behaviour of Ti6Al4V alloy coated with hydroxyapatite (HA) by plasma spraying was studied in Hank's balanced salt solution (HBSS) and compared with that of polished and grit-blasted passivated surfaces. Two different nominal thicknesses of HA (50 and 200 micro m) were used. Taking a polished passivated surface as reference, grit blasting of the substrate increased the electrical charge used in the oxidation of Ti6Al4V alloy at constant potential, as a result of increased surface area. However, only HA coatings with a thickness of 200 micro m were capable of reducing the charge to values lower than those measured for polished surfaces. Electrochemical impedance spectroscopy has also shown that only 200 micro m thick coatings are effective in reducing the oxidation rate of the substrate. Furthermore, in potentiostatic experiments the 50 micro m thick coating detached from the substrate, which did not occur with the 200 micro m thick coating. However, after 6 months immersion in HBSS, detachment occurred in some regions of both coatings. No titanium, aluminium or vanadium were detected in solution by electrothermal atomic absorption spectroscopy. These data indicate that HA is an effective barrier to metal ion release, even for the thinner coatings, due to formation of metal phosphates or to incorporation of metal ions in the HA structure. PMID:8938233

  3. Microstructural Changes Due to Friction Stir Processing of Investment-Cast Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Pilchak, A. L.; Juhas, M. C.; Williams, J. C.

    2007-02-01

    Friction stir processing (FSP) was used to modify the coarse fully lamellar microstructure on the surface of investment-cast and hot isostatically pressed (HIP) Ti-6Al-4V plate. The α colony and platelet structure in the base material (BM) was refined such that the effective slip length was reduced from the α colony size of the BM, several hundred microns, to that of fine equiaxed primary α grains that are on the order of 1 μm. This change in the microstructure resulting from FSP is expected to increase fatigue crack initiation resistance making it beneficial for titanium components for aerospace applications. The as-cast coarse lamellar microstructure has superior fatigue crack growth resistance compared to other microstructures that can be obtained by thermomechanical processing. Thus, it is likely that an increase in fatigue life is obtainable by FSP. Given the growing interest in friction stir welding (FSW) and FSP of titanium alloys, we believe some consistent microstructural descriptors will help avoid confusion. Accordingly, we propose terminology to standardize the descriptions of the microstructures created during FSP and FSW of titanium alloys. We also describe the microstructure changes that occur in the stir zone (SZ), transition zone (TZ), and heat-affected zone (HAZ) during FSP of Ti-6Al-4V.

  4. Collagen type I-coating of Ti6Al4V promotes adhesion of osteoblasts.

    PubMed

    Geissler, U; Hempel, U; Wolf, C; Scharnweber, D; Worch, H; Wenzel, K

    2000-09-15

    The initial contact of osteoblasts with implant surfaces is an important event for osseointegration of implants. Osseointegration of Ti6Al4V may be improved by precoating of its surface with collagen type I. In this study, the adhesion of rat calvarial osteoblasts to uncoated and collagen type I-coated titanium alloy was investigated over a period of 24 h. Collagen type I-coating accelerates initial adhesion of osteoblasts in the presence of fetal calf serum. One hour after plating, no differences in the percentage of adherent cells between the surfaces investigated were found. Adhesion of osteoblasts to uncoated surfaces was reduced by the GRGDSP peptide by about 70%, whereas adhesion to collagen type I-coated surfaces remained unaffected by treatment of the cells with the peptide. Cell adhesion to coated materials was reduced by about 80% by anti-integrin beta1 antibody. The integrin beta1 antibody did not influence the adhesion to uncoated titanium alloy. The results suggest that osteoblasts adhere to collagen type I-coated materials via integrin beta1 but not by interacting with RGD peptides, whereas adhesion to uncoated titanium alloy is mediated by RGD sequences but not via integrin beta1. Fibronectin does not seem to be involved in the adhesion of osteoblasts to either coated or uncoated titanium alloy. PMID:10880125

  5. Interaction behaviors at the interface between liquid Al-Si and solid Ti-6Al-4V in ultrasonic-assisted brazing in air.

    PubMed

    Chen, Xiaoguang; Yan, Jiuchun; Gao, Fei; Wei, Jinghui; Xu, Zhiwu; Fan, Guohua

    2013-01-01

    Power ultrasonic vibration (20 kHz, 6 μm) was applied to assist the interaction between a liquid Al-Si alloy and solid Ti-6Al-4V substrate in air. The interaction behaviors, including breakage of the oxide film on the Ti-6Al-4V surface, chemical dissolution of solid Ti-6Al-4V, and interfacial chemical reactions, were investigated. Experimental results showed that numerous 2-20 μm diameter-sized pits formed on the Ti-6Al-4V surface. Propagation of ultrasonic waves in the liquid Al-Si alloy resulted in ultrasonic cavitation. When this cavitation occurred at or near the liquid/solid interface, many complex effects were generated at the small zones during the bubble implosion, including micro-jets, hot spots, and acoustic streaming. The breakage behavior of oxide films on the solid Ti-6Al-4V substrate, excessive chemical dissolution of solid Ti-6Al-4V into liquid Al-Si, abnormal interfacial chemical reactions at the interface, and phase transformation between the intermetallic compounds could be wholly ascribed to these ultrasonic effects. An effective bond between Al-Si and Ti-6Al-4V can be produced by ultrasonic-assisted brazing in air. PMID:22824641

  6. Pharmacological and phytochemical studies of Cephäelis axillaris.

    PubMed

    Martín, M L; Gupta, M P; Ortiz de Urbina, A V; Karikas, G A; Gordaliza, M; Miguel del Corral, J M; San Román, L; Sánchez, C; San Feliciano, A

    1994-12-01

    The most significant effect, observed in the preliminary pharmacological evaluation of the whole ethanol extract and the alkaloidal fraction of Cephäelis axillaris, was the hyperemia of ears and external mucosas which was most probably due to an alpha-adrenergic blocking activity. In addition, both samples also induced a marked hypotension in normotensive as well as hypertensive (SHR) rats and inhibited the increases of blood pressure induced by i.v. administration of noradrenaline in pithed rats. The structures of the major alkaloidal components of the extract were elucidated on the basis of chemical characterization assays and IR, UV, 1H and 13C one and two-dimensional NMR analyses. PMID:7809213

  7. Influence of impact speed on water droplet erosion of TiAl compared with Ti6Al4V

    PubMed Central

    Mahdipoor, M.S.; Kirols, H.S.; Kevorkov, D.; Jedrzejowski, P.; Medraj, M.

    2015-01-01

    Water Droplet Erosion (WDE) as a material degradation phenomenon has been a concern in power generation industries for decades. Steam turbine blades and the compressor blades of gas turbines that use water injection usually suffer from WDE. The present work focuses on studying erosion resistance of TiAl as a potential alloy for turbine blades compared to Ti6Al4V, a frequently used blade alloy. Their erosion behaviour is investigated at different droplet impact speeds to determine the relation between erosion performance and impact speed. It is found that the relationship is governed by a power law equation, ER ~ Vn, where the speed exponent is 7–9 for Ti6Al4V and 11–13 for TiAl. There is a contrast between the observed speed exponent in this work and the ones reported in the literature for Ti6Al4V. It is attributed to the different erosion setups and impingement conditions such as different droplet sizes. To verify this, the erosion experiments were performed at two different droplet sizes, 464 and 603 μm. TiAl showed superior erosion resistance in all erosion conditions; however, its erosion performance exhibits higher sensitivity to the impact speed compared to Ti6Al4V. It means that aggressive erosion conditions decrease the WDE resistance superiority of TiAl. PMID:26391370

  8. Influence of impact speed on water droplet erosion of TiAl compared with Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Mahdipoor, M. S.; Kirols, H. S.; Kevorkov, D.; Jedrzejowski, P.; Medraj, M.

    2015-09-01

    Water Droplet Erosion (WDE) as a material degradation phenomenon has been a concern in power generation industries for decades. Steam turbine blades and the compressor blades of gas turbines that use water injection usually suffer from WDE. The present work focuses on studying erosion resistance of TiAl as a potential alloy for turbine blades compared to Ti6Al4V, a frequently used blade alloy. Their erosion behaviour is investigated at different droplet impact speeds to determine the relation between erosion performance and impact speed. It is found that the relationship is governed by a power law equation, ER ~ Vn, where the speed exponent is 7-9 for Ti6Al4V and 11-13 for TiAl. There is a contrast between the observed speed exponent in this work and the ones reported in the literature for Ti6Al4V. It is attributed to the different erosion setups and impingement conditions such as different droplet sizes. To verify this, the erosion experiments were performed at two different droplet sizes, 464 and 603 μm. TiAl showed superior erosion resistance in all erosion conditions; however, its erosion performance exhibits higher sensitivity to the impact speed compared to Ti6Al4V. It means that aggressive erosion conditions decrease the WDE resistance superiority of TiAl.

  9. Influence of impact speed on water droplet erosion of TiAl compared with Ti6Al4V.

    PubMed

    Mahdipoor, M S; Kirols, H S; Kevorkov, D; Jedrzejowski, P; Medraj, M

    2015-01-01

    Water Droplet Erosion (WDE) as a material degradation phenomenon has been a concern in power generation industries for decades. Steam turbine blades and the compressor blades of gas turbines that use water injection usually suffer from WDE. The present work focuses on studying erosion resistance of TiAl as a potential alloy for turbine blades compared to Ti6Al4V, a frequently used blade alloy. Their erosion behaviour is investigated at different droplet impact speeds to determine the relation between erosion performance and impact speed. It is found that the relationship is governed by a power law equation, ER ~ V(n), where the speed exponent is 7-9 for Ti6Al4V and 11-13 for TiAl. There is a contrast between the observed speed exponent in this work and the ones reported in the literature for Ti6Al4V. It is attributed to the different erosion setups and impingement conditions such as different droplet sizes. To verify this, the erosion experiments were performed at two different droplet sizes, 464 and 603 μm. TiAl showed superior erosion resistance in all erosion conditions; however, its erosion performance exhibits higher sensitivity to the impact speed compared to Ti6Al4V. It means that aggressive erosion conditions decrease the WDE resistance superiority of TiAl. PMID:26391370

  10. Radiographic inspection of porosity in Ti-6Al-4V laser-welded joints.

    PubMed

    Nuñez-Pantoja, Juliana Maria Costa; Takahashi, Jessica Mie Ferreira Koyama; Nóbilo, Mauro Antônio de Arruda; Consani, Rafael Leonardo Xediek; Mesquita, Marcelo Ferraz

    2011-01-01

    Widely used in dentistry, Ti-6Al-4V alloy is difficult to cast and solder, as it frequently exhibits pores inside the structure. This study was conducted to evaluate the effect of joint openings and diameters of laser-welded joints executed in Ti-6Al-4V structures on the presence of pores as checked by radiographic procedures. Sixty dumbbell rods with central diameters of 1.5, 2.0 and 3.5 mm were created from Ti-6Al-4V-wrought bars. Specimens were sectioned and welded using two joint openings (0.0 and 0.6 mm). The combination of variables created six groups (n = 10). Laser welding was executed using 360V/8ms (1.5 and 2.0 mm) and 380V/9ms (3.5 mm), with the focus and frequency set to zero. The joints were finished, polished and submitted to radiographic examination. The radiographs were visually examined for the presence of pores in the joints, qualitatively. The percentage of radiographic presence of pores was calculated without counting pores per joint. Data were analyzed using a chi-square test (α = 0.05). For the 1.5-mm specimens, the incidence of pore presence was significantly higher (p = 0.0001) when using 0.6-mm joint openings (40%) compared to 0.0-mm openings (0%). For the 2.0-mm specimens, there was no significant difference between groups (p = 0.2008). However, for the 3.5-mm specimens, the incidence of pore presence was lower (p = 0.0061) for 0.6-mm openings (50%) compared to 0.0-mm openings (70%). Therefore, laser welding of Ti-6Al-4V structures with thin diameters provides the best condition for the juxtaposition of the parts. PMID:21359490

  11. Structural characterization of the metal/glass interface in bioactive glass coatings on Ti-6Al-4V

    SciTech Connect

    Oku, T.; Suganuma, K.; Wallemberg, L.R.; Tomsia, A.P.; Gomez-Vega, J.M.; Saiz, E.

    1999-12-01

    Coating Ti-based implants with bioactive materials promotes joining between the prostheses and the bone as well as increasing long-term implant stability. In the present work, the interface between Ti-6Al-4V and bioactive silicate glass coatings, prepared using a simple enameling technique, is analyzed. High-resolution transmission electron microscopy of the glass/alloy interface shows the formation of a reaction layer ({approx}150 nm thick) composed of Ti5Si3 nanoparticles with a size of {approx}20 nm. This nanostructured interface facilitates the formation of a stable joint between the glass coating and the alloy.

  12. Structural characterization of the metal/glass interface in bioactive glass coatings on Ti-6Al-4V.

    PubMed

    Oku, T; Suganuma, K; Wallenberg, L R; Tomsia, A P; Gomez-Vega, J M; Saiz, E

    2001-05-01

    Coating Ti-based implants with bioactive materials promotes joining between the prostheses and the bone as well as increasing long-term implant stability. In the present work, the interface between Ti-6Al-4V and bioactive silicate glass coatings, prepared using a simple enameling technique, is analyzed. High-resolution transmission electron microscopy of the glass/alloy interface shows the formation of a reaction layer ( approximately 150 nm thick) composed of Ti5Si3 nanoparticles with a size of approximately 20 nm. This nanostructured interface facilitates the formation of a stable joint between the glass coating and the alloy. PMID:15348280

  13. Biocorrosion of TiO2 nanoparticle coating of Ti-6Al-4V in DMEM under specific in vitro conditions

    NASA Astrophysics Data System (ADS)

    Höhn, Sarah; Virtanen, Sannakaisa

    2015-02-01

    A TiO2 nanoparticle coating was prepared on a biomedical Ti-6Al-4V alloy using "spin-coating" technique with a colloidal suspension of TiO2 nanopowders with the aim to optimize the surface morphology (e.g., roughness) for improved biocompatibility. The influence of a TiO2 nanoparticle (NP) coating on the corrosion behavior, metal ion release, and biomimetic apatite formation was studied in DMEM, at 37.5 °C with a continuous supply of 5% CO2. Electrochemical impedance spectroscopy measurements indicate a formation of a new layer on the surface of the NP-coated sample upon 28 days immersion in DMEM. Scanning electron microscopy (SEM) and X-ray spectroscopy confirm that the surface of the NP-coated Ti-6Al-4V shows a complete coverage by a Ca-phosphate layer in contrast to the non-coated Ti-6Al-4V alloy. Hence, the TiO2-NP coating strongly enhances biomimetic apatite formation on the alloy surface. In addition, the TiO2-NP coating can efficiently reduce Al-release from the alloy, for which the bare Ti-6Al-4V alloy is significant for at least 28 days of immersion in DMEM.

  14. Dilatometric Analysis and Microstructural Investigation of the Sintering Mechanisms of Blended Elemental Ti-6Al-4V Powders

    NASA Astrophysics Data System (ADS)

    Kim, Youngmoo; Lee, Junho; Lee, Bin; Ryu, Ho Jin; Hong, Soon Hyung

    2016-09-01

    The densification behavior of mixed Ti and Al/V master alloy powders for Ti-6Al-4V was investigated by a series of dilatometry tests to measure the shrinkage of the samples with the sintering temperature. The corresponding microstructural changes were examined under various sintering conditions with optical microscopy, energy-dispersive spectroscopy, and X-ray diffraction analyses. From these results, the consolidation of the mixed powders was divided into two domains: (i) sintering densification and solute homogenization of Ti and Al/V master alloy particles below 1293 K (1020 °C), and (ii) densification of Ti alloy phases above 1293 K (1020 °C). In the lower temperature region, the inter-diffusion between Ti and Al/V master alloy particles dominated the sintering of the mixed powders because the chemical gradient between two types of particles outweighed the surface energy reduction. Following chemical homogenization, the densification induced the shrinkage of the Ti alloy phases to reduce their surface energies. These tendencies are also supported by the density and grain size variations of the sintered specimens with temperature. The apparent activation energies of the sintering and grain growth for Ti alloy particles are 85.91 ± 6.93 and 37.33 kJ/mol, respectively, similar to or slightly lower than those of pure Ti particles. The difference was attributed to the slower self-diffusion of Ti resulting from the alloying of Al and V into in the Ti matrix.

  15. Dilatometric Analysis and Microstructural Investigation of the Sintering Mechanisms of Blended Elemental Ti-6Al-4V Powders

    NASA Astrophysics Data System (ADS)

    Kim, Youngmoo; Lee, Junho; Lee, Bin; Ryu, Ho Jin; Hong, Soon Hyung

    2016-06-01

    The densification behavior of mixed Ti and Al/V master alloy powders for Ti-6Al-4V was investigated by a series of dilatometry tests to measure the shrinkage of the samples with the sintering temperature. The corresponding microstructural changes were examined under various sintering conditions with optical microscopy, energy-dispersive spectroscopy, and X-ray diffraction analyses. From these results, the consolidation of the mixed powders was divided into two domains: (i) sintering densification and solute homogenization of Ti and Al/V master alloy particles below 1293 K (1020 °C), and (ii) densification of Ti alloy phases above 1293 K (1020 °C). In the lower temperature region, the inter-diffusion between Ti and Al/V master alloy particles dominated the sintering of the mixed powders because the chemical gradient between two types of particles outweighed the surface energy reduction. Following chemical homogenization, the densification induced the shrinkage of the Ti alloy phases to reduce their surface energies. These tendencies are also supported by the density and grain size variations of the sintered specimens with temperature. The apparent activation energies of the sintering and grain growth for Ti alloy particles are 85.91 ± 6.93 and 37.33 kJ/mol, respectively, similar to or slightly lower than those of pure Ti particles. The difference was attributed to the slower self-diffusion of Ti resulting from the alloying of Al and V into in the Ti matrix.

  16. An integrated experimental and computational approach to laser surface nitriding of Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Dahotre, Sanket N.; Vora, Hitesh D.; Pavani, K.; Banerjee, Rajarshi

    2013-04-01

    Titanium and its alloys have been commonly used in many biological and industrial applications owing to their excellent mechanical and physical properties. However, they have been specifically inadequate for biomedical implants due to their inferior tribological properties (low wear resistance, higher coefficient of friction, and lower hardness). As a remedy, the process of laser nitriding has emerged from the past few decades as a unique method for tailoring the surface microstructures and/or composition of titanium for enhanced tribological characteristics of titanium and its alloys. In the present study, a multiphysics computational model was developed to predict the nitrogen diffusion length into the Ti-6Al-4V alloy under various laser processing conditions (laser power and scanning speed). XRD, SEM and EDS analyses were also conducted for phase identification, microstructural investigation, and estimating the nitrogen concentration, respectively. Both computational and experimental results indicated that the depth of nitrogen diffusion increased with decrease in scanning speed, and subsequent increase in laser interaction time and increase in input laser energy density.

  17. Thermal oxidation of medical Ti6Al4V blasted with ceramic particles: Effects on the microstructure, residual stresses and mechanical properties.

    PubMed

    Lieblich, M; Barriuso, S; Multigner, M; González-Doncel, G; González-Carrasco, J L

    2016-02-01

    Roughening of Ti6Al4V by blasting with alumina or zirconia particles improves the mechanical fixation of implants by increasing the surface area available for bone/implant apposition. Additional thermal oxidation treatments of the blasted alloy have already shown to be a complementary low-cost solution to enhancing the in vitro biocompatibility and corrosion resistance of the alloy. In this work, the effects of oxidation treatment on a grit blasted Ti6Al4V biomedical alloy have been analysed in order to understand the net effect of the combined treatments on the alloy fatigue properties. Synchrotron radiation diffraction experiments have been performed to measure residual stresses before and after the treatments and microstructural and hardness changes have been determined. Although blasting of Ti6Al4V with small spherical zirconia particles increases the alloy fatigue resistance with respect to unblasted specimens, fatigue strength after oxidation decreases below the unblasted value, irrespective of the type of particle used for blasting. Moreover, at 700°C the as-blasted compressive residual stresses (700MPa) are not only fully relaxed but even moderate tensile residual stresses, of about 120MPa, are found beneath the blasted surfaces. Contrary to expectations, a moderate increase in hardness occurs towards the blasted surface after oxidation treatments. This can be attributed to the fact that grit blasting modifies the crystallographic texture of the Ti6Al4V shifting it to a random texture, which affects the hardness values as shown by additional experiments on cold rolled samples. The results indicate that the oxidation treatment performed to improve biocompatibility and corrosion resistance of grit blasted Ti6Al4V should be carried out with caution since the alloy fatigue strength can be critically diminished below the value required for high load-bearing components. PMID:26458115

  18. PIRAC Ti nitride coated Ti-6AI-4V head against UHMWPE acetabular cup-hip wear simulator study.

    PubMed

    Gutmanas, E Y; Gotman, I

    2004-04-01

    Wear behaviour of TiN(titanium nitride)-coated Ti and Ti-6AI-4V alloy against UHMW polyethylene was studied in hip simulation test. Ti alloys possess an excellent combination of mechanical properties and biocompatibility, however, they suffer from inadequate wear resistance. Thus, their use as articulating components of total joint replacements requires surface hardening, e.g. by TiN. Thirty-two millimetre diameter cp-Ti and Ti-6AI-4V femoral heads were coated with several micrometre thick TiN layers employing an original PIRAC nitriding method based on interaction of Ti alloy substrate with highly reactive monatomic nitrogen. The heads were tested against UHMWPE cups at 37 degrees C in Ringer's solution or in distilled water. Simulator tests were performed at peak pressures of 1.5 and 2.0 MPa in a constant rotation mode at the frequency of 1.5 Hz. The wear of UHMWPE was estimated by weight loss, and the worn metallic and polyethylene surfaces were examined in SEM. The wear rate of UHMWPE cups articulating against PIRAC coated Ti and Ti-6AI-4V after up to 4 x 10(6) cycles was significantly lower than that of UHMWPE articulating against 316L stainless steel. No delamination of TiN coatings was observed after 4 x 10(6) cycles. These results suggest that TiN PIRAC coating on Ti-6AI-4V heads could minimise the wear of total hip replacements without compromising the mechanical properties of the femoral component. PMID:15332594

  19. Chaos in the Showalter-Noyes-Bar-Eli model of the Belousov-Zhabotinskii reaction

    NASA Astrophysics Data System (ADS)

    Lindberg, David; Turner, Jack S.; Barkley, Dwight

    1990-03-01

    The observation of robust, large-scale chaos in the Showalter-Noyes-Bar-Eli model of the Belousov-Zhabotinskii reaction is reported. The chaos observed is comparable to that found in CSTR experiments at low flow rates.

  20. Straight talk with... Mahendra Rao by Dolgin Elie.

    PubMed

    Rao, Mahendra

    2011-10-01

    In October 2005, Mahendra Rao shocked the scientific community when he quit his job as head of the US National Institute on Aging's stem cell section and announced plans to go into industry. Rao felt that a ban at the time on federal funding for most human embryonic stem cell research hampered researchers in his division and prohibited him from doing the job he was hired to do. So he joined the research-tool giant Invitrogen (which later became Life Technologies) as vice president of regenerative medicine at the company's Maryland facility. Six years on, times have changed in the field of stem cell biology: rules governing taxpayer-backed research involving embryonic stem (ES) cells have been relaxed in the US, and induced pluripotent stem (iPS) cells have come into the fray. Prompted by those changes, Rao opted to return to the US National Institutes of Health (NIH) in August to head the new Intramural Center for Regenerative Medicine. The $52 million center was launched in early 2010 by the agency to develop new therapies using stem cell approaches. With a heightened focus at the NIH on translational medicine, Elie Dolgin spoke to Rao to find out how he plans to turn stem cell discoveries into cell-based therapies. PMID:21988971

  1. Effect of the overlapping factor on the microstructure and mechanical properties of pulsed Nd:YAG laser welded Ti6Al4V sheets

    SciTech Connect

    Gao, Xiao-Long; Liu, Jing; Zhang, Lin-Jie Zhang, Jian-Xun

    2014-07-01

    The effect of the overlapping factor on the microstructures and mechanical properties of pulsed Nd:YAG laser welded Ti6Al4V alloy sheets was investigated by microstructural observations, microhardness tests, tensile tests and fatigue tests. A microstructural examination shows that by increasing the overlapping factor, the grains in the fusion zone become coarser, and the width of the heat affected zone increases. As overlapping factor increases, the width of region composed completely of martensite α′ and the secondary α phase in the heat affected zone increases, consequently the gradient of microstructure along the direction from the fusion zone to base metal decreases, so does the gradient of microhardness. The results of tensile and fatigue tests reveal that the joints made using medium overlapping factor exhibit better mechanical properties than those welded with low and high overlapping factors. Based on the experimental results, it can be stated that a sound weld of Ti6Al4V alloy can be obtained if an appropriate overlapping factor is used. - Highlights: • The weld quality of Ti6Al4V alloy under various overlapping factors was assessed. • Tensile and fatigue tests were conducted with as-welded specimen. • Localized strain across the weld was measured using DIC photogrammetry system. • A sound weld of Ti6Al4V alloy is obtained by using right overlapping factor.

  2. KD4v: comprehensible knowledge discovery system for missense variant

    PubMed Central

    Luu, Tien-Dao; Rusu, Alin; Walter, Vincent; Linard, Benjamin; Poidevin, Laetitia; Ripp, Raymond; Moulinier, Luc; Muller, Jean; Raffelsberger, Wolfgang; Wicker, Nicolas; Lecompte, Odile; Thompson, Julie D.; Poch, Olivier; Nguyen, Hoan

    2012-01-01

    A major challenge in the post-genomic era is a better understanding of how human genetic alterations involved in disease affect the gene products. The KD4v (Comprehensible Knowledge Discovery System for Missense Variant) server allows to characterize and predict the phenotypic effects (deleterious/neutral) of missense variants. The server provides a set of rules learned by Induction Logic Programming (ILP) on a set of missense variants described by conservation, physico-chemical, functional and 3D structure predicates. These rules are interpretable by non-expert humans and are used to accurately predict the deleterious/neutral status of an unknown mutation. The web server is available at http://decrypthon.igbmc.fr/kd4v. PMID:22641855

  3. Mechanical stability of Ti6Al4V implant material after femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Symietz, Christian; Lehmann, Erhard; Gildenhaar, Renate; Hackbarth, Andreas; Berger, Georg; Krüger, Jörg

    2012-07-01

    The surface of a titanium alloy (Ti6Al4V) implant material was covered with a bioactive calcium alkali phosphate ceramic with the aim to accelerate the healing and to form a stronger bond to living bone tissue. To fix the ceramic powder we used a femtosecond laser, which causes a thin surface melting of the metal. It is a requirement to prove that the laser irradiation would not reduce the lifetime of implants. Here we present the results of mechanical stability tests, determined by the rotating bending fatigue strength of sample rods. After describing the sample surfaces and their modifications caused by the laser treatment we give evidence for an unchanged mechanical stability. This applies not only to the ceramic fixation but also to a comparatively strong laser ablation.

  4. Yield Behavior of Solution Treated and Aged Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    Ring, Andrew J.; Baker, Eric H.; Salem, Jonathan A.; Thesken, John C.

    2014-01-01

    Post yield uniaxial tension-compression tests were run on a solution treated and aged (STA), titanium 6-percent aluminum 4-percent vanadium (Ti-6Al-4V) alloy to determine the yield behavior on load reversal. The material exhibits plastic behavior almost immediately on load reversal implying a strong Bauschinger effect. The resultant stress-strain data was compared to a 1D mechanics model and a finite element model used to design a composite overwrapped pressure vessel (COPV). Although the models and experimental data compare well for the initial loading and unloading in the tensile regime, agreement is lost in the compressive regime due to the Bauschinger effect and the assumption of perfect plasticity. The test data presented here are being used to develop more accurate cyclic hardening constitutive models for future finite element design analysis of COPVs.

  5. Gas nitriding of Ti-6Al-4V by induction heating

    SciTech Connect

    Grosch, J.; Saglitz, M.

    1995-12-31

    The usually poor wear behavior of titanium materials can be improved by thermochemical surface heat treatment. In contrast to conventional procedures, which necessitate prolonged treatment, it is possible to reduce the heat treatment period considerably by means of HF induction. Serving as an example in this context is a Ti-6Al-4V titanium alloy that is to demonstrate the possibilities of induction gas nitriding. Temperature variations between 900 C and 1,600 C have resulted in homogeneous surface structures whose microstructures can basically be explained by the titanium-nitrogen diagram. In particular with the 1,600 C variant, the wear resistance has been improved, compared with the untreated titanium material there is a seventyfold increase in wear resistance.

  6. Electron beam welding of titanium and Ti-6AL-4V Thick plates

    NASA Astrophysics Data System (ADS)

    Kohyama, Akira; Arata, Yoshiaki; Tomie, Michio; Igata, Naohiro

    1984-05-01

    This paper reports work as thick weld process development for Ti and Ti alloys in fusion reactor applications. The materials used are pure Ti and Ti-6A1-4V with a maximum plate thickness of 56 mm I-butt welded by a 100KW electron beam welding facility at Osaka University. Optimum welding conditions produced sound welded I-butt joints without detectable defects by X-ray when evaluated with tensile test and micro-Vickers hardness test. The microstructures of the welded joints were investigated with TEM and SEM. These results showed that welded joints were quite sound and were possibly acceptable as structural components of fusion reactor even in as welded state.

  7. Fracture Growth Testing of Titanium 6AL-4V in AF-M315E

    NASA Technical Reports Server (NTRS)

    Sampson, Jeffrey W.; Martinez, Jonathan; McLean, Christopher

    2015-01-01

    The Green Propellant Infusion Mission (GPIM) will demonstrate the performance of AF-M315E monopropellant in orbit. Flight certification requires a safe-life analysis of the titanium alloy fuel tank to ensure inherent flaws will not cause failure during the design life. Material property inputs for this analysis require testing to determine the stress intensity factor for environmentally-assisted cracking (K (sub EAC)) of Ti 6Al-4V in combination with the AF-M315E monopropellant. Testing of single-edge notched specimens SE(B) representing the bulk tank membrane and weld material were performed in accordance with ASTM E1681. Specimens with fatigue pre-cracks were loaded into test fixtures so that the crack tips were exposed to the monopropellant at 50 degrees Centigrade for a duration of 1,000 hours. Specimens that did not fail during exposure were opened to inspect the crack surfaces for evidence of crack growth. The threshold stress intensity value, KEAC, is the highest applied stress intensity that produced neither a failure of the specimen during the exposure nor showed evidence of crack growth. The threshold stress intensity factor of the Ti 6Al-4V forged tank material when exposed to AF-M315E monopropellant was found to be at least 22.0 kilopounds per square inch. The stress intensity factor of the weld material was at least 31.3 kilopounds per square inch.

  8. Fracture Mechanics Testing of Titanium 6AL-4V in AF-M315E

    NASA Technical Reports Server (NTRS)

    Sampson, J. W.; Martinez, J.; McLean, C.

    2016-01-01

    The Green Propellant Infusion Mission (GPIM) will demonstrate the performance of AF-M315E monopropellant on orbit. Flight certification requires a safe-life analysis of the titanium alloy fuel tank to ensure inherent processing flaws will not cause failure during the design life of the tank. Material property inputs for this analysis require testing to determine the stress intensity factor for environment-assisted cracking (KEAC) of Ti 6Al-4V in combination with the AF-M315E monopropellant. Testing of single-edge notched, or SE(B), specimens representing the bulk tank membrane and weld material were performed in accordance with ASTM E1681. Specimens with fatigue pre-cracks were loaded into test fixtures so that the crack tips were exposed to AF-M315E at 50 C for a duration of 1,000 hours. Specimens that did not fail during exposure were opened to inspect the crack surfaces for evidence of crack growth. The threshold stress intensity value, KEAC, is the highest applied stress intensity that produced neither a failure of the specimen during the exposure nor showed evidence of crack growth. The threshold stress intensity factor for environment-assisted cracking of the Ti 6Al-4V forged tank material was found to be at least 22 ksivin and at least 31 ksivin for the weld material when exposed to AF-M315E monopropellant.

  9. In vitro behavior of silicate glass coatings on Ti6Al4V

    SciTech Connect

    Saiz, Eduardo; Goldman, Marni; Gomez-Vega, Jose M.; Tomsia, Antoni P.; Marshall, Grayson W.; Marshall, Sally J.

    2002-01-09

    The in vitro response in simulated body fluid (SBF) of silicate glass coatings on Ti6Al4V was evaluated. Glasses belonging to the SiO2-CaO-MgO-Na2O-K2O-P2O5 system were used to prepare 50-70 (mu)m thick coatings on Ti6Al4V, employing a simple enameling technique. Glasses with silica content higher than 55 wt percent can be used to prepare coatings that do not crack or delaminate and exhibit good adhesion to the alloy. It has been found that coatings with silica content lower than 60 wt percent are more susceptible to corrosion and precipitate carbonated hydroxyapatite on their surface during in vitro tests. However, these coatings have a higher thermal expansion than the metal and are under tension. After 2 months in SBF cracks grow in the coating that reach the glass/metal interface and initiate delamination. Glasses with silica content higher than 60 wt percent are more resistant to corrosion and have lower thermal expansion. These coatings do not crack but they do not precipitate apatite, even after 2 months in SBF.

  10. Manufacturing Ti-6Al-4V Components by Shaped Metal Deposition: Microstructure and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Baufeld, Bernd; van der Biest, Omer; Gault, Rosemary; Ridgway, Keith

    2011-12-01

    The urge in aeronautics to reduce cost and time to flight of components without compromising safety and performance stimulates the investigation of novel manufacturing routes. Shaped Metal Deposition (SMD) is an innovative time-compression technology, which creates near-net shaped components layer by layer by weld deposition. Especially for Ti alloys, which are difficult to shape by traditional methods such as forging, machining and casting and for which the loss of material during the shaping process is also very expensive, SMD promises great advantages. Applying preliminary SMD parameter, four different tubular components with a square cross section and wall thicknesses of about 9 mm were built. The microstructure of the Ti-6Al-4V components consists of large prior β grains, elongated along the temperature gradient during welding, which transform into a lamellar α/β substructure at room temperature. The ultimate tensile strength was between 880 and 1054 MPa. The strain at failure was between 3.0 and 11.3 % for tensile testing parallel to the deposition plane and between 9.1 and 16.4 % perpendicular to the deposition plane. The micro-hardness (3.1 - 3.4 GPa), the Young's modulus (117 - 121 GPa) and the oxygen and nitrogen content are comparable to cast Ti-6Al-4V material.

  11. Fatigue behavior of Ti6Al4V and 316 LVM blasted with ceramic particles of interest for medical devices.

    PubMed

    Barriuso, S; Chao, J; Jiménez, J A; García, S; González-Carrasco, J L

    2014-02-01

    Grit blasting is used as a cost-effective method to increase the surface roughness of metallic biomaterials, as Ti6Al4V and 316 LVM, to enhance the osteointegration, fixation and stability of implants. Samples of these two alloys were blasted by using alumina and zirconia particles, yielding rough (up to Ra~8μm) and nearly smooth (up to Ra~1μm) surfaces, respectively. In this work, we investigate the sub-surface induced microstructural effects and its correlation with the mechanical properties, with special emphasis in the fatigue behavior. Blasting with zirconia particles increases the fatigue resistance whereas the opposite effect is observed using alumina ones. As in a conventional shot penning process, the use of rounded zirconia particles for blasting led to the development of residual compressive stresses at the surface layer, without zones of stress concentrators. Alumina particles are harder and have an angular shape, which confers a higher capability to abrade the surface, but also a high rate of breaking down on impact. The higher roughness and the presence of a high amount of embedded alumina particles make the blasted alloy prone to crack nucleation. Interestingly, the beneficial or detrimental role of blasting is more intense for the Ti6Al4V alloy than for the 316 steel. It is proposed that this behavior is related to their different strain hardening exponents and the higher mass fraction of particles contaminating the surface. The low value of this exponent for the Ti6Al4V alloy justifies the expected low sub-surface hardening during the severe plastic deformation, enhancing its capability to soft during cyclic loading. PMID:24216310

  12. High pressure coolant effect on PVD coated inserts during end milling of Ti-6AL-4V

    NASA Astrophysics Data System (ADS)

    Sridharan, Arvind

    Titanium alloys are being employed extensively in engineering and aerospace applications for their high strength to weight ratio, mechanical strength and ability to withstand high temperatures. Out of the different alloys of titanium available, the most commonly used alloy is Ti-6Al-4V. It is also called `Grade-5 titanium alloy' or 'α+β titanium alloy'. High speed machining of titanium alloys generates high temperatures in the cutting zone, promoting accelerated tool wear and reducing the efficiency in metal cutting. Consequently, the ability of the coolant to remove heat from the cutting zone plays an increasingly important role in the economics of the process as well as on the life of tool inserts. With the introduction of thru-tool coolant delivery, the coolant can now be delivered directly at the point of machining without having to flood the area of machining. This research tries to address the effects that high pressure and thru-tool coolant has on insert wear while end milling Ti-6Al-4V. The parameters used in this study are speed, feed, axial depth of cut, radial depth of cut and coolant pressure. A structured design of experiments along with a central composite design approach is used to determine the main effects of coolant pressure and its interactions with the remaining parameters. The results show that, within the parameters of this experiment, coolant pressure was not a significant main effect. However, pressure seems to react positively with feed rate. Contributions from this research can be used to recommend settings of the cutting factors in order to obtain the minimal tool wear.

  13. Human bone-lineage cell responses to anisotropic Ti6Al4V surfaces are dependent on their maturation state.

    PubMed

    Calzado-Martín, Alicia; Crespo, Lara; Saldaña, Laura; Boré, Alba; Gómez-Barrena, Enrique; Vilaboa, Nuria

    2014-09-01

    This article reports on the interactions of human bone cells, mesenchymal stem cells (hMSCs) from bone marrow and osteoblasts (hOBs), with a submicron-grooved Ti6Al4V alloy that promotes cell orientation in the direction of the anisotropy. Adhesion sites, actin and tubulin networks and fibronectin extracellular matrix of both cell types align with the direction of the grooves. hMSCs adhere at a higher rate on the patterned substrate than on the polished alloy, while no differences are found in hOBs attachment. Compared to the flat substrate, RhoA activity is higher in hMSCs and hOB cultured on the grooved alloy and treatment with C3 transferase leads to loss of organization of actin and tubulin cytoskeletons. Rho-associated kinase (ROCK) activity of hMSCs is upregulated on the anisotropic samples, but not affected in hOBs. Treatment with hydroxyfasudil disrupts the alignment of adhesion sites in hMSCs but not in hOBs. When cells are cultured in media that support osteogenic maturation, OPN secretion increases in hMSCs on the anisotropic alloy and it remains unaffected in hOBs. Cell layer calcification proceeds to a same extent in hMSCs cultured on the two metallic surfaces but decreases in hOBs cultured on the patterned samples. Taken together, these results indicate that hOBs are less sensitive than hMSCs to the patterned Ti6Al4V alloy. This effect can be attributed to their different stages of cell maturation and may be mediated, at least in part, through ROCK signaling because its activity increases on hMSCs cultured on the patterned alloy, while hOBs fail to upregulate it. PMID:24136907

  14. Improved ultrasonic detection of fatigue cracks in Ti-6A1-4V by thermo-optical modulation

    NASA Astrophysics Data System (ADS)

    Yan, Zhongyu; Nagy, Peter B.

    2000-05-01

    Pulsed infrared laser irradiation was used to positively identify small fatigue cracks on the surface of fatigue damaged Ti-6Al-4V specimens. The resulting transient thermoelastic deformation perceptibly changes the opening of partially closed surface cracks without affecting other scatterers, such as surface grooves, corrosion pits, coarse grains, etc., that might hide the fatigue crack from ultrasonic detection. We found that this method, which was previously shown to be very effective in 2024 aluminum alloy, must be modified in order to successfully adapt it to Ti-6Al-4V titanium alloy, where significant thermo-optical modulation was found even from straight corners or open notches. This spurious modulation is caused by direct thermal modulation of the sound velocity in the intact material rather than thermal stresses via crack closure. Different methods have been developed to distinguished direct thermal modulation from crack-closure modulation due to thermoelastic stresses. It was found that the modified thermo-optical modulation method can increase the detectability of hidden fatigue cracks in Ti-6Al-4V specimens by approximately one order of magnitude.—This effort was sponsored by the Defense Advanced Research Projects Agency (DARPA) Multidisciplinary University Research Initiative (MURI), under Air Force Office of Scientific Research grant number F49620-96-1-0442.

  15. Tribology and hydrophobicity of a biocompatible GPTMS/PFPE coating on Ti6Al4V surfaces.

    PubMed

    Panjwani, Bharat; Sinha, Sujeet K

    2012-11-01

    Tribological properties of perfluoropolyether (PFPE) coated 3-glycidoxypropyltrimethoxy silane (GPTMS) SAMs (self-assembled monolayers) onto Ti6Al4V alloy substrate were studied using ball-on-disk experiments. GPTMS SAMs deposition onto a Ti6Al4V alloy surface was carried out using solution phase method. Ultra-thin layer of PFPE was dip-coated onto SAMs modified specimens. Tribological tests were carried out at 0.2 N normal load and rotational speed of 200 rpm using track radius of 2 mm. Wear track and counterface surface conditions were investigated using optical microscopy. PFPE modified specimens were baked at 150 °C for 1h to investigate the effect of thermal treatment on tribological properties. Surface characterization tests such as contact angle measurement, AFM morphology and X-ray photoelectron spectroscopy were carried out for differently modified specimens. PFPE overcoat meets the requirements of cytotoxicity test using the ISO 10993-5 elution method. PFPE top layer lowered the coefficient of friction and increased wear durability for different specimens (with and without GPTMS intermediate layer). PFPE overcoat onto GPTMS showed significant increase in the wear resistance compared with overcoat onto bare Ti6Al4V specimens. The observed improvement in the tribological properties can be attributed to the change in the interaction of PFPE molecules with the substrate surface due to the GPTMS intermediate layer. PMID:23032430

  16. Fatigue crack growth rate of Ti-6Al-4V considering the effects of fracture toughness and crack closure

    NASA Astrophysics Data System (ADS)

    Zhang, Junhong; Yang, Shuo; Lin, Jiewei

    2015-03-01

    Fatigue fracture is one of the main failure modes of Ti-6Al-4V alloy, fracture toughness and crack closure have strong effects on the fatigue crack growth(FCG) rate of Ti-6Al-4V alloy. The FCG rate of Ti-6Al-4V is investigated by using experimental and analytical methods. The effects of stress ratio, crack closure and fracture toughness on the FCG rate are studied and discussed. A modified prediction model of the FCG rate is proposed, and the relationship between the fracture toughness and the stress intensity factor(SIF) range is redefined by introducing a correcting coefficient. Notched plate fatigue tests (including the fracture toughness test and the FCG rate test) are conducted to investigate the influence of affecting factors on the FCG rate. Comparisons between the predicted results of the proposed model, the Paris model, the Walker model, the Sadananda model, and the experimental data show that the proposed model gives the best agreement with the test data particularly in the near-threshold region and the Paris region, and the corresponding calculated fatigue life is also accurate in the same regions. By considering the effects of fracture toughness and crack closure, the novel FCG rate prediction model not only improves the estimating accuracy, but also extends the adaptability of the FCG rate prediction model in engineering.

  17. Diffusion Bonding of Ti-6Al-4V Sheet with Ti-6Al-4V Foam for Biomedical Implant Applications

    NASA Astrophysics Data System (ADS)

    Hamilton, Brittany; Oppenheimer, Scott; Dunand, David C.; Lewis, Daniel

    2013-12-01

    Advanced metallic bone implants are designed to have a porous surface to improve osseointegration and reduce risks of loosening. An alternative approach to existing surface treatments to create a porous surface is to bond separately produced metallic foams onto the implant. To assess the feasibility of this approach, a Ti-6Al-4V foam was diffusion bonded onto bulk Ti-6Al-4V in an argon atmosphere at temperatures between 1173 K and 1223 K (900 °C and 950 °C) for times between 45 and 75 minutes. These specimens were tested in tension to determine bond quality: failures occurred in the foam, indicating a strong diffusion-bonded interface. The quality of the bond was confirmed by metallographic studies, indicating that this approach, which can also be applied to creating of sandwich with porous cores, is successful.

  18. [Superplastic forming of titanium alloy denture base].

    PubMed

    Okuno, O; Nakano, T; Hamanaka, H; Miura, I; Ito, M; Ai, M; Okada, M

    1989-03-01

    Ti-6Al-4V alloy has both excellent biocompatibility and superior mechanical properties. This Ti-6Al-4V can be deformed greatly and easily at the superplastic temperature of 800 degrees C to 900 degrees C. The superplastic forming of Ti-6Al-4V was made to apply to fabrication of denture base. Almost the same procedure as for dental casting mold was employed in producing the superplastic forming die by the improved phosphate bonded investment. In the pressure vessel of heat resistant alloy, Ti-6Al-4V plate was formed superplastically on the die by argon gas pressure at 850 degrees C. The fit of superplactic forming Ti-6Al-4V denture base was better than that of casting Co-Cr alloy denture bases. The Ti-6Al-4V alloy might react a little with the die. Because micro Vikers hardness of the cross-section did not go up too much near the surfaces. Even just after being formed, the surfaces were much smoother than that of Co-Cr alloy casting. The tensile strength and yield strength of superplastic forming Ti-6Al-4V were higher than those of Co-Cr castings. The elongation was about 10%. These results show that superplastic forming of Ti-6Al-4V would be suitable for a denture base. PMID:2603084

  19. A review article: The mechanical properties and the microstructural behaviour of laser metal deposited Ti-6Al-4V and TiC composite

    NASA Astrophysics Data System (ADS)

    Erinosho, Mutiu F.; Akinlabi, Esther T.

    2016-03-01

    Titanium alloy (Ti-6Al-4V) Grade 5 has been regarded as the most useful alloy for the aerospace applications, due to their light weight properties. Today, laser technology is an energetic process in which the beam ejected can travel a longer distance and spot on the focused surface. The combination of metallic powder and laser beam has been used concurrently to form a solid figure. However, this combination has generated a permanently solidified metallurgical bonding between the laser-deposited metallic powders. Several research works have been conducted to improve the mechanical properties of the primary alloy, Ti-6Al-4V. This article conversely highlights the series of work that have been conducted on improving the mechanical properties and microstructures of the primary alloy with the addition of titanium carbide (TiC). The Ti-6Al-4V alloy has been widely selected in most critical part of a component. Their reinforcement with TiC composite particle has been achieved successfully through the optimal usage of laser technology. The characteristics of the reinforced component have vehemently improved the mechanical properties such as the tensile strength, wear resistance, fracture toughness and hardness; as well as the morphologies and phases of the microstructures.

  20. High strain rate and quasi-static tensile behaviour of Ti-6Al-4V after cyclic damage

    NASA Astrophysics Data System (ADS)

    Galán López, J.; Verleysen, P.; Degrieck, J.

    2012-08-01

    It is common that energy absorbing structural elements are subjected to a number of loading cycles before a crash event. Several studies have shown that previous fatigue can significantly influence the tensile properties of some materials, and hence the behaviour of structural elements made of them. However, when the capacity of absorbing energy of engineering materials is determined, fresh material without any fatigue damage is most often used. This study investigates the effect of fatigue damage on the dynamic tensile properties of Ti-6Al-4V in thin-sheet form. Results are completed with tests at quasi-static strain rates and observations of the fracture surfaces, and compared with results obtained from other alloys and steel grades. The experiments show that the dynamic properties of Ti-6Al-4V are not affected by a number of fatigue loading cycles high enough to significantly reduce the energy absorbing capabilities of EDM machined samples.

  1. On the Texture Formation of Selective Laser Melted Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Simonelli, Marco; Tse, Yau Yau; Tuck, Chris

    2014-06-01

    Selective laser melting (SLM) has been shown to be an attractive manufacturing route for the production of α/ β titanium alloys. The relationship between the SLM process parameters and the microstructure of titanium alloys has been the object of several works, but the texture formation during the SLM process has yet to be understood. In the present study, the texture formation of Ti-6Al-4V components was investigated in order to clarify which microstructural features can be tailored during the SLM process. The microstructural characterization of the as-built components was carried out using various microscopy techniques. Phase and texture analysis were carried out using backscattered electron imaging and diffraction. It was found that as-built components consist exclusively of α' martensitic phase precipitated from prior β columnar grains. The texture of the prior β phase was reconstructed and discussed in relation to the used SLM process parameters. It was found that the β grain solidification is influenced by the laser scan strategy and that the β phase has a strong <100> texture along its grain growth direction. The α' martensitic laths that originate from the parent β grains precipitate according to the Burgers orientation relationship. It was observed that α' laths clusters from the same β grain have a specific misorientation that minimizes the local shape strain. Texture inheritance across successive deposited layers was also observed and discussed in relation to various variant selection mechanisms.

  2. Properties of ion implanted Ti-6Al-4V processed using beamline and PSII techniques

    SciTech Connect

    Walter, K.C.; Woodring, J.S.; Nastasi, M.; Munson, C.M.; Williams, J.M.; Poker, D.B.

    1996-12-31

    The surface of Ti-6Al-4V (Ti64) alloy has been modified using beamline implantation of boron. In separate experiments, Ti64 has been implanted with nitrogen using a plasma source ion implantation (PSII) technique utilizing either ammonia (NH{sub 3}), nitrogen (N{sub 2}), or their combinations as the source of nitrogen ions. Beamline experiments have shown the hardness of the N-implanted surface saturates at a dose level of {approximately} 4 {times} 10{sup 17} at/cm{sup 2} at {approximately} 10 GPa. The present work makes comparisons of hardness and tribological tests of (1) B implantation using beamline techniques, and (2) N implanted samples using ammonia and/or nitrogen gas in a PSII process. The results show that PSII using N{sub 2} or NH{sub 3} gives similar hardness as N implantation using a beamline process. The presence of H in the Ti alloy surface does not affect the hardness of the implanted surface. Boron implantation increased the surface hardness by as much as 2.5x at the highest dose level. Wear testing by a pin-on-disk method indicated that nitrogen implantation reduced the wear rate by as much as 120x, and boron implantation reduced the wear rate by 6.5x. Increased wear resistance was accompanied by a decreased coefficient of friction.

  3. Warm Spray Forming of Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Molak, R. M.; Araki, H.; Watanabe, M.; Katanoda, H.; Ohno, N.; Kuroda, S.

    2014-01-01

    Warm spray (WS) is a modification of high-velocity oxy-fuel spraying, in which the temperature of the supersonic gas flow generated by the combustion of kerosene and oxygen is controlled by diluting the combustion flame with an inert gas such as nitrogen. The inert gas is injected into the mixing chamber placed between the combustion chamber and the powder feed ports, thus the temperature of the propellant gas can be controlled from ~700 to 2,000 K. Since WS allows for higher particle temperatures in comparison to cold spray, warm sprayed particles are more softened upon impact, thus resulting in greater deformation facilitating the formation of shear instability for bonding. Recently, the combustion pressure of WS has been increased from 1 (low-pressure warm spray) to 4 MPa (high-pressure warm spray) in order to increase the velocity of sprayed particles. Effects of spray parameters on microstructure, mechanical properties, and splats formation of Ti-6Al-4V were systematically studied. Obtained coatings were examined by analyzing the coating cross-section images, microhardness as well as oxygen content. In addition, flattening ratio of splats was calculated as a function of nitrogen flow rate. It was found that the increased particle velocity caused by the increased combustion pressure had significant beneficial effects in terms of improving density and controlling the oxygen level in the sprayed Ti-6Al-4V coatings.

  4. Anodizing color coded anodized Ti6Al4V medical devices for increasing bone cell functions

    PubMed Central

    Ross, Alexandra P; Webster, Thomas J

    2013-01-01

    Current titanium-based implants are often anodized in sulfuric acid (H2SO4) for color coding purposes. However, a crucial parameter in selecting the material for an orthopedic implant is the degree to which it will integrate into the surrounding bone. Loosening at the bone–implant interface can cause catastrophic failure when motion occurs between the implant and the surrounding bone. Recently, a different anodization process using hydrofluoric acid has been shown to increase bone growth on commercially pure titanium and titanium alloys through the creation of nanotubes. The objective of this study was to compare, for the first time, the influence of anodizing a titanium alloy medical device in sulfuric acid for color coding purposes, as is done in the orthopedic implant industry, followed by anodizing the device in hydrofluoric acid to implement nanotubes. Specifically, Ti6Al4V model implant samples were anodized first with sulfuric acid to create color-coding features, and then with hydrofluoric acid to implement surface features to enhance osteoblast functions. The material surfaces were characterized by visual inspection, scanning electron microscopy, contact angle measurements, and energy dispersive spectroscopy. Human osteoblasts were seeded onto the samples for a series of time points and were measured for adhesion and proliferation. After 1 and 2 weeks, the levels of alkaline phosphatase activity and calcium deposition were measured to assess the long-term differentiation of osteoblasts into the calcium depositing cells. The results showed that anodizing in hydrofluoric acid after anodizing in sulfuric acid partially retains color coding and creates unique surface features to increase osteoblast adhesion, proliferation, alkaline phosphatase activity, and calcium deposition. In this manner, this study provides a viable method to anodize an already color coded, anodized titanium alloy to potentially increase bone growth for numerous implant applications

  5. The Elicitin-Like Glycoprotein, ELI025, Is Secreted by the Pathogenic Oomycete Pythium insidiosum and Evades Host Antibody Responses

    PubMed Central

    Lerksuthirat, Tassanee; Lohnoo, Tassanee; Inkomlue, Ruchuros; Rujirawat, Thidarat; Yingyong, Wanta; Khositnithikul, Rommanee; Phaonakrop, Narumon; Roytrakul, Sittiruk; Sullivan, Thomas D.; Krajaejun, Theerapong

    2015-01-01

    Pythium insidiosum is a unique oomycete that can infect humans and animals. Patients with a P. insidiosum infection (pythiosis) have high rates of morbidity and mortality. The pathogen resists conventional antifungal drugs. Information on the biology and pathogenesis of P. insidiosum is limited. Many pathogens secrete proteins, known as effectors, which can affect the host response and promote the infection process. Elicitins are secretory proteins and are found only in the oomycetes, primarily in Phytophthora and Pythium species. In plant-pathogenic oomycetes, elicitins function as pathogen-associated molecular pattern molecules, sterol carriers, and plant defense stimulators. Recently, we reported a number of elicitin-encoding genes from the P. insidiosum transcriptome. The function of elicitins during human infections is unknown. One of the P. insidiosum elicitin-encoding genes, ELI025, is highly expressed and up-regulated at body temperature. This study aims to characterize the biochemical, immunological, and genetic properties of the elicitin protein, ELI025. A 12.4-kDa recombinant ELI025 protein (rELI025) was expressed in Escherichia coli. Rabbit anti-rELI025 antibodies reacted strongly with the native ELI025 in P. insidiosum’s culture medium. The detected ELI025 had two isoforms: glycosylated and non-glycosylated. ELI025 was not immunoreactive with sera from pythiosis patients. The region near the transcriptional start site of ELI025 contained conserved oomycete core promoter elements. In conclusion, ELI025 is a small, abundant, secreted glycoprotein that evades host antibody responses. ELI025 is a promising candidate for development of diagnostic and therapeutic targets for pythiosis. PMID:25793767

  6. The elicitin-like glycoprotein, ELI025, is secreted by the pathogenic oomycete Pythium insidiosum and evades host antibody responses.

    PubMed

    Lerksuthirat, Tassanee; Lohnoo, Tassanee; Inkomlue, Ruchuros; Rujirawat, Thidarat; Yingyong, Wanta; Khositnithikul, Rommanee; Phaonakrop, Narumon; Roytrakul, Sittiruk; Sullivan, Thomas D; Krajaejun, Theerapong

    2015-01-01

    Pythium insidiosum is a unique oomycete that can infect humans and animals. Patients with a P. insidiosum infection (pythiosis) have high rates of morbidity and mortality. The pathogen resists conventional antifungal drugs. Information on the biology and pathogenesis of P. insidiosum is limited. Many pathogens secrete proteins, known as effectors, which can affect the host response and promote the infection process. Elicitins are secretory proteins and are found only in the oomycetes, primarily in Phytophthora and Pythium species. In plant-pathogenic oomycetes, elicitins function as pathogen-associated molecular pattern molecules, sterol carriers, and plant defense stimulators. Recently, we reported a number of elicitin-encoding genes from the P. insidiosum transcriptome. The function of elicitins during human infections is unknown. One of the P. insidiosum elicitin-encoding genes, ELI025, is highly expressed and up-regulated at body temperature. This study aims to characterize the biochemical, immunological, and genetic properties of the elicitin protein, ELI025. A 12.4-kDa recombinant ELI025 protein (rELI025) was expressed in Escherichia coli. Rabbit anti-rELI025 antibodies reacted strongly with the native ELI025 in P. insidiosum's culture medium. The detected ELI025 had two isoforms: glycosylated and non-glycosylated. ELI025 was not immunoreactive with sera from pythiosis patients. The region near the transcriptional start site of ELI025 contained conserved oomycete core promoter elements. In conclusion, ELI025 is a small, abundant, secreted glycoprotein that evades host antibody responses. ELI025 is a promising candidate for development of diagnostic and therapeutic targets for pythiosis. PMID:25793767

  7. Implementation status of the extreme light infrastructure - nuclear physics (ELI-NP) project

    SciTech Connect

    Gales, S. Zamfir, N. V.

    2015-02-24

    The Project Extreme Light Infrastructure (ELI) is part of the European Strategic Forum for Research Infrastructures (ESFRI) Roadmap. ELI will be built as a network of three complementary pillars at the frontier of laser technologies. The ELI-NP pillar (NP for Nuclear Physics) is under construction near Bucharest (Romania) and will develop a scientific program using two 10 PW lasers and a Compton back-scattering high-brilliance and intense gamma beam, a marriage of laser and accelerator technology at the frontier of knowledge. In the present paper, the technical description of the facility, the present status of the project as well as the science, applications and future perspectives will be discussed.

  8. Implementation status of the extreme light infrastructure - nuclear physics (ELI-NP) project

    NASA Astrophysics Data System (ADS)

    Gales, S.; Zamfir, N. V.

    2015-02-01

    The Project Extreme Light Infrastructure (ELI) is part of the European Strategic Forum for Research Infrastructures (ESFRI) Roadmap. ELI will be built as a network of three complementary pillars at the frontier of laser technologies. The ELI-NP pillar (NP for Nuclear Physics) is under construction near Bucharest (Romania) and will develop a scientific program using two 10 PW lasers and a Compton back-scattering high-brilliance and intense gamma beam, a marriage of laser and accelerator technology at the frontier of knowledge. In the present paper, the technical description of the facility, the present status of the project as well as the science, applications and future perspectives will be discussed.

  9. Evaluation of ARCAM Deposited Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    Slattery, Kevin; Slaughter, Blake; Speorl, Emily; Good, James; Gilley, Scott; McLemore, Carole

    2008-01-01

    A wide range of Metal Additive Manufacturing (MAM) technologies are becoming available. One of the challenges in using new technologies for aerospace systems is demonstrating that the process and system has the ability to manufacture components that meet the high quality requirements on a statistically significant basis. The widest-used system for small to medium sized components is the ARCAM system manufactured in Gothenburg, Sweden. This system features a 4kW electron-beam gun, and has a chamber volume of 250mm long x 250mm wide x 250mm to 400mm tall. This paper will describe the basis for the quality and consistency requirements, the experimental and evaluation procedures used for the evaluation, and an analysis of the results for Ti-6Al-4V.

  10. Aquatic assessment of the Ely Copper Mine Superfund site, Vershire, Vermont

    USGS Publications Warehouse

    Seal, Robert R., II; Kiah, Richard G.; Piatak, Nadine M.; Besser, John M.; Coles, James F.; Hammarstrom, Jane M.; Argue, Denise M.; Levitan, Denise M.; Deacon, Jeffrey R.; Ingersoll, Christopher G.

    2010-01-01

    The information was used to develop an overall assessment of the impact on the aquatic system that appears to be a result of the acid rock drainage at the Ely Mine. More than 700 meters of Ely Brook, including two of the six ponds, were found to be severely impacted, on the basis of water-quality data and biological assessments. The reference location was of good quality based on the water quality and biological assessment. More than 3,125 meters of Schoolhouse Brook are also severely impacted, on the basis of water-quality data and biological assessments. The biological community begins to recover near the conflu

  11. Extreme Light Infrastructure Nuclear Physics (ELI-NP): Present status and perspectives

    NASA Astrophysics Data System (ADS)

    Zamfir, N. V.

    2016-05-01

    Extreme Light Infrastructure - Nuclear Physics (ELI-NP), a new Research Center under construction, will use extreme electromagnetic fields for nuclear physics research and will be operational in 2018. The status of the Project implementation will be presented. At ELI-NP, a high power laser system together with a very brilliant gamma beam are the two main research tools. Their targeted operational parameters will be described. The related experimental set-ups will be presented, together with the main directions of the research envisioned.

  12. Friction Stir Processing of Investment-Cast Ti-6Al-4V: Microstructure and Properties

    NASA Astrophysics Data System (ADS)

    Pilchak, A. L.; Norfleet, D. M.; Juhas, M. C.; Williams, J. C.

    2008-07-01

    Investment-cast titanium components are becoming increasingly common in the aerospace industry due to the ability to produce large, complex, one-piece components that were previously fabricated by mechanically fastening multiple pieces together. The fabricated components are labor-intensive and the fastener holes are stress concentrators and prime sites for fatigue crack initiation. The castings are typically hot-isostatically-pressed (HIP) to close internal porosity, but have a coarse, fully lamellar structure that has low resistance to fatigue crack initiation. The as-cast + HIP material exhibited 1- to 1.5-mm prior β grains containing a fully lamellar α + β microstructure consistent with slow cooling from above the β transus. Friction stir processing (FSP) was used to locally modify the microstructure on the surface of an investment-cast Ti-6Al-4V plate. Friction stir processing converted the as-cast microstructure to fine (1- to 2-μm) equiaxed α grains. Using micropillars created with a dual-beam focused ion beam device, it was found that the fine-grained equiaxed structure has about a 12 pct higher compressive yield stress. In wrought products, higher strength conditions are more resistant to fatigue crack initiation, while the coarse lamellar microstructure in the base material has better fatigue crack growth resistance. In combination, these two microstructures can increase the fatigue life of titanium alloy castings by increasing the number of cycles prior to crack initiation while retaining the same low-crack growth rates of the colony microstructure in the remainder of the component. In the current study, high-cycle fatigue testing of investment-cast Ti-6Al-4V was performed on four-point bend specimens. Early results show that FSP can increase fatigue strength dramatically.

  13. Characterization and mechanical properties investigation of TiN-Ag films onto Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Du, Dongxing; Liu, Daoxin; Zhang, Xiaohua; Tang, Jingang; Xiang, Dinggen

    2016-03-01

    To investigate their effect on fretting fatigue (FF) resistance of a Ti-6Al-4V alloy, hard solid lubricating composite films of TiN with varying silver contents (TiN-Ag) were deposited on a Ti-6Al-4V alloy using ion-assisted magnetron sputtering. The surface morphology and structure were analyzed by atomic force microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and transmission electron microscopy. The hardness, bonding strength, and toughness of films were tested using a micro-hardness tester, scratch tester, and a repeated press-press test system that was manufactured in-house, respectively. The FF resistance of TiN-Ag composite films was studied using self-developed devices. The results show that the FF resistance of a titanium alloy can be improved by TiN-Ag composite films, which were fabricated using hard TiN coating doped with soft Ag. The FF life of Ag0.5, Ag2, Ag5, Ag10 and Ag20 composite films is 2.41, 3.18, 3.20, 2.94 and 2.87 times as great as that of the titanium alloy, respectively. This is because the composite films have the better toughness, friction lubrication, and high bonding strength. When the atomic fraction of Ag changes from 2% to 5%, the FF resistance of the composite films shows the best performance. This is attributed to the surface integrity of the composite film is sufficiently fine to prevent the initiation and early propagation of FF cracks.

  14. A nano-scale mirror-like surface of Ti–6Al–4V attained by chemical mechanical polishing

    NASA Astrophysics Data System (ADS)

    Chenliang, Liang; Weili, Liu; Shasha, Li; Hui, Kong; Zefang, Zhang; Zhitang, Song

    2016-05-01

    Metal Ti and its alloys have been widely utilized in the fields of aviation, medical science, and micro-electro-mechanical systems, for its excellent specific strength, resistance to corrosion, and biological compatibility. As the application of Ti moves to the micro or nano scale, however, traditional methods of planarization have shown their short slabs. Thus, we introduce the method of chemical mechanical polishing (CMP) to provide a new way for the nano-scale planarization method of Ti alloys. We obtain a mirror-like surface, whose flatness is of nano-scale, via the CMP method. We test the basic mechanical behavior of Ti–6Al–4V (Ti64) in the CMP process, and optimize the composition of CMP slurry. Furthermore, the possible reactions that may take place in the CMP process have been studied by electrochemical methods combined with x-ray photoelectron spectroscopy (XPS). An equivalent circuit has been built to interpret the dynamic of oxidation. Finally, a model has been established to explain the synergy of chemical and mechanical effects in the CMP of Ti–6Al–4V. Project supported by the National Major Scientific and Technological Special Project during the Twelfth Five-year Plan Period of China (Grant No. 2009ZX02030-1), the National Natural Science Foundation of China (Grant No. 51205387), the Support by Science and Technology Commission of Shanghai City, China (Grant No. 11nm0500300), and the Science and Technology Commission of Shanghai City, China (Grant No. 14XD1425300).

  15. Hydroxyapatite coating on Ti6Al4V alloy by a sol-gel method.

    PubMed

    Wang, Diangang; Chen, Chuanzhong; He, Ting; Lei, Tingquan

    2008-06-01

    Using trimethyl phosphate and calcium nitrate tetrahydrate as the calcium and phosphorus precursors, respectively, HA films were prepared layer by layer by a sol-gel method. The phase constitution, microstructure and calcium/phosphorus (Ca/P) molar ratio of the sol-gel films were studied by X-ray diffraction (XRD) and electronic probe microanalysis (EPMA). The results show that the sol-gel films have high crystallinity and are composed of HA and CaO phases, and the Ca/P ratio is slightly higher than the theoretical value in HA because of the loss of phosphorous element. Two typical cauliflower-like and lamellar structures were observed in the films. Cauliflower-like structure, which increases the biological reactivity of the implant surface towards natural bone, formed mainly at low drying temperature and high calcining temperature, while the lamellar structure formed when the drying temperature is high (500 degrees C or above). PMID:18071873

  16. [Validation of the Essen Quality of Life-Index for Eating Disorders (ELI)].

    PubMed

    Tagay, Sefik; Lindner, Marion; Friederich, Hans-Christoph; Schlottbohm, Ellen

    2015-09-01

    The aim of this study was the validation of a short disease-specific questionnaire (ELI, Essen Quality of Life Index for Eating Disorders) to measure the health-related quality of life in patients with eating disorders. A total of 182 currently ill and former eating disordered patients and 87 healthy controls completed the ELI questionnaire as well as other reliable and valid instruments (EDQOL, SF-12, EDI-2, FKB-20, SEED, BSI, IIP-D and SOC-13). In addition, 46 eating disorder patients completed the same questionnaires at the end of therapy. The ELI proved to have a high internal consistency of α=0.96. As expected, one main factor was found with a high declaration of variance of 71.25%. There is also evidence for very good construct validity and good sensitivity for change. Therefore, the ELI is an economic, reliable and valid instrument that assesses disease-specific health-related quality of life of individuals with eating disorders. The questionnaire can be recommended for research as well as clinical care contexts. PMID:25919059

  17. 78 FR 21849 - Television Broadcasting Services; Ely, NV to Middletown Township, NJ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-12

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 73 Television Broadcasting Services; Ely, NV to Middletown Township, NJ AGENCY... U.S.C. 801(a)(1)(A). List of Subjects in 47 CFR Part 73 Television. Federal...

  18. Controllable two-scale network architecture and enhanced mechanical properties of (Ti5Si3+TiBw)/Ti6Al4V composites.

    PubMed

    Jiao, Y; Huang, L J; Duan, T B; Wei, S L; Kaveendran, B; Geng, L

    2016-01-01

    Novel Ti6Al4V alloy matrix composites with a controllable two-scale network architecture were successfully fabricated by reaction hot pressing (RHP). TiB whiskers (TiBw) were in-situ synthesized around the Ti6Al4V matrix particles, and formed the first-scale network structure (FSNS). Ti5Si3 needles (Ti5Si3) precipitated in the β phase around the equiaxed α phase, and formed the secondary-scale network structure (SSNS). This resulted in increased deformation compatibility accompanied with enhanced mechanical properties. Apart from the reinforcement distribution and the volume fraction, the ratio between Ti5Si3 and TiBw fraction were controlled. The prepared (Ti5Si3 + TiBw)/Ti6Al4V composites showed higher tensile strength and ductility than the composites with a one-scale microstructure, and superior wear resistance over the Ti6Al4V alloy under dry sliding wear conditions at room temperature. PMID:27622992

  19. Wear of Steel and Ti6Al4V Rollers in Vacuum

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.; Shareef, Iqbal

    2012-01-01

    This investigation was prompted by results of a qualification test of a mechanism to be used for the James Webb Space Telescope. Post-test inspections of the qualification test article revealed some loose wear debris and wear of the steel rollers and the mating Ti6Al4V surfaces. An engineering assessment of the design and observations from the tested qualification unit suggested that roller misalignment was a controlling factor. The wear phenomena were investigated using dedicated laboratory experiments. Tests were done using a vacuum roller rig for a range of roller misalignment angles. The wear in these tests was mainly adhesive wear. The measured wear rates were highly correlated to the misalignment angle. For all tests with some roller misalignment, the steel rollers lost mass while the titanium rollers gained mass indicating strong adhesion of the steel with the titanium alloy. Inspection of the rollers revealed that the adhesive wear was a two-way process as titanium alloy was found on the steel rollers and vice versa. The qualification test unit made use of 440F steel rollers in the annealed condition. Both annealed 440F steel rollers and hardened 440C rollers were tested in the vacuum roller rig to investigate possibility to reduce wear rates and the risk of loose debris formation. The 440F and 440C rollers had differing wear behaviors with significantly lesser wear rates for the 440C. For the test condition of zero roller misalignment, the adhesive wear rates were very low, but still some loose debris was formed

  20. Thermoelectric assessment of laser peening induced effects on a metallic biomaterial Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Carreón, H.; Barriuso, S.; Porro, J. A.; González-Carrasco, J. L.; Ocaña, J. L.

    2014-03-01

    Laser peening has recently emerged as a useful technique to overcome detrimental effects associated to another wellknown surface modification processes such as shot peening or grit blasting used in the biomedical field. It is worth to notice that besides the primary residual stress effect, thermally induced effects might also cause subtle surface and subsurface microstructural changes that might influence corrosion resistance. Moreover, since maximum loads use to occur at the surface, they could also play a critical role in the fatigue strength. In this work, plates of Ti-6Al-4V alloy of 7 mm in thickness were modified by laser peening without using a sacrificial outer layer. Irradiation by a Q-switched Nd-YAG laser (9.4 ns pulse length) working in fundamental harmonic at 2.8 J/pulse and with water as confining medium was used. Laser pulses with a 1.5 mm diameter at an equivalent overlapping density (EOD) of 5000 cm-2 were applied. Attempts to analyze the global induced effects after laser peening were addressed by using the contacting and non-contacting thermoelectric power (TEP) techniques. It was demonstrated that the thermoelectric method is entirely insensitive to surface topography while it is uniquely sensitive to subtle variations in thermoelectric properties, which are associated with the different material effects induced by different surface modification treatments. These results indicate that the stress-dependence of the thermoelectric power in metals produces sufficient contrast to detect and quantitatively characterize regions under compressive residual stress based on their thermoelectric power contrast with respect to the surrounding intact material. However, further research is needed to better separate residual stress effects from secondary material effects, especially in the case of low-conductivity engineering materials like titanium alloys.

  1. Phase Transformations and Formation of Ultra-Fine Microstructure During Hydrogen Sintering and Phase Transformation (HSPT) Processing of Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Sun, Pei; Fang, Zhigang Zak; Koopman, Mark; Xia, Yang; Paramore, James; Ravi Chandran, K. S.; Ren, Yang; Lu, Jun

    2015-12-01

    The hydrogen sintering and phase transformation (HSPT) process is a novel powder metallurgy method for producing Ti alloys, particularly the Ti-6Al-4V alloy, with ultra-fine microstructure in the as-sintered state. The ultra-fine microstructure is obtained as a direct result of the use of H2 gas during sintering. The refinement of the microstructure during HSPT is similar to that of thermal hydrogen processing (THP) of bulk Ti alloys. For both THP and HSPT of Ti-6Al-4V alloy, the mechanisms of the grain refinement depend on the phase equilibria and phase transformations in the presence of hydrogen, which are surprisingly still not well established to date and are still subjected to research and debate. In recent work by the present authors, a pseudo-binary phase diagram of (Ti-6Al-4V)-H has been determined by using in situ synchrotron XRD and TGA/DSC techniques. Aided by this phase diagram, the current paper focuses on the series of phase transformations during sintering and cooling of Ti-6Al-4V in a hydrogen atmosphere and the mechanisms for the formation of the ultra-fine microstructures obtained. Using experimental techniques, including in situ synchrotron XRD, SEM, EBSD, and TEM, the microstructural refinement was found to be the result of (1) the precipitation of ultra-fine α/α2 within coarse β grains during an isothermal hold at intermediate temperatures, and (2) the eutectoid transformation of β → α + δ at approximately 473 K (200 °C).

  2. Texture Evolution During Laser Direct Metal Deposition of Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Sridharan, Niyanth; Chaudhary, Anil; Nandwana, Peeyush; Babu, Sudarsanam Suresh

    2016-03-01

    Titanium alloys are used in a wide variety of high-performance applications and hence the processing of titanium and the resulting microstructures after additive manufacturing has received significant attention. During additive manufacturing, the processing route involves the transition from a liquid to solid state. The addition of successive layers results in a complex microstructure due to solid-state transformations. The current study focuses on understanding the phase transformations and relate them to the transformation texture in Ti-6Al-4V to identify conditions leading to a strong alpha transformation texture. The as-deposited builds were characterized using optical microscopy and electron backscattered diffraction. The results showed columnar prior β grains with a martensitic structure after the deposition of a single layer. On subsequent depositions, the martensitic microstructure decomposed to a colony and basketweave microstructure with a stronger transformation texture. The alpha texture with a colony and basketweave microstructure showed a stronger transformation texture as a result of variant selection. Thus, by controlling the cooling rate of the build from the β transus, it is possible to control the alpha transformation texture.

  3. Surface Deformation Behavior of BSTOA Ti-6Al-4V during Laser Shock Processing

    SciTech Connect

    El-Dasher, B S; Zaleski, T M; Gray, J J; Rybak, S J; Chen, H

    2005-07-21

    The surface of a beta solution treated and overaged (BSTOA) Ti-6Al-4V alloy specimen deformed by laser shock processing was studied using electron backscatter diffraction (EBSD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Slip steps were observed within grains oriented with their c-axis nearly parallel to the specimen surface normal. Based on the slip step traces and orientation information, the slip planes were determined to be (11{bar 2}2) for grains with their c-axis within 15{sup o} of the specimen surface normal and (11{bar 2}1) for grains with their c-axis between 15{sup o} and 40{sup o} away from the specimen surface normal. Although both these planes are known to belong to twinning systems, (11{bar 2}2)<11{bar 2}{bar 3}> and (11{bar 2}1)<11{bar 2}{bar 6}> respectively, the latter has not been observed to operate as a slip system. Examination of the Taylor factors associated with these slip systems shows that the grains with slip steps have the lowest Taylor factors. Determination of localized lattice rotations showed a unique behavior in grains with slip steps, such that all the lattice rotations were concentrated about the steps, with almost no orientation variations in between slip steps. This distribution indicates that stress concentrations exist at the slip steps, which could potentially affect the performance of the material.

  4. Texture Evolution During Laser Direct Metal Deposition of Ti-6Al-4V

    DOE PAGESBeta

    Sridharan, Niyanth; Chaudhary, Anil; Nandwana, Peeyush; Babu, Sudarsanam Suresh

    2016-01-20

    Titanium alloys are used in a wide variety of high performance applications and hence the processing of the titanium and the resulting microstructures after additive manufacturing has received significant attention. During additive manufacturing the processing route involves the transition from a liquid to solid state. The addition of successive layers results in a complex microstructure due to solid-state transformations. The current study focuses on understanding the phase transformations and relate it to the transformation texture in Ti-6Al-4V to identify conditions leading to a strong alpha transformation texture. The as deposited builds were characterized using optical microscopy and electron backscattered diffraction.more » The results showed columnar prior β grains with a martensitic structure after the deposition of a single layer. On subsequent depositions the martensitic microstructure decomposes to a colony and basketweave microstructure with a stronger transformation texture. The alpha texture with a colony and basketweave microstructure shows a stronger transformation texture as a result of variant selection. Thus by controlling the cooling rate of the build from the β transus it is possible to control the alpha transformation texture.« less

  5. Laser Ablation Surface Preparation of Ti-6A1-4V for Adhesive Bonding

    NASA Technical Reports Server (NTRS)

    Palmieri, Frank L.; Watson, Kent A.; Morales, Guillermo; Williams, Thomas; Hicks, Robert; Wohl, Christopher J.; Hopkins, John W.; Connell, John W.

    2012-01-01

    Adhesive bonding offers many advantages over mechanical fastening, but requires certification before it can be incorporated in primary structures for commercial aviation without disbond-arrestment features or redundant load paths. Surface preparation is widely recognized as the key step to producing robust and predictable bonds. Laser ablation imparts both topographical and chemical changes to a surface which can lead to increased bond durability. A laser based process provides an alternative to chemical-dip, manual abrasion and grit blast treatments which are expensive, hazardous, polluting, and less precise. This report documents preliminary testing of a surface preparation technique using laser ablation as a replacement for the chemical etch and abrasive processes currently applied to Ti-6Al-4V alloy adherends. Failure mode, surface roughness, and chemical makeup were analyzed using fluorescence enhanced visualization, microscopy, and X-ray photoelectron spectroscopy, respectively. Single lap shear tests were conducted on bonded and aged specimens to observe bond strength retention and failure mode. Some promising results showed increasing strength and durability of lap shear specimens as laser ablation coverage area and beam intensity increased. Chemical analyses showed trends for surface chemical species which correlated with improved bond strength and durability. Combined, these results suggest that laser ablation is a viable process for inclusion with or/and replacement of one or more currently used titanium surface treatments. On-going work will focus on additional mechanical tests to further demonstrate improved bond durability.

  6. Fatigue Properties of TI-6AL-4V Subjected to 0.9% Physiological Saline Solution

    NASA Astrophysics Data System (ADS)

    Cao, Xiaojian; Murakami, Ri-Ichi; Wang, Qingyuan

    Fatigue properties of Ti-6Al-4V (TC4) subjected to 0.9% physiological saline solutions were presented in this paper. The ultrasonic fatigue test method has been used to investigate the very high cycle fatigue properties of commercial titanium alloy TC4 with the microstructure of tramsformed lamellar dipped into 0.9% physiological saline solution prior to testing. Three estimated times have been decided for subjecting at 37 °C, such as 24 hours, 2 weeks and 4 weeks. The results show that physiological saline solution treatment makes a little influence on the ultrasonic fatigue life of TC4. The slope of S-N curve decreases as the dipping time increases. Dipping tests for three estimated times also have been performed. When TC4 has been dipped into physiological saline solution for 4 weeks, homogeneous white points have been observed on specular facet specimen. And in the fracture surface of which has been dipped for 4 weeks, new inclusion sized 5-10 µm in the crack initiation has been observed. The fractography pictures show the fracture to be transcrystalline plastic. Cracks are initiated because of the subsurface inclusion and the facet slip of α-phase.

  7. Synthesis and In vitro Evaluation of Electrodeposited Barium Titanate Coating on Ti6Al4V

    PubMed Central

    Rahmati, Shahram; Basiriani, Mohammad Basir; Rafienia, Mohammad; Yaghini, Jaber; Raeisi, Keyvan

    2016-01-01

    Osseointegration has been the concern of implantology for many years. Researchers have used various ceramic coatings for this purpose; however, piezoelectric ceramics (e.g., barium titanate [BTO]) are a novel field of interest. In this regard, BTO (BaTiO3) coating was fabricated by electrophoretic deposition on Ti6Al4V medical alloy, using sol-gel-synthesized nanometer BTO powder. Structure and morphologies were studied using X-ray diffraction and scanning electron microscopy (SEM), respectively. Bioactivity response of coated samples was evaluated by SEM and inductively coupled plasma (ICP) analysis after immersion in simulated body fluid (SBF). Cell compatibility was also studied via MTT assay and SEM imaging. Results showed homogenous coating with cubic structure and crystallite size of about 41 nm. SEM images indicated apatite formation on the coating after 7 days of SBF immersion, and ICP analysis approved ions concentration decrement in SBF. Cells showed flattened morphology in intimate contact with coating after 7 days of culture. Altogether, coated samples demonstrated appropriate bioactivity and biocompatibility. PMID:27186538

  8. Wetting Behavior of Laser Synthetic Surface Micro Textures on Ti-6Al-4V for Bioapplication

    SciTech Connect

    Dahotre, Narendra B; Paital, Sameer R; Samant, Anoop N; Daniel, Claus

    2010-01-01

    Wettability at the surface of an implant material play a key role in its success as it modulate the protein adsorption and thereby influences cell attachment and tissue integration at the interface. Hence, surface engineering of implantable materials to enhance wettability to physiological fluid under in vivo conditions is an area of active research. In light of this, in the present work a laser based optical interference and direct melting techniques were used to develop synthetic micro textures on Ti-6Al-4V alloys and their effects on wettability were systematically studied. Improved wettability to simulated body fluid and distilled water was observed for the Ca-P coatings obtained by direct melting technique. This superior wettability was attributed to both the appropriate surface chemistry and three dimensional surface features obtained using this technique. To assert a better control on surface texture and wettability a three dimensional thermal model based on COMSOL sTM multiphysics was employed to predict the features obtained by laser melting technique. The effect of physical texture and wetting on biocompatibility of laser processed Ca-P coating was evaluated in the preliminary efforts on culturing of mouse MC3T3-E1 osteoblast cells.

  9. Biocompatibility and compressive properties of Ti-6Al-4V scaffolds having Mg element.

    PubMed

    Kalantari, Seyed Mohammad; Arabi, Hossein; Mirdamadi, Shamsodin; Mirsalehi, Seyed Ali

    2015-08-01

    Porous scaffolds of Ti-6Al-4V were produced by mixing of this alloy with different amount of magnesium (Mg) powders. The mixtures were compacted in steel die by applying uniaxial pressure of 500 MPa before sintering the compacts in sealed quartz tubes at 900 °C for 2 h. Employing Archimedes׳ principle and Image Tool software, the total and open volume percentages of porosities within the scaffolds were found to be in the range of 47-64% and 41-47%, respectively. XRD results of titanium before and after sintering showed that no contamination, neither oxides nor nitrides formed during processes. Compressive properties of the scaffolds were studied using an Instron machine. The observed compressive strength and Young׳s module of the scaffolds were in the range of 72-132 MPa, and 37-47 GPa, respectively. Cell attachment and proliferation rate of MG-63 on porous samples were investigated. The results showed that proliferation rate increased with increasing Mg content. However no clear differences were observed between samples regarding cell attachment, so that bridges were observed in all cell gaps within the scaffolds. PMID:25955560

  10. Fracture toughness of Ti-6Al-4V after welding and postweld heat treatment

    SciTech Connect

    Murthy, K.K.; Sundaresan, S.

    1997-02-01

    The fracture toughness (J{sub IC}) of the fusion zone of Ti-6Al-4V alloy welds was studied in terms of microstructural changes in the as-welded condition and following postweld heat treatment. Gas tungsten arc and electron beam welds were produced in sheet material over a limited range of heat input and subsequently heat treated at 700 C and 900 C. In the as-welded condition, the weld microstructure was a mixture of diffusional and martensitic alpha phases, whose proportion varied wit heat input and cooling rate. The fusion zone exhibited low ductility resulting from the highly acicular microstructure and a large prior-beta grain size. Postweld heat treatment tempered the martensite and coarsened the microstructure, but a beneficial effect on ductility was realized only after treatment at 900 C. Fracture toughness in the as-welded condition was greater than for the base metal and was attributed to the lamellar microstructure of the fusion zone and absence of continuous alpha film along the grain boundaries. Postweld heat treatment at 700 C reduced the fracture toughness considerably and, as in the case of ductility, it was necessary to heat treat at 900 C to produce an improvement.

  11. Modelling and simulation of effect of ultrasonic vibrations on machining of Ti6Al4V.

    PubMed

    Patil, Sandip; Joshi, Shashikant; Tewari, Asim; Joshi, Suhas S

    2014-02-01

    The titanium alloys cause high machining heat generation and consequent rapid wear of cutting tool edges during machining. The ultrasonic assisted turning (UAT) has been found to be very effective in machining of various materials; especially in the machining of "difficult-to-cut" material like Ti6Al4V. The present work is a comprehensive study involving 2D FE transient simulation of UAT in DEFORM framework and their experimental characterization. The simulation shows that UAT reduces the stress level on cutting tool during machining as compared to that of in continuous turning (CT) barring the penetration stage, wherein both tools are subjected to identical stress levels. There is a 40-45% reduction in cutting forces and about 48% reduction in cutting temperature in UAT over that of in CT. However, the reduction magnitude reduces with an increase in the cutting speed. The experimental analysis of UAT process shows that the surface roughness in UAT is lower than in CT, and the UATed surfaces have matte finish as against the glossy finish on the CTed surfaces. Microstructural observations of the chips and machined surfaces in both processes reveal that the intensity of thermal softening and shear band formation is reduced in UAT over that of in CT. PMID:24103362

  12. Characterization of high energy ion implantation into Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Carroll, M. P.; Stephenson, K.; Findley, K. O.

    2009-06-01

    Ion implantation is a surface modification process that can improve the wear, fatigue, and corrosion resistance for several metals and alloys. Much of the research to date has focused on ion energies less than 1 MeV. With this in mind, Ti-6Al-4V was implanted with Al 2+, Au 3+, and N + ions at energies of 1.5 and 5 MeV and various doses to determine the effects on strengthening of a high energy beam. A post heat treatment on the specimens implanted with Al 2+ samples was conducted to precipitate Ti xAl type intermetallics near the surface. Novel techniques, such as nanoindentation, are available now to determine structure-mechanical property relationships in near-surface regions of the implanted samples. Thus, nanoindentation was performed on pre-implanted, as-implanted, and post heat treated samples to detect differences in elastic modulus and hardness at the sub-micron scale. In addition, sliding wear tests were performed to qualitatively determine the changes in wear performance. The effect of this processing was significant for samples implanted with Al 2+ ions at 1.5 MeV with a dose higher than 1 × 10 16 ions/cm 2 where precipitation hardening likely occurs and with N + ions.

  13. Synthesis and In vitro Evaluation of Electrodeposited Barium Titanate Coating on Ti6Al4V.

    PubMed

    Rahmati, Shahram; Basiriani, Mohammad Basir; Rafienia, Mohammad; Yaghini, Jaber; Raeisi, Keyvan

    2016-01-01

    Osseointegration has been the concern of implantology for many years. Researchers have used various ceramic coatings for this purpose; however, piezoelectric ceramics (e.g., barium titanate [BTO]) are a novel field of interest. In this regard, BTO (BaTiO3) coating was fabricated by electrophoretic deposition on Ti6Al4V medical alloy, using sol-gel-synthesized nanometer BTO powder. Structure and morphologies were studied using X-ray diffraction and scanning electron microscopy (SEM), respectively. Bioactivity response of coated samples was evaluated by SEM and inductively coupled plasma (ICP) analysis after immersion in simulated body fluid (SBF). Cell compatibility was also studied via MTT assay and SEM imaging. Results showed homogenous coating with cubic structure and crystallite size of about 41 nm. SEM images indicated apatite formation on the coating after 7 days of SBF immersion, and ICP analysis approved ions concentration decrement in SBF. Cells showed flattened morphology in intimate contact with coating after 7 days of culture. Altogether, coated samples demonstrated appropriate bioactivity and biocompatibility. PMID:27186538

  14. First insight on the impact of an osteoblastic layer on the bio-tribocorrosion performance of Ti6Al4V hip implants.

    PubMed

    Runa, M J; Mathew, M T; Fernandes, M H; Rocha, L A

    2015-01-01

    In uncemented Ti6Al4V hip implants, the bone-stem interface is subjected to cyclic loading motion driven by the daily activities of the patients, which may lead to the complete failure of the implant in the long term. It may also compromise the proliferation and differentiation processes of osteoblastic cells (bone-forming cells). The main objective of this work is to approach for the first time the role of these organic materials on the bio-tribocorrosion mechanisms of cultured Ti6Al4V alloys. The colonized materials with MG63 osteoblastic-like cells were characterized through cell viability/proliferation and enzymatic activity. Tribocorrosion tests were performed under a reciprocating sliding configuration and low contact pressure. Electrochemical techniques were used to measure the corrosion kinetics of the system, under free potential conditions. All tests were performed at a controlled atmosphere. The morphology and topography of the wear scar were evaluated. The results showed that the presence of an osteoblastic cell layer on the implant surface significantly influences the tribocorrosion behavior of Ti6Al4V alloy. It was concluded that the cellular material was able to form an extra protective layer that inhibits further wear degradation of the alloy and decreases its corrosion tendency. PMID:25448346

  15. Plasma-sprayed CaTiSiO5 ceramic coating on Ti-6Al-4V with excellent bonding strength, stability and cellular bioactivity

    PubMed Central

    Wu, Chengtie; Ramaswamy, Yogambha; Liu, Xuanyong; Wang, Guocheng; Zreiqat, Hala

    2008-01-01

    Novel Ca-Si-Ti-based sphene (CaTiSiO5) ceramics possess excellent chemical stability and cytocompatibility. The aim of this study was to prepare sphene coating on titanium alloy (Ti-6Al-4V) for orthopaedic applications using the plasma spray method. The phase composition, surface and interface microstructure, coating thickness, surface roughness and bonding strength of the plasma-sprayed sphene coating were analysed using X-ray diffraction, scanning electron microscopy, atomic force microscopy and the standard mechanical testing of the American Society for Testing and Materials, respectively. The results indicated that sphene coating was obtained with a uniform and dense microstructure at the interface of the Ti-6Al-4V surface and the thickness and surface roughness of the coating were approximately 150 and 10 μm, respectively. Plasma-sprayed sphene coating on Ti-6Al-4V possessed a significantly improved bonding strength and chemical stability compared with plasma-sprayed hydroxyapatite (HAp) coating. Plasma-sprayed sphene coating supported human osteoblast-like cell (HOB) attachment and significantly enhanced HOB proliferation and differentiation compared with plasma-sprayed HAp coating and uncoated Ti-6Al-4V. Taken together, plasma-sprayed sphene coating on Ti-6Al-4V possessed excellent bonding strength, chemical stability and cellular bioactivity, indicating its potential application for orthopaedic implants. PMID:18664431

  16. Clinical utility of the Duncan-Ely test for rectus femoris dysfunction during the swing phase of gait.

    PubMed

    Marks, M C; Alexander, J; Sutherland, D H; Chambers, H G

    2003-11-01

    The Ely Test (or Duncan-Ely test) has been accepted as a clinical tool to assess rectus femoris spasticity by passively flexing the knee rapidly while the patient lies prone in a relaxed state. In this retrospective review, patients' dynamic knee range of motion (ROM) during gait and an electromyogram (EMG) were compared with the results of the Ely test. Data for 70 patients (44 males, 26 females; 104 limbs) were included. Mean age of patients was 13 years, SD 9 years, range 4 years 5 months to 54 years. All patients were diagnosed with cerebral palsy (spastic diplegia, n = 42; spastic quadriplegia, n = 15, and hemiplegia, n = 13). All patients were ambulatory (50 independent, 20 with assistive devices). A standard matrix was used to calculate sensitivity and specificity of the Ely test as well as its positive and negative predictive value. For the gait variables examined (decreased dynamic knee ROM, timing of peak knee flexion, and abnormal EMG in swing) the sensitivity of the Ely test ranged from 56 to 59% and the specificity ranged from 64 to 85%. For the same variables the positive predictive value ranged from 91 to 98% and the negative predictive value ranged from 4 to 19%. The Ely test was shown to have a good positive predictive value (i.e. the certainty about the presence of rectus spasticity in patients with a positive Ely test result) for rectus femoris dysfunction during gait. PMID:14580132

  17. Laser-based acceleration for nuclear physics experiments at ELI-NP

    NASA Astrophysics Data System (ADS)

    Tesileanu, O.; Asavei, Th.; Dancus, I.; Gales, S.; Negoita, F.; Turcu, I. C. E.; Ursescu, D.; Zamfir, N. V.

    2016-05-01

    As part of the Extreme Light pan-European research infrastructure, Extreme Light Infrastructure - Nuclear Physics (ELI-NP) in Romania will focus on topics in Nuclear Physics, fundamental Physics and applications, based on very intense photon beams. Laser-based acceleration of electrons, protons and heavy ions is a prerequisite for a multitude of laser-driven nuclear physics experiments already proposed by the international research community. A total of six outputs of the dual-amplification chain laser system, two of 100TW, two of 1PW and two of 10PW will be employed in 5 experimental areas, with the possibility to use long and short focal lengths, gas and solid targets, reaching the whole range of laser acceleration processes. We describe the main techniques and expectations regarding the acceleration of electrons, protons and heavy nuclei at ELI-NP, and some physics cases for which these techniques play an important role in the experiments.

  18. Perspectives for neutron and gamma spectroscopy in high power laser driven experiments at ELI-NP

    NASA Astrophysics Data System (ADS)

    Negoita, F.; Gugiu, M.; Petrascu, H.; Petrone, C.; Pietreanu, D.; Fuchs, J.; Chen, S.; Higginson, D.; Vassura, L.; Hannachi, F.; Tarisien, M.; Versteegen, M.; Antici, P.; Balabanski, D.; Balascuta, S.; Cernaianu, M.; Dancus, I.; Gales, S.; Neagu, L.; Petcu, C.; Risca, M.; Toma, M.; Turcu, E.; Ursescu, D.

    2015-02-01

    The measurement of energy spectra of neutrons and gamma rays emitted by nuclei, together with charge particles spectroscopy, are the main tools for understanding nuclear phenomena occurring also in high power laser driven experiments. However, the large number of particles emitted in a very short time, in particular the strong X-rays flash produced in laser-target interaction, impose adaptation of technique currently used in nuclear physics experiment at accelerator based facilities. These aspects are discussed (Section 1) in the context of proposed studies at high power laser system of ELI-NP. Preliminary results from two experiments performed at Titan (LLNL) and ELFIE (LULI) facilities using plastic scintillators for neutron detection (Section 2) and LaBr3(Ce) scintillators for gamma detection (Section 3) are presented demonstrating the capabilities and the limitations of the employed methods. Possible improvements of these spectroscopic methods and their proposed implementation at ELI-NP will be discussed as well in the last section.

  19. 6D phase space electron beam analysis and machine sensitivity studies for ELI-NP GBS

    NASA Astrophysics Data System (ADS)

    Giribono, A.; Bacci, A.; Curatolo, C.; Drebot, I.; Palumbo, L.; Petrillo, V.; Rossi, A. R.; Serafini, L.; Vaccarezza, C.; Vannozzi, A.; Variola, A.

    2016-09-01

    The ELI-NP Gamma Beam Source (GBS) is now under construction in Magurele-Bucharest (RO). Here an advanced source of gamma photons with unprecedented specifications of brilliance (>1021), monochromaticity (0.5%) and energy tunability (0.2-19.5 MeV) is being built, based on Inverse Compton Scattering in the head-on configuration between an electron beam of maximum energy 750 MeV and a high quality high power ps laser beam. These requirements make the ELI-NP GBS an advanced and challenging gamma ray source. The electron beam dynamics analysis and control regarding the machine sensitivity to the possible jitter and misalignments are presented. The effects on the beam quality are illustrated providing the basis for the alignment procedure and jitter tolerances.

  20. Study of nuclear reactions in laser plasmas at future ELI-NP facility

    NASA Astrophysics Data System (ADS)

    Lanzalone, G.; Altana, C.; Anzalone, A.; Cappuzzello, F.; Cavallaro, M.; Gizzi, L. A.; Labate, L.; Lamia, L.; Mascali, D.; Muoio, A.; Negoita, F.; Odorici, F.; Petrascu, H.; Trifirò, A.; Trimarchi, M.; Tudisco, S.

    2016-05-01

    In this contribution we will present the future activities that our collaboration will carry out at ELI-NP (Extreme Light Infrastructure Nuclear Physics), the new multi peta-watt Laser facility, currently under construction at Bucharest (Romania). The activities concerns the study of nuclear reactions in laser plasmas. In this framework we proposed the construction of a new, general-purpose experimental set-up able to detect and identify neutrons and charged particles.

  1. Surface morphology of nanotube formed Ti alloy by electrochemical methods.

    PubMed

    Kim, Sung-Hwan; Choe, Han-Cheol

    2014-11-01

    In order to investigate the surface morphology of nanotube formed Ti alloy by electrochemical methods, the Ti-6Al-4V alloys for dental implant were used in this study. Heat treatment was carried out at 800 degrees C for 1 hour and then water quenching in argon atmosphere, that will be have a specimen name of 800 WQ. The formation of nanotube structure was conducted by electrochemical method on Ti-6Al-4V alloy in mixed electrolytes at 30 V for 1 hour. Microstructure of β phases showed dot-like structures at non-treated Ti-6Al-4V alloy, and needle-like in equiaxed structure from treated the alloy at 800 WQ. In non-treated Ti-6Al-4V alloy case, nanotubes only exhibited at α phase region with dissolved V-oxide area of β phase. However, in the case of 800 WQ, nanotubes of Ti-6Al-4V alloy exhibited at both α and βphase region. Electrochemical corrosion studies showed that the nanotubular alloy of 800 WQ possesses slightly higher corrosion resistance than that of non-treated nanotubular alloy. PMID:25958530

  2. Geographic variation in the elicitin-like glycoprotein, ELI025, of Pythium insidiosum isolated from human and animal subjects.

    PubMed

    Lerksuthirat, Tassanee; Lohnoo, Tassanee; Rujirawat, Thidarat; Yingyong, Wanta; Jongruja, Nujarin; Krajaejun, Theerapong

    2015-10-01

    Oomycetes are fungus-like in appearance, but form a distinct clade within the eukaryotes. While most pathogenic oomycetes infect plants, the understudied oomycete Pythium insidiosum infects humans and animals, and causes a life-threatening infectious disease, called pythiosis. Phylogenetic analyses divide P. insidiosum into 3 groups, according to geographic origins: Clade-I (Americas), Clade-II (Asia and Australia), and Clade-III (Thailand). Surgical removal of the infected organ is the inevitable treatment for patients with pythiosis, but it is often too late or unsuccessful, and many patients die from advanced infection. Understanding P. insidiosum's basic biology could lead to improved infection control. Elicitins, a unique group of proteins found only in oomycetes, are involved in sterol acquisition and stimulation of host responses. Recently, we identified glycosylated and non-glycosylated forms of the elicitin-like protein, ELI025, which is secreted by P. insidiosum, and detected during P. insidiosum infection. In this study, we investigated geographic variation of ELI025 in 24 P. insidiosum strains isolated from humans, animals, and the environment. Genotypes of ELI025, based on 2 sets of PCR primers, correlated well with rDNA-based phylogenetic grouping. Unlike strains in Clade-I and -II, Clade-III strains secreted no glycosylated ELI025. Sera from 17 pythiosis patients yielded a broad range of antibody responses against ELI025, and ∼30% lacked reactivity against the protein. Selective production or secretion of glycosylated ELI025 by different P. insidiosum strains might contribute to the variable host antibody responses. In conclusion, ELI025 was secreted by all P. insidiosum strains isolated from different hosts and geographic origins, but the protein had different biochemical, and immunological characteristics. These finding contribute to the better understanding of the biology and evolution of P. insidiosum, and could lead to appropriate clinical

  3. Friction and wear of titanium alloys and copper alloys sliding against titanium 6-percent-aluminum - 4-percent-vanadium alloy in air at 430 C

    NASA Technical Reports Server (NTRS)

    Wisander, D. W.

    1976-01-01

    Experiments were conducted to determine the friction and wear characteristics of aluminum bronzes and copper-tin, titanium-tin, and copper-silver alloys sliding against a titanium-6% aluminum-4% vanadium alloy (Ti-6Al-4V). Hemispherically tipped riders of aluminum bronze and the titanium and copper alloys were run against Ti-6Al-4V disks in air at 430 C. The sliding velocity was 13 cm/sec, and the load was 250 g. Results revealed that high tin content titanium and copper alloys underwent significantly less wear and galling than commonly used aluminum bronzes. Also friction force was less erratic than with the aluminum bronzes.

  4. Fixation of bioactive calcium alkali phosphate on Ti6Al4V implant material with femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Symietz, Christian; Lehmann, Erhard; Gildenhaar, Renate; Koter, Robert; Berger, Georg; Krüger, Jörg

    2011-04-01

    Bone implants made of metal, often titanium or the titanium alloy Ti6Al4V, need to be surface treated to become bioactive. This enables the formation of a firm and durable connection of the prosthesis with the living bone. We present a new method to uniformly cover Ti6Al4V with a thin layer of ceramics that imitates bone material. These calcium alkali phosphates, called GB14 and Ca10, are applied to the metal by dip coating of metal plates into an aqueous slurry containing the fine ceramic powder. The dried samples are illuminated with the 790 nm radiation of a pulsed femtosecond laser. If the laser fluence is set to a value just below the ablation threshold of the ceramic (ca. 0.4 J/cm 2) the 30 fs laser pulses penetrate the partly transparent ceramic layer of 20-40 μm thickness. The remaining laser fluence at the ceramic-metal interface is still high enough to generate a thin metal melt layer leading to the ceramic fixation on the metal. The laser processing step is only possible because Ti6Al4V has a lower ablation threshold (between 0.1 and 0.15 J/cm 2) than the ceramic material. After laser treatment in a fluence range between 0.1 and 0.4 J/cm 2, only the particles in contact with the metal withstand a post-laser treatment (ultrasonic cleaning). The non-irradiated rest of the layer is washed off. In this work, we present results of a successful ceramic fixation extending over larger areas. This is fundamental for future applications of arbitrarily shaped implants.

  5. On the Use of Infrared Thermography for Analysis of Fatigue Damage in Ti6Al4V-Welded Joints

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Gao, Xiao-Long; Zhang, Lin-Jie; Zhang, Jian-Xun

    2014-08-01

    The present work is aimed at comparatively studying fatigue damage evolution of a pulsed Nd:YAG laser beam-welded (LBW) joint and the base metal (BM) of Ti6Al4V alloy subjected to cyclic loading. To reveal crack nucleation and propagation during the fatigue process, in situ fatigue was generated using infrared measurement methods. The results indicate that the rate of damage accumulated in the LBW joint was higher than in the BM specimens during a fatigue test, which decreased the fatigue life of the LBW joint. This observation is attributable to the LBW joint fusion zone microstructure, which has a higher void nucleation and growth rate compared with the BM microstructure.

  6. Surface Residual Stresses in Ti-6Al-4V Friction Stir Welds: Pre- and Post-Thermal Stress Relief

    NASA Astrophysics Data System (ADS)

    Edwards, P.; Ramulu, M.

    2015-09-01

    The purpose of this study was to determine the residual stresses present in titanium friction stir welds and if a post-weld thermal stress relief cycle would be effective in minimizing those weld-induced residual stresses. Surface residual stresses in titanium 6Al-4V alloy friction stir welds were measured in butt joint thicknesses ranging from 3 to 12 mm. The residual stress states were also evaluated after the welds were subjected to a post-weld thermal stress relief cycle of 760 °C for 45 min. High (300-400 MPa) tensile residual stresses were observed in the longitudinal direction prior to stress relief and compressive residual stresses were measured in the transverse direction. After stress relief, the residual stresses were decreased by an order of magnitude to negligible levels.

  7. Microstructure and Mechanical Properties of Al2024/Ti-6Al-4V Transient Liquid Phase Bonded Joint

    NASA Astrophysics Data System (ADS)

    Samavatian, M.; Halvaee, A.; Amadeh, A.; Zakipour, S.

    2015-06-01

    Transient liquid phase bonding mechanism of two dissimilar alloys Al2024 and Ti-6Al-4V using Sn-Ag-Cu-Ni interlayer with different thicknesses (40, 80, 120 µm) was studied at 510 °C under 10-4 mBar. The results showed that with an increase in bonding time, the interlayer elements diffused into the parent metals and formed various intermetallic compounds in the joint zone. While diffusion mechanism led to isothermal solidification and process completion at 60 min bonding time, remaining interlayer was observed in the bond made with 120-μm-thick interlayer. With an increase in bonding time growth, the hardness of the joints at the interface rose to 139 VHN. Although the shear strength was proportional to the bonding time, the interlayer thickness showed a critical value at which the maximum shear strength was attained.

  8. Fracture characteristics of Ti-6Al-4V and Ti-5Al-2.5Fe with refined microstructure using hydrogen

    NASA Astrophysics Data System (ADS)

    Niinomi, M.; Gong, B.; Kobayashi, T.; Ohyabu, Y.; Toriyama, O.

    1995-05-01

    The hydrogenation behavior of Ti-6Al-4V, with the starting microstructures of coarse equiaxed α and coarse Widmanstätten α, respectively, was investigated under a hydrogen pressure of 0.1 MPa at temperatures between 843 and 1123 K. The hydrogen content was determined as a function of hydrogenation time, hydrogenation temperature, and hydrogen flow rate. The phases presented in the alloy of after hydrogenation were determined with X-ray and electron diffraction analysis in order to define the effect of Thermochemical Processing (TCP) on the microstructure of the alloy. Mechanical properties and fracture toughness of Ti-6Al-4V and Ti-5Al-2.5Fe subjected to the various TCP were then investigated. Hydrogenation of Ti-6Al-4V with the starting microstructure of coarse equiaxed α at 1023 K, just below hydrogen saturated β (denoted β″ (H)) transus temperature, produces a microstructure of a, orthohombic martensite (denoted α″ (H)) and β (H). Hydrogenation at 1123 K, above β (H) transus, results in a microstructure of α″ (H) and β (H). Microstructure refinement during TCP results mainly from decomposition of α″ (H) and ;β (H) into a fine mixture of α + β during dehydrogenation. An alternative TCP method is below β (H) transus hydrogenation (BTH), consisting of hydrogenation of the alloy below the hydrogenated β (H) transus temperature, air cooling to room temperature, and dehydrogenation at a lower temperature, which is found to improve mechanical properties significantly over a conventional TCP treatment. Compared with the untreated material, the BTH treatment increases the yield strength and increases the ultimate tensile strength significantly without decreasing the tensile elongation in the starting microstructure of coarse equiaxed α or with a little decrease in the tensile elongation in the starting microstructure of coarse Widmanstätten α, although the conventional TCP treatment results in a large decrease in elongation over the

  9. Energy and Force Analysis of Ti-6Al-4V Linear Friction Welds for Computational Modeling Input and Validation Data

    NASA Astrophysics Data System (ADS)

    McAndrew, Anthony R.; Colegrove, Paul A.; Addison, Adrian C.; Flipo, Bertrand C. D.; Russell, Michael J.

    2014-09-01

    The linear friction welding (LFW) process is finding increasing use as a manufacturing technology for the production of titanium alloy Ti-6Al-4V aerospace components. Computational models give an insight into the process, however, there is limited experimental data that can be used for either modeling inputs or validation. To address this problem, a design of experiments approach was used to investigate the influence of the LFW process inputs on various outputs for experimental Ti-6Al-4V welds. The finite element analysis software DEFORM was also used in conjunction with the experimental findings to investigate the heating of the workpieces. Key findings showed that the average interface force and coefficient of friction during each phase of the process were insensitive to the rubbing velocity; the coefficient of friction was not coulombic and varied between 0.3 and 1.3 depending on the process conditions; and the interface of the workpieces reached a temperature of approximately approximately 1273 K (1000 °C) at the end of phase 1. This work has enabled a greater insight into the underlying process physics and will aid future modeling investigations.

  10. Energy and Force Analysis of Ti-6Al-4V Linear Friction Welds for Computational Modeling Input and Validation Data

    NASA Astrophysics Data System (ADS)

    McAndrew, Anthony R.; Colegrove, Paul A.; Addison, Adrian C.; Flipo, Bertrand C. D.; Russell, Michael J.

    2014-12-01

    The linear friction welding (LFW) process is finding increasing use as a manufacturing technology for the production of titanium alloy Ti-6Al-4V aerospace components. Computational models give an insight into the process, however, there is limited experimental data that can be used for either modeling inputs or validation. To address this problem, a design of experiments approach was used to investigate the influence of the LFW process inputs on various outputs for experimental Ti-6Al-4V welds. The finite element analysis software DEFORM was also used in conjunction with the experimental findings to investigate the heating of the workpieces. Key findings showed that the average interface force and coefficient of friction during each phase of the process were insensitive to the rubbing velocity; the coefficient of friction was not coulombic and varied between 0.3 and 1.3 depending on the process conditions; and the interface of the workpieces reached a temperature of approximately approximately 1273 K (1000 °C) at the end of phase 1. This work has enabled a greater insight into the underlying process physics and will aid future modeling investigations.

  11. Review of Mechanical Properties of Ti-6Al-4V Made by Laser-Based Additive Manufacturing Using Powder Feedstock

    NASA Astrophysics Data System (ADS)

    Beese, Allison M.; Carroll, Beth E.

    2016-03-01

    Laser-based additive manufacturing (AM) of metals using powder feedstock can be accomplished via two broadly defined technologies: directed energy deposition (DED) and powder bed fusion (PBF). In these processes, metallic powder is delivered to a location and locally melted with a laser heat source. Upon deposition, the material undergoes a rapid cooling and solidification, and as subsequent layers are added to the component, the material within the component is subjected to rapid thermal cycles. In order to adopt AM for the building of structural components, a thorough understanding of the relationships among the complex thermal cycles seen in AM, the unique heterogeneous and anisotropic microstructure, and the mechanical properties must be developed. Researchers have fabricated components by both DED and PBF from the widely used titanium alloy Ti-6Al-4V and studied the resultant microstructure and mechanical properties. This review article discusses the progress to date on investigating the as-deposited and heat-treated microstructures and mechanical properties of Ti-6Al-4V structures made by powder-based laser AM using DED and PBF.

  12. The elevated-temperature mechanical behavior of as-cast and wrought Ti-6Al-4V-1B

    SciTech Connect

    Chen, Wei; Boehlert, C. J.; Howe, Jane Y; Payzant, E Andrew

    2011-01-01

    This work studied the effect of processing on the elevated-temperature [728 K (455 C)] fatigue deformation behavior of Ti-6Al-4V-1B for maximum applied stresses between 300 to 700 MPa (R = 0.1, 5 Hz). The alloy was evaluated in the as-cast form as well as in three wrought forms: cast-and-extruded, powder metallurgy (PM) rolled, and PM extruded. Processing caused significant differences in the microstructure, which in turn impacted the fatigue properties. The PM-extruded material exhibited a fine equiaxed {alpha} + {beta} microstructure and the greatest fatigue resistance among all the studied materials. The {beta}-phase field extrusion followed by cooling resulted in a strong {alpha}-phase texture in which the basal plane was predominately oriented perpendicular to the extrusion axis. The TiB whiskers were also aligned in the extrusion direction. The {alpha}-phase texture in the extrusions resulted in tensile-strength anisotropy. The tensile strength in the transverse orientation was lower than that in the longitudinal orientation, but the strength in the transverse orientation remained greater than that for the as-cast Ti-6Al-4V. The ratcheting behavior during fatigue is also discussed.

  13. Experimental analysis of selective laser melting process for Ti-6Al-4V turbine blade manufacturing

    NASA Astrophysics Data System (ADS)

    Caiazzo, Fabrizia; Cardaropoli, Francesco; Alfieri, Vittorio; Sergi, Vincenzo; Cuccaro, Luigi

    2012-01-01

    The present work focuses on the use of Selective Laser Melting (SLM) technique for manufacturing of near-net-shape aircraft component prototypes with Ti-6Al-4V titanium alloy, which has already successfully employed for the production of turbine blades since it combines mechanical properties with excellent wear resistance. The main characteristic of SLM is layer manufacturing which allows to obtain complex shaped elements using three dimensional computer aided design data, with the addition of particular features like channels or cavities which can not been easily obtained with traditional technologies. The other key aspect in comparison with investment casting is shorter post-processing. The feasibility of manufacturing turbine blades with mentioned process using a laser sintered machine EOSINT M 270 (Titanium version) is analysed. The first experimental phase has dealt with the definition of processing parameters which would guarantee laser sintered part maximum density. Preliminary specimens have been manufactured to define any material-dependent scaling value to control dimensional shrinkage. Afterwards a prototype of a turbine blade has been produced using optimal process parameter set. The element positioning and support definition are discussed as they influence the overall job time and the need of post processing operations. Further analyses have been carried out to check the whole structure of the prototype using X-rays and Fluorescent Penetrant Inspection, aiming to point out possible imperfections; no defects have been detected. Furthermore, laser sintered part dimensional inspection has been successively performed via coordinate measuring machine. Eventually, the microstructure of the prototype has been examined.

  14. Effect of prior {beta}-grain size on the hot deformation behavior of Ti-6Al-4V: Coarse vs coarser

    SciTech Connect

    Prasad, Y.V.R.K.; Seshacharyulu, T.; Medeiros, S.C.; Frazier, W.G.

    2000-04-01

    The hot deformation behavior of extra low interstitial (ELI) grade Ti-6Al-4V with a transformed {beta}-perform microstructure was studied in coarse (0.5 to 1 mm) and coarser (2 to 3 mm) (prior {beta}) grained materials using hot compression testing in the temperature range of 750 to 1,100 C and a strain rate range of 0.001 to 100 s{sup {minus}1}. Processing maps were developed on the basis of the flow stress data as a function of temperature and strain rate. The maps revealed that the domain of globularization of the lamellar structure and region of large grained superplasticity of {beta} were not influenced by the prior {beta}-grain size. However, the regimes of cracking at the prior {beta}-grain boundaries occurring at lower temperatures and strain rates and the flow instability occurring at lower temperatures and higher strain rates were both wider for the coarse grained material than the coarser grained material. The {beta}-instability regime, however, was more pronounced in the coarser grained material. From the hot workability viewpoint, the present results show that there is no remarkable benefit in refining the prior {beta}-grain size. On the contrary, it will somewhat restrict the workability domain by widening the adjacent regimes, causing microstructural damage.

  15. Free Radical Production in Immune Cell Systems Induced by Ti, Ti6Al4V and SS Assessed by Chemiluminescence Probe Pholasin Assay

    PubMed Central

    P. Cachinho, Sandra C.; Pu, Fanrong

    2012-01-01

    The oxidative burst of human blood cells in the presence of different metal materials was investigated using chemiluminescence assay. Commercial pure titanium (Ti), titanium alloy (Ti6Al4V), and stainless steel 316L (SS) in particulate form with <20 μm in size were used. The effect of particulate materials opsonisation on the upregulation of the respiratory burst production by blood cells was also assessed. The largest chemiluminescence response was achieved after simultaneous injection of the stimulants fMLP+PMA. Moreover, Ti and SS induced a greater inflammatory reaction compared to Ti6Al4V, since the respiratory burst mounted was higher for both materials after opsonisation treatment. These results suggest that in vitro chemiluminescence response and respiratory burst measurements proved to be composition and treatment dependent. PMID:22778739

  16. Diffusion bonding of mismatch dental alloys.

    PubMed

    Liu, Honghua; Ni, Jiahua; Wu, Luhai; He, Guo

    2010-04-01

    The diffusion bonding of Ti-6Al-4V and Co-Cr-Mo dental alloys has been investigated in terms of the atoms diffusion, the microstructure evolution, and the bonding strength. The bonding performance reveals asymmetry diffusion profiles for both the Co and Cr in Ti-6Al-4V and the Ti in Co-Cr-Mo alloy. Their diffusion coefficients (Arrhenius relations) have been established based on the experiments. Co and Cr diffusion into Ti-6Al-4V leads to alpha --> beta transformation and the intermetallics-formation. Maximum bonding strength occurs at about 840 degrees C. The bonding joint fails under the shear stress in the Ti-6Al-4V side near the bonding interface in brittle manner. The intermetallics in the diffusion layer together with the unbonded areas and other flaws in the bonding interface are responsible for the shear brittle fracture, which also weaken the bonding strength. PMID:19957358

  17. Osteogenic differentiation of adipose tissue-derived mesenchymal stem cells on nanostructured Ti6Al4V and Ti13Nb13Zr

    PubMed Central

    Marini, Francesca; Luzi, Ettore; Fabbri, Sergio; Ciuffi, Simone; Sorace, Sabina; Tognarini, Isabella; Galli, Gianna; Zonefrati, Roberto; Sbaiz, Fausto; Brandi, Maria Luisa

    2015-01-01

    Summary Bone tissue engineering and nanotechnology enable the design of suitable substitutes to restore and maintain the function of human bone tissues in complex fractures and other large skeletal defects. Long-term stability and functionality of prostheses depend on integration between bone cells and biocompatible implants. Human adipose tissue-derived mesenchymal stem cells (hAMSCs) have been shown to possess the same ability to differentiate into osteoblasts and to produce bone matrix of classical bone marrow derived stem cells (BMMSCs). Ti6A14V and Ti13Nb13Zr are two different biocompatible titanium alloys suitable for medical bone transplantation. Preliminary results from our Research Group demonstrated that smooth Ti6Al4V surfaces exhibit an osteoconductive action on hAMSCs, granting their differentiation into functional osteoblasts and sustaining bone matrix synthesis and calcification. The purpose of this study is to assay the ability of nanostructured Ti6Al4V and Ti13Nb13Zr alloys to preserve the growth and adhesion of hAMSCs and, mostly, to sustain and maintain their osteogenic differentiation and osteoblast activity. The overall results showed that both nanostructured titanium alloys are capable of sustaining cell adhesion and proliferation, to promote their differentiation into osteoblast lineage, and to support the activity of mature osteoblasts in terms of calcium deposition and bone extracellular matrix protein production. PMID:26811701

  18. Eruptive history of an alkali basaltic diatreme from Elie Ness, Fife, Scotland

    NASA Astrophysics Data System (ADS)

    Gernon, T. M.; Upton, B. G. J.; Hincks, T. K.

    2013-05-01

    The Elie Ness diatreme (Fife, Scotland) is an ideal place to study the internal architecture and emplacement processes of diatremes. Elie Ness is one of approximately 100 alkali basaltic diatremes and intrusions in the East Fife area, emplaced during Upper Carboniferous to Early Permian times into an extensive rift system in the northern Variscan foreland. Within the diatreme, seven lithofacies and three lithofacies associations (LFAs 1-3) are recognised. Field, petrographic and geochemical studies demonstrate that the diatreme experienced a protracted history of eruption and infill, initially driven by volatile expansion and later by magma-water interaction. Massive lapilli tuffs of LFA 1 contain abundant highly vesicular juvenile scoria and magma-coated clasts, which are best explained by a magmatic origin for the early explosive eruptions. On a large-scale, the tuffs are well mixed and locally exhibit small-scale degassing structures attributed to fluidisation processes occurring within the diatreme fill. The occurrence of abundant volcaniclastic autoliths and megablocks within LFA 1 can be explained by subsidence of volcaniclastic strata from the maar crater and upper diatreme during emplacement. Pyroclastic density current deposits of LFA 2 form a series of continuous sheets across the diatreme, some of which may have originated from phreatomagmatic explosions in a neighbouring vent. We attribute the overall bedding pattern to a combination of primary volcanic processes and post-depositional folding related to movement along an adjacent fault. Minor steeply inclined breccias and tuffs of LFA 3 cross-cut the LFA 2 succession and are interpreted as late-stage volcaniclastic dykes and conduits, signalling the final phase of eruptive activity at Elie Ness. The study offers new insights into the volcanic evolution of diatremes fed by low viscosity, alkali-rich magmas.

  19. Cryogenic stopping cell for photofission fragments at the ELI-NP facility

    SciTech Connect

    Constantin, P. Balabanski, D. L.; Cuong, P. V.

    2015-10-15

    The brilliant gamma beam at the future Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility will be used to generate a beam of exotic neutron-rich isotopes via photofission of actinide targets. We present simulations with the Geant4 toolkit of the photofission process for the design and optimization of the expected performance parameters of the Cryogenic Stopping Cell (CSC). The CSC will be used to extract the photofission fragments into the secondary beam of about 10{sup 6} ions/s. We propose an experimental program to study refractory neutron-rich isotopes.

  20. Depositional processes of the basaltic Elie Ness diatreme, East Fife, Scotland

    NASA Astrophysics Data System (ADS)

    Gernon, Thomas; Hincks, Thea

    2010-05-01

    The East Fife coast of Scotland exposes multiple (~100) volcanic vents or diatremes of late Carboniferous to early Permian age. Here, we present preliminary results of detailed geological mapping of the Elie Ness (EN) diatreme. The key objective was to map the volcanic structure and lithofacies of the vent-fill, and to determine the eruption styles and key emplacement processes that occur more generally in basaltic maar-diatreme systems. Within the EN diatreme, seven lithofacies and three lithofacies associations (LFA 1-3) were recognised. Preliminary results demonstrate that the diatreme had a protracted history of eruption and infill. The massive lapilli tuffs of LFA 1 are texturally and compositionally homogeneous with occasional degassing structures, making them similar to typical massive volcaniclastic deposits infilling kimberlite pipes. The formation of such deposits are attributed to gas-fluidisation processes operating within the vent. The occurrence within LFA 1 of abundant volcaniclastic autoliths and megablocks together with steeply inclined lenticular breccia and tuff packages, makes the deposits similar to marginal lithofacies of the Jwaneng Centre kimberlite pipe, Botswana. All these features can be explained by subsidence of volcaniclastic strata from the surrounding tephra ring during emplacement. The steep internal contacts between the lithofacies of LFA 1 can be explained by variations in gas flux as the main eruptive phase waned. Pyroclastic base surge deposits of LFA 2 form a series of continuous sheets across the EN diatreme, and are therefore likely to have originated from a neighbouring pipe. The most probable source of the LFA 2 pyroclastic surges is a small vent to the NE of Elie Ness, where similar diffuse stratified lithofacies are observed. Minor steeply-inclined breccias and tuffs of LFA 3 cross-cut bedded tuffs of LFA 2, and are therefore likely to represent late-stage dykes and conduits. A significant observation is that the diatreme

  1. 100-J level amplifier concepts for HiLASE and ELI-Beamlines

    NASA Astrophysics Data System (ADS)

    Sikocinski, P.; Divoky, M.; Lucianetti, A.; Sawicka, M.; Novak, J.; Rus, B.; Mocek, T.

    2012-07-01

    We present comparison of two alternative layouts of a 100 J cryogenically cooled Yb:YAG multi-slab laser system operating at 10 Hz for HiLASE and ELI Beamlines projects. In the first approach, the 100 J slab amplifier consists of a preamplifier and power amplifier, while in the second approach it uses single power amplifier with two amplifier heads. These two concepts are compared, with respect to output power, B-integral, accumulated B-integral, and peak fluence. Results are obtained by simulating beam propagation in MIRÓ code and calculating stored energy in the amplifier by homemade ray-tracing MATLAB code for amplified spontaneous emission evaluation.

  2. Tribocorrosive behaviour of commonly used temporomandibular implants in a synovial fluid-like environment: Ti-6Al-4V and CoCrMo

    NASA Astrophysics Data System (ADS)

    Royhman, D.; Yuan, J. C.; Shokuhfar, T.; Takoudis, C.; Sukotjo, C.; Mathew, M. T.

    2013-10-01

    The temporomandibular joint implant metal alloys, Ti6Al4V and CoCrMo, (n = 3/group) were tested under free-potential and potentiostatic conditions using a custom-made tribocorrosion apparatus. Sliding duration (1800 cycles), frequency (1.0 Hz) and load (16 N) mimicked the daily mastication process. Synovial-like fluid (bovine calf serum, pH = 7.6 at 37 °C) was used to simulate the in vivo environment. Changes in friction coefficient were monitored throughout the sliding process. Changes in surface topography, total weight loss and roughness values were calculated using scanning electron microscopy and white-light interferometry. Finally, statistical analyses were performed using paired t-tests to determine significance between regions within each metal type and also independent sample t-tests to determine statistical significance between metal alloy types. Ti6Al4V demonstrated a greater decrease of potential than CoCrMo, a higher weight loss from wear (Kw = 257.8 versus 2.62 µg p < 0.0001), a higher weight loss from corrosion (Kc = 17.44 versus 0.14 µg p < 0.0001) and a higher weight loss from the combined effects of wear and corrosion (Kwc = 275.28 versus 2.76 µg p < 0.0001). White-light interferometry measurements demonstrated a greater difference in surface roughness inside the wear region in Ti6Al4V than CoCrMo after the sliding (Ra = 323.80 versus 70.74 nm p < 0.0001). In conclusion, CoCrMo alloy shows superior anti-corrosive and biomechanical properties.

  3. Understanding the Role of Hot Isostatic Pressing Parameters on the Microstructural Evolution of Ti-6Al-4V and Inconel 718 Fabricated by Electron Beam Melting

    SciTech Connect

    Peter, William H.; Nandwana, Peeyush; Kirka, Michael M.; Dehoff, Ryan R.; Sames, William; Erdman, III, Donald L.; Eklund, Anders; Howard, Ron

    2015-04-01

    In this project, Avure and ORNL evaluated the influence of hot isostatic pressing (HIP) and thermal cycling as standalone post processing techniques on the microstructure of electron beam powder bed deposited Ti-6Al-4V and Inconel 718 alloys. Electron beam powder bed deposition is an effective technology for fabricating complex net shape components that cannot be manufactured with conventional processes. However, material deposited by this technology results in columnar grain growth which is detrimental for many applications. For Ti-6Al-4V, it has been found that thermal cycling alone is not sufficient to breakdown the columnar microstructure that is typical of electron beam powder bed technology. HIP, on the other hand, has the potential to be an effective technique to break down the columnar microstructure of Ti-6Al-4V into a more equiaxed and refined β grain structure, and provide a more homogeneous microstructure compared to the thermally cycled samples. Overall, the project showed that hot isostatic pressing reduced/eliminated porosity in both Ti-6Al-4V and Inconel 718 However, based on the unique thermal cycle and the application of pressure in the HIP vessel, Ti-6Al-4V e-beam deposited microstructures were modified from columnar grain growth to equiaxed microstructures; a significant outcome to this collaboration. Inconel 718, on the other hand, shows no change in the macrostructure as a result of the current HIP cycle based on the thermal history, and would require further investigation. Though the results of HIP cycle were very good at changing the microstructure, further development in optimizing the post heat treatments and HIP cycles is required to improve mechanical properties.

  4. Mixed-mode fatigue-crack growth thresholds in Ti-6Al-4V at high frequency

    SciTech Connect

    Campbell, J.P.; Ritchie, R.O.

    1999-10-22

    Multiaxial loading conditions exist at fatigue-critical locations within turbine engine components, particularly in association with fretting fatigue in the blade dovetail/disk contact section. For fatigue-crack growth in such situations, the resultant crack-driving force is a combination of the influence of a mode I (tensile opening) stress-intensity range, {Delta}K{sub I}, as well as mode II (in-plane shear) and/or mode III (anti-plane shear) stress-intensity ranges, {Delta}K{sub II} and {Delta}K{sub III}, respectively. For the case of the high-cycle fatigue of turbine-engine alloys, it is critical to quantify such behavior, as the extremely high cyclic loading frequencies ({approximately}1--2 kHz) and correspondingly short times to failure may necessitate a design approached based on the fatigue-crack growth threshold. Moreover, knowledge of such thresholds is required for accurate prediction of fretting fatigue failures. Accordingly, this paper presents the mixed-mode fatigue crack growth thresholds for mode I + II loading (phase angles from 0{degree} to 82{degree}) in a Ti-6Al-4V blade alloy. These results indicate that when fatigue-crack growth in this alloy is characterized in terms of the crack-driving force {Delta}G, which incorporates both the applied tensile and shear loading, the mode 1 fatigue-crack growth threshold is a lower bound (worst case) with respect to mixed-mode (I + II) crack-growth behavior.

  5. Hydrogen in titanium alloys

    SciTech Connect

    Wille, G W; Davis, J W

    1981-04-01

    The titanium alloys that offer properties worthy of consideration for fusion reactors are Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo-Si (Ti-6242S) and Ti-5Al-6Sn-2Zr-1Mo-Si (Ti-5621S). The Ti-6242S and Ti-5621S are being considered because of their high creep resistance at elevated temperatures of 500/sup 0/C. Also, irradiation tests on these alloys have shown irradiation creep properties comparable to 20% cold worked 316 stainless steel. These alloys would be susceptible to slow strain rate embrittlement if sufficient hydrogen concentrations are obtained. Concentrations greater than 250 to 500 wppm hydrogen and temperatures lower than 100 to 150/sup 0/C are approximate threshold conditions for detrimental effects on tensile properties. Indications are that at the elevated temperature - low hydrogen pressure conditions of the reactors, there would be negligible hydrogen embrittlement.

  6. Materials Characterization of Electron Beam Melted Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    Draper, Susan; Lerch, Brad; Rogers, Richard; Martin, Richard; Locci, Ivan; Garg, Anita

    2015-01-01

    An in-depth material characterization of Electron Beam Melted (EBM) Ti-6Al-4V material has been completed. Hot Isostatic Pressing (HIP) was utilized to close porosity from fabrication and also served as a material heat treatment to obtain the desired microstructure. The changes in the microstructure and chemistry from the powder to pre-HIP and post-HIP material have been analyzed. Computed tomography (CT) scans indicated porosity closure during HIP and high-density inclusions scattered throughout the specimens. The results of tensile and high cycle fatigue (HCF) testing are compared to conventional Ti-6Al-4V. The EBM Ti-6Al-4V had similar or superior mechanical properties compared to conventionally manufactured Ti-6Al-4V.

  7. Properties of Hot Pressed Titanium Alloy Powders for Cryogenic Applications.

    NASA Technical Reports Server (NTRS)

    Friedman, G. I.; Kazaroff, J. M.

    1970-01-01

    Evaluation of strength and toughness of hot-pressed titanium alloy powders at room and at cryogenic temperatures. The purpose was to determine how the mechanical properties of solid bodies formed from powder would compare with wrought specimens of the same size and with the same chemical analysis. It was found that of five titanium powder-making processes investigated, only the Rotating Electrode Process (REP) was capable of producing ELI-grade titanium alloy powder. Blocks hot-pressed from spherical REP powders had tensile properties equivalent to or better than those obtained from wrought bar.

  8. Identification of Conserved MEL-28/ELYS Domains with Essential Roles in Nuclear Assembly and Chromosome Segregation.

    PubMed

    Gómez-Saldivar, Georgina; Fernandez, Anita; Hirano, Yasuhiro; Mauro, Michael; Lai, Allison; Ayuso, Cristina; Haraguchi, Tokuko; Hiraoka, Yasushi; Piano, Fabio; Askjaer, Peter

    2016-06-01

    Nucleoporins are the constituents of nuclear pore complexes (NPCs) and are essential regulators of nucleocytoplasmic transport, gene expression and genome stability. The nucleoporin MEL-28/ELYS plays a critical role in post-mitotic NPC reassembly through recruitment of the NUP107-160 subcomplex, and is required for correct segregation of mitotic chromosomes. Here we present a systematic functional and structural analysis of MEL-28 in C. elegans early development and human ELYS in cultured cells. We have identified functional domains responsible for nuclear envelope and kinetochore localization, chromatin binding, mitotic spindle matrix association and chromosome segregation. Surprisingly, we found that perturbations to MEL-28's conserved AT-hook domain do not affect MEL-28 localization although they disrupt MEL-28 function and delay cell cycle progression in a DNA damage checkpoint-dependent manner. Our analyses also uncover a novel meiotic role of MEL-28. Together, these results show that MEL-28 has conserved structural domains that are essential for its fundamental roles in NPC assembly and chromosome segregation. PMID:27341616

  9. Perspectives for neutron and gamma spectroscopy in high power laser driven experiments at ELI-NP

    SciTech Connect

    Negoita, F. Gugiu, M. Petrascu, H. Petrone, C. Pietreanu, D.; Fuchs, J.; Chen, S.; Higginson, D.; Vassura, L.; Hannachi, F.; Tarisien, M.; Versteegen, M.; Antici, P.; Balabanski, D.; Balascuta, S.; Cernaianu, M.; Dancus, I.; Gales, S.; Neagu, L.; Petcu, C.; and others

    2015-02-24

    The measurement of energy spectra of neutrons and gamma rays emitted by nuclei, together with charge particles spectroscopy, are the main tools for understanding nuclear phenomena occurring also in high power laser driven experiments. However, the large number of particles emitted in a very short time, in particular the strong X-rays flash produced in laser-target interaction, impose adaptation of technique currently used in nuclear physics experiment at accelerator based facilities. These aspects are discussed (Section 1) in the context of proposed studies at high power laser system of ELI-NP. Preliminary results from two experiments performed at Titan (LLNL) and ELFIE (LULI) facilities using plastic scintillators for neutron detection (Section 2) and LaBr{sub 3}(Ce) scintillators for gamma detection (Section 3) are presented demonstrating the capabilities and the limitations of the employed methods. Possible improvements of these spectroscopic methods and their proposed implementation at ELI-NP will be discussed as well in the last section.

  10. Strong field physics and QED experiments with ELI-NP 2×10PW laser beams

    SciTech Connect

    Turcu, I. C. E. Balascuta, S. Negoita, F.; Jaroszynski, D.; McKenna, P.

    2015-02-24

    The ELI-NP facility will focus a 10 PW pulsed laser beam at intensities of ∼10{sup 23} W/cm{sup 2} for the first time, enabling investigation of the new physical phenomena at the interfaces of plasma, nuclear and particle physics. The electric field in the laser focus has a maximum value of ∼10{sup 15} V/m at such laser intensities. In the ELI-NP Experimental Area E6, we propose the study of Radiation Reaction, Strong Field Quantum Electrodynamics (QED) effects and resulting production of Ultra-bright Sources of Gamma-rays which could be used for nuclear activation. Two powerful, synchronized 10 PW laser beams will be focused in the E6 Interaction Chamber on either gas or solid targets. One 10 PW beam is the Pump-beam and the other is the Probe-beam. The focused Pump beam accelerates the electrons to relativistic energies. The accelerated electron bunches interact with the very high electro-magnetic field of the focused Probe beam. The layout of the experimental area E6 will be presented with several options for the experimental configurations.

  11. Identification of Conserved MEL-28/ELYS Domains with Essential Roles in Nuclear Assembly and Chromosome Segregation

    PubMed Central

    Hirano, Yasuhiro; Mauro, Michael; Lai, Allison; Ayuso, Cristina; Haraguchi, Tokuko; Hiraoka, Yasushi; Piano, Fabio

    2016-01-01

    Nucleoporins are the constituents of nuclear pore complexes (NPCs) and are essential regulators of nucleocytoplasmic transport, gene expression and genome stability. The nucleoporin MEL-28/ELYS plays a critical role in post-mitotic NPC reassembly through recruitment of the NUP107-160 subcomplex, and is required for correct segregation of mitotic chromosomes. Here we present a systematic functional and structural analysis of MEL-28 in C. elegans early development and human ELYS in cultured cells. We have identified functional domains responsible for nuclear envelope and kinetochore localization, chromatin binding, mitotic spindle matrix association and chromosome segregation. Surprisingly, we found that perturbations to MEL-28’s conserved AT-hook domain do not affect MEL-28 localization although they disrupt MEL-28 function and delay cell cycle progression in a DNA damage checkpoint-dependent manner. Our analyses also uncover a novel meiotic role of MEL-28. Together, these results show that MEL-28 has conserved structural domains that are essential for its fundamental roles in NPC assembly and chromosome segregation. PMID:27341616

  12. Novel insights into the molecular pathogenesis of CYP4V2-associated Bietti's retinal dystrophy

    PubMed Central

    Astuti, Galuh D N; Sun, Vincent; Bauwens, Miriam; Zobor, Ditta; Leroy, Bart P; Omar, Amer; Jurklies, Bernhard; Lopez, Irma; Ren, Huanan; Yazar, Volkan; Hamel, Christian; Kellner, Ulrich; Wissinger, Bernd; Kohl, Susanne; De Baere, Elfride; Collin, Rob W J; Koenekoop, Robert K

    2015-01-01

    Bietti's crystalline dystrophy (BCD) is a rare, autosomal recessive retinal degenerative disease associated with mutations in CYP4V2. In this study, we describe the genetic and clinical findings in 19 unrelated BCD patients recruited from five international retinal dystrophy clinics. Patients underwent ophthalmic examinations and were screened for CYP4V2 mutations by Sanger sequencing and quantitative polymerase chain reaction (qPCR) copy number variation screening. Eight CYP4V2 mutations were found in 10/19 patients, including three patients in whom only monoallelic mutations were detected. Four novel mutations were identified: c.604G>A; p.(Glu202Lys), c.242C>G; p.(Thr81Arg), c.604+4A>G; p.(?), and c.1249dup; p.(Thr417Asnfs*2). In addition, we identified a heterozygous paternally inherited genomic deletion of at least 3.8 Mb, encompassing the complete CYP4V2 gene and several other genes, which is novel. Clinically, patients demonstrated phenotypic variability, predominantly showing choroidal sclerosis, attenuated vessels, and crystalline deposits of varying degrees of severity. To our knowledge, our study reports the first heterozygous CYP4V2 deletion and hence a novel mutational mechanism underlying BCD. Our results emphasize the importance of copy number screening in BCD. Finally, the identification of CYP4V2-negative patients with indistinguishable phenotypes from CYP4V2-positive patients might suggest the presence of mutations outside the coding regions of CYP4V2, or locus heterogeneity, which is unreported so far. PMID:25629076

  13. Tribocorrosion behavior of veneering biomedical PEEK to Ti6Al4V structures.

    PubMed

    Sampaio, Miguel; Buciumeanu, Mihaela; Henriques, Bruno; Silva, Filipe S; Souza, Júlio C M; Gomes, José R

    2016-02-01

    In dentistry, prosthetic structures must be able to support masticatory loads combined with a high biocompatibility and wear resistance in the presence of a corrosive environment. In order to improve the simultaneous wear and corrosion response of highly biocompatible prosthetic structures, a veneering poly-ether-ether-ketone (PEEK) to Ti6Al4V substrate was assessed by tribocorrosion analyses under conditions mimicking the oral environment. Samples were synthesized by hot pressing the PEEK veneer onto Ti6Al4V cylinders. The tribocorrosion tests on Ti6Al4V or PEEK/Ti6Al4V samples were performed on a reciprocating ball-on-plate tribometer at 30N normal load, 1Hz and stroke length of 3mm. The tests were carried out in artificial saliva at 37°C. Open circuit potential (OCP) was measured before, during and after reciprocating sliding tests. The worn surfaces were characterized by scanning electron microscopy. The results revealed a lower wear rate on PEEK combined with a lower coefficient of friction (COF), when compared to Ti6Al4V. In fact, PEEK protected Ti6Al4V substrate against the corrosive environment and wear avoiding the release of metallic ions to the surrounding environment. PMID:26454136

  14. Helium concentrations in soil gas of the Ely and Delta 1 degree x 2 degrees quadrangles. Basin and Range Province

    USGS Publications Warehouse

    Reimer, G.M.; Bowles, C.G.

    1983-01-01

    A reconnaissance soil-gas helium survey was made of the Ely, Nevada and Delta, Utah 1? x 2? quadrangles in the Basin and Range Province. Helium concentrations in 510 samples ranged from -147 to 441 ppb He with respect to ambient air. The median helium value for the study area was 36 ppb. Concentrations of more than 100 ppb He, and less than -20 ppb He, occur more commonly in the Ely Quadrangle and are especially numerous in the western one-half of this quadrangle. The data are presented both in figures and tables, and some of the geologic factors that may affect the helium distribution are discussed.

  15. The Implications of John Hart Ely's Conceptual Framework for Interpretation of First Amendment Questions: The Continuation of Balancing in the Free Expression Arena.

    ERIC Educational Resources Information Center

    Trapp, Mary E.

    Examining interpretive approaches to the First Amendment free speech and press clause, this paper focuses on the conceptual framework proposed by John Hart Ely. Other First Amendment tests examined include clear and present danger, balancing, the absolute test, and A. Meiklejohn's "absolute" test. Following an analysis of Ely's First Amendment…

  16. H2O2/HCl and heat-treated Ti-6Al-4V stimulates pre-osteoblast proliferation and differentiation.

    PubMed

    Shi, Geng-sheng; Ren, Ling-fei; Wang, Lin-zhi; Lin, Hai-sheng; Wang, Sha-bin; Tong, Yong-qing

    2009-09-01

    The purpose of the present study was to evaluate the bioactivity of chemical treatment of titanium alloy (Ti-6Al-4V) in vitro. Smooth-surface discs of Ti-6Al-4V were used in this study. Sandblasted, dual acid-etched and H(2)O(2)/HCl heat-treated discs were set as test group, and sandblasted, dual acid-etched discs as control group. SEM and XRD analysis revealed a porous anatase gel layer on rough surface in the test group and a rough surface in the control group. Mouse pre-osteoblasts (MC3T3-E1 cells) were cultured on these 2 group discs, and then cell proliferation and differentiation were examined 4 days, 7 days, and 14 days after cell seeding. Cell proliferation was greatly stimulated at all time points when cultured in test group (P < .05). The alkaline phosphatase (ALP) activity and osteocalcin (OC) production were much higher in the test group compared with the control group at every time point investigated (P < .05). Furthermore, in the test group, the expressions of alkaline phosphatase-2, osteocalcin, and collagen type I alpha 1 mRNAs were significantly up-regulated as compared with those in the control group (P < .05 or P < .01). The results suggested that H(2)O(2)/HCl and heat-treatment might facilitate better integration of Ti-6Al-4V implants with bone. PMID:19716504

  17. Free-form-fabricated commercially pure Ti and Ti6Al4V porous scaffolds support the growth of human embryonic stem cell-derived mesodermal progenitors.

    PubMed

    de Peppo, G M; Palmquist, A; Borchardt, P; Lennerås, M; Hyllner, J; Snis, A; Lausmaa, J; Thomsen, P; Karlsson, C

    2012-01-01

    Commercially-pure titanium (cp-Ti) and the titanium-aluminum-vanadium alloy (Ti6Al4V) are widely used as reconstructive implants for skeletal engineering applications, due to their good mechanical properties, biocompatibility and ability to integrate with the surrounding bone. Electron beam melting technology (EBM) allows the fabrication of customized implants with tailored mechanical properties and high potential in the clinical practice. In order to augment the interaction with the biological tissue, stem cells have recently been combined with metallic scaffolds for skeletal engineering applications. We previously demonstrated that human embryonic stem cell-derived mesodermal progenitors (hES-MPs) hold a great potential to provide a homogeneous and unlimited supply of cells for bone engineering applications. This study demonstrates the effect of EBM-fabricated cp-Ti and Ti6Al4V porous scaffolds on hES-MPs behavior, in terms of cell attachment, growth and osteogenic differentiation. Displaying different chemical composition but similar surface properties, EBM-fabricated cp-Ti and Ti6Al4V scaffolds supported cell attachment and growth, and did not seem to alter the expression of genes involved in osteogenic differentiation and affect the alkaline phosphatase activity. In conclusion, interfacing hES-MPs to EBM-fabricated scaffolds may represent an interesting strategy for design of third-generation biomaterials, with the potential to promote implant integration in clinical conditions characterized by poor bone quality. PMID:22262956

  18. SiO2-CaO-K2O coatings on alumina and Ti6Al4V substrates for biomedical applications.

    PubMed

    Vitale-Brovarone, C; Verné, E

    2005-09-01

    Alumina and Ti6Al4V alloys are widely used for orthopedics and dental applications due to their good mechanical properties and biocompatibility. Unfortunately they can not provide a satisfactory osteointegration when implanted. In fact, both alumina and Ti6Al4V are not bioactive and thus they can only guarantee a morphological fixation with the surrounding tissues without a suitable chemical anchorage. Aiming to impart bioactive properties to these materials a coating can be proposed. At this purpose, a bioactive glass belonging to the SiO2-CaO-K2O system was selected and prepared. This glass, named SCK, possess a thermal expansion coefficient matching with the alumina (8.5x 10(- 6)/ degrees C) and Ti6Al4V (9 x 10(- 6)/ degrees C) ones and thus is a good candidate to produce coatings on both of them. Simple and low-cost enameling and glazing techniques were used to realize the coatings. Structural, morphological and compositional characterizations of the coatings were carried out by means of X-ray diffraction, optical and scanning microscopy and compositional analyses. The in vitro properties of the coatings were investigated by soaking them in a simulated body fluid (SBF) in order to study the precipitation, on their surfaces, of a biologically active layer of hydroxylapatite (HAp). PMID:16167116

  19. A Honeycomb-Structured Ti-6Al-4V Oil-Gas Separation Rotor Additively Manufactured by Selective Electron Beam Melting for Aero-engine Applications

    NASA Astrophysics Data System (ADS)

    Tang, H. P.; Wang, Q. B.; Yang, G. Y.; Gu, J.; Liu, N.; Jia, L.; Qian, M.

    2016-03-01

    Oil -gas separation is a key process in an aero-engine lubrication system. This study reports an innovative development in oil -gas separation. A honeycomb-structured rotor with hexagonal cone-shaped pore channels has been designed, additively manufactured from Ti-6Al-4V using selective electron beam melting (SEBM) and assessed for oil -gas separation for aero-engine application. The Ti-6Al-4V honeycomb structure showed a high compressive strength of 110 MPa compared to less than 20 MPa for metal foam structures. The oil -gas separation efficiency of the honeycomb-structured separation rotor achieved 99.8% at the rotation speed of 6000 rpm with much lower ventilation resistance (17.3 kPa) than that of the separator rotor constructed using a Ni-Cr alloy foam structure (23.5 kPa). The honeycomb-structured Ti-6Al-4V separator rotor produced by SEBM provides a promising solution to more efficient oil -gas separation in the aero-engine lubrication system.

  20. Influence of microstructure on high-cycle fatigue of Ti-6Al-4V: Bimodal vs. lamellar structures

    NASA Astrophysics Data System (ADS)

    Nalla, R. K.; Ritchie, R. O.; Boyce, B. L.; Campbell, J. P.; Peters, J. O.

    2002-03-01

    The high-cycle fatigue (HCF) of titanium alloy turbine engine components remains a principal cause of failures in military aircraft engines. A recent initiative sponsored by the United States Air Force has focused on the major drivers for such failures in Ti-6Al-4V, a commonly used turbine blade alloy, specifically for fan and compressor blades. However, as most of this research has been directed toward a single processing/heat-treated condition, the bimodal (solution-treated and overaged (STOA)) microstructure, there have been few studies to examine the role of microstructure. Accordingly, the present work examines how the overall resistance to high-cycle fatigue in Ti-6Al-4V compares between the bimodal microstructure and a coarser lamellar ( β-annealed) microstructure. Several aspects of the HCF problem are examined. These include the question of fatigue thresholds for through-thickness large and short cracks; microstructurally small, semi-elliptical surface cracks; and cracks subjected to pure tensile (mode I) and mixed-mode (mode I+II) loading over a range of load ratios (ratio of minimum to maximum load) from 0.1 to 0.98, together with the role of prior damage due to sub-ballistic impacts (foreign-object damage (FOD)). Although differences are not large, it appears that the coarse lamellar microstructure has improved smooth-bar stress-life (S-N) properties in the HCF regime and superior resistance to fatigue-crack propagation (in pure mode I loading) in the presence of cracks that are large compared to the scale of the microstructure; however, this increased resistance to crack growth compared to the bimodal structure is eliminated at extremely high load ratios. Similarly, under mixed-mode loading, the lamellar microstructure is generally superior. In contrast, in the presence of microstructurally small cracks, there is little difference in the HCF properties of the two microstructures. Similarly, resistance to HCF failure following FOD is comparable in the

  1. The bone tissue compatibility of a new Ti-Nb-Sn alloy with a low Young's modulus.

    PubMed

    Miura, Keiki; Yamada, Norikazu; Hanada, Shuji; Jung, Taek-Kyun; Itoi, Eiji

    2011-05-01

    A Ti-Nb-Sn alloy was developed as a new β-type titanium alloy which had a low Young's modulus and high strength. The Young's modulus of the Ti-Nb-Sn alloy was reduced to about 45 GPa by cold rolling, much closer to human cortical bone (10-30 GPa) than that of Ti-6Al-4V alloy (110 GPa) and other β-type titanium alloys developed for biomedical applications. The tensile strength of the Ti-Nb-Sn alloy was increased to a level greater than that of Ti-6Al-4V alloy by heat treatment after severe cold rolling. In this study the cytotoxicity of Ti-25Nb-11Sn alloy was evaluated in direct contact cell culture tests using metal disks and the bone tissue compatibility - examined using metal rods inserted into the medullary canal of rabbit femurs. The remarkable findings were that: (1) there were no significant differences in the relative growth ratio and relative absorbance ratio between cells grown with the Ti-Nb-Sn alloy, Ti-6Al-4V alloy and CP-Ti in direct contact cell culture tests; (2) there were no significant differences in the load at failure between the Ti-Nb-Sn alloy and Ti-6Al-4V alloy in pull-out metal rods tests; (3) there were no significant differences in new bone formation around metal rods between the Ti-Nb-Sn alloy and Ti-6Al-4V alloy in histological evaluations. The new Ti-Nb-Sn alloy with an elasticity closer to that of human bone is thus considered to be bioinert while also having a high degree of bone compatibility similar to that of Ti-6Al-4V alloy. PMID:21316491

  2. National uranium resource evaluation program: hydrogeochemical and stream sediment reconnaissance basic data for Ely quadrangle, Nevada; Utah

    SciTech Connect

    Not Available

    1981-10-15

    Field and laboratory data are presented for 1937 sediment samples from the Ely Quadrangle, Nevada; Utah. The samples were collected by Savannah River Laboratory; laboratory analysis and data reporting were performed by the Uranium Resource Evaluation Project at Oak Ridge, Tennessee.

  3. Eli Whitney's Patent for the Cotton Gin. The Constitution Community: Revolution and the New Nation (1754-1820s).

    ERIC Educational Resources Information Center

    Schur, Joan Brodsky

    This lesson focuses on the power of the U.S. Congress to pass laws related to issuing patents. Using Eli Whitney's 1812 Congressional petition to extend the patent on his cotton gin as an example, the lesson correlates to the National History Standards and the National Standards for Civics and Government. It contains two primary source documents,…

  4. ELI/SBP'S UVB (VACUUM VAPORIZATION WELL) SYSTEM FOR TREATMENT OF VOC-CONTAMINATED SOILS; INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    This report summarizes the findings of an evaluation of the Unterdruck-Verdampfer-Brunnen (UVB) technology developed by IEG Technologies (IEG) and licensed in the eastern United States by Environmental Laboratories, Inc. (ELI) and SBP Technologies (SBP). This evaluation was cond...

  5. CFL Labeling Harmonization in the United States, China, Brazil andELI Member Countries: Specifications, Testing, and MutualRecognition

    SciTech Connect

    Fridley, David; Lin, Jiang; Denver, Andrea; Biermayer, Peter; Dillavou, Tyler

    2005-07-20

    This report examines critical differences among energy-efficient labeling programs for CFLs in Brazil, China, the United States, and the seven members of the international Efficient Lighting Initiative (ELI) in terms of technical specifications and test procedures, and review issues related to international harmonization of these standards.

  6. Development of porous Ti6Al4V/chitosan sponge composite scaffold for orthopedic applications.

    PubMed

    Guo, Miao; Li, Xiang

    2016-01-01

    A novel composite scaffold consisting of porous Ti6Al4V part filled with chitosan sponge was fabricated using a combination of electron beam melting and freeze-drying. The mechanical properties of porous Ti6Al4V part were examined via compressive test. The ultimate compressive strength was 85.35 ± 8.68 MPa and the compressive modulus was 2.26 ± 0.42 GPa. The microstructure of composite scaffold was characterized using scanning electron microscopy. The chitosan sponge filled in Ti6Al4V part exhibited highly porous and well-interconnected micro-pore architecture. The osteoblastic cells were seeded on scaffolds to test their seeding efficiency and biocompatibility. Significantly higher cell seeding efficiency was found on composite scaffold. The biological response of osteoblasts on composite scaffolds was superior in terms of improved cell attachment, higher proliferation, and well-spread morphology in relation to porous Ti6Al4V part. These results suggest that the Ti6Al4V/chitosan composite scaffold is potentially useful as a biomedical scaffold for orthopedic applications. PMID:26478418

  7. An antibacterial and antiviral peptide produced by Enterococcus mundtii ST4V isolated from soya beans.

    PubMed

    Todorov, Svetoslav D; Wachsman, Mónica B; Knoetze, Hendriëtte; Meincken, Martina; Dicks, Leon M T

    2005-06-01

    Enterococcus mundtii ST4V, isolated from soya beans, produces a 3950Da antibacterial peptide active against Gram-positive and Gram-negative bacteria, including Enterococcus faecalis, Streptococcus spp., Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae and Staphylococcus aureus. The peptide also inactivated the herpes simplex viruses HSV-1 (strain F) and HSV-2 (strain G), a polio virus (PV3, strain Sabin) and a measles virus (strain MV/BRAZIL/001/91, an attenuated strain of MV). MV, HSV-1 and HSV-2 were 95.5%-99.9% inactivated by peptide ST4V at 400 microg/ml. Monkey kidney Vero cells were not inactivated, even at four times the level peptide ST4V displayed antiviral activity, indicating that the effect was not due to cytotoxicity. Complete inactivation or significant reduction in antimicrobial activity was observed after treatment of peptide ST4V with Proteinase K, pronase, pepsin and trypsin. No change in antimicrobial activity was recorded after treatment with alpha-amylase, suggesting that peptide ST4V was not glycosylated. This is the first description of an antibacterial and antiviral peptide with such broad-spectrum of activity, produced by a lactic acid bacterium. PMID:15869868

  8. Corrosion resistance tests on NiTi shape memory alloy.

    PubMed

    Rondelli, G

    1996-10-01

    The corrosion performances of NiTi shape memory alloys (SMA) in human body simulating fluids were evaluated in comparison with other implant materials. As for the passivity current in potentiostatic conditions, taken as an index of ion release, the values are about three times higher for NiTi than for Ti6Al4V and austenitic stainless steels. Regarding the localized corrosion, while plain potentiodynamic scans indicated for NiTi alloy good resistance to pitting attack similar to Ti6Al4V, tests in which the passive film is abruptly damaged (i.e. potentiostatic scratch test and modified ASTM F746) pointed out that the characteristics of the passive film formed on NiTi alloy (whose strength can be related to the alloy's biocompatibility) are not as good as those on Ti6Al4V but are comparable or inferior to those on austenitic stainless steels. PMID:8894095

  9. Positron production at extreme light infrastructure – nuclear physics (ELI-NP)

    SciTech Connect

    Oprisa, A. Balascuta, S. Ur, C. A.

    2015-02-24

    Applied and material physics studies with positron beams of Fermi–surfaces, defects, interfaces etc. offer excellent diagnostics tools. At ELI-NP, an intense γ beam of about 10{sup 11} photons/s with energies up to 3.5 MeV will be used to generate a positron beam via pair production in a tungsten converter target. To obtain a high intensity beam of moderated positrons the design of the positron source is of high importance. The design of a dedicated positron source at ELI–NP is being investigated based on extensive GEANT4 simulations. The goal of the simulations is to optimize the geometry of the target and the gamma beam collimation. We present here the characteristics of the positron beam obtained for different geometries of the converter target.

  10. A Journey with Elie Metchnikoff: From Innate Cell Mechanisms in Infectious Diseases to Quantum Biology

    PubMed Central

    Merien, Fabrice

    2016-01-01

    Many reviews of Elie Metchnikoff’s work have been published, all unanimously acknowledging the significant contributions of his cellular theory to the fields of immunology and infectious diseases. In 1883, he published a key paper describing phagocytic cells in frogs. His descriptions were not just about phagocytes involved in host defense, he also described how these specialized cells eliminated degenerating or dying cells of the host. This perspective focuses on key concepts developed by Metchnikoff by presenting relevant excerpts of his 1883 paper and matching these concepts with challenges of modern immunology. A new approach to macrophage polarization is included to introduce some creative thinking about the exciting emerging area of quantum biology. PMID:27379227

  11. The development of molecularly targeted anticancer therapies: an Eli Lilly and Company perspective.

    PubMed

    Perry, William L; Weitzman, Aaron

    2005-03-01

    The ability to identify activated pathways that drive the growth and progression of cancer and to develop specific and potent inhibitors of key proteins in these pathways promises to dramatically change the treatment of cancer: A patient's cancer could be characterized at the molecular level and the information used to select the best treatment options. The development of successful therapies not only requires extensive target validation, but also new approaches to evaluating drug efficacy in animal models and in the clinic compared to the development of traditional cytotoxic agents. This article highlights Eli Lilly and Company's approach to developing targeted therapies, from target identification and validation through evaluation in the clinic. A selection of drugs in the Lilly Oncology pipeline is also discussed. PMID:16166991

  12. A conceptual design of an electron spectrometer for ELI-NP

    SciTech Connect

    Balascuta, S. Turcu, I. C. E.

    2015-02-24

    We present the geometry and field parameters of an Electron Spectrometer (ES) with two dipole magnets, considered for electron energy measurements at the High Fields QED experimental area at ELI-NP. The first magnet is a 2 meter long permanent magnet, placed inside the Interaction Chamber (IC). The second magnet is a 1.5 meters long electromagnet, placed outside IC. The pulsed electron beam will be produced by the 10 PW pulsed Laser, ‘pump-beam’, focused into one meter long capillary low density plasma cell. A second 10 PW pulsed Laser, ‘probe-beam’, will interact with the relativistic electron bunch providing the strong electromagnetic field. The ES will measure the subtle changes in the electron energy spectrum as a result of the electron beam interaction with the probe-beam field.

  13. ELI-Beamlines: development of next generation short-pulse laser systems

    NASA Astrophysics Data System (ADS)

    Rus, B.; Bakule, P.; Kramer, D.; Naylon, J.; Thoma, J.; Green, J. T.; Antipenkov, R.; Fibrich, M.; Novák, J.; Batysta, F.; Mazanec, T.; Drouin, M. A.; Kasl, K.; Baše, R.; Peceli, D.; Koubíková, L.; Trojek, P.; Boge, R.; Lagron, J. C.; Vyhlídka, Å.; Weiss, J.; Cupal, J.,; Hřebíček, J.; Hříbek, P.; Durák, M.; Polan, J.; Košelja, M.; Korn, G.; Horáček, M.; Horáček, J.; Himmel, B.; Havlíček, T.; Honsa, A.; Korouš, P.; Laub, M.; Haefner, C.; Bayramian, A.; Spinka, T.; Marshall, C.; Johnson, G.; Telford, S.; Horner, J.; Deri, B.; Metzger, T.; Schultze, M.; Mason, P.; Ertel, K.; Lintern, A.; Greenhalgh, J.; Edwards, C.; Hernandez-Gomez, C.; Collier, J.; Ditmire, T.,; Gaul, E.; Martinez, M.; Frederickson, C.; Hammond, D.; Malato, C.; White, W.; Houžvička, J.

    2015-05-01

    Overview of the laser systems being built for ELI-Beamlines is presented. The facility will make available high-brightness multi-TW ultrashort laser pulses at kHz repetition rate, PW 10 Hz repetition rate pulses, and kilojoule nanosecond pulses for generation of 10 PW peak power. The lasers will extensively employ the emerging technology of diode-pumped solid-state lasers (DPSSL) to pump OPCPA and Ti:sapphire broadband amplifiers. These systems will provide the user community with cutting-edge laser resources for programmatic research in generation and applications of high-intensity X-ray sources, in particle acceleration, and in dense-plasma and high-field physics.

  14. Radiation field characterization and shielding studies for the ELI Beamlines facility

    NASA Astrophysics Data System (ADS)

    Ferrari, A.; Amato, E.; Margarone, D.; Cowan, T.; Korn, G.

    2013-05-01

    The ELI (Extreme Light Infrastructure) Beamlines facility in the Czech Republic, which is planned to complete the installation in 2015, is one of the four pillars of the ELI European project. Several laser beamlines with ultrahigh intensities and ultrashort pulses are foreseen, offering versatile radiation sources in an unprecedented energy range: laser-driven particle beams are expected to range between 1 and 50 GeV for electrons and from 100 MeV up to 3 GeV for protons. The number of particles delivered per laser shot is estimated to be 109-1010 for the electron beams and 1010-1012 for the proton beams. The high energy and current values of the produced particles, together with the potentiality to operate at 10 Hz laser repetition rate, require an accurate study of the primary and secondary radiation fields to optimize appropriate shielding solutions: this is a key issue to minimize prompt and residual doses in order to protect the personnel, reduce the radiation damage of electronic devices and avoid strong limitations in the operational time. A general shielding study for the 10 PW (0.016 Hz) and 2 PW (10 Hz) laser beamlines is presented here. Starting from analytical calculations, as well as from dedicated simulations, the main electron and proton fields produced in the laser-matter interaction have been described and used to characterize the "source terms" in full simulations with the Monte Carlo code FLUKA. The secondary radiation fields have been then analyzed to assess a proper shielding. The results of this study and the proposed solutions for the beam dumps of the high energy beamlines, together with a cross-check analysis performed with the Monte Carlo code GEANT4, are presented.

  15. Characterization of the Ti-10Nb-10Zr-5Ta Alloy for Biomedical Applications. Part 2: Wettability, Tribological Performance and Biocompatibility

    NASA Astrophysics Data System (ADS)

    Braic, V.; Balaceanu, M.; Braic, M.; Vitelaru, C.; Titorencu, I.; Pruna, V.; Parau, A. C.; Fanara, C.; Vladescu, A.

    2014-01-01

    The Ti-10Nb-10Zr-5Ta alloy, prepared in a levitation melting furnace, was investigated as a possible candidate for replacing Ti6Al4V alloy in medical applications. The sessile drop method, pin-on-disc and in vitro tests were used to analyze wettability, wear resistance, and biocompatibility of the new alloy. The characteristics of the Ti-10Nb-10Zr-5Ta alloy were assessed in comparison to those of the Ti6Al4V alloy. The Ti-10Nb-10Zr-5Ta system was found to have hydrophilic characteristics with similar contact angle as the Ti6Al4V alloy. In all environments (deionized water, simulated body fluid and Fusayama Meyer artificial saliva), the friction coefficient showed a stable evolution versus sliding distance, being similar for both alloys. On overall, the wear resistance of Ti-10Nb-10Zr-5Ta alloy was lower than that of Ti6Al4V for all testing environments. The Ti-10Nb-10Zr-5Ta alloy exhibited good biocompatibility characteristics at in vitro test compared to Ti6Al4V alloy. The cell viability on Ti-10Nb-10Zr-5Ta surfaces was higher than the one observed on Ti6Al4V samples, regardless the number of days spent in osteoblast-like cells culture. A high degree of cell attachment and spreading was observed on both alloys.

  16. Dissimilar friction welding of titanium alloys to alloy 718

    SciTech Connect

    Kuo, M.; Albright, C.E.; Baeslack, W.A. III

    1994-12-31

    The design of advanced, high-performance gas-turbine engines will require the utilization of elevated-temperature titanium-based materials, including conventional alloys, titanium aluminides, and titanium metal-matrix composites. The most efficient utilization of these materials in the engine compressor section would be achieved by directly joining these materials to existing nickel-base superalloys, such as Alloy 718. To date, the dissimilar welding of titanium alloys to nickel-based alloys has not been common practice because intermetallic compounds form in the weld and cause embrittlement. Special welding techniques must be developed to inhibit this compound formation and to provide high strength welds. In this investigation, a friction welding process was developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to nickel-based superalloy Alloy 718. An interlayer system comprised of copper and niobium sheet layers was employed as a diffusion barrier and weld deformation enhancer. A postweld heat treatment (PWHT, 700{degrees}C for 20 min in vacuum) under axial pressure (Ksi) was used to improve the joint strength consistency. The following conclusions can be drawn from this investigation: (1) A friction welding technique has been developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to Alloy 718 using an interlayer system of niobium and copper. Joint strengths averaging approximately 50 Ksi were achieved. (2) Deformation was concentrated in the interlayers, especially the copper interlayer, during friction welding. Increased reduction in length (RIL) during friction welding resulted in a decrease in the interlayer thicknesses. (3) The EDS results showed that the niobium and copper interlayers prevent interdiffusion between the two parent metals, producing formation of detrimental phases.

  17. Finite Element Simulations of Micro Turning of Ti-6Al-4V using PCD and Coated Carbide tools

    NASA Astrophysics Data System (ADS)

    Jagadesh, Thangavel; Samuel, G. L.

    2016-07-01

    The demand for manufacturing axi-symmetric Ti-6Al-4V implants is increasing in biomedical applications and it involves micro turning process. To understand the micro turning process, in this work, a 3D finite element model has been developed for predicting the tool chip interface temperature, cutting, thrust and axial forces. Strain gradient effect has been included in the Johnson-Cook material model to represent the flow stress of the work material. To verify the simulation results, experiments have been conducted at four different feed rates and at three different cutting speeds. Since titanium alloy has low Young's modulus, spring back effect is predominant for higher edge radius coated carbide tool which leads to the increase in the forces. Whereas, polycrystalline diamond (PCD) tool has smaller edge radius that leads to lesser forces and decrease in tool chip interface temperature due to high thermal conductivity. Tool chip interface temperature increases by increasing the cutting speed, however the increase is less for PCD tool as compared to the coated carbide tool. When uncut chip thickness decreases, there is an increase in specific cutting energy due to material strengthening effects. Surface roughness is higher for coated carbide tool due to ploughing effect when compared with PCD tool. The average prediction error of finite element model for cutting and thrust forces are 11.45 and 14.87 % respectively.

  18. Increased osteoblast adhesion on nanophase metals: Ti, Ti6Al4V, and CoCrMo.

    PubMed

    Webster, Thomas J; Ejiofor, Jeremiah U

    2004-08-01

    Previous studies have demonstrated increased functions of osteoblasts (bone-forming cells) on nanophase compared to conventional ceramics (specifically, alumina, titania, and hydroxyapatite), polymers (such as poly lactic-glycolic acid and polyurethane), carbon nanofibers/nanotubes, and composites thereof. Nanophase materials are unique materials that simulate dimensions of constituent components of bone since they possess particle or grain sizes less than 100 nm. However, to date, interactions of osteoblasts on nanophase compared to conventional metals remain to be elucidated. For this reason, the objective of the present in vitro study was to synthesize, characterize, and evaluate osteoblast adhesion on nanophase metals (specifically, Ti, Ti6Al4V, and CoCrMo alloys). Such metals in conventional form are widely used in orthopedic applications. Results of this study provided the first evidence of increased osteoblast adhesion on nanophase compared to conventional metals. Interestingly, osteoblast adhesion occurred preferentially at surface particle boundaries for both nanophase and conventional metals. Since more particle boundaries are present on the surface of nanophase compared to conventional metals, this may be an explanation for the measured increased osteoblast adhesion. Lastly, material characterization studies revealed that nanometal surfaces possessed similar chemistry and only altered in degree of nanometer surface roughness when compared to their respective conventional counterparts. Because osteoblast adhesion is a necessary prerequisite for subsequent functions (such as deposition of calcium-containing mineral), the present study suggests that nanophase metals should be further considered for orthopedic implant applications. PMID:15120519

  19. Investigation of Aging Processes of Ti-6Al-4 V Powder Material in Laser Melting

    NASA Astrophysics Data System (ADS)

    Seyda, V.; Kaufmann, N.; Emmelmann, C.

    Laser melting of titanium material, e.g. Ti-6Al-4 V, offers great potential in manufacturing automotive components, lightweight structures and medical implants. In order to achieve required mechanical properties of laser melted components quality of powder materials is essential. Unmelted powder is recycled and reused in a subsequent process. Due to repeated recycling it is suggested that powder material changes. In this paper aging processes of Ti-6Al-4 V powder are studied. It was observed that powder particles coarsen and flowability increases. Comparing examined powder characteristics to bulk material properties it was noticed that there are significant effects of aged powder on laser melted components.

  20. New metallographic preparation techniques for tantalum and tantalum alloys

    SciTech Connect

    Kelly, A.M.; Bingert, S.R.; Reiswig, R.D.

    1995-09-01

    Two new metallographic techniques have been developed for tantalum and its alloys. The first is a chemical polishing method that can even be used on specimens immediately after grinding on silicon carbide papers. The second is an etching technique that even delineates low-angle grain boundaries, making it particularly suitable for quantitative grain size measurements. It has also been determined that these are suitable for the preparation of a surprisingly large variety of other metals and alloys, including, titanium, tungsten, Ti-6Al-4V, molybdenum, a Zr-Ti-Cu-Ni alloy, a Ti-Ta-Sc alloy, Fansteel 85, and a Hf-Zr alloy to name a few.

  1. Ti-6Al-4V Additively Manufactured by Selective Laser Melting with Superior Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Xu, W.; Sun, S.; Elambasseril, J.; Liu, Q.; Brandt, M.; Qian, M.

    2015-03-01

    The Achilles' heel of additively manufactured Ti-6Al-4V by selective laser melting (SLM) is its inferior mechanical properties compared with its wrought (forged) counterparts. Acicular α' martensite resulted from rapid cooling by SLM is primarily responsible for high strength but inadequate tensile ductility achieved in the as-fabricated state. This study presents a solution to eliminating the adverse effect of the nonequilibrium α' martensite. This is achieved by enabling in situ martensite decomposition into a novel ultrafine (200-300 nm) lamellar ( α + β) microstructure via the selection of an array of processing variables including the layer thickness, energy density, and focal offset distance. The resulting tensile elongation reached 11.4% while the yield strength was kept above 1100 MPa. These properties compare favorably with those of mill-annealed Ti-6Al-4V consisting of globular α and β. The fatigue life of SLM-fabricated Ti-6Al-4V with an ultrafine lamellar ( α + β) structure has approached that of the mill-annealed counterparts and is much superior to that of SLM-fabricated Ti-6Al-4V with α' martensite.

  2. XPS Analysis of Ti6Al4V Oxidation Under UHV Conditions

    NASA Astrophysics Data System (ADS)

    Hierro-Oliva, M.; Gallardo-Moreno, A. M.; González-Martín, M. L.

    2014-12-01

    Oxidation of Ti6Al4V is studied by X-ray photoelectron spectroscopy (XPS). Oxide layer growth was monitored on the Ti6Al4V surface for 24 hours. The surface was previously etched with Ar+ ions under ultra-high vacuum conditions. XPS spectra show that TiO and Ti2O3, together with Al2O3, were the earliest oxides formed. Vanadium, despite being detected in its elementary form in the bulk, was not found in any of its oxidized states. TiO2, directly related to the good performance of Ti6Al4V for biomedical applications, did not contribute significantly to the passive layer at the beginning; nevertheless, it was identified after the oxidation process progressed to a more advanced stage. This behavior indicates that reoxidation of Ti6Al4V permits auto-healing of its passive layer, with the presence of TiO2, even in conditions of low oxygen availability.

  3. XPS Analysis of Ti6Al4V Oxidation Under UHV Conditions

    NASA Astrophysics Data System (ADS)

    Hierro-Oliva, M.; Gallardo-Moreno, A. M.; González-Martín, M. L.

    2014-09-01

    Oxidation of Ti6Al4V is studied by X-ray photoelectron spectroscopy (XPS). Oxide layer growth was monitored on the Ti6Al4V surface for 24 hours. The surface was previously etched with Ar+ ions under ultra-high vacuum conditions. XPS spectra show that TiO and Ti2O3, together with Al2O3, were the earliest oxides formed. Vanadium, despite being detected in its elementary form in the bulk, was not found in any of its oxidized states. TiO2, directly related to the good performance of Ti6Al4V for biomedical applications, did not contribute significantly to the passive layer at the beginning; nevertheless, it was identified after the oxidation process progressed to a more advanced stage. This behavior indicates that reoxidation of Ti6Al4V permits auto-healing of its passive layer, with the presence of TiO2, even in conditions of low oxygen availability.

  4. Influence of UFG structure formation on mechanical and fatigue properties in Ti-6Al-7Nb alloy

    NASA Astrophysics Data System (ADS)

    Polyakova, V. V.; Anumalasetty, V. N.; Semenova, I. P.; Valiev, R. Z.

    2014-08-01

    Ultrafine-grained (UFG) Ti alloys have potential applications in osteosynthesis and orthopedics due to high bio-compatibility and increased weight-to- strength ratio. In current study, Ti6Al7Nb ELI alloy is processed through equal channel angular pressing-conform (ECAP-Conform) and subsequent thermomechanical processing to generate a UFG microstructure. The fatigue properties of UFG alloys are compared to coarse grained (CG) alloys. Our study demonstrates that the UFG alloys with an average grain size of ~180 nm showed 35% enhancement of fatigue endurance limit as compared to coarse-grained alloys. On the fracture surfaces of the UFG and CG samples fatigue striations and dimpled relief were observed. However, the fracture surface of the UFG sample looks smoother; fewer amounts of secondary micro-cracks and more ductile rupture were also observed, which testifies to the good crack resistance in the UFG alloy after high-cyclic fatigue tests.

  5. A Constitutive Equation Relating Composition and Microstructure to Properties in Ti-6Al-4V: As Derived Using a Novel Integrated Computational Approach

    NASA Astrophysics Data System (ADS)

    Ghamarian, Iman; Samimi, Peyman; Dixit, Vikas; Collins, Peter C.

    2015-11-01

    While it is useful to predict properties in metallic materials based upon the composition and microstructure, the complexity of real, multi-component, and multi-phase engineering alloys presents difficulties when attempting to determine constituent-based phenomenological equations. This paper applies an approach based upon the integration of three separate modeling approaches, specifically artificial neural networks, genetic algorithms, and Monte Carlo simulations to determine a mechanism-based equation for the yield strength of α+ β processed Ti-6Al-4V (all compositions in weight percent) which consists of a complex multi-phase microstructure with varying spatial and morphological distributions of the key microstructural features. Notably, this is an industrially important alloy yet an alloy for which such an equation does not exist in the published literature. The equation ultimately derived in this work not only can accurately describe the properties of the current dataset but also is consistent with the limited and dissociated information available in the literature regarding certain parameters such as intrinsic yield strength of pure hexagonal close-packed alpha titanium. In addition, this equation suggests new interesting opportunities for controlling yield strength by controlling the relative intrinsic strengths of the two phases through solid solution strengthening.

  6. Improved tribological behavior of boron implanted Ti-6Al-4V

    SciTech Connect

    Baker, N.P.; Walter, K.C.; Nastasi, M.

    1998-03-01

    Boron implanted of Ti6Al4V has been conducted at combinations of 32 and 40 keV to supplement that done previously at 75 keV. Shallower boron depth profiles with higher B-concentrations in the Ti64 surface have been obtained by tailoring the combinations of ion energy and dose. This work used three different ion energy and dose combinations of 4 {times} 10{sup 17} B-at/cm{sup 2} at 40 keV plus 2 {times} 10{sup 17} B-at/cm{sup 2} at 32 keV, 4 {times} 10{sup 17} B-at/cm{sup 2} at 40 keV, and 4 {times} 10{sup 17} B-at/cm{sup 2} at 32 keV plus 2 {times} 10{sup 17} B-at/cm{sup 2} at 40 keV. Comparisons are made between Ti6Al4V with a shallow implanted boron depth profile, Ti6Al4V with a deeper boron depth profile and nitrogen implanted using a plasma source ion implantation process. It has been previously shown that while boron implanted Ti64 has a {approximately} 30% higher surface hardness than nitrogen implanted Ti64, the N-implantation reduced the wear coefficient of Ti64 by 25--120x, while B-implantation reduced the wear coefficient by 6.5x or less. The results show that no significant improvement is made in the wear resistance of boron implanted Ti6Al4V by increasing the concentration of boron at the surface from approximately 10% to 43%. Transmission electron microscopy (TEM) and selected area diffraction (SAD) indicated the formation of crystalline TiB in the implanted surface layer. Shallower depth profiles result in reductions of the Ti6Al4V wear coefficient by 6.5x or less which is the same result obtained earlier with the deeper boron depth profile. Surface hardness of Ti6Al4V with shallower boron depth profiles was improved approximately 10% compared to the results previously acquired with deeper boron depth profiles.

  7. Evaluation of superplastic forming and co-diffusion bonding of Ti-6Al-4V titanium alloy expanded sandwich structures

    NASA Technical Reports Server (NTRS)

    Arvin, G. H.; Israeli, L.; Stolpestad, J. H.; Stacher, G. W.

    1981-01-01

    The application of the superplastic forming/diffusion bonding (SPF/DB) process to supersonic cruise research is investigated. The capability of an SPF/DB titanium structure to meet the structural requirements of the inner wing area of the NASA arrow-wing advanced supersonic transport design is evaluated. Selection of structural concepts and their optimization for minimum weight, SPF/DB process optimization, fabrication of representative specimens, and specimen testing and evaluation are described. The structural area used includes both upper and lower wing panels, where the upper wing panel is used for static compression strength evaluation and the lower panel, in tension, is used for fracture mechanics evaluations. The individual test specimens, cut from six large panels, consist of 39 static specimens, 10 fracture mechanics specimens, and one each full size panel for compression stability and fracture mechanics testing. Tests are performed at temperatures of -54 C (-65 F), room temperature, and 260 C (500 F).

  8. Preliminary study of raw material for calcium silicate/PVA coating on Ti-6Al-4V alloy

    NASA Astrophysics Data System (ADS)

    Azam, Farah Atiqah bt Abdul; Shamsudin, Roslinda

    2015-09-01

    Calcium silicate bioceramic was prepared from the rice husk and limestone resources using the sol gel method. The preparations of CaSiO3 formulation were differ from the previous study due CaO/SiO2 amount with 45:55 ratio. X-Ray Fluorescence analysis was carried out to clarify the amount of SiO2 and CaO content in the limestone and rice husk ash. The high amount of CaO was found in the limestone with the percentages of 97.22%, whereby 89% of SiO2 content of the rice husk ash. Several milling time were studied to obtain the optimized milling ti me and speed in progress to obtain nano size particle. The particle size analysis result confirms that increase in milling time does not certainly reduce the size of particle. The addition of 0.05% polyvinyl alcohol as a binder did not change the phases or composition of calcium silicates after examined by X-Ray diffraction analysis which make it suitable to be used as a binder for calcium silicate coating without changing the chemical structure.

  9. Preliminary study of raw material for calcium silicate/PVA coating on Ti-6Al-4V alloy

    SciTech Connect

    Azam, Farah 'Atiqah bt Abdul; Shamsudin, Roslinda

    2015-09-25

    Calcium silicate bioceramic was prepared from the rice husk and limestone resources using the sol gel method. The preparations of CaSiO{sub 3} formulation were differ from the previous study due CaO/SiO{sub 2} amount with 45:55 ratio. X-Ray Fluorescence analysis was carried out to clarify the amount of SiO{sub 2} and CaO content in the limestone and rice husk ash. The high amount of CaO was found in the limestone with the percentages of 97.22%, whereby 89% of SiO{sub 2} content of the rice husk ash. Several milling time were studied to obtain the optimized milling ti me and speed in progress to obtain nano size particle. The particle size analysis result confirms that increase in milling time does not certainly reduce the size of particle. The addition of 0.05% polyvinyl alcohol as a binder did not change the phases or composition of calcium silicates after examined by X-Ray diffraction analysis which make it suitable to be used as a binder for calcium silicate coating without changing the chemical structure.

  10. The ecotoxicological recovery of Ely Creek and tributaries (Lee County, VA) after remediation of acid mine drainage.

    PubMed

    Simon, Mathew L; Cherry, Donald S; Currie, Rebecca J; Zipper, Carl E

    2012-04-01

    The Ely Creek watershed (Lee County, VA) was determined in 1995 to be the most negatively affected by acid mine drainage (AMD) within the Virginia coalfield. This determination led the US Army Corps of Engineers to design and build passive wetland remediation systems at two major AMD seeps affecting Ely Creek. This study was undertaken to determine if ecological recovery had occurred in Ely Creek. The results indicate that remediation had a positive effect on all monitoring sites downstream of the remediated AMD seeps. At the site most impacted by AMD, mean pH was 2.93 prior to remediation and improved to 7.14 in 2004. Benthic macroinvertebrate surveys revealed that one AMD influenced site had increased taxa richness from zero taxa in 1997 to 24 in 2004. While in situ testing of Asian clams resulted in zero survival at five of seven AMD influenced sites prior to remediation, some clams survived at all sites after. Clam survival was found to be significantly less than upstream references at only two sites, both downstream of un-mitigated AMD seeps in 2004. An ecotoxicological rating (ETR) system that combined ten biotic and abiotic parameters was developed as an indicator of the ecological status for each study site. A comparison of ETRs from before and after remediation demonstrated that all sites downstream of the remediation had experienced some level of recovery. Although the remediation has improved the ecological health of Ely Creek, un-mitigated AMD discharges are still negatively impacting the watershed. PMID:22371009

  11. The ecotoxicological recovery of Ely Creek and tributaries (Lee County, VA) after remediation of acid mine drainage.

    PubMed

    Simon, Matthew L; Cherry, Donald S; Currie, Rebecca J; Zipper, Carl E

    2006-12-01

    The Ely Creek watershed (Lee County, VA) was determined in 1995 to be the most negatively affected by acid mine drainage (AMD) within the Virginia coalfield. This determination led the US Army Corps of Engineers to design and build passive wetland remediation systems at two major AMD seeps affecting Ely Creek. This study was undertaken to determine if ecological recovery had occurred in Ely Creek. The results indicate that remediation had a positive effect on all monitoring sites downstream of the remediated AMD seeps. At the site most impacted by AMD, mean pH was 2.93 prior to remediation and improved to 7.14 in 2004. Benthic macroinvertebrate surveys revealed that one AMD influenced site had increased taxa richness from zero taxa in 1997 to 24 in 2004. While in situ testing of Asian clams resulted in zero survival at five of seven AMD influenced sites prior to remediation, some clams survived at all sites after. Clam survival was found to be significantly less than upstream references at only two sites, both downstream of un-mitigated AMD seeps in 2004. An ecotoxicological rating (ETR) system that combined ten biotic and abiotic parameters was developed as an indicator of the ecological status for each study site. A comparison of ETRs from before and after remediation demonstrated that all sites downstream of the remediation had experienced some level of recovery. Although the remediation has improved the ecological health of Ely Creek, un-mitigated AMD discharges are still negatively impacting the watershed. PMID:16770499

  12. Ultrafast beam dump materials and mirror coatings tested with the ELI beamlines LIDT test station

    NASA Astrophysics Data System (ADS)

    Durák, Michal; Kramer, Daniel; Velpula, Praveen K.; Cupal, Josef; Medřík, TomáÅ.¡; Hřebíček, Jan; Golasowski, Jiří; Peceli, Davorin; Fekete, Ladislav; Å tepán, Václav; Kozlová, Michaela; Rus, Bedřich

    2015-11-01

    The ELI Beamlines project will deliver ultrafast laser pulses with peak powers up to 10PW available every minute and PW class beams at 10Hz complemented by a 10TW 1kHz beamline. To properly determine damage thresholds of involved optical components in conditions similar to the operational environment and with expected laser parameters, a high vacuum LIDT test station was constructed at PALS facility. Our study presents results of ISO based S-on-1 and R-on-1 tests in femtosecond regime (50fs, 800nm, 10Hz/1kHz) performed on two different types of coatings: a) highabsorption black coatings with low outgassing rates, intended for use as a beam dump surface; and b) high-reflectivity, low-dispersion 45° AOI ultrafast mirror coatings. Testing of absorptive coatings was accompanied with QMS residual gas analysis to verify, that high intensity laser radiation approaching the damage threshold does not increase concentration of volatile organic compounds in the vacuum chamber. In case of HR mirror coatings, we also investigate the effect of cleaning on LIDT value, comparing characteristic S-on-1 curves of given sample with values obtained after 12h immersion in ethanol-water solution.

  13. Benthic macroinvertebrate assemblages and sediment toxicity testing in the Ely Creek watershed restoration project

    SciTech Connect

    Soucek, D.J.; Currie, R.J.; Cherry, D.S.; Latimer, H.A.; Trent, G.C.

    1998-12-31

    The Ely Creek watershed in Lee County, Virginia, contains an abundance of abandoned mined land (AML) seeps that contaminate the majority of the creek and its confluence into Big Stone Creek. Contaminated sediments had high concentrations of iron ({approximately}10,000 mg/kg), aluminum ({approximately}1,500 mg/kg), magnesium ({approximately}400 mg/kg) and manganese ({approximately}150 mg/kg). Copper and zinc generally ranged from 3 to 20 mg/kg. Benthic macroinvertebrates surveys at six of 20 sites sampled in the watershed yielded no macroinvertebrates, while eight others had total abundances of 1 to 9 organisms. Four reference sites contained {ge}100 organisms and at least 14 different taxa. Laboratory, 10-day survival/impairment sediments tests with Daphnia magna did not support the field data. Mortality of 92 to 100% for D. magna occurred in samples collected from six cities. Daphnid reproduction was more sensitive than laboratory test organism survivorship; however, neither daphnid survivorship nor reproduction were good predictors of taxa richness. Laboratory test concerns included the use of a reference diluent water rather than site specific diluent water.

  14. Straight talk with...Stephen O'Brien. Interviewed by Elie Dolgin.

    PubMed

    O'Brien, Stephen

    2013-01-01

    Stephen O'Brien joined the US National Cancer Institute as a post doc in 1971 and climbed the ranks to become head of the institute's Laboratory of Genomic Diversity, a position he held for 25 years. But, after four decades at the government agency, O'Brien was ready for something new. In December 2011, he stepped down and took up a three-year, $5 million 'megagrant' in Russia through a program started a year earlier by the Russian Ministry of Education and Science to attract big-name researchers to work at least part-time in that country. O'Brien used his money to help launch the Theodosius Dobzhansky Center for Genome Bioinformatics at Saint Petersburg State University. Although O'Brien is a cancer researcher, he has diverse scientific interests. He led the team that discovered the CCR5-Δ32 mutation that confers resistance to HIV, and he has helped document the remarkable genetic uniformity of African cheetahs. Recently, he and two California scientists started the Genome 10K project, which aims to sequence the genetic blueprints of 10,000 vertebrate species. On a trip back to the US, O'Brien spoke with Elie Dolgin about how comparative genomics and his new Russian center will help advance the search for new therapeutics. PMID:23295996

  15. ELiXIR—Solid-State Luminaire With Enhanced Light Extraction by Internal Reflection

    NASA Astrophysics Data System (ADS)

    Allen, Steven C.; Steckl, Andrew J.

    2007-06-01

    A phosphor-converted light-emitting diode (pcLED) luminaire featuring enhanced light extraction by internal reflection (ELiXIR) with efficacy of 60 lm/W producing 18 lumens of yellowish green light at 100 mA is presented. The luminaire consists of a commercial blue high power LED, a polymer hemispherical shell lens with interior phosphor coating, and planar aluminized reflector. High extraction efficiency of the phosphor-converted light is achieved by separating the phosphor from the LED and using internal reflection to steer the light away from lossy reflectors and the LED package and out of the device. At 10 and 500 mA, the luminaire produces 2.1 and 66 lumens with efficacies of 80 and 37 lm/W, respectively. Technological improvements over existing commercial LEDs, such as more efficient pcLED packages or, alternatively, higher efficiency green or yellow for color mixing, will be essential to achieving 150 200 lm/W solid-state lighting. Advances in both areas are demonstrated.

  16. Mutational analysis of the human immunodeficiency virus type 1 Eli Nef function.

    PubMed Central

    Zazopoulos, E; Haseltine, W A

    1992-01-01

    The studies presented here define an internally consistent experimental system that permits systematic analysis of the effect of nef on the rate of the human immunodeficiency virus type 1 (HIV-1) replication in a CD4+ tumor T-cell line and in primary peripheral blood mononuclear cells. The parental full-length Nef protein, derived from the Eli strain of HIV-1, accelerates virus replication in both cell types. Mutations that destabilize or alter the intracellular location of the protein affect the ability of the Nef protein to accelerate virus replication. A set of mutants was made in amino acids proposed to be required for Nef function, including threonine and serine residues proposed to be targets for phosphorylation, and in sequences thought to resemble the G-1, G-3, and G-4 sites of the family of G proteins. In most cases alterations of the critical amino acids yield stable Nef proteins of parental phenotype. These results challenge the existing theories for the mechanism of Nef function. The results also identify two residues in the carboxyl half of the protein that are important for Nef function. Images PMID:1631166

  17. Nuclear Physics with 10 PW laser beams at Extreme Light Infrastructure - Nuclear Physics (ELI-NP)

    NASA Astrophysics Data System (ADS)

    Zamfir, N. V.

    2014-05-01

    The field of the uncharted territory of high-intensity laser interaction with matter is confronted with new exotic phenomena and, consequently, opens new research perspectives. The intense laser beams interacting with a gas or solid target generate beams of electrons, protons and ions. These beams can induce nuclear reactions. Electrons also generate ions high-energy photons via bremsstrahlung processes which can also induce nuclear reactions. In this context a new research domain began to form in the last decade or so, namely nuclear physics with high power lasers. The observation of high brilliance proton beams of tens of MeV energy from solid targets has stimulated an intense research activity. The laser-driven particle beams have to compete with conventional nuclear accelerator-generated beams. The ultimate goal is aiming at applications of the laser produced beams in research, technology and medicine. The mechanism responsible for ion acceleration are currently subject of intensive research in many laboratories in the world. The existing results, experimental and theoretical, and their perspectives are reviewed in this article in the context of IZEST and the scientific program of ELI-NP.

  18. Evaluation of Ti-6Al-4V surface treatments for use with a polyphenylquinoxaline adhesive

    NASA Technical Reports Server (NTRS)

    Progar, D. J.

    1986-01-01

    Three surface treatments for Ti-6Al-4V adherends were evaluated using a thermoplastic polymer monoether polyphenylquinoxaline, MEPPQ, which had been shown in previous studies to have good potential as a high temperature adhesive for aerospace applications. Initial results based on long term thermal exposure at 232 C (450 F) using the phosphate-fluoride (PF) and chromic acid anodized (CAA) treatments with MEPPQ adhesive were not encouraging. A significant improvement in strength retention and a change in failure mode (cohesive) at 232 C (450F) was found for the SHA treated specimens compared to the PF and CAA treatments. Although an improvement in long term thermal durability was obtained with the SHA treatment of Ti-6Al-4V, an improved surface treatment with better long term durability is still required for aerospace applications.

  19. Evaluation of Ti-6Al-4V surface treatments for use with a polyphenylquinoxaline adhesive

    NASA Technical Reports Server (NTRS)

    Progar, Donald J.

    1987-01-01

    Three surface treatments for Ti-6Al-4V adherends were evaluated using a thermoplastic polymer monoether polyphenylquinoxaline, MEPPQ, which had been shown in previous studies to have good potential as a high temperature adhesive for aerospace applications. Initial results based on long term thermal exposure at 232 C (450 F) using the phosphate-fluoride (PF) and chromic acid anodized (CAA) treatments with MEPPQ adhesive were not encouraging. A significant improvement in strength retention and a change in failure mode (cohesive) at 232 C (450 F) was found for the SHA treated specimens compared to the PF and CAA treatments. Although an improvement in long term thermal durability was obtained with the SHA treatment of Ti-6Al-4V, an improved surface treatment with better long term durability is still required for aerospace applications.

  20. Reducing Wear of Steel Rolling Against Ti6Al4V Operating in Vacuum

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.

    2014-01-01

    This work was motivated by a qualification test of a mechanism for a space telescope. During the test undesired wear debris was formed. In this project alterative materials and coatings were tested with intent to reduce wear and debris when steel has a misaligned rolling contact against Ti6Al4V. Testing was done using a vacuum roller rig mimicking the mechanism's contact conditions. Ten configurations were tested. Most configurations resulted in significant debris. A sputtered 1-micrometer-thick nan-ocomposite molybdenum disulfide (MoS2) film provided the best wear protection. The best configuration made use of the MoS2 coating on both materials, and in preparing for sputtering the anodized Ti6Al4V working surface was smoothed using an ultrasonic process.

  1. HOS cell adhesion on Ti6Al4V surfaces texturized by laser engraving

    NASA Astrophysics Data System (ADS)

    Sandoval Amador, A.; Carreño Garcia, H.; Escobar Rivero, P.; Peña Ballesteros, D. Y.; Estupiñán Duran, H. A.

    2016-02-01

    The cell adhesion of the implant is determinate by the chemical composition, topography, wettability, surface energy and biocompatibility of the biomaterial. In this work the interaction between human osteosarcoma HOS cells and textured Ti6Al4V surfaces were evaluated. Ti6Al4V surfaces were textured using a CO2 laser in order to obtain circular spots on the surfaces. Test surfaces were uncoated (C1) used as a control surface, and surfaces with points obtained by laser engraving, with 1mm spacing (C2) and 0.5mm (C3). The HOS cells were cultured in RPMI-1640 medium with 10% fetal bovine serum and 1% antibiotics. No cells toxicity after one month incubation time occurred. The increased cell adhesion and cell spreading was observed after 1, 3 and 5 days without significant differences between the sample surfaces (C2 and C3) and control (uncoated) at the end of the experiment.

  2. Surface Oxidation of Ti-6Al-4V for Bio-Implant Application

    NASA Astrophysics Data System (ADS)

    Biswas, A.; Bhattacharjee, U.; Manna, I.; Dutta Majumdar, J.

    The present study aims at enhancing the wear resistance and biocompatibility of Ti-6Al-4V by forming a thin layer of oxide. Surface oxidation has been carried out by controlled heating of the surface of Ti-6Al-4V substrate in air at the temperature ranging from 400-600°C and time from 25-60 h. The phase formed under thermal oxidation was predominantly the rutile and anatase phase. The thickness of the oxide layer varied from 1.5-7.0 μm. The microhardness on the surface was significantly improved as compared to the as-received substrate. Both the corrosion resistance property and biocompatibility were improved.

  3. Fatigue performance of laser additive manufactured Ti-6Al-4V in very high cycle fatigue (VHCF) regime up to 109 cycles

    NASA Astrophysics Data System (ADS)

    Wycisk, Eric; Siddique, Shafaqat; Herzog, Dirk; Walther, Frank; Emmelmann, Claus

    2015-12-01

    Additive manufacturing technologies are in the process of establishing themselves as an alternative production technology to conventional manufacturing such as casting or milling. Especially laser additive manufacturing (LAM) enables the production of metallic parts with mechanical properties comparable to conventionally manufactured components. Due to the high geometrical freedom in LAM the technology enables the production of ultra-light weight designs and therefore gains increasing importance in aircraft and space industry. The high quality standards of these industries demand predictability of material properties for static and dynamic load cases. However, fatigue properties especially in the very high cycle fatigue regime until 109 cycles have not been sufficiently determined yet. Therefore this paper presents an analysis of fatigue properties of laser additive manufactured Ti-6Al-4V under cyclic tension-tension until 107 cycles and tension-compression load until 109 cycles. For the analysis of laser additive manufactured titanium alloy Ti-6Al-4V Woehler fatigue tests under tension-tension and tension-compression were carried out in the high cycle and very high cycle fatigue regime. Specimens in stress-relieved as well as hot-isostatic-pressed conditions were analyzed regarding crack initiation site, mean stress sensitivity and overall fatigue performance. The determined fatigue properties show values in the range of conventionally manufactured Ti-6Al-4V with particularly good performance for hot-isostatic-pressed additive-manufactured material. For all conditions the results show no conventional fatigue limit but a constant increase in fatigue life with decreasing loads. No effects of test frequency on life span could be determined. However, independently of testing principle, a shift of crack initiation from surface to internal initiation could be observed with increasing cycles to failure.

  4. Evaluation of Biological Properties of Electron Beam Melted Ti6Al4V Implant with Biomimetic Coating In Vitro and In Vivo

    PubMed Central

    Wang, Cheng-Tao; Li, Guo-Chen; Lei, Wei; Zhang, Zhi-Yong; Wang, Lin

    2012-01-01

    Background High strength porous titanium implants are widely used for the reconstruction of craniofacial defects because of their similar mechanical properties to those of bone. The recent introduction of electron beam melting (EBM) technique allows a direct digitally enabled fabrication of patient specific porous titanium implants, whereas both their in vitro and in vivo biological performance need further investigation. Methods In the present study, we fabricated porous Ti6Al4V implants with controlled porous structure by EBM process, analyzed their mechanical properties, and conducted the surface modification with biomimetic approach. The bioactivities of EBM porous titanium in vitro and in vivo were evaluated between implants with and without biomimetic apatite coating. Results The physical property of the porous implants, containing the compressive strength being 163 - 286 MPa and the Young’s modulus being 14.5–38.5 GPa, is similar to cortical bone. The in vitro culture of osteoblasts on the porous Ti6Al4V implants has shown a favorable circumstance for cell attachment and proliferation as well as cell morphology and spreading, which were comparable with the implants coating with bone-like apatite. In vivo, histological analysis has obtained a rapid ingrowth of bone tissue from calvarial margins toward the center of bone defect in 12 weeks. We observed similar increasing rate of bone ingrowth and percentage of bone formation within coated and uncoated implants, all of which achieved a successful bridging of the defect in 12 weeks after the implantation. Conclusions This study demonstrated that the EBM porous Ti6Al4V implant not only reduced the stress-shielding but also exerted appropriate osteoconductive properties, as well as the apatite coated group. The results opened up the possibility of using purely porous titanium alloy scaffolds to reconstruct specific bone defects in the maxillofacial and orthopedic fields. PMID:23272208

  5. Effects of laser-weld joint opening size on fatigue strength of Ti-6Al-4V structures with several diameters.

    PubMed

    Nuñez-Pantoja, J M C; Vaz, L G; Nóbilo, M A A; Henriques, G E P; Mesquita, M F

    2011-03-01

    This study was conducted to evaluate the fatigue strength of Ti-6Al-4V laser-welded joints with several diameters and joint openings. Sixty dumbbell rods were machined in Ti-6Al-4V alloy with central diameters of 1·5, 2·0 and 3·5 mm. The specimens were sectioned and then welded using two joint openings (0·0 and 0·6 mm). The combination of variables created six groups, which when added to the intact groups made a total of nine groups (n = 10). Laser welding was executed as follows: 360 V per 8 ms (1·5 and 2·0 mm) and 380 V per 9 ms (3·5 mm) with focus and frequency regulated to zero. The joints were finished, polished and submitted to radiographic examination to be analysed visually for the presence of porosity. The specimens were then subjected to a mechanical cyclic test, and the number of cycles until failure was recorded. The fracture surface was examined with a scanning electron microscope (SEM). The Kruskal-Wallis test and Dunn test (α = 0·05) indicated that the number of cycles required for fracture was lower for all specimens with joint openings of 0·6 mm, and for 3·5-mm-diameter specimens with joint openings of 0·0 mm. The Spearman correlation coefficient (α = 0·05) indicated that there was a negative correlation between the number of cycles and the presence of porosity. So, laser welding of Ti-6Al-4V structures with a thin diameter provides the best conditions for the juxtaposition of parts. Radiographic examination allows for the detection of internal voids in titanium joints. PMID:20678101

  6. Novel CYP4V2 mutations associated with Bietti crystalline corneoretinal dystrophy in Chinese patients

    PubMed Central

    Tian, Rong; Wang, Shu-Ran; Wang, Jing; Chen, You-Xin

    2015-01-01

    AIM To analyze the CYP4V2 mutations in five unrelated Chinese patients with Bietti crystalline corneoretinal dystrophy (BCD) and to provide clinical features of these patients. BCD is a rare monogenic autosomal recessively inherited disorder characterized by the presence of crystals in the retina and retinal pigment epithelium atrophy. Mutations in the CYP4V2 gene have been found to be causative for BCD. METHODS Ophthalmic examinations were carried out in the affected individuals. Peripheral blood samples were collected and genomic DNA was extracted. All exons and flanking intronic regions of the CYP4V2 gene were amplified with polymerase chain reaction and screened for mutations by direct DNA sequencing. One hundred control chromosomes were also screened to exclude nonpathogenic polymorphisms. RESULTS Fundus examination revealed the presence of tiny yellowish-sparkling crystals at the posterior pole of the fundus and atrophy of the retinal pigment epithelium in all patients. Choroid neovascularization was noted in one patient. Five different CYP4V2 mutations were identified, including two missense mutations (p.F73L, p.R400H), two splice site mutations (c.802-8_810del17insGC, c.1091-2A>G), and one single base-pair deletion (p.T479TfsX7 or c.1437delC). The two splice site mutations were identified in three of the patients with BCD. Mutation p.T479TfsX7 was a novel mutation not observed in any of 100 ethnically matched control chromosomes. CONCLUSION Mutation c.802-8_810del17insGC and c.1091-2A>G are common mutations in Chinese patients with BCD. Our results expand the allelic heterogeneity of BCD. PMID:26085992

  7. Dielectric spectra of bismuth vanadate Bi4V2O11

    NASA Astrophysics Data System (ADS)

    Borisov, V. N.; Pashkov, V. M.; Poplavko, Iu. M.; Avakian, P. B.; Osipian, V. G.

    1990-06-01

    Results of a study of the temperature-frequency dependence of the behavior of the dielectric parameters of bismuth vanadate, Bi4V2O11, in the frequency range 1-100 GHz are reported. It is shown that bismuth vanadate is characterized by a large number of phase transitions. Yet another, previously unknown, phase transition in bismuth vanadate, masked by a relaxation process, has been observed in the temperature range 410-420 K.

  8. The effect of ion implantation on tribology and hot rolling contact fatigue of Cr4Mo4Ni4V bearing steel

    NASA Astrophysics Data System (ADS)

    Jin, Jie; Chen, Yunbo; Gao, Kewei; Huang, Xiaolin

    2014-06-01

    The Cr4Mo4Ni4V bearing material was implanted by N + Zr dual element implantation process. The mechanical properties were investigated by nanohardness tests, friction and wear tests, as well as hot rolling contact fatigue life tests. The surface structures of the planted samples were studied by GXRD, AES, XPS and TEM tests. The results showed that the N + Zr implanted sample exhibits higher surface hardness, anti-friction and wear-resistance properties and resistance to hot contact fatigue. After implantation, amorphous phase, microcrystalline phase and new alloy phases are formed in implanted region. The new phases and structures take the important roles in improving the surface mechanical properties of the bearing material.

  9. Physical characteristics of Ti-6A1-4V implants fabricated by electrodischarge compaction.

    PubMed

    Okazaki, K; Lee, W H; Kim, D K; Kopczyk, R A

    1991-12-01

    Physical characteristics of a Ti-6A1-4V implant were evaluated following fabrication using a new electrodischarge compaction technique. Ti-6A1-4V atomized powders were loaded into Pyrex tubes (3.3 mm ID) and subjected to a high-voltage, high-current-density pulse in air for a period of less than 300 microseconds. Single pulses (1.0, 1.5, 2.0 and 2.5 KJ/grampowder) were applied from a capacitor bank (240, 480 or 720 microF) to produce solid core implants with porous surface layers. Implants were evaluated microscopically for core size, neck size, pore size, grain structure, and incorporated oxide film. Hardness was also evaluated. Implants were compared with Ti-6A1-4V commercial powders. Core size increased and pore size decreased with increases in energy and capacitance. The cores were composed of equiaxed grains which were free of oxide at the grain boundary. Porous layers, consisting of particles connected in three dimensions by necks, were free of oxide films at the connecting interfaces. Neck size increased with increases in input energy and capacitance. Hardness readings of the core, necks, and porous particles resulted in readings higher than or similar to control materials. Electrodischarge compaction did not alter the physical characteristics during compaction. PMID:1794992

  10. Time exposure studies on stress corrosion cracking of aluminum 2014-T6, aluminum 7075-T651, and titanium 6Al-4V

    NASA Technical Reports Server (NTRS)

    Terrell, J.

    1972-01-01

    The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 7075-T651 and titanium 6A1-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 6) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity). Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, a similar observation was not noted for titanium stressed specimens. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl); while they (both alloys) seem to resist stress corrosion cracking in methyl alcohol, ethyl alcohol, iso-propyl alcohol, and demineralized distilled water. Titanium 6A1-4V showed some evidence of susceptibility to SCC in methanol, while no such susceptibility was exhibited in ethanol, iso-propyl alcohol and demineralized distilled water.

  11. The influence of cell morphology on the compressive fatigue behavior of Ti-6Al-4V meshes fabricated by electron beam melting.

    PubMed

    Zhao, S; Li, S J; Hou, W T; Hao, Y L; Yang, R; Misra, R D K

    2016-06-01

    Additive manufacturing technique is a promising approach for fabricating cellular bone substitutes such as trabecular and cortical bones because of the ability to adjust process parameters to fabricate different shapes and inner structures. Considering the long term safe application in human body, the metallic cellular implants are expected to exhibit superior fatigue property. The objective of the study was to study the influence of cell shape on the compressive fatigue behavior of Ti-6Al-4V mesh arrays fabricated by electron beam melting. The results indicated that the underlying fatigue mechanism for the three kinds of meshes (cubic, G7 and rhombic dodecahedron) is the interaction of cyclic ratcheting and fatigue crack growth on the struts, which is closely related to cumulative effect of buckling and bending deformation of the strut. By increasing the buckling deformation on the struts through cell shape design, the cyclic ratcheting rate of the meshes during cyclic deformation was decreased and accordingly, the compressive fatigue strength was increased. With increasing bending deformation of struts, fatigue crack growth in struts contributed more to the fatigue damage of meshes. Rough surface and pores contained in the struts significantly deteriorated the compressive fatigue strength of the struts. By optimizing the buckling and bending deformation through cell shape design, Ti-6Al-4V alloy cellular solids with high fatigue strength and low modulus can be fabricated by the EBM technique. PMID:26878293

  12. Microstructure and mechanical behavior of porous Ti-6Al-4V parts obtained by selective laser melting.

    PubMed

    Sallica-Leva, E; Jardini, A L; Fogagnolo, J B

    2013-10-01

    Rapid prototyping allows titanium porous parts with mechanical properties close to that of bone tissue to be obtained. In this article, porous parts of the Ti-6Al-4V alloy with three levels of porosity were obtained by selective laser melting with two different energy inputs. Thermal treatments were performed to determine the influence of the microstructure on the mechanical properties. The porous parts were characterized by both optical and scanning electron microscopy. The effective modulus, yield and ultimate compressive strength were determined by compressive tests. The martensitic α' microstructure was observed in all of the as-processed parts. The struts resulting from the processing conditions investigated were thinner than those defined by CAD models, and consequently, larger pores and a higher experimental porosity were achieved. The use of the high-energy input parameters produced parts with higher oxygen and nitrogen content, their struts that were even thinner and contained a homogeneous porosity distribution. Greater mechanical properties for a given relative density were obtained using the high-energy input parameters. The as-quenched martensitic parts showed yield and ultimate compressive strengths similar to the as-processed parts, and these were greater than those observed for the fully annealed samples that had the lamellar microstructure of the equilibrium α+β phases. The effective modulus was not significantly influenced by the thermal treatments. A comparison between these results and those of porous parts with similar geometry obtained by selective electron beam melting shows that the use of a laser allows parts with higher mechanical properties for a given relative density to be obtained. PMID:23773976

  13. Enhancement of local bone remodeling in osteoporotic rabbits by biomimic multilayered structures on Ti6Al4V implants.

    PubMed

    Huang, Ling; Luo, Zhong; Hu, Yan; Shen, Xinkun; Li, Menghuan; Li, Liqi; Zhang, Yuan; Yang, Weihu; Liu, Peng; Cai, Kaiyong

    2016-06-01

    To enhance long-term survival of titanium implants in patients with osteoporosis, chitosan/gelatin multilayers containing bone morphogenetic protein 2(BMP2) and an antiosteoporotic agent of calcitonin (CT) are deposited on the Ti6Al4V (TC4) implants through layer-by-layer (LBL) electrostatic assembly technique. Here, the obtained titanium alloy implant (TC4/LBL/CT/BMP2) can regulate the release of loaded calcitonin and BMP2 agents in a sustaining manner to accelerate the bone formation and simultaneously inhibit bone resorption. In vitro results show that the bone-related cells on TC4/LBL/CT/BMP2 present the lowest production level of tartrate resistant acid phosphatase (TRAP) but the highest (p < 0.05) level of alkaline phosphatase (ALP) activity, osteocalcin production, mineralization capacity and osteoblast-related gene expression among all groups after treatment for 7 or 21 days, respectively. Besides, in vivo studies of micro-CT analysis, routine histological and immunohistochemical analysis also collectively demonstrate that the TC4/LBL/CT/BMP2 implant can dramatically promote the formation and remodeling of new bone in osteoporotic rabbits after implantation for 30 days and 90 days, respectively. In vivo push-out testing further confirms that the TC4/LBL/CT/BMP2 implant has the highest (p < 0.01) interfacial shear strength and favorable bone-implant osseointegration. Overall, this study establishes a simple and profound methodology to fabricate a biofunctional TC4 implant for the treatment of local osteoporotic fractures in vivo. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1437-1451, 2016. PMID:26822259

  14. Comparison of oxide measurement techniques applied to Ti6Al4V

    SciTech Connect

    Reissig, L.; Czubayko, U.; Wanderka, N.; Voelkl, R.; Glatzel, U. . E-mail: uwe.glatzel@uni-bayreuth.de

    2005-08-15

    Titanium and his alloys can solve high amounts of oxygen, which generally worsen mechanical properties. This paper compares energy dispersive X-ray analysis, three-dimensional-atom-probe and carrier-gas-hot-extraction as techniques in order to quantify the oxygen content in commercial grade titanium alloys. Assets and drawbacks of the techniques are pointed out. Oxygen enrichment by machining processes is verified in the drill hole of automotive connecting rod.

  15. On the effect of deep-rolling and laser-peening on the stress-controlled low- and high-cycle fatigue behavior of Ti-6Al-4V at elevated temperatures up to 550?C

    SciTech Connect

    Ritchie, IAltenberger, RKNalla, YSano LWagner, RO

    2012-04-01

    The effect of surface treatment on the stress/life fatigue behavior of a titanium Ti-6Al-4V turbine fan blade alloy is investigated in the regime of 102 to 106 cycles to failure under fully reversed stress-controlled isothermal push-pull loading between 25? and 550?C at a frequency of 5 Hz. Specifically, the fatigue behavior was examined in specimens in the deep-rolled and laser-shock peened surface conditions, and compared to results on samples in the untreated (machined and stress annealed) condition. Although the fatigue resistance of the Ti-6Al-4V alloy declined with increasing test temperature regardless of surface condition, deep-rolling and laser-shock peening surface treatments were found to extend the fatigue lives by factors of more than 30 and 5-10, respectively, in the high-cycle and low-cycle fatigue regimes at temperatures as high as 550?C. At these temperatures, compressive residual stresses are essentially relaxed; however, it is the presence of near-surface work hardened layers, with a nanocystalline structure in the case of deep-rolling and dense dislocation tangles in the case of laser-shock peening, which remain fairly stable even after cycling at 450?-550?C, that provide the basis for the beneficial role of mechanical surface treatments on the fatigue strength of Ti-6Al-4V at elevated temperatures.

  16. Microstructures and mechanical properties of electron beam-rapid manufactured Ti-6Al-4V biomedical prototypes compared to wrought Ti-6Al-4V

    SciTech Connect

    Murr, L.E. Esquivel, E.V.; Quinones, S.A.; Gaytan, S.M.; Lopez, M.I.; Martinez, E.Y.; Medina, F.; Hernandez, D.H.; Martinez, E.; Martinez, J.L.; Stafford, S.W.; Brown, D.K.; Hoppe, T.; Meyers, W.; Lindhe, U.; Wicker, R.B.

    2009-02-15

    This study represents an exploratory characterization and comparison of electron-beam melted (EBM) or rapid manufacturing (RM) of Ti-6Al-4V components (from nominal 30 {mu}m diameter powder) with wrought products. Acicular {alpha} and associated {beta} microstructures observed by optical metallography and electron microscopy (SEM and TEM) are compared along with corresponding tensile test and hardness data; including the initial powder particles where the Vickers microindentation hardness averaged 5.0 GPa in comparison with the fully dense, EB manufactured product with an average microindentation hardness ranging from 3.6 to 3.9 GPa. This compared with wrought products where the Vickers microindentation hardness averaged 4.0 GPa. Values of UTS for the EBM samples averaged 1.18 GPa for elongations ranging from 16 to 25%. Biomaterials/biomedical applications of EBM prototypes in direct prosthesis or implant manufacturing from CT or MRI data are discussed in the context of this work, especially prospects for tailoring physical properties through EB control to achieve customized and optimized implant and prosthetic products direct from CT-scans.

  17. ETV REPORT: REMOVAL OF CHEMICAL CONTAMINANTS IN DRINKING WATER – WATTS PREMIER INC. WP-4V DRINKING WATER TREATMENT SYSTEM

    EPA Science Inventory

    The Watts Premier WP-4V POU drinking water treatment system was tested for removal of aldicarb, benzene, cadmium, carbofuran, cesium, chloroform, dichlorvos, dicrotophos, fenamiphos, mercury, mevinphos, oxamyl, strontium, and strychnine. The WP-4V employs a reverse osmosis (RO) m...

  18. Alloy materials

    DOEpatents

    Hans Thieme, Cornelis Leo; Thompson, Elliott D.; Fritzemeier, Leslie G.; Cameron, Robert D.; Siegal, Edward J.

    2002-01-01

    An alloy that contains at least two metals and can be used as a substrate for a superconductor is disclosed. The alloy can contain an oxide former. The alloy can have a biaxial or cube texture. The substrate can be used in a multilayer superconductor, which can further include one or more buffer layers disposed between the substrate and the superconductor material. The alloys can be made a by process that involves first rolling the alloy then annealing the alloy. A relatively large volume percentage of the alloy can be formed of grains having a biaxial or cube texture.

  19. Copper speciation in variably toxic sediments at the Ely Copper Mine, Vermont, United States

    USGS Publications Warehouse

    Kimball, Bryn E.; Foster, Andrea L.; Seal, Robert; Piatak, Nadine; Webb, Samuel M.; Hammarstrom, Jane M.

    2016-01-01

    At the Ely Copper Mine Superfund site, Cu concentrations exceed background values in both streamwater (160–1200 times) and sediments (15–79 times). Previously, these sediment samples were incubated with laboratory test organisms, and they exhibited variable toxicity for different stream sites. In this study we combined bulk- and microscale techniques to determine Cu speciation and distribution in these contaminated sediments on the basis of evidence from previous work that Cu was the most important stressor in this environment and that variable observed toxicity could have resulted from differences in Cu speciation. Copper speciation results were similar at microscopic and bulk scales. The major Cu species in the more toxic samples were sorbed or coprecipitated with secondary Mn (birnessite) and Fe minerals (jarosite and goethite), which together accounted for nearly 80% of the total Cu. The major Cu species in the less toxic samples were Cu sulfides (chalcopyrite and a covellite-like phase), making up about 80–95% of the total Cu, with minor amounts of Cu associated with jarosite or goethite. These Cu speciation results are consistent with the toxicity results, considering that Cu sorbed or coprecipitated with secondary phases at near-neutral pH is relatively less stable than Cu bound to sulfide at lower pH. The more toxic stream sediment sites were those that contained fewer detrital sulfides and were upstream of the major mine waste pile, suggesting that removal and consolidation of sulfide-bearing waste piles on site may not eliminate all sources of bioaccessible Cu.

  20. Copper Speciation in Variably Toxic Sediments at the Ely Copper Mine, Vermont, United States.

    PubMed

    Kimball, Bryn E; Foster, Andrea L; Seal, Robert R; Piatak, Nadine M; Webb, Samuel M; Hammarstrom, Jane M

    2016-02-01

    At the Ely Copper Mine Superfund site, Cu concentrations exceed background values in both streamwater (160-1200 times) and sediments (15-79 times). Previously, these sediment samples were incubated with laboratory test organisms, and they exhibited variable toxicity for different stream sites. In this study we combined bulk- and microscale techniques to determine Cu speciation and distribution in these contaminated sediments on the basis of evidence from previous work that Cu was the most important stressor in this environment and that variable observed toxicity could have resulted from differences in Cu speciation. Copper speciation results were similar at microscopic and bulk scales. The major Cu species in the more toxic samples were sorbed or coprecipitated with secondary Mn (birnessite) and Fe minerals (jarosite and goethite), which together accounted for nearly 80% of the total Cu. The major Cu species in the less toxic samples were Cu sulfides (chalcopyrite and a covellite-like phase), making up about 80-95% of the total Cu, with minor amounts of Cu associated with jarosite or goethite. These Cu speciation results are consistent with the toxicity results, considering that Cu sorbed or coprecipitated with secondary phases at near-neutral pH is relatively less stable than Cu bound to sulfide at lower pH. The more toxic stream sediment sites were those that contained fewer detrital sulfides and were upstream of the major mine waste pile, suggesting that removal and consolidation of sulfide-bearing waste piles on site may not eliminate all sources of bioaccessible Cu. PMID:26734712

  1. A Study on the Laser Spatter and the Oxidation Reactions During Selective Laser Melting of 316L Stainless Steel, Al-Si10-Mg, and Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Simonelli, Marco; Tuck, Chris; Aboulkhair, Nesma T.; Maskery, Ian; Ashcroft, Ian; Wildman, Ricky D.; Hague, Richard

    2015-09-01

    The creation of an object by selective laser melting (SLM) occurs by melting contiguous areas of a powder bed according to a corresponding digital model. It is therefore clear that the success of this metal Additive Manufacturing (AM) technology relies on the comprehension of the events that take place during the melting and solidification of the powder bed. This study was designed to understand the generation of the laser spatter that is commonly observed during SLM and the potential effects that the spatter has on the processing of 316L stainless steel, Al-Si10-Mg, and Ti-6Al-4V. With the exception of Ti-6Al-4V, the characterization of the laser spatter revealed the presence of surface oxides enriched in the most volatile alloying elements of the materials. The study will discuss the implication of this finding on the material quality of the built parts.

  2. SOD1A4V-mediated ALS: absence of a closely linked modifier gene and origination in Asia.

    PubMed

    Broom, W J; Johnson, D V; Auwarter, K E; Iafrate, A J; Russ, C; Al-Chalabi, A; Sapp, P C; McKenna-Yasek, D; Andersen, P M; Brown, R H

    2008-01-17

    Familial amyotrophic lateral sclerosis (ALS) accounts for 10% of all ALS. Approximately 20% of cases are due to mutations in the Cu/Zn superoxide dismutase gene (SOD1). In North America, SOD1(A4V) is the most common SOD1 mutation. Carriers of the SOD1(A4V) mutation share a common phenotype with rapid disease progression and death on average occurring at 1.4 years (versus 3-5 years with other dominant SOD1 mutations). Previous studies of SOD1(A4V) carriers identified a common haplotype around the SOD1 locus, suggesting a common founder for most SOD1(A4V) patients. In the current study we sequenced the entire common haplotypic region around SOD1 to test the hypothesis that polymorphisms in either previously undescribed coding regions or non-coding regions around SOD1 are responsible for the more aggressive phenotype in SOD1(A4V)-mediated ALS. We narrowed the conserved region around the SOD1 gene in SOD1(A4V) ALS to 2.8Kb and identified five novel SNPs therein. None of these variants was specifically found in all SOD1(A4V) patients. It therefore appears likely that the aggressive nature of the SOD1(A4V) mutation is not a result of a modifying factor within the region around the SOD1 gene. Founder analysis estimates that the A4V mutation occurred 540 generations (approximately 12,000 years) ago (95% CI 480-700). The conserved minimal haplotype is statistically more similar to Asian than European population DNA sets, suggesting that the A4V mutation arose in native Asian-Americans who reached the Americas through the Bering Strait. PMID:18055113

  3. Adsorption of human fibrinogen and albumin onto hydrophobic and hydrophilic Ti6Al4V powder

    NASA Astrophysics Data System (ADS)

    Rodríguez-Sánchez, Jesús; Gallardo-Moreno, Amparo M.; Bruque, José M.; González-Martín, M. Luisa

    2016-07-01

    Adsorption of proteins on solid surfaces has been widely studied because of its importance in various biotechnological, medical and technical applications, such as medical implants or biosensors. One of the main problems is the adsorption-induced conformational changes because they often modify the biological activity of the proteins, which is believed to be a key factor on the subsequent cellular adhesion. The aim of this work is the study of the adsorption of human fibrinogen (Fg) and human serum albumin (HSA) onto Ti6Al4V particles, commercially available on different size, that are used to elaborate scaffolds to provide structural support to cell proliferation, promoting tissue development and bone regeneration among others. The study was done through the analysis of the adsorption isotherms and the electrical characterization of surfaces after adsorption in terms of the zeta potential (ζ). From this analysis it seems that Fg adsorbs preferentially vertically oriented (end-on) and HSA moves sequentially over the surface of the Ti6Al4V particles through dimmer formation, allowing adsorption progress over this initial bilayer. The zeta potential values of both proteins remain constant when the monolayer is formed. The study also extends the analysis of both adsorption behaviour and ζ potential characterization factors to the influence of the substrate hydrophobicity as this property can be modified for the Ti6Al4V by irradiating it with ultraviolet light (UV-C) without changes on its chemical composition [1,2]. Differences at low protein concentrations were found for both isotherms and zeta-potential values.

  4. Mechanical evaluation of porous titanium (Ti6Al4V) structures with electron beam melting (EBM).

    PubMed

    Parthasarathy, Jayanthi; Starly, Binil; Raman, Shivakumar; Christensen, Andy

    2010-04-01

    Patient specific porous implants for the reconstruction of craniofacial defects have gained importance due to their better performance over their generic counterparts. The recent introduction of electron beam melting (EBM) for the processing of titanium has led to a one step fabrication of porous custom titanium implants with controlled porosity to meet the requirements of the anatomy and functions at the region of implantation. This paper discusses an image based micro-structural analysis and the mechanical characterization of porous Ti6Al4V structures fabricated using the EBM rapid manufacturing process. SEM studies have indicated the complete melting of the powder material with no evidence of poor inter-layer bonding. Micro-CT scan analysis of the samples indicate well formed titanium struts and fully interconnected pores with porosities varying from 49.75%-70.32%. Compression tests of the samples showed effective stiffness values ranging from 0.57(+/-0.05)-2.92(+/-0.17)GPa and compressive strength values of 7.28(+/-0.93)-163.02(+/-11.98)MPa. For nearly the same porosity values of 49.75% and 50.75%, with a variation in only the strut thickness in the sample sets, the compressive stiffness and strength decreased significantly from 2.92 GPa to 0.57 GPa (80.5% reduction) and 163.02 MPa to 7.28 MPa (93.54 % reduction) respectively. The grain density of the fabricated Ti6Al4V structures was found to be 4.423 g/cm(3) equivalent to that of dense Ti6Al4V parts fabricated using conventional methods. In conclusion, from a mechanical strength viewpoint, we have found that the porous structures produced by the electron beam melting process present a promising rapid manufacturing process for the direct fabrication of customized titanium implants for enabling personalized medicine. PMID:20142109

  5. Identification of CYP4V2 mutation in 36 Chinese families with Bietti crystalline corneoretinal dystrophy.

    PubMed

    Yin, Xiaobei; Yang, Liping; Chen, Ningning; Cui, Hui; Zhao, Lin; Feng, Lina; Li, Aijun; Zhang, Huirong; Ma, Zhizhong; Li, Genlin

    2016-05-01

    Bietti crystalline corneoretinal dystrophy (BCD) is an inherited eye disease that is most common in the Chinese. It is caused by a mutation in the CYP4V2 gene. In this study, 43 Chinese BCD families were recruited; most patients manifested the characteristic phenotype of BCD, with 2 families initially misdiagnosed with retinitis pigmentosa. Five patients in our cohort presented with BCD and choroidal neovascularization (CNV), and 1 patient presented with typical BCD and abnormality in the terminals of both fingers and toes. A total of 17 pathogenic mutations involving 68 alleles were identified from 36 families using targeted exon sequencing and Sanger sequencing; we achieved a diagnostic rate of approximately 84%. Fifteen families were found to carry homozygous mutations, 17 families carried compound heterozygous mutations, and 4 families carried a single heterozygous mutation. Of the mutations identified, four variants c.802-8_810del17bpinsGC, c.802-8_810del17bpinsGT, c.992A > C (p.H331P), and c.1091-2A > G accounted for 71% of the mutations identified in CYP4V2. These mutations were hotspots in Chinese populations for BCD. Five among them were novel and predicted to be disease-causing, including c.65T > A (p.L22H), c.681_4delTGAG (p.S227Rfs*1), c.802-8_810del17bpinsGT, c.965_7delAAG (p.321delE), and c.994G > A (p.D332N). No apparent correlation between genotype and phenotype was identified. Our findings broaden the spectrum of CYP4V2 mutations that cause BCD and the phenotypic spectrum of the disease in Chinese families. These results will be useful for the genetic diagnosis of BCD, genetic consultation, and gene therapy in the future. PMID:26971461

  6. Laser Surface Preparation for Adhesive Bonding of Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    Belcher, Marcus A.; List, Martina S.; Wohl, Christopher J.; Ghose, Sayata; Watson, Kent A.; Hopkins, John W.; Connell, John W.

    2010-01-01

    Adhesively bonded structures are potentially lighter in weight than mechanically fastened ones, but existing surface treatments are often considered unreliable. Two main problems in achieving reproducible and durable adhesive bonds are surface contamination and variability in standard surface preparation techniques. In this work three surface pretreatments were compared: laser etching with and without grit blasting and conventional Pasa-Jell treatment. Ti-6Al-4V surfaces were characterized by contact angle goniometry, optical microscopy, and X-ray photoelectron spectroscopy (XPS). Laser -etching was found to produce clean surfaces with precisely controlled surface topographies and PETI-5 lap shear strengths and durabilities were equivalent to those produced with Pasa-Jell.

  7. Overcharge Protection for 4 V Lithium Batteries at High Rates and Low Temperature

    SciTech Connect

    Chen, Guoying; Richardson, Thomas J.

    2010-01-04

    Overcharge protection for 4 V Li{sub 1.05}Mn{sub 1.95}O{sub 4}/lithium cells at charging rates in excess of 1 mA/cm{sup 2} (3C) and at temperatures as low as -20 C was achieved using a bilayer separator coated with two electroactive polymers. High rate and low temperature overcharge protection and discharge performance were improved by employing a design in which the polymer-coated portion of the separator is in parallel with the cell rather than between the electrodes. The effects of different membrane supports for the electroactive polymers are also examined.

  8. Optical Monitoring in Laser Cladding of Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Smurov, I.; Doubenskaia, M.; Grigoriev, S.; Nazarov, A.

    2012-12-01

    The TRUMPF 505 DMD machine with a 5-kW CO2 laser was used to enable scaling-up laser cladding (LC) to an industrial level. The aim of this study is to enhance product quality and to assure process stability and reproducibility by means of optical monitoring. Two originally developed pyrometers and an infrared camera FLIR Phoenix RDAS™ are employed in the LC of Ti6Al4V powder. The variations of brightness temperature versus laser power and cladding velocity are analyzed. A CCD camera-based diagnostic tool is applied for online monitoring of particle-in-flight velocity in coaxial powder injection.

  9. Microstructural Evolution of Ti-6Al-4V during High Strain Rate Conditions of Metal Cutting

    NASA Technical Reports Server (NTRS)

    Dong, Lei; Schneider, Judy

    2009-01-01

    The microstructural evolution following metal cutting was investigated within the metal chips of Ti-6Al-4V. Metal cutting was used to impose a high strain rate on the order of approx.10(exp 5)/s within the primary shear zone as the metal was removed from the workpiece. The initial microstructure of the parent material (PM) was composed of a bi-modal microstructure with coarse prior grains and equiaxed primary located at the boundaries. After metal cutting, the microstructure of the metal chips showed coarsening of the equiaxed primary grains and lamellar. These metallographic findings suggest that the metal chips experienced high temperatures which remained below the transus temperature.

  10. Laser surface micro-texturing of Ti 6Al 4V substrates for improved cell integration

    NASA Astrophysics Data System (ADS)

    Mirhosseini, N.; Crouse, P. L.; Schmidth, M. J. J.; Li, L.; Garrod, D.

    2007-07-01

    Biological behaviour of an implant, such as osseointegration, depends on both the chemical composition and the morphology of the surface of the implant. This paper reports the surface modification of Ti-6Al-4V - which is widely used in implantation - by Nd:YAG ( λ = 1064 nm, τ = 100 ns) laser irradiation in order to enhance biointegration. Surface parameters are evaluated in terms contact angle measurement and surface roughness. Biocompatibility of the samples is investigated in vitro by monitoring 2T3 osteoblast cell growth on the samples through MTT assay.

  11. Ti-6Al-4V electron beam weld qualification using laser scanning confocal microscopy

    SciTech Connect

    Wanjara, P. . E-mail: priti.wanjara@cnrc-nrc.gc.ca; Brochu, M.; Jahazi, M.

    2005-03-15

    Processing conditions for manufacturing Ti-6Al-4V components by welding using an electron beam source are known to influence the transformation microstructure in the narrow fusion and heat-affected zones of the weld region. This work examined the effect of multiple-sequence welding on the characteristics of the transformed beta microstructure, using laser scanning confocal microscopy to resolve the Widmanstaetten alpha-beta structure in the fusion zone. The evolution in the alpha interlamellar spacing and plate thickness with processing was then related to microhardness measurements in the weld region.

  12. The Development of Titanium Alloys for Application in the Space Shuttle Main Engine

    NASA Technical Reports Server (NTRS)

    Halchak, John A.; Jerman, Gregory A.; Zimmerman, Frank R.

    2010-01-01

    The high-strength-to-weight ratio of titanium alloys, particularly at cryogenic temperatures, make them attractive for application in rocket engines - offering the potential of superior performance while minimizing component weight. This was particularly attractive for rotating components, such as pump impellers, where titanium alloys presented the potential to achieve a major advance in rotational tip speed, with a reduction in stages and resultant saving in pump weight and complexity. The investigation into titanium alloys for application in cryogenic turbopumps began in the early 1960's. However, it was found that the reactivity of titanium limited applications and produced unique processing challenges. Specialized chemical compositions and processing techniques had to be developed. A substantial amount of material properties testing and trials in experimental turbopumps occurred, ultimately leading to application in the Space Shuttle Main Engine. One particular alloy stood out for use at liquid hydrogen temperatures, Ti-5Al-2.5Sn ELI. This alloy was employed for several critical components. This presentation deals with the development effort, the challenges that were encountered and operational experiences with Ti-5Al-2.5Sn ELI in the SSME.

  13. Electrochemical behavior of nano and femtosecond laser textured titanium alloy for implant surface modification.

    PubMed

    Jeong, Yong-Hoon; Kim, Won-Gi; Choe, Han-Cheol

    2011-02-01

    In this study, the electrochemical behavior of nano and femtosecond laser textured titanium alloy for implant surface modification has been researched using the potentiostat equipment. Cp-Ti and Ti-6Al-4V alloy, located on X-Y motorized stage, were irradiated using femtosecond laser. The corrosion properties were examined by a potentiodynamic and AC impedance test. PMID:21456241

  14. Examination of the distribution of the tensile deformation systems in tension and tension-creep of Ti-6Al-4V (wt.%) at 296 K and 728 K

    NASA Astrophysics Data System (ADS)

    Li, H.; Boehlert, C. J.; Bieler, T. R.; Crimp, M. A.

    2015-03-01

    The deformation behaviour of an α + β Ti-6Al-4V (wt.%) alloy was investigated during in situ deformation inside a scanning electron microscopy (SEM). Tensile experiments were performed at 296 and 728 K (~0.4Tm), while a tensile-creep experiment was performed at 728 K and 310 MPa (σ/σys = 0.74). The active deformation systems were identified using electron backscattered diffraction-based slip-trace analysis and SEM images of the specimen surface. The distribution of the active deformation systems varied as a function of temperature. Basal slip deformation played a major role in the tensile deformation behaviour, and the relative activity of basal slip increased with increasing temperature. For the 296 K tension deformation, basal slip was less active than prismatic slip, whereas this was reversed at 728 K. Twinning was observed in both the 296 and 728 K tension experiments; however, no more than 4% of the total deformation systems observed was twins. The tension-creep experiment revealed no slip traces, however grain boundary ledge formation was observed, suggesting that grain boundary sliding was an active deformation mechanism. The results of this work were compared with those from previous studies on commercially pure Ti, Ti-5Al-2.5Sn (wt.%) and Ti-8Al-1Mo-1V (wt.%), and the effects of alloying on the deformation behaviour are discussed. The relative amount of basal slip activity increased with increasing Al content.

  15. [Standardized testing of bone implant surfaces with an osteoblast cell culture cyste. III. PVD hard coatings and Ti6Al4V].

    PubMed

    Steinert, A; Hendrich, C; Merklein, F; Rader, C P; Schütze, N; Thull, R; Eulert, J

    2000-12-01

    The effect of titanium-based PVD coatings and a titanium alloy on the proliferation and differentiation of osteoblasts was investigated using a standardised cell culture system. Human fetal osteoblasts (hFOB 1.19) were cultured on titanium-niobium-nitride ([Ti,Nb]N), titanium-niobium-oxy-nitride coatings ([Ti,Nb]ON) and titanium-aluminium-vanadium alloy (Ti6Al4V) for 17 days. Cell culture polystyrene (PS) was used as reference. For the assessment of proliferation, the numbers and viability of the cells were determined, while alkaline phosphatase activity, collagen I and osteocalcin synthesis served as differentiation parameters. On the basis of the cell culture experiments, a cytotoxic effect of the materials can be excluded. In comparison with the other test surfaces, [Ti,Nb]N showed greater cell proliferation. The [Ti,Nb]N coating was associated with the highest level of osteocalcin production, while all other differentiation parameters were identical on all three surfaces. The test system described reveals the influence of PVD coatings on the osteoblast differentiation cycle. The higher oxygen content of the [Ti,Nb]ON surface does not appear to have any positive impact on cell proliferation. The excellent biocompatibility of the PVD coatings is confirmed by in vivo findings. The possible use of these materials in the fields of osteosynthesis and articular surfaces is still under discussion. PMID:11194641

  16. Evaluation of Interfacial Interactions Between Ti-6Al-4V and Mold Use Ti-Added Backup Coat in Investment Casting

    NASA Astrophysics Data System (ADS)

    Cheng, Xu; Chai, Lianjing; Wu, Guoqing; Wang, Hong; Nan, Hai

    2016-05-01

    In this article, the chemical inertness of shell using Ti-added mullite backup coat against molten Ti-6Al-4V (Ti64) alloy was investigated. The metal/shell interfacial microstructures and compositions were characterized using an optical microscope, scanning electron microscope, roughness tester, and X-ray diffractometer; the hardened layer thickness was evaluated using a microhardness tester. By adding titanium powder into the mullite backup coat, the alpha case and hardened layer thickness of the Ti64 castings were largely reduced with good surface finishing. Silicon ions, from the backup coat, penetrated into the alloy and coarsened the β lath at the metal/shell interfacial area. The Ti powder in the mullite backup coat oxidized and interacted with silica during mold firing and casting, which reduced the silicon and oxygen concentrations at the metal/shell interfacial area. The oxygen penetration depth is thicker than the alpha case layer thickness, and around 0.26 wt pct, oxygen can obviously coarsen the alpha lath at the metal/shell interfacial area during investment casting.

  17. Laser assisted fabrication of Co on Ti-6Al-4V for bio-implant application

    NASA Astrophysics Data System (ADS)

    Dutta Majumdar, J.; Ganesan, S. M.; Manna, I.; Nath, A. K.

    2006-07-01

    In the present study, attempts have been made to fabricate a Co layer on the surface of Ti-6Al-4V substrate by laser assisted fabrication technique with an objective to develop compositionally graded hip and femoral prostheses. Laser processing was carried out by melting of Co powder (of 25 m particle size) with a continuous wave CO2 laser and depositing it on Ti-6Al-4V substrate in a layer by layer fashion using Ar as shrouding environment to avoid oxidation. The process variables were applied power density, scan speed and number of layers. During the development of 1st layer, laser power and scan speeds were varied to develop a compositionally graded interface, following which the successive layers were formed. A detailed microstructural study of the fabricated layers was carried out to understand the influence of laser parameters on microstructure. X-ray diffraction study and energy dispersive spectroscopic analysis were undertaken to see if non-equilibrium cooling associated with the process has caused formation of any new phase or segregation of elements in the microstructure. Following characterization, the mechanical property (wear resistance) and electrochemical property of the fabricated components have been evaluated.

  18. Study of the dynamic Bauschinger effect in Ti6Al4V by torsion experiments

    NASA Astrophysics Data System (ADS)

    Peirs, J.; Verleysen, P.; Degrieck, J.

    2012-08-01

    The materials kinematic hardening behaviour and Bauschinger effect is indispensible to describe complex deformation processes involving strain path changes. Moreover, the Bauschinger effect provides valuable information about underlying microstructural plasticity mechanisms. Until now, the Bauschinger effect at high strain rates remains a largely unexplored topic. However, different studies demonstrated the strain rate dependent character of the Bauschinger effect. The aim of this work is to study the dynamic Bauschinger effect by means of a novel experimental technique. A modified torsional split Hopkinson bar setup is used to conduct Bauschinger experiments on Ti6Al4V. Forward and reverse loading of the specimen take place successively in only one experiment. This has the advantage of having the same thermal conditions during the two loading cycles. Besides high strain rate tests, quasi-static torsional Bauschinger experiments are conducted. The Bauschinger effect at the different strain rates is quantified with a dimensionless Bauschinger stress parameter. It is found that the Bauschinger effect is present at all tested strain rates. However, it is more pronounced at high strain rates. This implies that the kinematic hardening of Ti6Al4V is strain rate sensitive.

  19. Staphylococcus epidermidis adhesion on surface-treated open-cell Ti6Al4V foams.

    PubMed

    Türkan, Uğur; Güden, Mustafa; Sudağıdan, Mert

    2016-06-01

    The effect of alkali and nitric acid surface treatments on the adhesion of Staphylococcus epidermidis to the surface of 60% porous open-cell Ti6Al4V foam was investigated. The resultant surface roughness of foam particles was determined from the ground flat surfaces of thin foam specimens. Alkali treatment formed a porous, rough Na2Ti5O11 surface layer on Ti6Al4V particles, while nitric acid treatment increased the number of undulations on foam flat and particle surfaces, leading to the development of finer surface topographical features. Both surface treatments increased the nanometric-scale surface roughness of particles and the number of bacteria adhering to the surface, while the adhesion was found to be significantly higher in alkali-treated foam sample. The significant increase in the number of bacterial attachment on the alkali-treated sample was attributed to the formation of a highly porous and nanorough Na2Ti5O11 surface layer. PMID:26057214

  20. Effect of inflammatory conditions and H2O2 on bare and coated Ti-6Al-4V surfaces: Corrosion behavior, metal ion release and Ca-P formation under long-term immersion in DMEM

    NASA Astrophysics Data System (ADS)

    Höhn, Sarah; Virtanen, Sannakaisa

    2015-12-01

    The surface oxide film and calcium-phosphate (Ca-P) formation on Ti-6Al-4V during long-term immersion in biological environments play a decisive role for the biocompatibility of the implant. Hence, the aim of the study was to evaluate the corrosion resistance, metal ion release and Ca-P formation in DMEM under physiological conditions at pH values of 7.4 and in comparison under simulated inflammatory conditions with pH 5 and in presence of H2O2. Furthermore, the influence of the immersion conditions was investigated on different surface treatments: on bare Ti-6Al-4V, after anodization, and for TiO2 nanoparticle (NP) and hydroxyapatite (HA)-incorporated TiO2-NP coatings. In the absence of H2O2, the impedance response indicated a stable thin oxide film and Ca-P formation after 28 days or 56 days depending on the coating, while under inflammatory conditions the Ca-P formation on the surface is time-delayed and dissolution of the anodized oxide layer as well as selective etching of the β-phase and phase boundaries in case of the bare alloy occur. Electrochemical impedance spectroscopy (EIS), however, indicates a good general corrosion behavior in all cases. The quantities of Ti, Al and V released from the bare and coated Ti-6Al-4V alloy markedly increased with decreasing pH (pH ≤ 5). Although the rapid increase of metal release was observed for all samples at pH 5, the quantities were significantly higher for the bare and anodized alloy than after coating with TiO2-NP or HA.

  1. Regulating Direct-to-Consumer Drug Information: A Case Study of Eli Lilly's Canadian 40over40 Erectile Dysfunction Campaign.

    PubMed

    Pipon, Jean-Christophe Bélisle; Williams-Jones, Bryn

    2015-05-01

    Like most jurisdictions, Canada prohibits direct-to-consumer advertising (DTCA) of prescribed drugs. However, direct-to-consumer information (DTCI) is permitted, allowing companies to inform the public about medical conditions. An analysis of Eli Lilly's 40over40 promotion campaign for erectile dysfunction (ED), which included a quiz on ED, shows that DTCI, like DTCA, can be an effective means of drug familiarization. The pharmaceutical industry is "playing by the rules" currently in effect in Canada. Regulators should thus seriously consider whether existing rules permitting DTCI actually meet stated objectives of protecting the public from marketing campaigns (i.e., DTCA) that may deliver misleading information. PMID:26142356

  2. Front end for high-repetition rate thin disk-pumped OPCPA beamline at ELI-beamlines

    NASA Astrophysics Data System (ADS)

    Green, Jonathan T.; Novák, Jakub; Antipenkov, Roman; Batysta, František; Zervos, Charalampos; Naylon, Jack A.; Mazanec, TomáÅ.¡; Horáček, Martin; Bakule, Pavel; Rus, Bedřich

    2015-02-01

    The ELI-Beamlines facility, currently under construction in Prague, Czech Republic, will house multiple high power laser systems with varying pulse energies, pulse durations, and repetition rates. Here we present the status of a high repetition rate beamline currently under construction with target parameters of 20 fs pulse duration, 100 mJ pulse energy, and 1 kHz repetition rate. Specifically we present the Yb:YAG thin disk lasers which are intended to pump picosecond OPCPA, synchronization between pump and signal pulses in the OPCPA, and the first stages of OPCPA.

  3. The effect of weld porosity on the cryogenic fatigue strength of ELI grade Ti-5Al-2.5Sn

    NASA Technical Reports Server (NTRS)

    Rogers, P. R.; Lambdin, R. C.; Fox, D. E.

    1992-01-01

    The effect of weld porosity on the fatigue strength of ELI grade Ti-5Al-2.5Sn at cryogenic temperature was determined. A series of high cycle fatigue (HCF) and tensile tests were performed at -320 F on specimens made from welded sheets of the material. All specimens were tested with weld beads intact and some amount of weld offset. Specimens containing porosity and control specimens containing no porosity were tested. Results indicate that for the weld configuration tested, the fatigue life of the material is not affected by the presence of spherical embedded pores.

  4. Regulating Direct-to-Consumer Drug Information: A Case Study of Eli Lilly's Canadian 40over40 Erectile Dysfunction Campaign

    PubMed Central

    Williams-Jones, Bryn

    2015-01-01

    Like most jurisdictions, Canada prohibits direct-to-consumer advertising (DTCA) of prescribed drugs. However, direct-to-consumer information (DTCI) is permitted, allowing companies to inform the public about medical conditions. An analysis of Eli Lilly's 40over40 promotion campaign for erectile dysfunction (ED), which included a quiz on ED, shows that DTCI, like DTCA, can be an effective means of drug familiarization. The pharmaceutical industry is “playing by the rules” currently in effect in Canada. Regulators should thus seriously consider whether existing rules permitting DTCI actually meet stated objectives of protecting the public from marketing campaigns (i.e., DTCA) that may deliver misleading information. PMID:26142356

  5. Cryogenic acoustic loss of pure and alloyed titanium

    NASA Astrophysics Data System (ADS)

    Matacz, A. L.; Veitch, P. J.; Blair, D. G.

    Low acoustic loss, high yield strength cryogenic materials are required for various high precision experiments, resonant-bar gravitational radiation antennae in particular. We report here acoustic loss measurements of commerically pure and alloyed titanium samples between 4.2 and 300 K. It is shown that machining damage of the surface significantly increased the acoustic loss of pure titanium, particularly below 100 K, and that the high strength alloy Ti-6AI-4V had significantly greater acoustic loss than pure titanium.

  6. Microstructure Evolution During Friction Stir Processing and Hot Torsion Simulation of Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Lippold, John C.; Livingston, Jason J.

    2013-08-01

    Friction stir processing of three variants of Ti-6Al-4V was conducted at processing temperatures both above and below the β-transus. The base metal substrates that were processed included wrought base metal in the α/ β-processed and β-processed condition and weld overlay that was deposited using the gas tungsten arc welding process. Friction stir processing below the β-transus for the α/ β-processed condition and the weld overlay produced fully equiaxed- α grains with submicron grain size, while in the β-processed condition, elongated equiaxed- α grains and regions of transformed- β with grain size in the 1 to 2 μm range were observed. Friction stir processing above the β-transus was microstructurally evident by a stir zone composed of 10 to 40 μm recrystallized β-grains with either a basket weave or colony structure and a continuous network of α at the grain boundary. Path and normal forces were recorded for in situ processing of Ti-6Al-4V in all three initial conditions. Comparatively, above-transus processing reduced the path force at the tool-to-workpiece interface, while processing below the β-transus caused the path force to increase by ~300 pct. Based on the dimensionless heat input, it appears that the stir zone microstructure is more dependent on spindle speed (RPM) than travel speed and that the heat input parameter is not a good indicator of the processing temperature. Hot torsion testing of α/ β-processed Ti-6Al-4V was used as a method for physically simulating the stir zone microstructure produced from friction stir processing. At a strain rate of 2.5 s-1 (250 RPM rotation rate), the transition from equiaxed- α to a transformed beta microstructure occurred at approximately 1223 K (950 °C). A comparison of FSP and hot torsion microstructures revealed nearly identical matching depending on the selection of hot torsion conditions.

  7. C.T. Jackson's 15 October 1846 letter to J.-B.A.L. Elie de Beaumont: Jackson's thoughts on Ether Day's Eve?

    PubMed

    Bause, George S; Sim, Patrick P

    2011-01-01

    As did the previous letter on 30 November 1845 from Charles T. Jackson to J.-B.A.L. Elie de Beaumont, this 15 October 1846 missive underscores the cordial professional relationship between the two geologists. Remarkably, in this "Ether Day's Eve" letter, Jackson never reveals whether he had any clue that W.T.G. Morton would be publicly demonstrating ether anesthesia for surgery the next morning. More importantly, since Elie de Beaumont would play a future pivotal role in assigning initial credit for "discovering anesthesia" to his geological colleague Jackson, rather than to Morton, letters such as these from November of 1845 and October of 1846 can only raise more questions about the impartiality of Elie de Beaumont. PMID:22849206

  8. Nuclear Science and Applications with the Next Generation of High-Power Lasers and Brilliant Low-Energy Gamma Beams at ELI-NP

    NASA Astrophysics Data System (ADS)

    Gales, S.; ELI-NP Team

    2015-10-01

    The development of high power lasers and the combination of such novel devices with accelerator technology has enlarged the science reach of many research fields, in particular High Energy, Nuclear and Astrophysics as well as societal applications in Material Science, Nuclear Energy and Medicine. The European Strategic Forum for Research Infrastructures (ESFRI) has selected a proposal based on these new premises called "ELI" for Extreme Light Infrastructure. ELI will be built as a network of three complementary pillars at the frontier of laser technologies. The ELI-NP pillar (NP for Nuclear Physics) is under construction near Bucharest (Romania) and will develop a scientific program using two 10 PW class lasers and a Back Compton Scattering High Brilliance and Intense Low Energy Gamma Beam, a marriage of Laser and Accelerator technology at the frontier of knowledge. In the present paper, the technical and scientific status of the project as well as the applications of the gamma source will be discussed.

  9. Rapidly solidified titanium alloys by melt overflow

    NASA Technical Reports Server (NTRS)

    Gaspar, Thomas A.; Bruce, Thomas J., Jr.; Hackman, Lloyd E.; Brasmer, Susan E.; Dantzig, Jonathan A.; Baeslack, William A., III

    1989-01-01

    A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling.

  10. Rapidly solidified titanium alloys by melt overflow

    SciTech Connect

    Gaspar, T.A.; Bruce, T.J. Jr.; Hackman, L.E.; Brasmer, S.E.; Dantzig, J.A.; Baeslack, W.A. III.

    1989-09-01

    A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling.

  11. Cracking of Ti-6Al-4V in methanol solutions containing sulfates.

    NASA Technical Reports Server (NTRS)

    Haney, E. G.; Fugassi, P.

    1973-01-01

    Whether cracking of unnotched Ti-6Al-4V specimens occurs in methanol containing H2SO4, Li2SO4, or Fe2(SO4)3 is a function of the age of the solution and the concentration of the sulfate. With H2SO4 concentrations of 0.10 N to 0.25 N, the methanol solutions lose their ability to crack the specimens with time after mixing and prior to exposure. The aging time required to inhibit the cracking varies inversely with the water content of the solution. With larger quantities of H2SO4, 0.5 N and 1 N, no cracking is observed. Interpretations of Raman spectroscopic studies of the aging solution suggests that the nature of the O-H group may play a role in the crack initiation or inhibiting mechanism.

  12. Inverse Thermal Analysis of Ti-6Al-4V Deep-Penetration Welds Using Volumetric Constraints

    NASA Astrophysics Data System (ADS)

    Lambrakos, S. G.

    2014-11-01

    Case study inverse thermal analyses of Ti-6Al-4V deep-penetration welds are presented. These analyses employ a methodology that is in terms of numerical-analytical basis functions for inverse thermal analysis of steady state energy deposition in plate structures. The results of the case studies provide parametric representations of weld temperature histories that can be adopted as input data to various types of computational procedures, such as those for prediction of solid-state phase transformations. In addition, these temperature histories can be used to construct parametric-function representations for inverse thermal analysis of welds corresponding to other process parameters or welding processes whose process conditions are within similar regimes. The present study applies an inverse thermal analysis procedure that provides for the inclusion of volumetric constraint conditions whose two-dimensional projections are mappings onto transverse cross sections of experimentally measured solidification and transformation boundaries.

  13. Surface morphology of Ti-6Al-4V plate fabricated by vacuum selective laser melting

    NASA Astrophysics Data System (ADS)

    Sato, Y.; Tsukamoto, M.; Yamashita, Y.

    2015-06-01

    A plate made of Ti-6Al-4V (Ti64) was built by vacuum selective laser melting (SLM) at a pressure of 10-2 Pa. The vacuum SLM system employed a single-mode fiber laser and three-axis galvanic mirror in order to form 3D metallic structure. In order to investigate the surface morphology on the fabricated plates, Vickers microhardness and surface roughness R a were measured. From the results, the Vickers microhardness of the fabricated plates was recorded at 391 HV, higher than the typical 340 HV for a Ti64 plate. It was also determined that crystal orientation was evaluated with X-ray diffraction. From the results, the crystal orientation of powder is composed mainly of martensitic alpha. Diffraction peaks corresponding to β (110) were detected in vacuum SLM processed samples.

  14. Investigating the Effects of Pin Tool Design on Friction Stir Welded Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    Rubisoff, H. A.; Querin, J. A.; Schneider, Judy A.; Magee, D.

    2009-01-01

    Friction stir welding (FSWing), a solid state joining technique, uses a non-consumable rotating pin tool to thermomechanically join materials. Heating of the weldment caused by friction and deformation is a function of the interaction between the pin tool and the work piece. Therefore, the geometry of the pin tool is in part responsible for the resulting microstructure and mechanical properties. In this study microwave sintered tungsten carbide (WC) pin tools with tapers and flats were used to FSW Ti-6Al-4V. Transverse sections of welds were mechanically tested, and the microstructure was characterized using optical microscopy (OM) and scanning election microscopy (SEM). X-ray diffraction (XRD) and electron back-scatter diffraction (EBSD) were used to characterize the texture within the welds produced from the different pin tool designs.

  15. Fluorapatite-mullite glass sputter coated Ti6Al4V for biomedical applications.

    PubMed

    Bibby, J K; Bubb, N L; Wood, D J; Mummery, P M

    2005-05-01

    A number of bioactive ceramics have been researched since the development of Bioglass in the 1970's. Fluorapatite mullite has been developed from the dental glass-ceramics used for more general hard tissue replacement. Being brittle in nature, glass-ceramics are currently used mainly as coatings. This paper shows that fluorapatite glass LG112 can be used as a sputtered glass coating on roughened surfaces of Ti6Al4V for possible future use for medical implants. An AFM was used to measure the roughness of the surface before and after coating to determine the change in the topography due to the coating process as this greatly affects cell attachment. The sputter coating partially filled in the artificially roughened surface, changing the prepared topography. Osteoblasts have been successfully grown on the surface of these coatings, showing biocompatibility with bone tissue and therefore potential use in hard tissue repair. PMID:15875245

  16. Microstructure Evolution in Cut Metal Chips of Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    Dong, L.; Schneider, J. A.

    2008-01-01

    The microstructural evolution following metal cutting was investigated within metal chips of Ti-6Al-4V. Metal cutting was used to impose a high strain rate on the order of approx.10(exp 5)/s within the primary shear zone as the metal was removed from the workpiece. The initial microstructure of the parent material (PM) was composed of a bi-modal microstructure with coarse prior beta grains and equiaxed primary alpha located at the boundaries. After metal cutting, the microstructure of the metal chips showed coarsening of the equiaxed primary alpha grains and beta lamellar. These metallographic findings suggest that the metal chips experienced high temperatures which remained below the beta transus temperature.

  17. Investigation of Microstructural Uniformity During Isothermal Forging of Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Mirahmadi, S. Javid; Hamedi, Mohsen; Habibi Parsa, Mohammad

    2014-09-01

    The effect of strain on microstructural changes and the primary alpha (αP) volume fraction as well as the workability of Ti-6Al-4V are studied by isothermal compression of wedge-shaped specimens at the initial temperatures of 850, 900, and 950 °C and platen velocities of 2.5, 25, and 250 mm/min in combination with finite element method. The results show that higher platen velocity leads to a lesser αP volume fraction at all of the temperatures. Higher temperature reduces the αP volume fraction, but increases the impact of strain and platen velocity on the microstructure through the specimen. A more uniform distribution of the primary alpha volume fraction can be achieved by decreasing the initial temperature and/or platen velocity. All of the specimens were free from any defects and can withstand a compression with the normalized Cockcroft-Latham damage value of 0.61.

  18. Elastic properties of low density core (LDC) Ti-6Al-4V sandwich cores

    SciTech Connect

    Queheillalt, D.T.; Wadley, H.N.G.; Schwartz, D.S.

    1998-12-31

    Lightweight, structurally efficient low density core (LDC) sandwich structures can be produced by entrapping argon gas within a finely dispersed distribution of pores in a microstructure and using a high temperature anneal to cause pore growth by gas expansion. This results in a porous microstructure with a relative density as low as {approximately}0.70. Laser ultrasonic methods have been used to measure the longitudinal and shear wave velocities and hence the elastic properties of LDC Ti-6Al-4V cores prior to, and after gas expansion treatments of up to 48 hr at 920 C. The data were compared with several analytical models for predicting the volume fraction of porosity dependent elastic properties of porous materials.

  19. Investigation of Porosity Changes in Cast Ti6Al4V Rods After Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    du Plessis, Anton; Rossouw, Pierre

    2015-08-01

    The porosities of cast Ti6Al4V rods were investigated nondestructively using x-ray microcomputed tomography (microCT) before and after HIP. This allowed the visualization and quantification of porosity changes in the same samples, which indicate excellent pore closure for large pores. This is the first reported application of x-ray microCT for direct analysis of investment casting porosity before and after HIP. The method shows promise for further investigations using delayed HIP treatments or monitoring of pore closure at further varying HIP cycle settings. The nondestructive nature of the analysis has resulted in the interesting observation of small subsurface pores (<250 μm) unaffected by hot isostatic pressing in two of the samples.

  20. Microstructure of Interpass Rolled Wire + Arc Additive Manufacturing Ti-6Al-4V Components

    NASA Astrophysics Data System (ADS)

    Martina, Filomeno; Colegrove, Paul A.; Williams, Stewart W.; Meyer, Jonathan

    2015-12-01

    Mechanical property anisotropy is one of the issues that are limiting the industrial adoption of additive manufacturing (AM) Ti-6Al-4V components. To improve the deposits' microstructure, the effect of high-pressure interpass rolling was evaluated, and a flat and a profiled roller were compared. The microstructure was changed from large columnar prior β grains that traversed the component to equiaxed grains that were between 56 and 139 μm in size. The repetitive variation in Widmanstätten α lamellae size was retained; however, with rolling, the overall size was reduced. A "fundamental study" was used to gain insight into the microstructural changes that occurred due to the combination of deformation and deposition. High-pressure interpass rolling can overcome many of the shortcomings of AM, potentially aiding industrial implementation of the process.