Science.gov

Sample records for octonary alloys based

  1. SUPERCONDUCTING VANADIUM BASE ALLOY

    DOEpatents

    Cleary, H.J.

    1958-10-21

    A new vanadium-base alloy which possesses remarkable superconducting properties is presented. The alloy consists of approximately one atomic percent of palladium, the balance being vanadium. The alloy is stated to be useful in a cryotron in digital computer circuits.

  2. NICKEL-BASE ALLOY

    DOEpatents

    Inouye, H.; Manly, W.D.; Roche, T.K.

    1960-01-19

    A nickel-base alloy was developed which is particularly useful for the containment of molten fluoride salts in reactors. The alloy is resistant to both salt corrosion and oxidation and may be used at temperatures as high as 1800 deg F. Basically, the alloy consists of 15 to 22 wt.% molybdenum, a small amount of carbon, and 6 to 8 wt.% chromium, the balance being nickel. Up to 4 wt.% of tungsten, tantalum, vanadium, or niobium may be added to strengthen the alloy.

  3. TUNGSTEN BASE ALLOYS

    DOEpatents

    Schell, D.H.; Sheinberg, H.

    1959-12-15

    A high-density quaternary tungsten-base alloy having high mechanical strength and good machinability composed of about 2 wt.% Ni, 3 wt.% Cu, 5 wt.% Pb, and 90wt.% W is described. This alloy can be formed by the powder metallurgy technique of hot pressing in a graphite die without causing a reaction between charge and the die and without formation of a carbide case on the final compact, thereby enabling re-use of the graphite die. The alloy is formable at hot- pressing temperatures of from about 1200 to about 1350 deg C. In addition, there is little component shrinkage, thereby eliminating the necessity of subsequent extensive surface machining.

  4. Tissue Response to Base-Metal Dental Alloys.

    DTIC Science & Technology

    RESPONSE(BIOLOGY), *CASTING ALLOYS, *BASE METAL, * DENTAL PROSTHESES, TISSUES(BIOLOGY), COMPATIBILITY, NICKEL ALLOYS, BERYLLIUM, DENTISTRY, CANCER, HISTOLOGY, DENTAL IMPLANTOLOGY , COBALT ALLOYS, CHROMIUM ALLOYS.

  5. High strength forgeable tantalum base alloy

    NASA Technical Reports Server (NTRS)

    Buckman, R. W., Jr.

    1975-01-01

    Increasing tungsten content of tantalum base alloy to 12-15% level will improve high temperature creep properties of existing tantalum base alloys while retaining their excellent fabrication and welding characteristics.

  6. Cobalt-Base Alloy Gun Barrel Study

    DTIC Science & Technology

    2014-07-01

    Cobalt -Base Alloy Gun Barrel Study by William S. de Rosset and Jonathan S. Montgomery ARL-RP-0491 July 2014 A reprint...21005-5069 ARL-RP-0491 July 2014 Cobalt -Base Alloy Gun Barrel Study William S. de Rosset and Jonathan S. Montgomery Weapons and Materials...DATE (DD-MM-YYYY) July 2014 2. REPORT TYPE Reprint 3. DATES COVERED (From - To) October–November 2013 4. TITLE AND SUBTITLE Cobalt -Base Alloy

  7. Development of Lightweight Titanium Base Alloys

    DTIC Science & Technology

    1989-04-15

    program on Development of Lightweight Titanium Base Alloys was to develop new titanium alloys with 10% lower density, 50% higher elastic modulus, and...program. permitted the cvaluation of a low-dc-isity. dislicrsion-strengthcnicd 02 + y titanium aluminide , which has excellent high temperature strength...713e alloy has significantly higher strength than the titanium aluminides . The limited data for ’i-34AI-4Be show it to be very strong above 7(X)°C

  8. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    DOEpatents

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  9. Hot Corrosion of Cobalt-Base Alloys

    DTIC Science & Technology

    1975-06-01

    Cast Alloys : NASA VIA, B-1900, 713C and 738X", Report NASA TN D-7682, Lewis Research Center, Cleveland, Ohio, August 1974. 36. Giggins, C.S. and...resistance of cobalt-base and nickel-base alloys . The contract was accomplished under the technical direction of Dr. H. C. Graham of the Aerospace Research...Interpretation of Results 3. SODIUM SULFATE INDUCED HOT CORROSION OF Co-25Al AND Co-35Cr ALLOYS a. Introduction b. Experimental Co-25Al c. Experimental

  10. Transient oxidation of multiphase Ni-Cr base alloys

    SciTech Connect

    Baran, G.; Meraner, M.; Farrell, P.

    1988-06-01

    Four commercially available Ni-Cr-based alloys used with porcelain enamels were studied. Major alloying elements were Al, Be, Si, B, Nb, and Mo. All alloys were multiphase. During heat treatments simulating enameling conditions, phase changes occurred in most alloys and were detected using hardness testing, differential thermal analysis (DTA), and microscopy. Oxidation of these alloys at 1000/degrees/C for 10 min produced an oxide layer consisting principally of chromium oxide, but the oxide morphology varied with each alloy depending on the alloy microstructure. Controlling alloy microstructure while keeping the overall composition unchanged may be a means of preventing wrinkled poorly adherent scales from forming.

  11. Welding and brazing of nickel and nickel-base alloys

    NASA Technical Reports Server (NTRS)

    Mortland, J. E.; Evans, R. M.; Monroe, R. E.

    1972-01-01

    The joining of four types of nickel-base materials is described: (1) high-nickel, nonheat-treatable alloys, (2) solid-solution-hardening nickel-base alloys, (3) precipitation-hardening nickel-base alloys, and (4) dispersion-hardening nickel-base alloys. The high-nickel and solid-solution-hardening alloys are widely used in chemical containers and piping. These materials have excellent resistance to corrosion and oxidation, and retain useful strength at elevated temperatures. The precipitation-hardening alloys have good properties at elevated temperature. They are important in many aerospace applications. Dispersion-hardening nickel also is used for elevated-temperature service.

  12. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  13. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  14. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  15. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  16. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  17. Irradiation creep of vanadium-base alloys

    SciTech Connect

    Tsai, H.; Billone, M.C.; Strain, R.V.; Smith, D.L.; Matsui, H.

    1998-03-01

    A study of irradiation creep in vanadium-base alloys is underway with experiments in the Advanced Test Reactor (ATR) and the High Flux Isotope Reactor (HFIR) in the United States. Test specimens are thin-wall sealed tubes with internal pressure loading. The results from the initial ATR irradiation at low temperature (200--300 C) to a neutron damage level of 4.7 dpa show creep rates ranging from {approx}0 to 1.2 {times} 10{sup {minus}5}/dpa/MPa for a 500-kg heat of V-4Cr-4Ti alloy. These rates were generally lower than reported from a previous experiment in BR-10. Because both the attained neutron damage levels and the creep strains were low in the present study, however, these creep rates should be regarded as only preliminary. Substantially more testing is required before a data base on irradiation creep of vanadium alloys can be developed and used with confidence.

  18. Oxygen diffusion in vanadium-based alloys

    SciTech Connect

    de Avillez, R.R.

    1981-01-01

    The experimental study of transport and equilibrium properties of oxygen in vanadium-based alloys was made by EMF measurements on solid electrolytic cells over the temperature range of 873 to 1423/sup 0/K. The oxygen diffusion in vanadium was not significantly modified by small additions of Ti, Cr, Ni, Nb and Ta. The increase in the activation energy for oxygen diffusion in the V-based alloys containing Cr, Ni, Nb and Ta probably reflects the effect of these substitutional solutes on the activity coefficient of oxygen. The oxygen activity was increased by the addition of 1 at % of Cr, Ni and Nb, and decreased by the addition of Ti and Ta. However, the effects in the alloys containing Nb and Ta are very small.

  19. Rapid solidification of Nb-base alloys

    NASA Technical Reports Server (NTRS)

    Gokhale, A. B.; Javed, K. R.; Abbaschian, G. J.; Lewis, R. E.

    1988-01-01

    New Nb-base alloys are of interest for aerospace structural applications at high temperatures, viz, 800 to 1650 C. Fundamental information regarding the effects of rapid solidification in achieving greatly refined microstructures, extended solid solubility, suppression of embrittling equilibrium phases, and formation of new phases is desired in a number of Nb-X alloys. The microstructures and selected properties of Nb-Si and other Nb-base alloys are presented for materials both rapidly quenched from the equilibrium liquidus and rapidly solidified following deep supercooling. Electromagnetic levitation was used to achieve melting and supercooling in a containerless inert gas environment. A variety of solidification conditions were employed including splatting or drop casting of supercooled samples. The morphology and composition of phases formed are discussed in terms of both solidification history and bulk composition.

  20. Progress in ODS Alloys: A Synopsis of a 2010 Workshop on Fe- Based ODS Alloys

    SciTech Connect

    Kad, Bimal; Dryepondt, Sebastien N; Jones, Andy R.; Vito, Cedro III; Tatlock, Gordon J; Pint, Bruce A; Tortorelli, Peter F; Rawls, Patricia A.

    2012-01-01

    In Fall 2010, a workshop on the role and future of Fe-based Oxide Dispersion Strengthened (ODS) alloys gathered together ODS alloy suppliers, potential industrial end-users, and technical experts in relevant areas. Presentations and discussions focused on the current state of development of these alloys, their availability from commercial suppliers, past major evaluations of ODS alloy components in fossil and nuclear energy applications, and the technical and economic issues attendant to commercial use of ODS alloys. Significant progress has been achieved in joining ODS alloys, with creep resistant joints successfully made by inertia welding, friction stir welding and plasma-assisted pulse diffusion bonding, and in improving models for the prediction of lifetime components. New powder and alloy fabrication methods to lower cost or improve endproduct properties were also described. The final open discussion centered on challenges and pathways for further development and large-scale use of ODS alloys.

  1. THERMOSTATICS AND KINETICS OF TRANSFORMATIONS IN PU-BASED ALLOYS

    SciTech Connect

    Turchi, P; Kaufman, L; Liu, Z

    2006-06-30

    CALPHAD assessment of the thermodynamic properties of a series of Pu-based alloys is briefly presented together with some results on the kinetics of phase formation and transformations in Pu-Ga alloys.

  2. Vanadium-base alloys for fusion reactor applications

    SciTech Connect

    Smith, D.L.; Loomis, B.A.; Diercks, D.R.

    1984-10-01

    Vanadium-base alloys offer potentially significant advantages over other candidate alloys as a structural material for fusion reactor first wall/blanket applications. Although the data base is more limited than that for the other leading candidate structural materials, viz., austenitic and ferritic steels, vanadium-base alloys exhibit several properties that make them particularly attractive for the fusion reactor environment. This paper presents a review of the structural material requirements, a summary of the materials data base for selected vanadium-base alloys, and a comparison of projected performance characteristics compared to other candidate alloys. Also, critical research and development (R and D) needs are defined.

  3. Fabric cutting application of FeAl-based alloys

    SciTech Connect

    Sikka, V.K.; Blue, C.A.; Sklad, S.P.; Deevi, S.C.; Shih, H.R.

    1998-11-01

    Four intermetallic-based alloys were evaluated for cutting blade applications. These alloys included Fe{sub 3}Al-based (FAS-II and FA-129), FeAl-based (PM-60), and Ni{sub 3}Al-based (IC-50). These alloys were of interest because of their much higher work-hardening rates than the conventionally used carbon and stainless steels. The FeAl-based PM-60 alloy was of further interest because of its hardening possibility through retention of vacancies. The vacancy retention treatment is much simpler than the heat treatments used for hardening of steel blades. Blades of four intermetallic alloys and commercially used M2 tool steel blades were evaluated under identical conditions to cut two-ply heavy paper. Comparative results under identical conditions revealed that the FeAl-based alloy PM-60 outperformed the other intermetallic alloys and was equal to or somewhat better than the commercially used M2 tool steel.

  4. Characterization of two ceramic-base-metal alloys.

    PubMed

    Huget, E F; Vlica, J M; Wall, R M

    1978-12-01

    Compositions, microstructures, properties, and heat treatment characteristics of two ceramic-base-metal alloys were studied. The materials displayed significant compositional and structural differences. Both alloys were strengthened by precipitation hardening. Strength and rigidity of the nickel-chromium alloys suggest their potential usefulness in fixed prosthodontic procedures.

  5. DISPERSION STRENGTHENED NICKEL-BASE ALLOYS.

    DTIC Science & Technology

    The swaged cone of extruded Nichrome-thoria alloys prepared by the thermal decomposition of thorium nitrate onto alloy powder indicated descreased... swaging of these dispersion-strengthened Nichrome alloys was dependent on the presence of a mild steel jacket on the alloy rod as a result of the canned...extrusion practice. Efforts to cold swage the alloy materials without this jacket were unsuccessful. (Author)

  6. Grain Refinement of Permanent Mold Cast Copper Base Alloys

    SciTech Connect

    M.Sadayappan; J.P.Thomson; M.Elboujdaini; G.Ping Gu; M. Sahoo

    2005-04-01

    Grain refinement is a well established process for many cast and wrought alloys. The mechanical properties of various alloys could be enhanced by reducing the grain size. Refinement is also known to improve casting characteristics such as fluidity and hot tearing. Grain refinement of copper-base alloys is not widely used, especially in sand casting process. However, in permanent mold casting of copper alloys it is now common to use grain refinement to counteract the problem of severe hot tearing which also improves the pressure tightness of plumbing components. The mechanism of grain refinement in copper-base alloys is not well understood. The issues to be studied include the effect of minor alloy additions on the microstructure, their interaction with the grain refiner, effect of cooling rate, and loss of grain refinement (fading). In this investigation, efforts were made to explore and understand grain refinement of copper alloys, especially in permanent mold casting conditions.

  7. Cast Fe-base cylinder/regenerator housing alloy

    NASA Technical Reports Server (NTRS)

    Larson, F.; Kindlimann, L.

    1980-01-01

    The development of an iron-base alloy that can meet the requirements of automotive Stirling engine cylinders and regenerator housings is described. Alloy requirements are as follows: a cast alloy, stress for 5000-hr rupture life of 200 MPa (29 ksi) at 775 C (1427 F), oxidation/corrosion resistance comparable to that of N-155, compatibility with hydrogen, and an alloy cost less than or equal to that of 19-9DL. The preliminary screening and evaluation of ten alloys are described.

  8. Cast iron-base alloy for cylinder/regenerator housing

    NASA Technical Reports Server (NTRS)

    Witter, Stewart L.; Simmons, Harold E.; Woulds, Michael J.

    1985-01-01

    NASACC-1 is a castable iron-base alloy designed to replace the costly and strategic cobalt-base X-40 alloy used in the automotive Stirling engine cylinder/generator housing. Over 40 alloy compositions were evaluated using investment cast test bars for stress-rupture testing. Also, hydrogen compatibility and oxygen corrosion resistance tests were used to determine the optimal alloy. NASACC-1 alloy was characterized using elevated and room temperature tensile, creep-rupture, low cycle fatigue, heat capacity, specific heat, and thermal expansion testing. Furthermore, phase analysis was performed on samples with several heat treated conditions. The properties are very encouraging. NASACC-1 alloy shows stress-rupture and low cycle fatigue properties equivalent to X-40. The oxidation resistance surpassed the program goal while maintaining acceptable resistance to hydrogen exposure. The welding, brazing, and casting characteristics are excellent. Finally, the cost of NASACC-1 is significantly lower than that of X-40.

  9. The development of nontoxic Ag-based brazing alloys

    SciTech Connect

    Timmins, P.F. )

    1994-09-01

    An experimental investigation wad conducted to produce nontoxic, Cd-free brazing alloys that possessed similar melting ranges and mechanical properties to those alloys within the Ag-Cu-Zn-Cd system. The investigation consisted of phase equilibria, Zn equivalence, thermal analysis, extrusion, wire drawing and mechanical testing of alloys based in the Ag-Cu-Zn system. Thermal analysis of these new alloys yielded liquidus temperatures in the range 680 to 775 C (1256--1427 F) and solidus temperatures in the range 625 to 675 C (1157--1247 F). These values compared favorably to the Ag-Cu-Zn-Cd alloys, which have liquidus and solidus temperatures in the ranges of 640 to 710 C (1184--1310 F) and 610 to 620 C (1130--1148 F), respectively, for Ag contents in the 20 to 50 wt-% range. Tensile tests revealed the ultimate tensile strengths of the as-cast Ag-Cu-Zn-Sn alloys to be higher than the toxic Cd-containing alloys of higher Ag content and higher than the ternary Ag-Cu-Zn alloys. For example, the alloy at 35Ag-34Cu-30Zn-1Sn exhibited an as-cast tensile strength of 47.6 kg/mm[sup 2] (67.7 ksi) compared to the alloy at 50Ag-15Cu-16Zn-19Cd with an as-cast tensile strength of 45.7 kg/mm[sup 2] (65 ksi).

  10. On the cytocompatibility of biodegradable Fe-based alloys.

    PubMed

    Schinhammer, Michael; Gerber, Isabel; Hänzi, Anja C; Uggowitzer, Peter J

    2013-03-01

    Biodegradable iron-based alloys are potential candidates for application as temporary implant material. This study summarizes the design strategy applied in the development of biodegradable Fe-Mn-C-Pd alloys and describes the key factors which make them suitable for medical applications. The study's in vitro cytotoxicity tests using human umbilical vein endothelial cells revealed acceptable cytocompatibility based on the alloys' eluates. An analysis of the eluates revealed that Fe is predominantly bound in insoluble degradation products, whereas a considerable amount of Mn is in solution. The investigation's results are discussed using dose-response curves for the main alloying elements Fe and Mn. They show that it is mainly Mn which limits the cytocompatibility of the alloys. The study also supplies a summary of the alloying elements' influence on metabolic processes. The results and discussion presented are considered important and instructive for future alloy development. The Fe-based alloys developed show an advantageous combination of microstructural, mechanical and biological properties, which makes them interesting as degradable implant material.

  11. Tantalum modified ferritic iron base alloys

    NASA Technical Reports Server (NTRS)

    Oldrieve, R. E.; Blankenship, C. P. (Inventor)

    1977-01-01

    Strong ferritic alloys of the Fe-CR-Al type containing 0.4% to 2% tantalum were developed. These alloys have improved fabricability without sacrificing high temperature strength and oxidation resistance in the 800 C (1475 F) to 1040 C (1900 F) range.

  12. Octonary resistance states in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 multiferroic tunnel junctions

    DOE PAGES

    Yue -Wei Yin; Tao, Jing; Huang, Wei -Chuan; ...

    2015-10-06

    General drawbacks of current electronic/spintronic devices are high power consumption and low density storage. A multiferroic tunnel junction (MFTJ), employing a ferroelectric barrier layer sandwiched between two ferromagnetic layers, presents four resistance states in a single device and therefore provides an alternative way to achieve high density memories. Here, an MFTJ device with eight nonvolatile resistance states by further integrating the design of noncollinear magnetization alignments between the ferromagnetic layers is demonstrated. Through the angle-resolved tunneling magnetoresistance investigations on La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 junctions, it is found that, besides collinear parallel/antiparallel magnetic configurations, the MFTJ shows at least two other stable noncollinear (45°more » and 90°) magnetic configurations. As a result, combining the tunneling electroresistance effect caused by the ferroelectricity reversal of the BaTiO3 barrier, an octonary memory device is obtained, representing potential applications in high density nonvolatile storage in the future.« less

  13. Ab initio modeling of decomposition in iron based alloys

    NASA Astrophysics Data System (ADS)

    Gorbatov, O. I.; Gornostyrev, Yu. N.; Korzhavyi, P. A.; Ruban, A. V.

    2016-12-01

    This paper reviews recent progress in the field of ab initio based simulations of structure and properties of Fe-based alloys. We focus on thermodynamics of these alloys, their decomposition kinetics, and microstructure formation taking into account disorder of magnetic moments with temperature. We review modern theoretical tools which allow a consistent description of the electronic structure and energetics of random alloys with local magnetic moments that become totally or partially disordered when temperature increases. This approach gives a basis for an accurate finite-temperature description of alloys by calculating all the relevant contributions to the Gibbs energy from first-principles, including a configurational part as well as terms due to electronic, vibrational, and magnetic excitations. Applications of these theoretical approaches to the calculations of thermodynamics parameters at elevated temperatures (solution energies and effective interatomic interactions) are discussed including atomistic modeling of decomposition/clustering in Fe-based alloys. It provides a solid basis for understanding experimental data and for developing new steels for modern applications. The precipitation in Fe-Cu based alloys, the decomposition in Fe-Cr, and the short-range order formation in iron alloys with s-p elements are considered as examples.

  14. Cr{sub 2}Nb-based alloy development

    SciTech Connect

    Liu, C.T.; Tortorelli, P.F.; Horton, J.A.

    1996-08-01

    Alloys of Cr-Cr{sub 2}Nb with exceptionally high strength at 1200{degrees}C have been developed. However, these compositions suffer from limited ductility and toughness at room temperature. Despite improvements from processing modifications, as-fabricated defects still limit room temperature mechanical behavior. In contrast, an alloy system with only a small mismatch of the coefficients of thermal expansion of the two phases, Cr-Cr{sub 2}Zr, showed good fabricability. However, these alloys are weaker than Cr-Cr{sub 2}Nb compositions at high temperatures and have poor oxidation resistance. Silicide coatings can provide high-temperature oxidation and sulfidation protection of these alloys. Improvements in room temperature mechanical properties of Laves-phase-strengthened alloys will rely on further development based on increasing the ductility of the matrix phase by impurity control and compositional modifications.

  15. Evaluation of soldered connectors of two base metal ceramic alloys.

    PubMed

    Lima Verde, M A; Stein, R S

    1994-04-01

    Soldered connectors for two base metal ceramic alloys (nickel-chromium and cobalt-chromium) were compared by use of four different techniques: (1) infrared preceramic soldering, (2) gas and oxygen preceramic soldering, (3) porcelain furnace postsoldering under vacuum, and (4) porcelain furnace postsoldering without vacuum. A control group was established with solid cast specimens of each alloy. No statistically significant difference was noted between infrared and torch preceramic soldering techniques for either of the two alloys. However, the joints postsoldered under vacuum were significantly superior to postsoldered connectors without vacuum (p < 0.0001). No significant differences were observed among techniques 1, 2, and 3, although the three groups were substantially superior to technique 4 for both alloys (p = 0.05). The control group for both alloys was appreciably stronger than the soldered groups (p < 0.0001), and the nickel-chromium samples within the control group were significantly stronger than the Co-Cr samples.

  16. Rapidly Solidified Oxidation Resistant Niobium Base Alloys

    DTIC Science & Technology

    1992-03-01

    107 Figure 4.25 Graph showing the weight change / area versus time for Nb-Ti alioys, commercial Nb alloys and Rene ’ 41 during the 800’C...properties with better oxidation resistance than Nb alloys ............................. J09 Figure 4.29 Cross sectional optical micrographs of Rene ’ 41 ...186 Figure 5.58 Optical cross sectional micrographs of etched Rene ’ 41 after 760*C cyclic oxidation and hardness testing. A

  17. New Fe-Ni based metal-metalloid glassy alloys prepared by mechanical alloying and rapid solidification

    SciTech Connect

    Sunol, J.J.; Clavaguera-Mora, M.T.; Clavaguera, N.; Pradell, T.

    1997-12-31

    Mechanical alloying and rapid solidification are two important routes to obtain glassy alloys. New Fe-Ni based metal-metalloid (P-Si) alloys prepared by these two different processing routes were studied by differential scanning calorimetry and transmission Moessbauer spectroscopy. Mechanical alloyed samples were prepared with elemental precursors, and different nominal compositions. Rapidly solidified alloys were obtained by melt-spinning. The structural analyses show that, independent of the composition, the materials obtained by mechanical alloying are not completely disordered whereas fully amorphous alloys were obtained by rapid solidification. Consequently, the thermal stability of mechanically alloyed samples is lower than that of the analogous material prepared by rapid solidification. The P/Si ratio controls the magnetic interaction of the glassy ribbons obtained by rapid solidification. The experimental results are discussed in terms of the degree of amorphization and crystallization versus processing route and P/Si ratio content.

  18. Exploratory Investigation of Advanced-Temperature Nickel-Base Alloys

    NASA Technical Reports Server (NTRS)

    Freche, John C.; Waters, William J.

    1959-01-01

    An investigation was conducted to provide an advanced-temperature nickel-base alloy with properties suitable for aircraft turbine blades as well as for possible space vehicle applications. An entire series of alloys that do not require vacuum melting techniques and that generally provide good stress-rupture and impact properties was evolved. The basic-alloy composition of 79 percent nickel, 8 percent molybdenum, 6 percent chromium, 6 percent aluminum, and 1 percent zirconium was modified by a series of element additions such as carbon, titanium, and boron, with the nickel content adjusted to account for the additives. Stress-rupture, impact, and swage tests were made with all the alloys. The strongest composition (basic alloy plus 1.5 percent titanium plus 0.125 percent carbon) displayed 384- and 574-hour stress-rupture lives at 1800 F and 15,000 psi in the as-cast and homogenized conditions, respectively. All the alloys investigated demonstrated good impact resistance. Several could not be broken in a low-capacity Izod impact tester and, on this basis, all compared favorably with several high-strength high-temperature alloys. Swaging cracks were encountered with all the alloys. In several cases, however, these cracks were slight and could be detected only by zyglo examination. Some of these compositions may become amenable to hot working on further development. On the basis of the properties indicated, it appears that several of the alloys evolved, particularly the 1.5 percent titanium plus 0.125 percent carbon basic-alloy modification, could be used for advanced- temperature turbine blades, as well as for possible space vehicle applications.

  19. Corrosion evaluation of gold-based dental alloys.

    PubMed

    Corso, P P; German, R M; Simmons, H D

    1985-05-01

    Three commercial gold-based dental alloys and three constant-nobility ternary alloys (Au-Ag-Cu) were evaluated for corrosion using a quantitative test battery. Integration of the current density, in a de-aerated solution of 1% NaCl along the approximate potential range found in the mouth (-300 mV to +300 mV vs. SCE), yields a quantitative rank ordering of the test alloys. The results are combined with prior findings on other commercial alloys to demonstrate the interaction of nobility and microstructure. Nobility determines the overall corrosion resistance for gold-based alloys. However, because of mutual insolubility, alloying with copper induces silver segregation, resulting in a higher corrosion rate at a given nobility. Thus, microstructure has an influence on corrosion, but heat treatments are largely ineffective in altering the basic corrosion characteristics. The test techniques, in combination with tarnish evaluations, provide a quantitative battery for alloy evaluation. The results indicate the combinations of nobility, microstructure, and environment most likely to avoid corrosion difficulties.

  20. Microstructures and oxidation behavior of some Molybdenum based alloys

    SciTech Connect

    Ray, Pratik Kumar

    2011-01-01

    The advent of Ni based superalloys revolutionized the high temperature alloy industry. These materials are capable of operating in extremely harsh environments, comprising of temperatures around 1050 C, under oxidative conditions. Demands for increased fuel efficiency, however, has highlighted the need for materials that can be used under oxidative conditions at temperatures in excess of 1200 C. The Ni based superalloys are restricted to lower temperatures due to the presence of a number of low melting phases that melt in the 1250 - 1450 C, resulting in softening of the alloys above 1000 C. Therefore, recent research directions have been skewed towards exploring and developing newer alloy systems. This thesis comprises a part of such an effort. Techniques for rapid thermodynamic assessments were developed and applied to two different systems - Mo-Si alloys with transition metal substitutions (and this forms the first part of the thesis) and Ni-Al alloys with added components for providing high temperature strength and ductility. A hierarchical approach towards alloy design indicated the Mo-Ni-Al system as a prospective candidate for high temperature applications. Investigations on microstructures and oxidation behavior, under both isothermal and cyclic conditions, of these alloys constitute the second part of this thesis. It was seen that refractory metal systems show a marked microstructure dependence of oxidation.

  1. Cladding burst behavior of Fe-based alloys under LOCA

    DOE PAGES

    Terrani, Kurt A.; Dryepondt, Sebastien N.; Pint, Bruce A.; ...

    2015-12-17

    Burst behavior of austenitic and ferritic Fe-based alloy tubes has been examined under a simulated large break loss of coolant accident. Specifically, type 304 stainless steel (304SS) and oxidation resistant FeCrAl tubes were studied alongside Zircaloy-2 and Zircaloy-4 that are considered reference fuel cladding materials. Following the burst test, characterization of the cladding materials was carried out to gain insights regarding the integral burst behavior. Given the widespread availability of a comprehensive set of thermo-mechanical data at elevated temperatures for 304SS, a modeling framework was implemented to simulate the various processes that affect burst behavior in this Fe-based alloy. Themore » most important conclusion is that cladding ballooning due to creep is negligible for Fe-based alloys. Thus, unlike Zr-based alloys, cladding cross-sectional area remains largely unchanged up to the point of burst. Furthermore, for a given rod internal pressure, the temperature onset of burst in Fe-based alloys appears to be simply a function of the alloy's ultimate tensile strength, particularly at high rod internal pressures.« less

  2. Cladding burst behavior of Fe-based alloys under LOCA

    SciTech Connect

    Terrani, Kurt A.; Dryepondt, Sebastien N.; Pint, Bruce A.; Massey, Caleb P.

    2015-12-17

    Burst behavior of austenitic and ferritic Fe-based alloy tubes has been examined under a simulated large break loss of coolant accident. Specifically, type 304 stainless steel (304SS) and oxidation resistant FeCrAl tubes were studied alongside Zircaloy-2 and Zircaloy-4 that are considered reference fuel cladding materials. Following the burst test, characterization of the cladding materials was carried out to gain insights regarding the integral burst behavior. Given the widespread availability of a comprehensive set of thermo-mechanical data at elevated temperatures for 304SS, a modeling framework was implemented to simulate the various processes that affect burst behavior in this Fe-based alloy. The most important conclusion is that cladding ballooning due to creep is negligible for Fe-based alloys. Thus, unlike Zr-based alloys, cladding cross-sectional area remains largely unchanged up to the point of burst. Furthermore, for a given rod internal pressure, the temperature onset of burst in Fe-based alloys appears to be simply a function of the alloy's ultimate tensile strength, particularly at high rod internal pressures.

  3. METHOD FOR ANNEALING AND ROLLING ZIRCONIUM-BASE ALLOYS

    DOEpatents

    Picklesimer, M.L.

    1959-07-14

    A fabrication procedure is presented for alpha-stabilized zirconium-base alloys, and in particular Zircaloy-2. The alloy is initially worked at a temperature outside the alpha-plus-beta range (810 to 970 deg ), held at a temperature above 970 deg C for 30 minutes and cooled rapidly. The alloy is then cold-worked to reduce the size at least 20% and annealed at a temperature from 700 to 810 deg C. This procedure serves both to prevent the formation of stringers and to provide a randomly oriented crystal structure.

  4. Hydrogen transport in nickel-base alloys

    NASA Astrophysics Data System (ADS)

    Turnbull, A.; Ballinger, R. G.; Hwang, I. S.; Morra, M. M.; Psaila-Dombrowski, M.; Gates, R. M.

    1992-12-01

    The electrochemical permeation technique has been used to characterize hydrogen transport and trapping in pure nickel and in alloys 600, X-750, and 718 at a temperature of 80 °C. The “effective diffusivity ” of hydrogen atoms in alloy 600 is reduced by a factor of about 5 compared to pure nickel. This is attributed to both compositional changes and the presence of [(Ti, Nb)C] carbides. Aging of alloy 600, with subsequent M23C6 carbide precipitation, does not significantly influence the measured “effective diffusivity,” which is explained by the dominant effect of preexisting [(Ti, Nb)C] carbides. The “effective diffusivity” of hydrogen atoms in solution-annealed alloy X-750 is reduced by a factor of about 9 compared to that of pure nickel. This is also attributed to compositional changes and [(Ti,Nb)C] carbides. Aging of alloy X-750, which causes precipitation of γ'[Ni3(Al, Ti)], reduces the “effective diffusivity” by an additional factor of 5 or more. Double aging at 885 °C/24 hours, 704 °C/20 hours following hot working yields the greatest reduction in “effective diffusivity.” Analysis of permeation transients using a diffusion- trapping model indicates a binding energy associated with trapping due to the γ phase of be- tween -31 and -37 kJ/mol. The “effective diffusivity” of hydrogen in alloy 718 is about 40 pct greater than for alloy X-750 for the same double and direct aging treatments. The average “effective diffusivities” of the double-aged and direct-aged alloy 718 are comparable, but the permeation transients for the double-aged treatment are significantly steeper. The double-aged treatment with predominantly δ phase (orthorhombic Ni3Nb) yields a binding energy of about -30 kJ/mol. Analysis of the direct aged-treated 718, which contains predominantly γ″ phase (body-centered tetragonal Ni3Nb) gave a binding energy between -23 and -27 kJ/mol. Seg- regation of hydrogen atoms to the γ matrix interface, combined with a

  5. Amorphous phase formation in mechanically alloyed iron-based systems

    NASA Astrophysics Data System (ADS)

    Sharma, Satyajeet

    Bulk metallic glasses have interesting combination of physical, chemical, mechanical, and magnetic properties which make them attractive for a variety of applications. Consequently there has been a lot of interest in understanding the structure and properties of these materials. More varied applications can be sought if one understands the reasons for glass formation and the methods to control them. The glass-forming ability (GFA) of alloys can be substantially increased by a proper selection of alloying elements and the chemical composition of the alloy. High GFA will enable in obtaining large section thickness of amorphous alloys. Ability to produce glassy alloys in larger section thicknesses enables exploitation of these advanced materials for a variety of different applications. The technique of mechanical alloying (MA) is a powerful non-equilibrium processing technique and is known to produce glassy (or amorphous) alloys in several alloy systems. Metallic amorphous alloys have been produced by MA starting from either blended elemental metal powders or pre-alloyed powders. Subsequently, these amorphous alloy powders could be consolidated to full density in the temperature range between the glass transition and crystallization temperatures, where the amorphous phase has a very low viscosity. This Dissertation focuses on identifying the various Fe-based multicomponent alloy systems that can be amorphized using the MA technique, studying the GFA of alloys with emphasis on improving it, and also on analyzing the effect of extended milling time on the constitution of the amorphous alloy powder produced at earlier times. The Dissertation contains seven chapters, where the lead chapter deals with the background, history and introduction to bulk metallic glasses. The following four chapters are the published/to be published work, where the criterion for predicting glass formation, effect of Niobium addition on glass-forming ability (GFA), lattice contraction on

  6. Damping capacity of TiNi-based shape memory alloys

    NASA Astrophysics Data System (ADS)

    Rong, L. J.; Jiang, H. C.; Liu, S. W.; Zhao, X. Q.

    2007-07-01

    Damping capacity is another primary characteristic of shape memory alloys (SMA) besides shape memory effect and superelasticity. Damping behavior of Ti-riched TiNi SMA, porous TiNi SMA and a novel TiNi/AlSi composite have been investigated using dynamic mechanical analyzer (DMA) in this investigation. All these alloys are in martensitic state at room temperature and thus possess the high potential application value. Ti 50.2Ni 49.8 SMA has better damping capacity in pure martensitic state and phase transformation region due to the motion of martensite twin interface. As a kind of promising material for effective dampers and shock absorbing devices, porous TiNi SMA can exhibit higher damping capacity than the dense one due to the existence of the three-dimensioned connecting pore structure. It is found that the internal friction of porous TiNi SMA mainly originates from microplastic deformation and mobility of martensite interface and increases with the increase of the porosity. A novel TiNi/AlSi composite has been developed successfully by infiltrating AlSi alloy into the open pores of porous TiNi alloy with 60% porosity through compression casting. It shows the same phase transformation characteristics as the porous TiNi alloy. The damping capacity of the composite has been increased and the compressive strength has been also promoted remarkably. Suggestions for developing higher damping alloys based on TiNi shape memory alloy are proposed in this paper.

  7. Fe-based long range ordered alloys

    DOEpatents

    Liu, C.T.

    Malleable long range ordered alloys with high critical ordering temperatures exist in the V(Co,Fe)/sub 3/ and V(Co,Fe,Ni)/sub 3/ system. The composition comprising by weight 22 to 23% V, 35 to 50% Fe, 0 to 22% Co and 19 to 40% Ni with an electron density no greater than 8.00. Excellent high temperature properties occur in alloys having compositions comprising by weight 22 to 23% V, 35 to 45% Fe, 0 to 10% Co, 25 to 35% Ni; 22 to 23% V, 28 to 33% Ni and the remainder Fe; and 22 to 23% V, 19 to 22% Co and the remainder Fe. The alloys are fabricable by casting, deforming and annealing for sufficient time to provide ordered structure.

  8. Fe-based long range ordered alloys

    DOEpatents

    Liu, Chain T; Inouye, Henry; Schaffhauser, Anthony C.

    1980-01-01

    Malleable long range ordered alloys having high critical ordering temperatures exist in the V(Co,Fe).sub.3 and V(Co,Fe,Ni).sub.3 system having the composition comprising by weight 22-23% V, 35-50% Fe, 0-22% Co and 19-40% Ni with an electron density no greater than 8.00. Excellent high temperature properties occur in alloys having compositions comprising by weight 22-23% V, 35-45% Fe, 0-10% Co, 25-35% Ni; 22-23% V, 28-33% Ni and the remainder Fe; and 22-23% V, 19-22% Ni, 19-22% Co and the remainder Fe. The alloys are fabricable by casting, deforming and annealing for sufficient time to provide ordered structure.

  9. Directionally solidified iron-base eutectic alloys

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.

    1976-01-01

    Pseudobinary eutectic alloys with nominal compositions of Fe-25Ta-22Ni-10Cr and Fe-15.5Nb-14.5Ni-6.0Cr were directionally solidified at 0.5 centimeter per hour. Their microstructure consisted of the fcc, iron solid-solution, matrix phase reinforced by about 41-volume-percent, hcp, faceted Fe2Ta fibers and 41-volume-percent, hcp, Fe2Nb lamellae for the tantalum- and niobium-containing alloys, respectively. The microstructural stability under thermal cycling and the temperature dependence of tensile properties were investigated. These alloys showed low elevated-temperature strength and were not considered suitable for application in aircraft-gas-turbine blades although they may have applicability as vane materials.

  10. Fabrication of tungsten wire reinforced nickel-base alloy composites

    NASA Technical Reports Server (NTRS)

    Brentnall, W. D.; Toth, I. J.

    1974-01-01

    Fabrication methods for tungsten fiber reinforced nickel-base superalloy composites were investigated. Three matrix alloys in pre-alloyed powder or rolled sheet form were evaluated in terms of fabricability into composite monotape and multi-ply forms. The utility of monotapes for fabricating more complex shapes was demonstrated. Preliminary 1093C (2000F) stress rupture tests indicated that efficient utilization of fiber strength was achieved in composites fabricated by diffusion bonding processes. The fabrication of thermal fatigue specimens is also described.

  11. Improved Toughness Alloys Based on Titanium Aluminides

    DTIC Science & Technology

    1989-10-26

    2Sn-4Zr2Mo and creep rupture =to inconel 718). 6C AVIAGIE 20 -- ALLOYS Am VERAGE FOR to 400 O’)ALLOYS 20 x" T, 20kl- I Oft3V 1 46 T1. IF 110 kb 3V O0MQ...I~j 00 00 I 0 0 (A 30 ) C L 0 o ( 0(D D ( - r_ 00 . C-0. -n r- r- Cfr -H - CD 1- LO t Ne4) C) 00U’ L S..)~O 0c% 0~~ o~~r 𔃺 C,4 0 - - . o. I I - LAC. 0

  12. The development of lightweight hydride alloys based on magnesium

    SciTech Connect

    Guthrie, S.E.; Thomas, G.J.; Yang, N.Y.C.; Bauer, W.

    1996-02-01

    The development of a magnesium based hydride material is explored for use as a lightweight hydrogen storage medium. It is found that the vapor transport of magnesium during hydrogen uptake greatly influences the surface and hydride reactions in these alloys. This is exploited by purposely forming near-surface phases of Mg{sub 2}Ni on bulk Mg-Al-Zn alloys which result in improved hydrogen adsorption and desorption behavior. Conditions were found where these near-surface reactions yielded a complex and heterogeneous microstructure that coincided with excellent bulk hydride behavior. A Mg-Al alloy hydride is reported with near atmospheric plateau pressures at temperatures below 200{degrees}C. Additionally, a scheme is described for low temperature in-situ fabrication of Mg{sub 2}Ni single phase alloys utilizing the high vapor pressure of Mg.

  13. Salt Fog Testing Iron-Based Amorphous Alloys

    SciTech Connect

    Rebak, Raul B.; Aprigliano, Louis F.; Day, S. Daniel; Farmer, Joseph C.

    2007-07-01

    Iron-based amorphous alloys are hard and highly corrosion resistant, which make them desirable for salt water and other applications. These alloys can be produced as powder and can be deposited as coatings on any surface that needs to be protected from the environment. It was of interest to examine the behavior of these amorphous alloys in the standard salt-fog testing ASTM B 117. Three different amorphous coating compositions were deposited on 316L SS coupons and exposed for many cycles of the salt fog test. Other common engineering alloys such as 1018 carbon steel, 316L SS and Hastelloy C-22 were also tested together with the amorphous coatings. Results show that amorphous coatings are resistant to rusting in salt fog. Partial devitrification may be responsible for isolated rust spots in one of the coatings. (authors)

  14. Ductile superconducting copper-base alloys.

    PubMed

    Tsuei, C C

    1973-04-06

    A new class of ductile superconductors has been prepared by casting and appropriate heat treatments. These alloys superconduct between 4 degrees and 18 degrees K and contain at least 90 atom percent copper and a superconducting phase such as Nb(3)Sn or niobium. They can be processed into wires by conventional metallurgical techniques.

  15. The resistance of selected high strength alloys to embrittlement by a hydrogen environment. [iron and cobalt base alloys

    NASA Technical Reports Server (NTRS)

    Benson, R. B., Jr.

    1974-01-01

    Selected high strength iron base and cobalt base alloys were resistant to degradation of mechanical properties in a one atmosphere hydrogen environment at ambient temperature. These alloys were strengthened initially by cold working which produced strain induced martensite and fcc mechanical twins in an fcc matrix. Heat treatment of the cobalt base alloy after cold working produced carbide precipitates with retention of an hcp epsilon phase which increased the yield strength level. High strength alloys can be produced which have some resistance to degradation of mechanical properties by a hydrogen environment under certain conditions.

  16. Study on hemocompatibility and corrosion behavior of ion implanted TiNi shape memory alloy and Co-based alloys.

    PubMed

    Liang, Chenghao; Huang, Naibao

    2007-10-01

    Biomedical TiNi shape memory alloy and Co-based alloys were ion implanted, and corrosion resistance and hemocompatibility of these had been investigated with electrochemical method, dynamic clotting time, and hemolysis rate tests. The results indicated that the electrochemical stability and anodic polarization behavior of the materials were improved significantly after ion implantation. When TiNi, Co-based alloys were implanted Mo + C and Ti + C, respectively, the corrosion potentials were enhanced more than 200 mV, passive current densities decreased, and passive ranges were broadened. Dynamic clotting time of the ion implanted substances was prolonged and hemolysis rate decreased. All the results pointed out that corrosion resistance and hemocompatibility of the alloys were improved by ion implantation, and effects of dual implantation was better than that of C single implantation. X-ray diffraction analysis of the alloys after dual implantation revealed that TiC, Mo(2)C, Mo(9)Ti(4), and Mo appeared on the surface of TiNi alloy, and CoC(x), Co(3)Ti, TiC, and TiO on the surface of Co-based alloys. These phases dispersing on the alloy surface formed amorphous film, prevented dissolving of alloy elements and improved the corrosion resistance and hemocompatibility of the alloys.

  17. Iron and iron-based alloys for temporary cardiovascular applications.

    PubMed

    Francis, A; Yang, Y; Virtanen, S; Boccaccini, A R

    2015-03-01

    In the last decade, biodegradable metals have emerged as a topic of interest for particular biomedical applications which require high strength to bulk ratio, including for cardiovascular stents. The advantages of biodegradable materials are related to the reduction of long term risks associated with the presence of permanent metal implants, e.g. chronic inflammation and in-stent restenosis. From a structural point of view, the analysis of the literature reveals that iron-based alloys used as temporary biodegradable stents have several advantages over Mg-based alloys in terms of ductility and strength. Efforts on the modification and tunability of iron-based alloys design and compositions have been mainly focused on controlling the degradation rate while retaining the mechanical integrity within a reasonable period. The early pre-clinical results of many iron-based alloys seem promising for future implants developments. This review discusses the available literature focusing mainly on: (i) Fe and Fe-based alloys design and fabrication techniques; (ii) in vitro and in vivo performance; (iii) cytotoxicity and cell viability tests.

  18. Stress Corrosion Cracking and Oxidation Characteristics of Boride-Strengthend Microcrystalline Iron and Nickel Based Alloys.

    DTIC Science & Technology

    1984-10-22

    through subsequent thermomechanical treatments make this class of alloy attractive for many applications. One such relatively new class of alloys based...crystallizing it in the solid state) using controlled thermal or thermomechanical treatments. Preliminary evaluations of the Fe, Ni, and Co-based micrystalline...and iron in alloys 3 and 4). Each of the four microcrystalline alloys was processed in similar ways. Each alloy was induction melted and chill block

  19. DEVELOPMENT OF PROTECTIVE COATINGS FOR TANTALUM-BASE ALLOYS

    DTIC Science & Technology

    PHASE STUDIES, PHYSICAL PROPERTIES, REFRACTORY MATERIALS, SILICIDES , SILICON COATINGS , SILICON COMPOUNDS, TANTALUM, TENSILE PROPERTIES, TITANIUM COMPOUNDS, TUNGSTEN ALLOYS, VANADIUM ALLOYS, VAPOR PLATING, ZINC COATINGS ....TANTALUM ALLOYS, ALLOYS, ALUMINUM COATINGS , ALUMINUM COMPOUNDS, BORON COMPOUNDS, CERAMIC COATINGS , CHROMIUM COMPOUNDS, COATINGS , FLAME SPRAYING...HAFNIUM ALLOYS, HAFNIUM COMPOUNDS, HARDNESS, HEAT RESISTANT ALLOYS, INTERMETALLIC COMPOUNDS, METAMATHEMATICS, NIOBIUM ALLOYS, OSCILLOGRAPHS, OXIDES

  20. Durable pd-based alloy and hydrogen generation membrane thereof

    DOEpatents

    Benn, Raymond C.; Opalka, Susanne M.; Vanderspurt, Thomas Henry

    2010-02-02

    A durable Pd-based alloy is used for a H.sub.2-selective membrane in a hydrogen generator, as in the fuel processor of a fuel cell plant. The Pd-based alloy includes Cu as a binary element, and further includes "X", where "X" comprises at least one metal from group "M" that is BCC and acts to stabilize the .beta. BCC phase for stability during operating temperatures. The metal from group "M" is selected from the group consisting of Fe, Cr, Nb, Ta, V, Mo, and W, with Nb and Ta being most preferred. "X" may further comprise at least one metal from a group "N" that is non-BCC, preferably FCC, that enhances other properties of the membrane, such as ductility. The metal from group "N" is selected from the group consisting of Ag, Au, Re, Ru, Rh, Y, Ce, Ni, Ir, Pt, Co, La and In. The at. % of Pd in the binary Pd--Cu alloy ranges from about 35 at. % to about 55 at. %, and the at. % of "X" in the higher order alloy, based on said binary alloy, is in the range of about 1 at. % to about 15 at. %. The metals are selected according to a novel process.

  1. Several Issues in the Development of Ti-Nb-Based Shape Memory Alloys

    NASA Astrophysics Data System (ADS)

    Kim, Hee Young; Miyazaki, Shuichi

    2016-12-01

    Ni-free Ti-based shape memory alloys, particularly Ti-Nb-based alloys, have attracted increasing attraction since the early 2000s due to their wide application potentials in biomedical fields. Recently, there has been significant progress in understanding the martensitic transformation behavior of Ti-Nb-based alloys and many novel superelastic alloys have been developed. The superelastic properties of Ti-Nb-based alloys have been remarkably improved through the optimization of alloying elements and microstructure control. In this paper, in order to explore and establish the alloy design strategy, several important issues in the development of Ti-Nb-based shape memory alloys are reviewed. Particularly, the effects of alloying elements on the martensitic transformation temperature and the transformation strain are analyzed. The effects of omega phase and texture on the superelastic properties are also discussed.

  2. The effect of selected alloying element additions on properties of Mg-based alloy as bioimplants: A literature review

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Nan; Hou, Zeng-Tao; Ye, Xin; Xu, Zhao-Bin; Bai, Xue-Ling; Shang, Peng

    2013-09-01

    This review investigates the current application limitations of Mg and Mg alloys. The key issues hindering the application of biodegradable Mg alloys as implants are their fast degradation rate and biological consideration. We have discussed the effect of some selected alloying element additions on the properties of the Mg-based alloy, especially the nutrient elements in human (Zn, Mn, Ca, Sr). Different grain sizes, phase constituents and distributions consequently influence the mechanical properties of the Mg alloys. Solution strengthening and precipitation strengthening are enhanced by the addition of alloying elements, generally improving the mechanical properties. Besides, the hot working process can also improve the mechanical properties. Combination of different processing steps is suggested to be adopted in the fabrication of Mg-based alloys. Corrosion properties of these Mg-based alloys have been measured in vitro and in vivo. The degradation mechanism is also discussed in terms of corrosion types, rates, byproducts and response of the surrounding tissues. Moreover, the clinical response and requirements of degradable implants are presented, especially for the nutrient elements (Ca, Mn, Zn, Sr). This review provides information related to different Mg alloying elements and presents the promising candidates for an ideal implant.

  3. Recrystallization characteristics of oxide dispersion strengthened nickel-base alloys

    NASA Technical Reports Server (NTRS)

    Hotzler, R. K.; Glasgow, T. K.

    1980-01-01

    Electron microscopy was employed to study the process of recrystallization in two oxide dispersion strengthened (ODS) mechanically alloyed nickel-base alloys, MA 754 and MA 6000E. MA 754 contained both fine, uniformly dispersed particles and coarser oxides aligned along the working direction. Hot rolled MA 754 had a grain size of 0.5 microns and high dislocation densities. After partial primary recrystallization, the fine grains transformed to large elongated grains via secondary (or abnormal) grain growth. Extruded and rolled MA 6000E contained equiaxed grains of 0.2 micron diameter. Primary recrystallization occurring during working eliminated virtually all dislocations. Conversion from fine to coarse grains was triggered by gamma prime dissolution; this was also a process of secondary or abnormal grain growth. Comparisons were made to conventional and oxide dispersion strengthened nickel-base alloys.

  4. Cr{sub 2}Nb-based alloy development

    SciTech Connect

    Liu, C.T.; Tortorelli, P.F.; Horton, J.A.; Easton, D.S.; Heatherly, L.

    1996-06-01

    The objective of this work is to develop a new generation of structural materials based on intermetallic alloys for use at high temperatures in advanced fossil energy conversion systems. Target applications of such ultrahigh strength alloys include hot components (for example, air heat exchangers) in advanced energy conversion systems and heat engines. However, these materials may also find use as wear-resistant parts in coal handling systems (for example, nozzles), drill bits for oil/gas wells, and valve guides in diesel engines. One potential class of such alloys is that based on Cr-Cr{sub 2}Nb alloys. The intermetallic phase, Cr{sub 2}Nb, with a complex cubic structure (C-15) has been selected for initial development because of its high melting point (1770{degrees}C), relatively low material density (7.7 g/cm{sup 2}), and excellent high-temperature strength (at 1000 to 1250{degrees}C). This intermetallic phase, like many other Laves phases, has a wide range of compositional homogeneity suggesting the possibility of improving its mechanical and metallurgical properties by alloying additions.

  5. Melting and casting of FeAl-based cast alloy

    SciTech Connect

    Sikka, V.K.; Wilkening, D.; Liebetrau, J.; Mackey, B.

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  6. In vitro corrosion of dental Au-based casting alloys in polyvinylpyrrolidone-iodine solution.

    PubMed

    Takasusuki, Norio; Ida, Yusuke; Hirose, Yukito; Ochi, Morio; Endo, Kazuhiko

    2013-01-01

    The corrosion and tarnish behaviors of two Au-based casting alloys (ISO type 1 and type 4 Au alloys) and their constituent pure metals, Au, Ag, Cu, Pt, and Pd in a polyvinylpyrrolidone-iodine solution were examined. The two Au alloys actively corroded, and the main anodic reaction for both was dissolution of Au as AuI₂(-). The amount of Au released from the ISO type 1 Au alloy was significantly larger than that from the ISO type 4 Au alloy (P<0.05). Visible light spectrophotometry revealed that the type 1 alloy exhibited higher susceptibility to tarnishing than the type 4 alloy. The corrosion forms of the two Au alloys were found to be completely different, i.e., the type 1 alloy exhibited the corrosion attack over the entire exposed surface with a little irregularity whereas the type 4 alloy exhibited typical intergranular corrosion, which was caused by local cells produced by segregation of Pd and Pt.

  7. The Bain path of paramagnetic Fe-Cr based alloys

    NASA Astrophysics Data System (ADS)

    Al-Zoubi, N.; Johansson, B.; Nilson, G.; Vitos, L.

    2011-07-01

    Employing the first-principles exact muffin-tin orbital method in combination with the coherent potential approximation, we calculated the total energy and local magnetic moments of paramagnetic Fe-Cr-M (M = Cr, Mn, Fe, Co, Ni) alloys along the tetragonal distortion (Bain) path connecting the body centered cubic (bcc) and the face centered cubic (fcc) structures. The paramagnetic phase is modeled by the disordered local magnetic moment scheme. For all alloys, the local magnetic moments on Fe atoms decrease from the maximum value corresponding to the bcc phase toward the minimum value realized for the fcc phase. Cobalt atoms have non-vanishing local magnetic moments only for tetragonal lattices with c/a < 1.30, whereas the local magnetic moments of Mn show weak crystal structure dependence. We find that Cr stabilizes the bcc lattice and increases the energy barrier as going from the bcc toward the fcc phase. Both Co and Ni favor the fcc lattice and decrease the energy barrier relative to the bcc phase. On the other hand, the tetragonal distortion around the fcc phase is facilitated by Cr and to a somewhat lesser extent also by Ni, but strongly impeded by Co. Manganese has negligible effect on the structural energy difference as well as on the energy barrier along the Bain path. Our findings on the alloying induced softening or hardening of Fe-Cr based alloys against tetragonal distortions are important for understanding the interstitial driven martensitic transformations in alloy steels.

  8. Advanced nickel base alloys for high strength, corrosion applications

    DOEpatents

    Flinn, J.E.

    1998-11-03

    Improved nickel-base alloys of enhanced strength and corrosion resistance, produced by atomization of an alloy melt under an inert gas atmosphere and of composition 0--20Fe, 10--30Cr, 2--12Mo, 6 max. Nb, 0.05--3 V, 0.08 max. Mn, 0.5 max. Si, less than 0.01 each of Al and Ti, less than 0.05 each of P and S, 0.01--0.08C, less than 0.2N, 0.1 max. 0, bal. Ni. 3 figs.

  9. Advanced nickel base alloys for high strength, corrosion applications

    DOEpatents

    Flinn, John E.

    1998-01-01

    Improved nickel-base alloys of enhanced strength and corrosion resistance, produced by atomization of an alloy melt under an inert gas atmosphere and of composition 0-20Fe, 10-30Cr, 2-12Mo, 6 max. Nb, 0.05-3 V, 0.08 max. Mn, 0.5 max. Si, less than 0.01 each of Al and Ti, less than 0.05 each of P and S, 0.01-0.08C, less than 0.2N, 0.1 max. 0, bal. Ni.

  10. Hot corrosion of S-57, 1 cobalt-base alloy

    NASA Technical Reports Server (NTRS)

    Santoro, G. J.

    1977-01-01

    A cobalt base alloy, S-57, was hot corrosion tested in Mach 0.3 burner rig combustion gases at maximum alloy temperatures of 900 and 1000 C. Various salt concentrations were injected into the burner: 0.5, 2, 5, and 10 ppm synthetic sea salt and 4 ppm sodium sulfate (Na2SO4). S-57 underwent accelerated corrosion only under the most severe test conditions, for example, 4 ppm Na2SO4 at 900 C. The process of the accelerated corrosion was primarily sulfidation.

  11. Improved Mg-based alloys for hydrogen storage

    SciTech Connect

    Sapru, K.; Ming, L.; Stetson, N.T.; Evans, J.

    1998-08-01

    The overall objective of this on-going work is to develop low temperature alloys capable of reversibly storing at least 3 wt.% hydrogen, allowing greater than for 2 wt.% at the system level which is required by most applications. Surface modification of Mg can be used to improve its H-sorption kinetics. The authors show here that the same Mg-transition metal-based multi-component alloy when prepared by melt-spinning results in a more homogeneous materials with a higher plateau pressure as compared to preparing the material by mechanical grinding. They have also shown that mechanically alloyed Mg{sub 50}Al{sub 45}Zn{sub 5} results in a sample having a higher plateau pressure.

  12. Enhanced Corrosion Resistance of Iron-Based Amorphous Alloys

    SciTech Connect

    Rebak, R B; Day, S D; Lian, T; Aprigliano, L F; Hailey, P D; Farmer, J C

    2007-02-18

    Iron-based amorphous alloys possess enhanced hardness and are highly resistant to corrosion, which make them desirable for wear applications in corrosive environments. It was of interest to examine the behavior of amorphous alloys during anodic polarization in concentrated salt solutions and in the salt-fog testing. Results from the testing of one amorphous material (SAM2X5) both in ribbon form and as an applied coating are reported here. Cyclic polarization tests were performed on SAM2X5 ribbon as well as on other nuclear engineering materials. SAM2X5 showed the highest resistance to localized corrosion in 5 M CaCl{sub 2} solution at 105 C. Salt fog tests of 316L SS and Alloy 22 coupons coated with amorphous SAM2X5 powder showed resistance to rusting. Partial devitrification may be responsible for isolated pinpoint rust spots in some coatings.

  13. Nickel base alloy. [for gas turbine engine stator vanes

    NASA Technical Reports Server (NTRS)

    Freche, J. C.; Waters, W. J. (Inventor)

    1977-01-01

    A nickel base superalloy for use at temperatures of 2000 F (1095 C) to 2200 F (1205 C) was developed for use as stator vane material in advanced gas turbine engines. The alloy has a nominal composition in weight percent of 16 tungsten, 7 aluminum, 1 molybdenum, 2 columbium, 0.3 zirconium, 0.2 carbon and the balance nickel.

  14. Bulk amorphous steels based on Fe alloys

    DOEpatents

    Lu, ZhaoPing; Liu, Chain T.

    2006-05-30

    A bulk amorphous alloy has the approximate composition: Fe.sub.(100-a-b-c-d-e)Y.sub.aMn.sub.bT.sub.cM.sub.dX.sub.e wherein: T includes at least one of the group consisting of: Ni, Cu, Cr and Co; M includes at least one of the group consisting of W, Mo, Nb, Ta, Al and Ti; X includes at least one of the group consisting of Co, Ni and Cr; a is an atomic percentage, and a<5; b is an atomic percentage, and b.ltoreq.25; c is an atomic percentage, and c.ltoreq.25; d is an atomic percentage, and d.ltoreq.25; and e is an atomic percentage, and 5.ltoreq.e.ltoreq.30.

  15. NOREM wear-resistant, iron-based hard-facing alloys: Final report

    SciTech Connect

    Grobner, P.; Ohriner, E.K.; Wada, T.; Whelan, E.P.

    1989-07-01

    Wear-resistance cobalt-free hardfacing alloys are needed to replace the cobalt-base alloys used to hardface nuclear valves in order to reduce the exposure of maintenance personnel. Some thirty heats of cast iron-base alloys were prepared and characterized. Selected heats were prepared and applied as hardfacing overlays on austenitic steel substrates using both GTA and PTA welding processes. Some of the iron-base alloys exhibited galling wear resistance as high as that of cobalt-base standards both in the cast condition and in the PTA overlays. Hardness, mechanical properties, and galling wear resistance were determined on weld overlays and on cast alloys. Dilution and thermal expansivity were determined for weld overlays. X-ray diffraction and scanning electron microscopy were used to determine the alloys' microstructures. Other commercially available alloys were tested for galling wear resistance and compared to iron-base alloys. 7 refs., 2 figs., 2 tabs.

  16. Zirconium-based alloys, nuclear fuel rods and nuclear reactors including such alloys, and related methods

    DOEpatents

    Mariani, Robert Dominick

    2014-09-09

    Zirconium-based metal alloy compositions comprise zirconium, a first additive in which the permeability of hydrogen decreases with increasing temperatures at least over a temperature range extending from 350.degree. C. to 750.degree. C., and a second additive having a solubility in zirconium over the temperature range extending from 350.degree. C. to 750.degree. C. At least one of a solubility of the first additive in the second additive over the temperature range extending from 350.degree. C. to 750.degree. C. and a solubility of the second additive in the first additive over the temperature range extending from 350.degree. C. to 750.degree. C. is higher than the solubility of the second additive in zirconium over the temperature range extending from 350.degree. C. to 750.degree. C. Nuclear fuel rods include a cladding material comprising such metal alloy compositions, and nuclear reactors include such fuel rods. Methods are used to fabricate such zirconium-based metal alloy compositions.

  17. Electrochemical hydrogen storage alloys and batteries fabricated from Mg containing base alloys

    DOEpatents

    Ovshinsky, Stanford R.; Fetcenko, Michael A.

    1996-01-01

    An electrochemical hydrogen storage material comprising: (Base Alloy).sub.a M.sub.b where, Base Alloy is an alloy of Mg and Ni in a ratio of from about 1:2 to about 2:1, preferably 1:1; M represents at least one modifier element chosen from the group consisting of Co, Mn, Al, Fe, Cu, Mo, W, Cr, V, Ti, Zr, Sn, Th, Si, Zn, Li, Cd, Na, Pb, La, Mm, and Ca; b is greater than 0.5, preferably 2.5, atomic percent and less than 30 atomic percent; and a+b=100 atomic percent. Preferably, the at least one modifier is chosen from the group consisting of Co, Mn, Al, Fe, and Cu and the total mass of the at least one modifier element is less than 25 atomic percent of the final composition. Most preferably, the total mass of said at least one modifier element is less than 20 atomic percent of the final composition.

  18. Ni3Al-based alloys for die and tool application

    DOEpatents

    Liu, Chain T.; Bloom, Everett E.

    2001-01-01

    A novel Ni.sub.3 Al-based alloy exhibits strengths and hardness in excess of the standard base alloy IC-221M at temperatures of up to about 1000.degree. C. The alloy is useful in tool and die applications requiring such temperatures, and for structural elements in engineering systems exposed to such temperatures.

  19. Analysis of thermoelectric properties of high-temperature complex alloys of nickel-base, iron-base and cobalt-base groups

    NASA Technical Reports Server (NTRS)

    Holanda, R.

    1984-01-01

    The thermoelectric properties alloys of the nickel-base, iron-base, and cobalt-base groups containing from 1% to 25% 106 chromium were compared and correlated with the following material characteristics: atomic percent of the principle alloy constituent; ratio of concentration of two constituents; alloy physical property (electrical resistivity); alloy phase structure (percent precipitate or percent hardener content); alloy electronic structure (electron concentration). For solid-solution-type alloys the most consistent correlation was obtained with electron concentration, for precipitation-hardenable alloys of the nickel-base superalloy group, the thermoelectric potential correlated with hardener content in the alloy structure. For solid-solution-type alloys, no problems were found with thermoelectric stability to 1000; for precipitation-hardenable alloys, thermoelectric stability was dependent on phase stability. The effects of the compositional range of alloy constituents on temperature measurement uncertainty are discussed.

  20. Elevated temperature tribology of cobalt and tantalum-based alloys

    SciTech Connect

    Scharf, T. W.; Prasad, S. V.; Kotula, P. G.; Michael, J. R.; Robino, C. V.

    2014-12-31

    This paper describes the friction and wear behavior of a Co–Cr alloy sliding on a Ta–W alloy. Measurements were performed in a pin-on-flat configuration with a hemispherically tipped Co-base alloy pin sliding on a Ta–W alloy flat from ambient to 430°C. Focused ion beam-scanning electron microscopy (FIB-SEM) and cross-sectional transmission electron microscopy (TEM) were used to identify the friction-induced changes to the chemistry and crystal structure in the subsurface regions of wear tracks. During sliding contact, transfer of material varied as a function of the test temperature, either from pin-to-flat, flat-to-pin, or both, resulting in either wear loss and/or volume gain. Friction coefficients (μ) and wear rates also varied as a function of test temperature. The lowest friction coefficient (μ=0.25) and wear rate (1×10–4 mm3/N•m) were observed at 430°C in argon atmosphere. This was attributed to the formation of a Co-base metal oxide layer (glaze), predominantly (Co, Cr)O with Rocksalt crystal structure, on the pin surface. Part of this oxide film transferred to the wear track on Ta–W, providing a self-mated oxide-on-oxide contact. Once the oxide glaze is formed, it is able to provide friction reduction for the entire temperature range of this study, ambient to 430°C. Furthermore, the results of this study indicate that glazing the surfaces of Haynes alloys with continuous layers of cobalt chrome oxide prior to wear could protect the cladded surfaces from damage.

  1. Elevated temperature tribology of cobalt and tantalum-based alloys

    DOE PAGES

    Scharf, T. W.; Prasad, S. V.; Kotula, P. G.; ...

    2014-12-31

    This paper describes the friction and wear behavior of a Co–Cr alloy sliding on a Ta–W alloy. Measurements were performed in a pin-on-flat configuration with a hemispherically tipped Co-base alloy pin sliding on a Ta–W alloy flat from ambient to 430°C. Focused ion beam-scanning electron microscopy (FIB-SEM) and cross-sectional transmission electron microscopy (TEM) were used to identify the friction-induced changes to the chemistry and crystal structure in the subsurface regions of wear tracks. During sliding contact, transfer of material varied as a function of the test temperature, either from pin-to-flat, flat-to-pin, or both, resulting in either wear loss and/or volumemore » gain. Friction coefficients (μ) and wear rates also varied as a function of test temperature. The lowest friction coefficient (μ=0.25) and wear rate (1×10–4 mm3/N•m) were observed at 430°C in argon atmosphere. This was attributed to the formation of a Co-base metal oxide layer (glaze), predominantly (Co, Cr)O with Rocksalt crystal structure, on the pin surface. Part of this oxide film transferred to the wear track on Ta–W, providing a self-mated oxide-on-oxide contact. Once the oxide glaze is formed, it is able to provide friction reduction for the entire temperature range of this study, ambient to 430°C. Furthermore, the results of this study indicate that glazing the surfaces of Haynes alloys with continuous layers of cobalt chrome oxide prior to wear could protect the cladded surfaces from damage.« less

  2. Tungsten wire-nickel base alloy composite development

    NASA Technical Reports Server (NTRS)

    Brentnall, W. D.; Moracz, D. J.

    1976-01-01

    Further development and evaluation of refractory wire reinforced nickel-base alloy composites is described. Emphasis was placed on evaluating thermal fatigue resistance as a function of matrix alloy composition, fabrication variables and reinforcement level and distribution. Tests for up to 1,000 cycles were performed and the best system identified in this current work was 50v/o W/NiCrAlY. Improved resistance to thermal fatigue damage would be anticipated for specimens fabricated via optimized processing schedules. Other properties investigated included 1,093 C (2,000 F) stress rupture strength, impact resistance and static air oxidation. A composite consisting of 30v/o W-Hf-C alloy fibers in a NiCrAlY alloy matrix was shown to have a 100-hour stress rupture strength at 1,093 C (2,000 F) of 365 MN/square meters (53 ksi) or a specific strength advantage of about 3:1 over typical D.S. eutectics.

  3. Magnesium-based hydrogen storage materials modified by mechanical alloying

    SciTech Connect

    Cui, N.; He, P.; Luo, J.L.

    1999-10-26

    The effects of mechanical alloying on microstructure and electrochemical performance of a Mg-Ni-Y-Al hydrogen storage alloy in 6 M KOH solution were studied. The ball-milled powders were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected-area electron diffraction (SED) and energy dispersion spectrometry (EDS). TEM and EDS results clearly reveal that the smaller nickel clusters or particles were well dispersed on the surface of larger magnesium alloy particles by mechanical grinding for 72 h. With an increase in milling time to 240 h, the nickel clusters or particles disappeared and a new monophase alloy with amorphous structure was formed. The electrochemical capacity of the modified material significantly increased with increasing milling time within 72 h and then dropped to nearly nil when the milling time reached 240 h. The capacity decay, however, was always improved with increasing grinding time. Further analysis and discussion were made based on d.c. polarization and a.c. impedance spectroscopy measurement results.

  4. Microstructure Evolution of Gas Atomized Iron Based ODS Alloys

    SciTech Connect

    Rieken, J.R.; Anderson, I.E.; Kramer, M.J.; Anderegg, J.W.; Shechtman, D.

    2009-12-01

    In a simplified process to produce precursor powders for oxide dispersion-strength- ened (ODS) alloys, gas-atomization reaction synthesis (GARS) was used to induce a surface oxide layer on molten droplets of three differing erritic stainless steel alloys during break-up and rapid solidification. The chemistry of the surface oxide was identified using auger electron spectroscopy (AES) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The precursor iron-base powders were consolidated at 850 C and 1,300 C using hot isostatic pressing (HIPing). Consolidation at the lower temperature resulted in a fully dense microstructure, while preventing substantial prior particle-boundary-oxide dissociation. Microstructural analysis of the alloys consolidated at the higher temperature confirmed a significant reduction in prior-particle-boundary-oxide volume fraction, in comparison with the lower-temperature-consolidated sample. This provided evidence that a high-temperature internal oxygen-exchange reaction occurred between the metastable prior particle-boundary-oxide phase (chromium oxide) and the yttrium contained within each prior particle. This internal oxygen-exchange reaction is shown to result in the formation of yttrium-enriched oxide dispersoids throughout the alloy microstructure. The evolving microstructure was characterized using transmission electron microscopy (TEM) and high-energy X-ray diffraction (HE-XRD).

  5. Microstructure Evolution of Gas Atomized Iron Based ODS Alloys

    SciTech Connect

    Rieken, J.R.; Anderson, I.E.; Kramer, M.J.

    2011-08-09

    In a simplified process to produce precursor powders for oxide dispersion-strengthened (ODS) alloys, gas-atomization reaction synthesis (GARS) was used to induce a surface oxide layer on molten droplets of three differing erritic stainless steel alloys during break-up and rapid solidification. The chemistry of the surface oxide was identified using auger electron spectroscopy (AES) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The precursor iron-base powders were consolidated at 850 C and 1,300 C using hot isostatic pressing (HIPing). Consolidation at the lower temperature resulted in a fully dense microstructure, while preventing substantial prior particle-boundary-oxide dissociation. Microstructural analysis of the alloys consolidated at the higher temperature confirmed a significant reduction in prior-particle-boundary-oxide volume fraction, in comparison with the lower-temperature-consolidated sample. This provided evidence that a high-temperature internal oxygen-exchange reaction occurred between the metastable prior particle-boundary-oxide phase (chromium oxide) and the yttrium contained within each prior particle. This internal oxygen-exchange reaction is shown to result in the formation of yttrium-enriched oxide dispersoids throughout the alloy microstructure. The evolving microstructure was characterized using transmission electron microscopy (TEM) and high-energy X-ray diffraction (HE-XRD).

  6. Processing, properties, and applications of Ni{sub 3}Al-based alloys

    SciTech Connect

    Sikka, V.K.; Santella, M.L.; Liu, C.T.

    1997-06-01

    The Ni{sub 3}Al-based alloys represent a quantum jump in advanced alloys for structural applications at elevated temperatures. These alloys offer benefits of oxidation, carburization, and chlorination resistance, and significantly higher strength than many commercially used alloys. The commercial applications of the Ni{sub 3}Al-based alloys have begun to occur because of their comprehensive development This paper is to provide a review of. (1) alloy development, (2) melting, casting, and processing of alloys, (3) property data, (4) welding process and weldment properties, and (5) case histories of current applications. It is concluded that the cast alloy IC-221M is on its way to commercialization. 22 refs., 8 figs., 2 tabs.

  7. Dendritic growth and structure of undercooled nickel base alloys

    NASA Technical Reports Server (NTRS)

    Flemings, M. C.; Shiohara, Y.

    1988-01-01

    The principal objectives of this overall investigation are to: study means for obtaining high undercooling in levitation melted droplets, and study structures produced upon the solidification of these undercooled specimens. Thermal measurements are made of the undercooling, and of the rapid recalescence, to develop an understanding of the solidification mechanism. Comparison of results is made with the modeling studies. Characterization and metallographic work is done to gain an understanding of the relationship between rapid solidification variables and the structures so produced. In ground based work to date, solidification of undercooled Ni-25 wt percent Sn alloy was observed by high-speed cinematography and the results compared with optical temperature measurements. Also in ground based work, high-speed optical temperature measurements were made of the solidification behavior of levitated metal samples within a transparent glass medium. Two undercooled Ni-Sn alloys were examined. Measurements were carried out on samples at undercoolings up to 330 K. Microstructures of samples produced in ground based work were determined by optical metallography and by SEM, and microsegregation by electron microprobe measurements. A series of flight tests were planned to conduct experiments similar to the ground based experiments. The Space Shuttle Columbia carried an alloy undercooled experiment in the STS 61-C mission in January 1986. A sample of Ni-32.5 wt percent Sn eutectic was melted and solidified under microgravity conditions.

  8. Synthesis and characterization of nanostructured palladium-based alloy electrocatalysts

    NASA Astrophysics Data System (ADS)

    Sarkar, Arindam

    Low temperature fuel cells like proton exchange membrane fuel cells (PEMFC) are expected to play a crucial role in the future hydrogen economy, especially for transportation applications. These electrochemical devices offer significantly higher efficiency compared to conventional heat engines. However, use of exotic and expensive platinum as the electrocatalyst poses serious problems for commercial viability. In this regard, there is an urgent need to develop low-platinum or non-platinum electrocatalysts with electrocatalytic activity for the oxygen reduction reaction (ORR) superior or comparable to that of platinum. This dissertation first investigates non-platinum, palladium-based alloy electrocatalysts for ORR. Particularly, Pd-M (M = Mo and W) alloys are synthesized by a novel thermal decomposition of organo-metallic precursors. The carbon-supported Pd-M (M = Mo, W) electrocatalyts are then heat treated up to 900°C in H2 atmosphere and investigated for their phase behavior. Cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements reveal that the alloying of Pd with Mo or W significantly enhances the catalytic activity for ORR as well as the stability (durability) of the electrocatalysts. Additionally, both the alloy systems exhibit high tolerance to methanol, which is particularly advantageous for direct methanol fuel cells (DMFC). The dissertation then focuses on one-pot synthesis of carbon-supported multi-metallic Pt-Pd-Co nanoalloys by a rapid microwave-assisted solvothermal (MW-ST) method. The multi-metallic alloy compositions synthesized by the MW-ST method show much higher catalytic activity for ORR compared to their counterparts synthesized by the conventional borohydride reduction method. Additionally, a series of Pt encapsulated Pd-Co nanoparticle electrocatalysts are synthesized by the MW-ST method and characterized to understand their phase behavior, surface composition, and electrocatalytic activity for ORR. Finally, the dissertation

  9. Cr{sub 2}Nb-based alloy development

    SciTech Connect

    Liu, C.T.; Tortorelli, P.F.; Horton, J.A.

    1995-06-01

    The objective of this task is to develop a new generation of structural materials based on intermetallic alloys for use as critical hot components in advanced fossil energy conversion systems. The intermetallic phase, Cr{sub 2}Nb, with a complex cubic structure (C-15) has been selected for this development because of its high melting point (1770{degrees}C), relatively low material density (7.7 g/cm{sup 2}), excellent high-temperature strength (at 1000 to 1250{degrees}C), and potential resistance to oxidation and corrosion. This intermetallic phase, like many other Laves phases, has a wide range of compositional homogeneity suggesting the possibility of improving its mechanical and metallurgical properties by alloying additions. The major engineering concern with Cr{sub 2}Nb and other A{sub 2}B Laves phases is their poor fracture toughness and fracture resistance at ambient temperatures. The single-phase Cr{sub 2}Nb is very hard ({approximately}800 DPH) and brittle at room temperature. Because of this brittleness, the development effort has concentrated on two-phase structures containing the hard intermetallic phase Cr{sub 2}Nb and the softer Cr-rich solid solution phase. Potential applications of Cr-Cr{sub 2}Nb alloys include hot components (for example, air heat exchangers and turbine blades) in advanced energy conversion systems and heat engines, wear-resistant parts in coal handling systems (e.g., nozzles), drill bits for oil/gas wells, and valve guides in diesel engines. Current studies are focuses on enhancement of fracture resistance in tension at ambient temperatures and oxidation resistance above 1000{degrees}C. This report summarizes recent progress on controlling microstructure and improving the mechanical and metallurgical properties and the high-temperature corrosion behavior of Cr-Cr{sub 2}Nb alloys through alloying conditions, material processing, and heat treatment.

  10. Microscopic study of the structure of the Steel Ni-based Alloy: Hastelloy G35 Alloy

    NASA Astrophysics Data System (ADS)

    Sabir, F.; Ben Lenda, O.; Saissi, S.; Marbouh, K.; Tyouke, B.; Zerrouk, L.; Ibnlfassi, A.; Ouzaouit, K.; Elmadani, S.

    2017-03-01

    The study of the influence of heat treatment on changes of mechanical and structural properties of Steel Ni-based Alloy is a highly interdisciplinary topic at the interface of the physical chemistry of metallic materials, which also helps in environmental and economic protection.After heat treatment, the structural and micro-structural studies for the different transformation temperature led to identify phases formed and the morphology. This work has been carried out using different techniques: X-ray diffraction, optical microscopy and scanning electron microscopy.

  11. Investigation on the primary creep of a nickel based alloy. [Nimonic 75 type alloy

    SciTech Connect

    Kong, Q.P.; Wang, X. )

    1993-07-01

    It is widely accepted that dislocation climb is involved in the steady state (i.e. secondary) creep at high temperatures, which is characterized by the formation and evolution of substructures. In current theories of steady state creep, dislocation climb is regarded as the rate controlling process. However, the role of dislocation climb in the primary (i.e. transient) creep at high temperatures is not clear. The present paper is to report the observations by transmission electron microscopy (TEM) on high temperature creep of a nickel based alloy. It will be shown that dislocation climb plays an important role not only in the steady state creep, but also in the primary creep.

  12. Polarization-corrosion behavior of commercial gold- and silver-base casting alloys in Fusayama solution.

    PubMed

    Johnson, D L; Rinne, V W; Bleich, L L

    1983-12-01

    Based on polarization measurements, high Au alloys are highly corrosion-resistant and exhibit the lowest corrosion rates; intermediate Au, Ag, and Pd alloys with Cu are passive but exhibit higher corrosion rates. Twenty weight percent (w/o) In-Ag alloys exhibit active corrosion behavior at potentials only 100 mV noble to the corrosion potential.

  13. An investigation of the initiation stage of hot corrosion in Ni-base alloys

    NASA Technical Reports Server (NTRS)

    Huang, T. T.; Meier, G. H.

    1979-01-01

    The commercial nickel base alloy, IN-738, and high purity laboratory alloys were prepared to simulate the effects of the major elements in IN-738. Results indicate that the initiation of hot corrosion attack of IN-738 and other similar alloys is the result of local penetration of molten salt through the protective oxide scale.

  14. Method of polishing nickel-base alloys and stainless steels

    DOEpatents

    Steeves, Arthur F.; Buono, Donald P.

    1981-01-01

    A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels. The chemical attack polish comprises Fe(NO.sub.3).sub.3, concentrated CH.sub.3 COOH, concentrated H.sub.2 SO.sub.4 and H.sub.2 O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

  15. Attack polish for nickel-base alloys and stainless steels

    DOEpatents

    Steeves, Arthur F.; Buono, Donald P.

    1983-01-01

    A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels. The chemical attack polish comprises Fe(NO.sub.3).sub.3, concentrated CH.sub.3 COOH, concentrated H.sub.2 SO.sub.4 and H.sub.2 O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

  16. Attack polish for nickel-base alloys and stainless steels

    DOEpatents

    Not Available

    1980-05-28

    A chemical attack polish and polishing procedure for use on metal surfaces such as nickel base alloys and stainless steels is described. The chemical attack polich comprises FeNO/sub 3/, concentrated CH/sub 3/COOH, concentrated H/sub 2/SO/sub 4/ and H/sub 2/O. The polishing procedure includes saturating a polishing cloth with the chemical attack polish and submicron abrasive particles and buffing the metal surface.

  17. Iron-based alloys with corrosion resistance to oxygen-sulfur mixed gases

    DOEpatents

    Natesan, K.

    1992-11-17

    An iron-based alloy with improved performance with exposure to oxygen-sulfur mixed gases with the alloy containing about 9--30 wt. % Cr and a small amount of Nb and/or Zr implanted on the surface of the alloy to diffuse a depth into the surface portion, with the alloy exhibiting corrosion resistance to the corrosive gases without bulk addition of Nb and/or Zr and without heat treatment at temperatures of 1000--1100 C. 7 figs.

  18. Iron-based alloys with corrosion resistance to oxygen-sulfur mixed gases

    DOEpatents

    Natesan, Krishnamurti

    1992-01-01

    An iron-based alloy with improved performance with exposure to oxygen-sulfur mixed gases with the alloy containing about 9-30 wt. % Cr and a small amount of Nb and/or Zr implanted on the surface of the alloy to diffuse a depth into the surface portion, with the alloy exhibiting corrosion resistance to the corrosive gases without bulk addition of Nb and/or Zr and without heat treatment at temperatures of 1000.degree.-1100.degree. C.

  19. Resistance of a directionally solidified gamma/gamma prime-delta eutectic alloy to recrystallization. [Ni-base alloy

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Scheuermann, C. M.; Andrews, C. W.

    1976-01-01

    A lamellar nickel-base directionally-solidified eutectic gamma/gamma prime-delta alloy has potential as an advanced gas turbine blade material. The microstructural stability of this alloy was investigated. Specimens were plastically deformed by uniform compression or Brinell indentation, then annealed between 750 and 1120 C. Microstructural changes observed after annealing included gamma prime coarsening, pinch-off and spheroidization of delta lamellae, and appearance of an unidentified blocky phase in surface layers. All but the first of these was localized in severely deformed regions, suggesting that microstructural instability may not be a serious problem in the use of this alloy.

  20. Wear resistant zirconium base alloy article for water reactors

    SciTech Connect

    Gillett, J.E.; Shockling, L.A.; Sherwood, D.G.

    1988-03-01

    In a water reactor operating environment, the combination having improved fretting wear resistance is described comprising: an elongated tubular water displacer rod; having a low neutron absorption cross section guide support plates distributed along the length of the water displacer rod; the water displacer rod intersecting the guide support plates through apertures in the guide support plates; the water displacer rod having a plurality of spaced apart annular electrospark deposited coatings, each coating facing the wall of a respective aperture, the electrospark deposited coatings comprising Cr/sub 2/C/sub 3/; wherein the water displacer rod has a tube wall composed of a zirconium base alloy; and wherein the guide support plates are composed of a stainless steel alloy.

  1. DEVELOPMENT OF PROTECTIVE COATING FOR TANTALUM BASE ALLOYS.

    DTIC Science & Technology

    TANTALUM ALLOYS, PROTECTIVE TREATMENTS), (*REFRACTORY COATINGS , SILICIDES ), TUNGSTEN ALLOYS, OXIDATION, OXIDES, OXYGEN, DIFFUSION, HIGH TEMPERATURE...HAFNIUM COMPOUNDS, ZIRCONIUM COMPOUNDS, NIOBIUM ALLOYS, VANADIUM ALLOYS, THERMAL EXPANSION, THERMAL STRESSES, MICROSTRUCTURE, YTTRIUM COMPOUNDS...TANTALUM COMPOUNDS, ADDITIVES, ALUMINUM, BORON, CHROMIUM, MANGANESE, MOLYBDENUM, TITANIUM, TUNGSTEN, VANADIUM, NIOBIUM , SODIUM COMPOUNDS, FLUORIDES, SILICON

  2. Role of alloying elements in adhesive transfer and friction of copper-base alloys

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1978-01-01

    Sliding friction experiments were conducted in a vacuum with binary-copper alloy riders sliding against a conventional bearing-steel surface with normal residual oxides present. The binary alloys contained 1 atomic percent of various alloying elements. Auger spectroscopy analysis was used to monitor the adhesive transfer of the copper alloys to the bearing-steel surface. A relation was found to exist between adhesive transfer and the reaction potential and free energy of formation of the alloying element in the copper. The more chemically active the element and the more stable its oxide, the greater was the adhesive transfer and wear of the copper alloy. Transfer occurred in all the alloys except copper-gold after relatively few (25) passes across the steel surface.

  3. Alloys based on NiAl for high temperature applications

    NASA Technical Reports Server (NTRS)

    Vedula, K. M.; Pathare, V.; Aslanidis, I.; Titran, R. H.

    1984-01-01

    The NiAl alloys for potential high temperature applications were studied. Alloys were prepared by powder metallurgy techniques. Flow stress values at slow strain rates and high temperatures were measured. Some ternary alloying additions (Hf, Ta and Nb) were identified. The mechanism of strengthening in alloys containing these additions appears to be a form of particle dislocation interaction. The effects of grain size and stoichiometry in binary alloys are also presented.

  4. Pack cementation diffusion coatings for iron-base alloys

    SciTech Connect

    Rapp, R.A.

    1995-02-01

    With the aid of computer-assisted calculations of the equilibrium vapor pressures in halide-activated cementation packs, processing conditions have been identified and experimentally verified for the codeposition of two or more alloying elements in a diffusion coating on a variety of steels. The Cr-Si ferrite layers have proven to be very resistant to high temperature cyclic oxidation and to pitting in aqueous solutions. The process has been patented, and is being transferred for industrial application, e.g. for water walls of utility boilers, etc. In the proposed extension of this project, the use of mixed pure metal powders in the pack will be extended to achieve similar ferrite Fe-Cr-Al coatings with excellent oxidation resistance, with the eventual transfer of the technology to industry. In other recent studies, Ni-base alloy rods were aluminized by the halide-activated pack cementation process to bring their average composition to that for the ORNL-developed Ni{sub 3}Al, for use as a welding rod. A similar effort to develop a welding rod for the ORNL Fe{sub 3}Al alloy did not yield reproducible coating compositions or growth kinetics. The continued effort to produce Duriron-type (Fe-18Si-5Cr) coatings on steels was not successful. Literature for the intrinsic diffusion coefficients suggests that this task cannot be achieved.

  5. Compressive creep behavior of alloys based on B2 FeAl

    NASA Technical Reports Server (NTRS)

    Mantravadi, N.; Vedula, K.; Gaydosh, D.; Titran, R. H.

    1986-01-01

    Alloys based on FeAl are attractive alternate materials for environmental resistance at intermediate temperatures. Addition of small amounts of Nb, Hf, Ta, Mo, Zr, and B were shown to improve the compressive creep of this alloy at 1100 K. Boron, in particular, was found to have a synergistic effect along with Zr in providing properties substantially better than the binary alloy. This improvement seems to be related to the higher activation energy found for this alloy, suggesting a modification in the diffusion behavior due to the alloying additions.

  6. Thermogravimetric study of reduction of oxides present in oxidized nickel-base alloy powders

    NASA Technical Reports Server (NTRS)

    Herbell, T. P.

    1976-01-01

    Carbon, hydrogen, and hydrogen plus carbon reduction of three oxidized nickel-base alloy powders (a solid solution strengthened alloy both with and without the gamma prime formers aluminum and titanium and the solid solution strengthened alloy NiCrAlY) were evaluated by thermogravimetry. Hydrogen and hydrogen plus carbon were completely effective in reducing an alloy containing chromium, columbium, tantalum, molybdenum, and tungsten. However, with aluminum and titanium present the reduction was limited to a weight loss of about 81 percent. Carbon alone was not effective in reducing any of the alloys, and none of the reducing conditions were effective for use with NiCrAlY.

  7. Compressive creep behavior of alloys based on B2 FeAl

    NASA Technical Reports Server (NTRS)

    Mantravadi, N.; Vedula, K.; Gaydosh, D.; Titran, R. H.

    1987-01-01

    Alloys based on FeAl are attractive alternative materials for environmental resistance at intermediate temperatures. Addition of small amounts of Nb, Hf, Ta, Mo, Zr, and B were shown to improve the compressive creep of this alloy at 1100 K. Boron, in particular, was found to have a synergistic effect along with Zr in providing properties substantially better than the binary alloy. This improvement seems to be related to the higher activation energy found for this alloy, suggesting a modification in the diffusion behavior due to the alloying additions.

  8. On the corrosion behavior and biocompatibility of palladium-based dental alloys

    NASA Astrophysics Data System (ADS)

    Sun, Desheng

    Palladium-based alloys have been used as dental restorative materials for about two decades with good clinical history. But there have been clinical case reports showing possible allergy effects from these alloys. The aim of this study was to characterize the corrosion behavior and mechanisms of several palladium-based dental alloys by potentiodynamic polarization methods, electrochemical impedance spectroscopy (EIS), and scanning Kelvin probe force microscopy/atomic force microscopy (SKPFM/AFM), and to evaluate their biocompatibility by a cell culture technique and an animal model. Using SKPFM/AFM and scanning electron microscopy, the Ru-enriched phase from the use of ruthenium as a grain-refining element was identified as being slightly more noble than the palladium solid solution matrix in a high-palladium alloy. Other secondary precipitates that exist in the microstructures of these high-palladium alloys have minimal differences in Volta potential compared to the matrix. For high-palladium alloys, corrosion is generally uniform due to the predominant palladium content in the different phases. Potentiodynamic polarization and EIS have shown that representative palladium-silver alloys have low corrosion tendency and high corrosion resistance, which are equivalent to a well-known high-noble gold-palladium alloy in simulated body fluid and oral environments. The palladium-silver alloys tested are resistant to chloride ion corrosion. Passivation and dealloying have been identified for all of the tested palladium-silver alloys. The great similarity in corrosion behavior among the palladium-silver alloys is attributed to their similar chemical compositions. The variation in microstructures of palladium-silver alloys tested does not cause significant difference in corrosion behavior. The corrosion resistance of these palladium-silver alloys at elevated potentials relevant to oral environment is still satisfactory. The release of elements from representative dental

  9. Crystallization kinetics of Fe based amorphous alloy

    NASA Astrophysics Data System (ADS)

    Shanker Rao, T.; Lilly Shanker Rao, T.

    2015-02-01

    Differential Scanning Calorimetry(DSC) experimental data under non-isothermal conditions for Fe based Metglas 2605SA1 (wt% Fe=85-95, Si=5-10, B=1-5) metallic glass ribbons are reported and discussed. The DSC Scans performed at different heating rates showed two step crystallization processes and are interpreted in terms of different models like Kissinger, Ozawa, Boswell, Augis & Bennett and Gao & Wang. From the heating rate dependence of the onset temperature (To) and the crystallization peak temperature (Tp), the kinetic triplet, activation energy of crystallization (E), Avrami exponent (n) and the frequency factor (A) are determined. The determined E for peak I is 354.5 ± 2.5 kJ/mol and for the peak II is 348.2 ± 2.2 kJ/mol, respectively. The frequency factor for peak I is 1.1 × 1023sec-1 and for peak II is 6.1 × 1020sec-1.

  10. Rare-earth metals in nickel aluminide-based alloys: III. Structure and properties of multicomponent Ni3Al-based alloys

    NASA Astrophysics Data System (ADS)

    Bazyleva, O. A.; Povarova, K. B.; Kazanskaya, N. K.; Drozdov, A. A.

    2009-04-01

    The possibility of increasing the life of heterophase cast light Ni3Al-based superalloys at temperatures higher than 0.8 T m of Ni3Al is studied when their directional structure is additionally stabilized by nanoprecipitates, which form upon additional alloying of these alloys by refractory and active metals, and using special methods for preparing and melting of an alloy charge. The effect of the method of introducing the main components and refractory reaction-active and surface-active alloying elements into Ni3Al-based cast superalloys, which are thermally stable natural composite materials of the eutectic type, on the structure-phase state and the life of these alloys is studied. When these alloys are melted, it is necessary to perform a set of measures to form particles of refractory oxide cores covered with the β-NiAl phase and, then, γ'prim-Ni3Al phase precipitates during solidification. The latter phase forms the outer shell of grain nuclei, which provides high thermal stability and hot strength of an intermetallic compound-based alloy. As a result, a modified structure that is stabilized by the nanoprecipitates of nickel and aluminum lanthanides and the nanoprecipitates of phases containing refractory metals is formed. This structure enhances the life of the alloy at 1000 °C by a factor of 1.8-2.5.

  11. Energy Absorption of Polyurethane-Based Polymer Alloys.

    DTIC Science & Technology

    1986-01-31

    AD-fli64 537 ENERGY BSORPTION OF POLYURETHANE-BASED POLYMER ALLOYS i/i (U) DETROIT UN V MI POLYME INST S ONI ET AL. UNCLASSIFIED U R R-26 -SDR2...Preparation of Samples 1 1. IPN Elastomers 1 2. IPN Foams 2 C. Testing 2 1. Dynamic Mechanical Spectroscopy 2 2. Standing Wave Apparatus (Bruel & 3...conditioned at 250C and 50% relative humidity for at least three days prior to testing. C. Testing 1. Dynamic Mechanical Spectroscopy All dynamic

  12. HIP clad nickel base Alloy 625 for deep sour wells

    SciTech Connect

    Uhl, W.K.; Pendley, M.R.

    1984-05-01

    The hot isostatic pressing (HIP) process was used to clad nickel base Alloy 625 to AISI 4130 low alloy steel. The performance of the HIP clad material in the corrosive environment characteristic of deep, sour oil and gas wells was evaluated in laboratory tests. Included in the test program were NACE TM-01-77 sulfide stress cracking tests, chloride stress corrosion cracking tests in boiling MgCl /SUB 2'/ , and pitting and crevice corrosion tests. The HIP clad 625 performed excellently, displaying essentially the same corrosion resistance as wrought 625. Specifically the HIP clad 625 resisted sulfide stress cracking at applied stresses as high as 120% of yield strength and resisted chloride stress corrosion cracking at stresses exceeding 100% of yield. The HIP clad 625 also displayed immunity to pitting and crevice corrosion, with corrosion rates of <0.025 mm/y (1 mil/y). The 4130 base metal, however, was attacked severly in all tests. SEM/EDX analysis of the 625/4130 interface demonstrated that dilution of the cladding by the base metal was essentially eliminated.

  13. In vitro biocompatibility of novel Au-Pt-based metal-ceramic alloys.

    PubMed

    Johnson, Anthony; Shiraishi, Takanobu; Hurrell-Gillingham, Kathryn

    2011-09-01

    The aim of this research was to evaluate the effect of individual metallic elements within experimental Au-Pt-based metal-ceramic alloys on in vitro biocompatibility. A binary Au-10 at.% Pt alloy (AP10) was designed as a parent alloy. Six ternary AP10-X (X = In/Fe/Sn/Zn) alloys and four quaternary (AP10-In2)-Y (Y = Fe/Sn/Zn) with different compositions were cast into square plates with size 10X10X0.5 mm(3) and subjected to porcelain-firing thermal cycling. A commercial alloy was used as a control. In vitro biocompatibility was investigated using L929 murine aneuploid fibrosarcoma cell line. The test samples and cells were incubated at 37°C in a 5% CO(2) atmosphere for 72 h. Alamar™ Blue Assay was carried out to determine the respiratory viability of cultures maintained in the presence of the different materials. The cell only control showed significantly higher levels of cell viability than all six of the ternary alloys and two of the four quaternary alloys, (AP10-In2)-Zn2.1 and (AP10-In2)-Sn1.0 (P < 0.05). The quaternary alloys showed slightly higher levels of cell viability than the ternary alloys, with the exception of AP10-Sn0.9. No statistical differences were seen between the ternary and quaternary alloy groups. Acceptable cell viability was observed on the surfaces of all the alloys.

  14. Method for improve x-ray diffraction determinations of residual stress in nickel-base alloys

    DOEpatents

    Berman, Robert M.; Cohen, Isadore

    1990-01-01

    A process for improving the technique of measuring residual stress by x-ray diffraction in pieces of nickel-base alloys which comprises covering part of a predetermined area of the surface of a nickel-base alloy with a dispersion, exposing the covered and uncovered portions of the surface of the alloy to x-rays by way of an x-ray diffractometry apparatus, making x-ray diffraction determinations of the exposed surface, and measuring the residual stress in the alloy based on these determinations. The dispersion is opaque to x-rays and serves a dual purpose since it masks off unsatisfactory signals such that only a small portion of the surface is measured, and it supplies an internal standard by providing diffractogram peaks comparable to the peaks of the nickel alloy so that the alloy peaks can be very accurately located regardless of any sources of error external to the sample.

  15. Method for improving x-ray diffraction determinations of residual stress in nickel-base alloys

    DOEpatents

    Berman, R.M.; Cohen, I.

    1988-04-26

    A process for improving the technique of measuring residual stress by x-ray diffraction in pieces of nickel-base alloys is discussed. Part of a predetermined area of the surface of a nickel-base alloy is covered with a dispersion. This exposes the covered and uncovered portions of the surface of the alloy to x-rays by way of an x-ray diffractometry apparatus, making x-ray diffraction determinations of the exposed surface, and measuring the residual stress in the alloy based on these determinations. The dispersion is opaque to x-rays and serves a dual purpose, since it masks off unsatisfactory signals such that only a small portion of the surface is measured, and it supplies an internal standard by providing diffractogram peaks comparable to the peaks of the nickel alloy so that the alloy peaks can be very accurately located regardless of any sources of error external to the sample. 2 figs.

  16. MODELING OF NI-CR-MO BASED ALLOYS: PART II - KINETICS

    SciTech Connect

    Turchi, P A; Kaufman, L; Liu, Z

    2006-07-07

    The CALPHAD approach is applied to kinetic studies of phase transformations and aging of prototypes of Ni-Cr-Mo-based alloys selected for waste disposal canisters in the Yucca Mountain Project (YMP). Based on a previous study on alloy stability for several candidate alloys, the thermodynamic driving forces together with a newly developed mobility database have been used to analyze diffusion-controlled transformations in these Ni-based alloys. Results on precipitation of the Ni{sub 2}Cr-ordered phase in Ni-Cr and Ni-Cr-Mo alloys, and of the complex P- and {delta}-phases in a surrogate of Alloy 22 are presented, and the output from the modeling are compared with experimental data on aging.

  17. Effect of Alloy 625 Buffer Layer on Hardfacing of Modified 9Cr-1Mo Steel Using Nickel Base Hardfacing Alloy

    NASA Astrophysics Data System (ADS)

    Chakraborty, Gopa; Das, C. R.; Albert, S. K.; Bhaduri, A. K.; Murugesan, S.; Dasgupta, Arup

    2016-04-01

    Dashpot piston, made up of modified 9Cr-1Mo steel, is a part of diverse safety rod used for safe shutdown of a nuclear reactor. This component was hardfaced using nickel base AWS ER NiCr-B alloy and extensive cracking was experienced during direct deposition of this alloy on dashpot piston. Cracking reduced considerably and the component was successfully hardfaced by application of Inconel 625 as buffer layer prior to hardface deposition. Hence, a separate study was undertaken to investigate the role of buffer layer in reducing the cracking and on the microstructure of the hardfaced deposit. Results indicate that in the direct deposition of hardfacing alloy on modified 9Cr-1Mo steel, both heat-affected zone (HAZ) formed and the deposit layer are hard making the thickness of the hard layer formed equal to combined thickness of both HAZ and deposit. This hard layer is unable to absorb thermal stresses resulting in the cracking of the deposit. By providing a buffer layer of Alloy 625 followed by a post-weld heat treatment, HAZ formed in the modified 9Cr-1Mo steel is effectively tempered, and HAZ formed during the subsequent deposition of the hardfacing alloy over the Alloy 625 buffer layer is almost completely confined to Alloy 625, which does not harden. This reduces the cracking susceptibility of the deposit. Further, unlike in the case of direct deposition on modified 9Cr-1Mo steel, dilution of the deposit by Ni-base buffer layer does not alter the hardness of the deposit and desired hardness on the deposit surface could be achieved even with lower thickness of the deposit. This gives an option for reducing the recommended thickness of the deposit, which can also reduce the risk of cracking.

  18. Effect of different alloyed layers on the high temperature oxidation behavior of newly developed Ti 2AlNb-based alloys

    NASA Astrophysics Data System (ADS)

    Wu, Hongyan; Zhang, Pingze; Zhao, Haofeng; Wang, Ling; Xie, Aigen

    2011-01-01

    The application of titanium aluminide orthorhombic alloys (O-phase alloys) as potential materials in aircraft and jet engines was limited by their poor oxidation resistance at high temperature. The Ti 2AlNb-based alloys were chromised (Cr), chromium-tungstened (Cr-W) and nickel-chromised (Ni-Cr) by the double glow plasma surface alloying process to improve their high temperature oxidation resistance. The discontinuous oxidative behavior of Cr, Cr-W and Ni-Cr alloyed layers on Ti 2AlNb-based alloy at 1093 K was explored in this study. After exposing at 1093 K, the TiO 2 layer was formed on the bare alloy and accompanied by the occurrence of crack, which promoted oxidation rate. The oxidation behavior of Ti 2AlNb-based alloys was improved by surface alloying due to the formation of protective Al 2O 3 scale or continuous and dense NiCr 2O 4 film. The Ni-Cr alloyed layer presented the best high-temperature oxidation resistance among three alloyed layers.

  19. Method for producing La/Ce/MM/Y base alloys, resulting alloys and battery electrodes

    SciTech Connect

    Gschneidner, Jr., Karl A.; Schmidt, Frederick A.

    2016-12-20

    A carbothermic reduction method is provided for reducing a La-, Ce-, MM-, and/or Y-containing oxide in the presence of carbon and a source of a reactant element comprising Si, Ge, Sn, Pb, As, Sb, Bi, and/or P to form an intermediate alloy material including a majority of La, Ce, MM, and/or Y and a minor amount of the reactant element. The intermediate material is useful as a master alloy for in making negative electrode materials for a metal hydride battery, as hydrogen storage alloys, as master alloy additive for addition to a melt of commercial Mg and Al alloys, steels, cast irons, and superalloys; or in reducing Sm.sub.2O.sub.3 to Sm metal for use in Sm--Co permanent magnets.

  20. Near-Threshold Fatigue Crack Growth Behavior of Fine-Grain Nickel-Based Alloys

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Piascik, Robert S.

    2003-01-01

    Constant-Kmax fatigue crack growth tests were performed on two finegrain nickel-base alloys Inconel 718 (DA) and Ren 95 to determine if these alloys exhibit near-threshold time-dependent crack growth behavior observed for fine-grain aluminum alloys in room-temperature laboratory air. Test results showed that increases in K(sub max) values resulted in increased crack growth rates, but no evidence of time-dependent crack growth was observed for either nickel-base alloy at room temperature.

  1. Environmental Effects in Niobium Base Alloys and Other Selected Intermetallic Compounds

    DTIC Science & Technology

    1991-04-30

    anions as well as being highly stable. Thus the addition of Al to Ni, as in the case of aluminide coatings on nickel-base alloys , or Si to Mo, as in...For example, Ni-Al alloys form protective alumina scales more readily at high temperatures whereas y-TiAl forms alumina scales at low temperatures in... coatings on Ni-base alloys (1’, Fe-silicides €9), and Ni-silicides(" ) indicate similar behavior to that described above. 8 EFFECTS OF ALLOYING ELEMENTS

  2. Co-based alloys design based on first-principles calculations: Influence of transition metal and rare-earth alloying element on stacking fault energy

    NASA Astrophysics Data System (ADS)

    Achmad, Tria Laksana; Fu, Wenxiang; Chen, Hao; Zhang, Chi; Yang, Zhi-Gang

    2017-01-01

    The main idea of alloy design is to reduce costs and time required by the traditional (trial and error) method, then finding a new way to develop the efficiency of the alloy design is necessary. In this study, we proposed a new approach to the design of Co-based alloys. It is based on the concept that lowering the ratio of stable and unstable stacking fault energy (SFE) could bring a significant increase in the tendency of partial dislocation accumulation and FCC to HCP phase transformation then enhance mechanical properties. Through the advance development of the computing techniques, first-principles density-functional-theory (DFT) calculations are capable of providing highly accurate structural modeling at the atomic scale without any experimental data. The first-principles calculated results show that the addition of some transition metal (Cr, Mo, W, Re, Os, Ir) and rare-earth (Sc, Y, La, Sm) alloying elements would decrease both stable and unstable SFE of pure Co. The dominant deformation mechanism of binary Co-4.5 at.% X (X = alloying element) is extended partial dislocation. Our study reveals Re, W, Mo and La as the most promising alloying additions for the Co-based alloys design with superior performances. Furthermore, the underlying mechanisms for the SFE reduction can be explained regarding the electronic structure.

  3. In vitro corrosion of dental Ag-based alloys in polyvinylpyrrolidone iodine solution.

    PubMed

    Ochi, Morio; Endo, Kazuhiko; Ohno, Hiroki; Takasusuki, Norio; Matsubara, Hideki; Maida, Takeo

    2005-09-01

    The corrosion and tarnish behaviors of three Ag-based alloys (Ag-Pd-Cu-Au alloy, Ag-In alloy, and Ag-Sn-Zn alloy) in polyvinylpyrrolidone iodine (povidone-iodine) solution were examined. The degree of tarnish was evaluated by visible-ray spectrocolorimetry. Corrosion potential measurements and analyses of corrosion products by X-ray diffractometry were carried out to elucidate the corrosion mechanism. The corrosion rate of the three Ag-based alloys in povidone-iodine solution at its practical concentration used as a gargle solution was so fast that the alloys tarnished within 10 seconds of immersion with the formation of AgI. Thermodynamic consideration and the results of surface analysis by X-ray diffractometry revealed that the main anodic and cathodic reactions were Ag + I(-)-->AgI + e- and I2 + 2e(-)-->2I- respectively.

  4. Effect of composition on antiphase boundary energy in Ni3Al based alloys: Ab initio calculations

    NASA Astrophysics Data System (ADS)

    Gorbatov, O. I.; Lomaev, I. L.; Gornostyrev, Yu. N.; Ruban, A. V.; Furrer, D.; Venkatesh, V.; Novikov, D. L.; Burlatsky, S. F.

    2016-06-01

    The effect of composition on the antiphase boundary (APB) energy of Ni-based L 12-ordered alloys is investigated by ab initio calculations employing the coherent potential approximation. The calculated APB energies for the {111} and {001} planes reproduce experimental values of the APB energy. The APB energies for the nonstoichiometric γ' phase increase with Al concentration and are in line with the experiment. The magnitude of the alloying effect on the APB energy correlates with the variation of the ordering energy of the alloy according to the alloying element's position in the 3 d row. The elements from the left side of the 3 d row increase the APB energy of the Ni-based L 12-ordered alloys, while the elements from the right side slightly affect it except Ni. The way to predict the effect of an addition on the {111} APB energy in a multicomponent alloy is discussed.

  5. Adhesion and friction of iron-base binary alloys in contact with silicon carbide in vacuum

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1980-01-01

    Single pass sliding friction experiments were conducted with various iron base binary alloys (alloying elements were Ti, Cr, Mn, Ni, Rh, and W) in contact with a single crystal silicon carbide /0001/ surface in vacuum. Results indicate that atomic size and concentration of alloying elements play an important role in controlling adhesion and friction properties of iron base binary alloys. The coefficient of friction generally increases with an increase in solute concentration. The coefficient of friction increases linearly as the solute to iron atomic radius ratio increases or decreases from unity. The chemical activity of the alloying elements was also an important parameter in controlling adhesion and friction of alloys, as these latter properties are highly dependent upon the d bond character of the elements.

  6. Progress in the Modeling of NiAl-Based Alloys Using the BFS Method

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Ferrante, John; Garg, Anita

    1997-01-01

    The BFS method has been applied to the study of NiAl-based materials to assess the effect of alloying additions on structure. Ternary, quaternary and even pent-alloys based on Ni-rich NiAl with additions of Ti, Cr and Cu were studied. Two approaches were used, Monte Carlo simulations to determine ground state structures and analytical calculations of high symmetry configurations which give physical insight into preferred bonding. Site occupancy energetics for ternary and the more complicated case of quaternary additions were determined, and solubility limits and precipitate formation with corresponding information concerning structure and lattice parameter were also 'observed' computationally. The method was also applied to determine the composition of alloy surfaces and interfaces. Overall, the results demonstrate that the BFS method for alloys is a powerful tool for alloy design and with its simplicity and obvious advantages can be used to complement any experimental alloy design program.

  7. Study of Alloy Microstructure Based on TiNi After High-Temperature Treatment

    NASA Astrophysics Data System (ADS)

    Senkevich, K. S.; Gusev, D. E.

    2016-09-01

    Features of microstructure formation for alloy based on titanium nickelide after high-temperature treatment at 1050 - 1250°C are studied. Heat treatment conditions are stipulated diffusion welding and sintering regimes developed previously for alloys based on TiNi.

  8. Thermodynamic Modeling and Experimental Study of Phase Transformations in Alloys Based on γ-TiAl

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. V.; Sokolovskii, V. S.; Salishchev, G. A.; Belov, N. A.; Nochovnaya, N. A.

    2016-09-01

    Thermo-Calc software is used to model the composition diagram for alloys based on γ-TiAl of the systems Ti - Al - Mo - (4 - 10) at.% Nb and Ti - Al - Nb - X ( X is Cr, Mo, V). The effect of alloying on critical points and sequence of phase transformations is established. Changes in phase composition in relation to alloy TNM-B1 temperature are analyzed using a polythermal section of the Ti - Al - Nb - Mo system.

  9. Some properties of a stir-cast Ni-Cr based dental alloy.

    PubMed

    Boswell, P G; Stevens, L

    1980-06-01

    A Ni-Cr based crown and bridge alloy has been successfully stir-cast into small investment mould spaces using a modified induction melting and casting machine. Stir-casting produced substantial improvements to the mechanical properties of the cast alloy. A model for the development of the stir-cast microstructure is described and the clinical significance of the improvements in the alloy's properties is discussed.

  10. Helium Accumulation Behavior in Iron Based Model Alloys

    SciTech Connect

    Sugano, R.; Morishita, K.; Kimura, A.

    2003-09-15

    Helium desorption from Fe-based model alloys irradiated by energetic helium ions was measured during post-irradiation annealing to investigate the energetics and kinetics of formation and annihilation of helium-related defects. Desorption temperatures were observed to be widely ranged from 450 to 1500 K, indicating that helium is bound to a wide variety of trapping sites such as vacancies and dislocations at various binding states. Such a feature is also observed in fusion ferritic steel. A comparison of helium desorption spectra obtained using Fe, Fe-Cr and Fe-Cr-Ni alloys showed that helium is more strongly trapped in bcc Fe than fcc Fe. It indicates that the long distance migration of helium takes place less frequently in bcc matrix, which may reduce the probability of helium clustering. Fusion ferric steel has a lot of trapping sites for helium such as dislocations, solute atoms, the interface of precipitates, impurities and lath boundaries, and so on, and in addition, it has bct matrix, indicating that most of helium atoms must be dispersed in the matrix and therefore it is difficult for them to cluster as a bubble. This may be a reason for higher helium resistance of the steel.

  11. Oxidation/vaporization of silicide coated columbium base alloys

    NASA Technical Reports Server (NTRS)

    Kohl, F. J.; Stearns, C. A.

    1971-01-01

    Mass spectrometric and target collection experiments were made at 1600 K to elucidate the mode of oxidative vaporization of two columbium alloys, fused-slurry-coated with a complex silicide former (Si-20Cr-Fe). At oxygen pressures up to 0.0005 torr the major vapor component detected by mass spectrometry for oxidized samples was gaseous silicon monoxide. Analysis of condensates collected at oxygen pressures of 0.1, 1.0 and 10 torr revealed that chromium-, silicon-, iron- and tungsten- containing species were the major products of vaporization. Equilibrium thermochemical diagrams were constructed for the metal-oxygen system corresponding to each constituent metal in both the coating and base alloy. The major vaporizing species are expected to be the gaseous oxides of chromium, silicon, iron and tungsten. Plots of vapor phase composition and maximum vaporization rate versus oxygen pressure were calculated for each coating constituent. The major contribution to weight loss by vaporization at oxygen pressures above 1 torr was shown to be the chromium-containing species.

  12. A Shape Memory Alloy Based Cryogenic Thermal Conduction Switch

    NASA Technical Reports Server (NTRS)

    Notardonato, W. U.; Krishnan, V. B.; Singh, J. D.; Woodruff, T. R.; Vaidyanathan, R.

    2005-01-01

    Shape memory alloys (SMAs) can produce large strains when deformed (e.g., up to 8%). Heating results in a phase transformation and associated recovery of all the accumulated strain. This strain recovery can occur against large forces, resulting in their use as actuators. Thus an SMA element can integrate both sensory and actuation functions, by inherently sensing a change in temperature and actuating by undergoing a shape change as a result of a temperature-induced phase transformation. Two aspects of our work on cryogenic SMAs are addressed here. First - a shape memory alloy based cryogenic thermal conduction switch for operation between dewars of liquid methane and liquid oxygen in a common bulkhead arrangement is discussed. Such a switch integrates the sensor element and the actuator element and can be used to create a variable thermal sink to other cryogenic tanks for liquefaction, densification, and zero boil-off systems for advanced spaceport applications. Second - fabrication via arc-melting and subsequent materials testing of SMAs with cryogenic transformation temperatures for use in the aforementioned switch is discussed.

  13. Effects of neutron irradiation on deformation behavior of nickel-base fastener alloys

    SciTech Connect

    Bajaj, R.; Mills, W.J.; Kammenzind, B.F.; Burke, M.G.

    1999-07-01

    This paper presents the effects of neutron irradiation on the fracture behavior and deformation microstructure of high-strength nickel-base alloy fastener materials, Alloy X-750 and Alloy 625. Alloy X-750 in the HTH condition, and Alloy 625 in the direct aged condition were irradiated to a fluence of 2.4x10{sup 20} n/cm{sup 2} at 264 C in the Advanced Test Reactor. Deformation structures at low strains were examined. It was previously shown that Alloy X-750 undergoes hardening, a significant degradation in ductility and an increase in intergranular fracture. In contrast, Alloy 625 had shown softening with a concomitant increase in ductility and transgranular failure after irradiation. The deformation microstructures of the two alloys were also different. Alloy X-750 deformed by a planar slip mechanism with fine microcracks forming at the intersections of slip bands with grain boundaries. Alloy 625 showed much more homogeneous deformation with fine, closely spaced slip bands and an absence of microcracks. The mechanism(s) of irradiation assisted stress corrosion cracking (IASCC) are discussed.

  14. Thermodynamics-Based Computational Design of Al-Mg-Sc-Zr Alloys

    NASA Astrophysics Data System (ADS)

    Haidemenopoulos, G. N.; Katsamas, A. I.; Kamoutsi, H.

    2010-04-01

    Alloying additions of Sc and Zr raise the yield strength of Al-Mg alloys significantly. We have studied the effects of Sc and Zr on the grain refinement and recrystallization resistance of Al-Mg alloys with the aid of computational alloy thermodynamics. The grain refinement potential has been assessed by Scheil-Gulliver simulations of solidification paths, while the recrystallization resistance (Zener drag) has been assessed by calculation of the precipitation driving forces of the Al3Sc and Al3Zr intermetallics. Microstructural performance indices have been derived, used to rank several alloy composition variants, and finally select the variant with the best combination of grain refinement and recrystallization resistance. The method can be used, with certain limitations, for a thermodynamics-based design of Al-Mg and other alloy compositions.

  15. Dual Microstructure Heat Treatment of a Nickel-Base Disk Alloy

    NASA Technical Reports Server (NTRS)

    Gayda, John

    2001-01-01

    Existing Dual Microstructure Heat Treat (DMHT) technology was successfully applied to Alloy 10, a high strength, nickel-base disk alloy, to produce a disk with a fine grain bore and coarse grain rim. Specimens were extracted from the DMHT disk and tested in tension, creep, fatigue, and crack growth using conditions pertinent to disk applications. These data were then compared with data from "traditional" subsolvus and supersolvus heat treatments for Alloy 10. The results showed the DMHT disk to have a high strength, fatigue resistant bore comparable to that of subsolvus Alloy 10. Further, creep resistance of the DMHT rim was comparable to that of supersolvus Alloy 10. Crack growth resistance in the DMHT rim, while better than that for subsolvus, was inferior to that of supersolvus Alloy 10. The slow cool at the end of the DMHT conversion and/or the subsolvus resolution step are thought to be responsible for degrading rim DMHT crack growth resistance.

  16. Evaluation of Nb-base alloys for the divertor structure in fusion reactors

    SciTech Connect

    Purdy, I.M.

    1996-04-01

    Niobium-base alloys are candidate materials for the divertor structure in fusion reactors. For this application, an alloy should resist aqueous corrosion, hydrogen embrittlement, and radiation damage and should have high thermal conductivity and low thermal expansion. Results of corrosion and embrittlement screening tests of several binary and ternary Nb alloys in high-temperature water indicated the Mb-1Zr, Nb-5MO-1Zr, and Nb-5V-1Z4 (wt %) showed sufficient promise for further investigation. These alloys, together with pure Nb and Zircaloy-4 have been exposed to high purity water containing a low concentration of dissolved oxygen (<12 ppb) at 170, 230, and 300{degrees}C for up to {approx}3200 h. Weight-change data, microstructural observations, and qualitative mechanical-property evaluation reveal that Nb-5V-1Zr is the most promising alloy at higher temperatures. Below {approx}200{degrees}C, the alloys exhibit similiar corrosion behavior.

  17. Thermodynamic properties of gadolinium in Ga-Sn and Ga-Zn eutectic based alloys

    NASA Astrophysics Data System (ADS)

    Maltsev, Dmitry S.; Volkovich, Vladimir A.; Yamshchikov, Leonid F.; Chukin, Andrey V.

    2016-09-01

    Thermodynamic properties of gadolinium in Ga-Sn and Ga-Zn eutectic based alloys were studied. Temperature dependences of gadolinium activity in the studied alloys were determined at 573-1073 K employing the EMF method. Solubility of gadolinium in the Ga-Sn and Ga-Zn alloys was measured at 462-1073 K using IMCs sedimentation method. Activity coefficients as well as partial and excess thermodynamic functions of gadolinium in the studied alloys were calculated on the basis of the obtained experimental data.

  18. Steam Oxidation Behavior of Advanced Steels and Ni-Based Alloys at 800 °C

    NASA Astrophysics Data System (ADS)

    Dudziak, T.; Boroń, L.; Deodeshmukh, V.; Sobczak, J.; Sobczak, N.; Witkowska, M.; Ratuszek, W.; Chruściel, K.

    2017-02-01

    This publication studies the steam oxidation behavior of advanced steels (309S, 310S and HR3C) and Ni-based alloys (Haynes® 230®, alloy 263, alloy 617 and Haynes® 282®) exposed at 800 °C for 2000 h under 1 bar pressure, in a pure water steam system. The results revealed that all exposed materials showed relatively low weight gain, with no spallation of the oxide scale within the 2000 h of exposure. XRD analysis showed that Ni-based alloys developed an oxide scale consisting of four main phases: Cr2O3 (alloy 617, Haynes® 282®, alloy 263 and Haynes® 230®), MnCr2O4 (alloy 617, Haynes® 282® and Haynes® 230®), NiCr2O4 (alloy 617) and TiO2 (alloy 263, Haynes® 282®). In contrast, advanced steels showed the development of Cr2O3, MnCr2O4, Mn7SiO12, FeMn(SiO4) and SiO2 phases. The steel with the highest Cr content showed the formation of Fe3O4 and the thickest oxide scale.

  19. Steam Oxidation Behavior of Advanced Steels and Ni-Based Alloys at 800 °C

    NASA Astrophysics Data System (ADS)

    Dudziak, T.; Boroń, L.; Deodeshmukh, V.; Sobczak, J.; Sobczak, N.; Witkowska, M.; Ratuszek, W.; Chruściel, K.

    2017-03-01

    This publication studies the steam oxidation behavior of advanced steels (309S, 310S and HR3C) and Ni-based alloys (Haynes® 230®, alloy 263, alloy 617 and Haynes® 282®) exposed at 800 °C for 2000 h under 1 bar pressure, in a pure water steam system. The results revealed that all exposed materials showed relatively low weight gain, with no spallation of the oxide scale within the 2000 h of exposure. XRD analysis showed that Ni-based alloys developed an oxide scale consisting of four main phases: Cr2O3 (alloy 617, Haynes® 282®, alloy 263 and Haynes® 230®), MnCr2O4 (alloy 617, Haynes® 282® and Haynes® 230®), NiCr2O4 (alloy 617) and TiO2 (alloy 263, Haynes® 282®). In contrast, advanced steels showed the development of Cr2O3, MnCr2O4, Mn7SiO12, FeMn(SiO4) and SiO2 phases. The steel with the highest Cr content showed the formation of Fe3O4 and the thickest oxide scale.

  20. Corrosion resistance and electrochemical potentiokinetic reactivation testing of some iron-base hardfacing alloys

    SciTech Connect

    Cockeram, B.V.

    1999-11-01

    Hardfacing alloys are weld deposited on a base material to provide a wear resistant surface. Commercially available iron-base hardfacing alloys are being evaluated for replacement of cobalt-base alloys to reduce nuclear plant activation levels. Corrosion testing was used to evaluate the corrosion resistance of several iron-base hardfacing alloys in highly oxygenated environments. The corrosion test results indicate that iron-base hardfacing alloys in the as-deposited condition have acceptable corrosion resistance when the chromium to carbon ratio is greater than 4. Tristelle 5183, with a high niobium (stabilizer) content, did not follow this trend due to precipitation of niobium-rich carbides instead of chromium-rich carbides. This result indicates that iron-base hardfacing alloys containing high stabilizer contents may possess good corrosion resistance with Cr:C < 4. NOREM 02, NOREM 01, and NoCo-M2 hardfacing alloys had acceptable corrosion resistance in the as-deposited and 885 C/4 hour heat treated condition, but rusting from sensitization was observed in the 621 C/6 hour heat treated condition. The feasibility of using an Electrochemical Potentiokinetic Reactivation (EPR) test method, such as used for stainless steel, to detect sensitization in iron-base hardfacing alloys was evaluated. A single loop-EPR method was found to provide a more consistent measurement of sensitization than a double loop-EPR method. The high carbon content that is needed for a wear resistant hardfacing alloy produces a high volume fraction of chromium-rich carbides that are attacked during EPR testing. This results in inherently lower sensitivity for detection of a sensitized iron-base hardfacing alloy than stainless steel using conventional EPR test methods.

  1. Elevated temperature fretting fatigue of nickel based alloys

    NASA Astrophysics Data System (ADS)

    Gean, Matthew C.

    This document details the high temperature fretting fatigue of high temperature nickel based alloys common to turbine disk and blade applications. The research consists of three area of focus: Experiments are conducted to determine quantitatively the fretting fatigue lives of advanced nickel based alloys; Analytical tools are developed and used to investigate the fretting fatigue response of the material; Fractographic analysis of the experimental results is used to improve the analytical models employed in the analysis of the experiments. Sixty three fretting fatigue experiments were conducted at 649 °C using a polycrystalline Nickel specimen in contact with directionally solidified and single crystal Nickel pads. Various influences on the fretting fatigue life are investigated. Shot peened Rene' 95 had better fretting fatigue life compared to shot peened Rene' 88. Shot peening produced a 2x increase in life for Rene' 95, but only a marginal improvement in the fretting fatigue life for Rene' 88. Minor cycles in variable amplitude loading produces significant damage to the specimen. Addition of occasional overpeaks in load produces improvements in fretting fatigue life. Contact tractions and stresses are obtained through a variety of available tools. The contact tractions can be efficiently obtained for limited geometries, while FEM can provide the contact tractions for a broader class of problems, but with the cost of increased CPU requirements. Similarly, the subsurface contact stresses can be obtained using the contact tractions as a boundary condition with either a semi-analytical FFT method or FEM. It is found that to calculate contact stresses the FFT was only marginally faster than FEM. The experimental results are combined with the analysis to produce tools that are used to design against fretting fatigue. Fractographic analysis of the fracture surface indicates the nature of the fretting fatigue crack behavior. Interrupted tests were performed to analyze

  2. Thermophysical Properties of Liquid AlTi-Based Alloys

    NASA Astrophysics Data System (ADS)

    Egry, I.; Holland-Moritz, D.; Novakovic, R.; Ricci, E.; Wunderlich, R.; Sobczak, N.

    2010-05-01

    The surface tension and density of three liquid AlTi-based alloys (AlTiV, AlTiNb, and AlTiTa) have been measured using electromagnetic levitation as a tool for containerless processing. Surface tension has been determined by the oscillating-drop method, while the density was measured using a shadowgraph technique. Both quantities were determined over a wide temperature range, including the undercooled regime. In addition, sessile-drop and pendant-drop experiments to determine the surface tension were performed in a recently built high-temperature furnace. The measured data were compared to thermodynamic calculations using phenomenological models and the Butler equation. Generally, good agreement was found.

  3. Processing of New Materials by Additive Manufacturing: Iron-Based Alloys Containing Silver for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Niendorf, Thomas; Brenne, Florian; Hoyer, Peter; Schwarze, Dieter; Schaper, Mirko; Grothe, Richard; Wiesener, Markus; Grundmeier, Guido; Maier, Hans Jürgen

    2015-07-01

    In the biomedical sector, production of bioresorbable implants remains challenging due to improper dissolution rates or deficient strength of many candidate alloys. Promising materials for overcoming the prevalent drawbacks are iron-based alloys containing silver. However, due to immiscibility of iron and silver these alloys cannot be manufactured based on conventional processing routes. In this study, iron-manganese-silver alloys were for the first time synthesized by means of additive manufacturing. Based on combined mechanical, microscopic, and electrochemical studies, it is shown that silver particles well distributed in the matrix can be obtained, leading to cathodic sites in the composite material. Eventually, this results in an increased dissolution rate of the alloy. Stress-strain curves showed that the incorporation of silver barely affects the mechanical properties.

  4. Modern Refractory Alloys Based on Titanium Gamma-Aluminide: Prospects of Development and Application

    NASA Astrophysics Data System (ADS)

    Nochovnaya, N. A.; Panin, P. V.; Kochetkov, A. S.; Bokov, K. A.

    2014-11-01

    The recent scientific and engineering level of refractory intermetallic alloys based on equiatomic titanium gamma-aluminide (TiAl) for aircraft engines and power plants is reviewed. The main tendencies and prospects of development of such alloys, processes of their production and treatment are described.

  5. Welding of NOREM iron-base hardfacing alloy wire products: Procedures for gas tungsten arc welding

    SciTech Connect

    Phillps, M.K.; Findlan, S.J. . Nondestructive Evaluation Center)

    1992-09-01

    New wire products have been successfully fabricated and procedures developed for automatic gas tungsten arc welding of wear-resistant NOREM iron-base alloys. Research demonstrated that sound multilayer welds on carbon and stainless steel substrates can be obtained without the use of preheating. These developments point to the advantages of NOREM alloys for field applications, such as valve refurbishing.

  6. Pore Formation Upon Nitriding Iron and Iron-Based Alloys: The Role of Alloying Elements and Grain Boundaries

    NASA Astrophysics Data System (ADS)

    Schwarz, B.; Göhring, H.; Meka, S. R.; Schacherl, R. E.; Mittemeijer, E. J.

    2014-12-01

    Pure iron and a series of iron-based Fe-Me alloys (with Me = Al, Si, Cr, Co, Ni, and Ge) were nitrided in a NH3/H2 gas mixture at 923 K (650 °C). Different nitriding potentials were applied to investigate the development of pores under ferrite and austenite stabilizing conditions. In all cases, pores developed in the nitrided microstructure, i.e., also and strikingly pure ferritic iron exhibited pore development. The pore development is shown to be caused by the decomposition of (homogeneous) nitrogen-rich Fe(-Me)-N phase into nitrogen-depleted Fe(-Me)-N phase and molecular N2 gas. The latter, gas phase can be associated with such high pressure that the surrounding iron-based matrix can yield. Thermodynamic assessments indicate that continued decomposition, i.e., beyond the state where yielding is initiated, is possible. Precipitating alloying-element nitrides, i.e., AlN, CrN, or Si3N4, in the diffusion zone below the surface, hinder the formation of pores due to the competition of alloying-element nitride (Me x N y ) precipitation and pore (N2) development; alloying elements reducing the solubility of nitrogen enhance pore formation. No pore formation was observed upon nitriding a single crystalline pure iron specimen, nitrided under ferrite stabilizing conditions, thereby exhibiting the essential function of grain boundaries for nucleation of pores.

  7. Band gaps by design: Tailoring ZnO based semiconductor alloy films

    NASA Astrophysics Data System (ADS)

    Che, Hui

    This dissertation presents the research on the synthesis of ZnO based ternary semiconductor alloy films with tailored band gaps and the studies in their structural and optical properties. MgxZn1-xO alloys expanded the band gaps from 3.20 eV to deeper UV region of 5.67 eV. While ZnSxO1-x reduced the band gaps into the visible region of 2.9 eV. The alloy films were grown via reactive sputtering deposition, which is a cost effective and environment-friendly technique. An analytical method was developed for accurately determining the band gaps of alloys via transmission spectroscopy. The structural inhomogeneity issues in the Mg xZn1-xO alloys were studied via Selective Resonant Raman Scattering. Urbach energy analysis and Raman spectral line width analysis indicated that structural defects and alloy composition fluctuations in the MgxZn1-xO alloy films are the dominant origins of the localized electronic tail states and the Raman line broadening. While the Raman line broadening due to the anharmonicity of the alloys is not significant. The achievement of ZnSxO1-x alloy films with reduced band gaps paved the way for further research on band gap engineering of ZnO in the visible region.

  8. Influence of S. mutans on base-metal dental casting alloy toxicity.

    PubMed

    McGinley, E L; Dowling, A H; Moran, G P; Fleming, G J P

    2013-01-01

    We have highlighted that exposure of base-metal dental casting alloys to the acidogenic bacterium Streptococcus mutans significantly increases cellular toxicity following exposure to immortalized human TR146 oral keratinocytes. With Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), S. mutans-treated nickel-based (Ni-based) and cobalt-chromium-based (Co-Cr-based) dental casting alloys were shown to leach elevated levels of metal ions compared with untreated dental casting alloys. We targeted several biological parameters: cell morphology, viable cell counts, cell metabolic activity, cell toxicity, and inflammatory cytokine expression. S. mutans-treated dental casting alloys disrupted cell morphology, elicited significantly decreased viable cell counts (p < 0.0001) and cell metabolic activity (p < 0.0001), and significantly increased cell toxicity (p < 0.0001) and inflammatory cytokine expression (p < 0.0001). S. mutans-treated Ni-based dental casting alloys induced elevated levels of cellular toxicity compared with S. mutans-treated Co-Cr-based dental casting alloys. While our findings indicated that the exacerbated release of metal ions from S. mutans-treated base-metal dental casting alloys was the likely result of the pH reduction during S. mutans growth, the exact nature of mechanisms leading to accelerated dissolution of alloy-discs is not yet fully understood. Given the predominance of S. mutans oral carriage and the exacerbated cytotoxicity observed in TR146 cells following exposure to S. mutans-treated base-metal dental casting alloys, the implications for the long-term stability of base-metal dental restorations in the oral cavity are a cause for concern.

  9. Cerium-based conversion coatings on magnesium alloys

    NASA Astrophysics Data System (ADS)

    Castano Londono, Carlos Eduardo

    This research is primarily focused on gaining a better understanding of the deposition and corrosion behavior of cerium-based conversion coatings (CeCCs) on AZ31B and AZ91D Mg alloys. Deposition of homogenous and protective CeCCs was highly dependent on the surface preparation steps. The best results were obtained when Mg samples underwent grinding, acid cleaning, and alkaline cleaning processes. This reduced the number of active cathodic sites and promoted the formation of a protective Al-rich Mg oxide/hydroxide layer. Electrochemical properties of the CeCCs were also strongly correlated with morphological, microstructural, and chemical characteristics. Protective CeCCs were deposited on both AZ31 and AZ91 Mg alloys using a range of deposition times (5 to 180 s) and temperatures (10 to 80 °C). However, shorter deposition times (5 s) and lower deposition temperatures (~10 °C) showed higher impedance and longer bath stability than other deposition conditions. The increase in impedance was related with fewer cracks and smaller nodule sizes. Additional investigations of post-treated CeCCs exposed to NaCl environments showed an increased in the total impedance. The increase in corrosion protection of the CeCCs was associated with an overall increase in coating thickness from 400 to 800 nm. A microstructural evolution from ~3 nm nodular nanocrystals of CeO2/CePO4*H2O embedded in an amorphous matrix to >50 nm CePO4*H2O nanocrystals was responsible for the electrochemically active corrosion protection. Exposure of CeCCs to sunlight in humid environments promoted the reduction of Ce(IV) into Ce(III) species compared to unexposed coatings. This reduction process was related with photocatalytic water oxidation reaction.

  10. Infection free titanium alloys by stabile thiol based nanocoating.

    PubMed

    Cökeliler, Dilek; Göktaş, Hilal; Tosun, Pinar Deniz; Mutlu, Selma

    2010-04-01

    As biomedical materials, titanium and titanium alloys (Ti-6Al-4V) are superior to many materials in terms of mechanical properties and biocompatibility. However, they are still not sufficient for prolonged clinical use because the biocompatibility of these materials must be improved. In this study, the prevention of the attachment of test microorganism on the Ti alloy surfaces by thiol (-SH) and hydroxyl (-OH) functional group containing monomer in plasma based electron beam generator was reported in order to prepare anti-fouling surfaces. The precursor, 11-mercaptoundecanoic acid is used as plasma source to create nano-film with 30-60 nm approximately. The surface chemistry and topology of uncoated and coated samples are characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Force Microscopy (AFM). Static contact angle measurements are performed to state the change of surface hydrophilicity. All coated samples are tested in-vitro environment with Staphylococcus epidermidis that is chosen as the test bacteria strain in view of its significance for the pathogenesis of medical-device-related infections. This test is repeated after certain period of times and samples are waited in dynamic fluid media in order to investigate the stability of nano-coating. Plasma polymerized 11-mercaptoundecanoic acid film (PP MUA) with 42 +/- 4 nm is found alternative, stabile and simple method to create bacterial anti-fouling surfaces. The static contact angle of the coated surface is 34 +/- 80 whereas the uncoated surface is 57 +/- 50. For the coated surface, the presence of C-OH and C==O groups in infrared spectra defining the PP MUA is achieved by the plasma polymerization. The attachment of the model microorganism on the biomaterial surface prepared by PP MUA is reduced 85.3% if compared to unmodified control surface.

  11. NEUTRON REACTOR FUEL ELEMENT UTILIZING ZIRCONIUM-BASE ALLOYS

    DOEpatents

    Saller, H.A.; Keeler, J.R.; Szumachowski, E.R.

    1957-11-12

    This patent relates to clad fuel elements for use in neutronic reactors and is drawn to such a fuel element which consists of a core of fissionable material, comprised of an alloy of zirconium and U/sup 235/ enriched uranium, encased in a jacket of a binary zirconium-tin alloy in which the tin content ranges between 1 and 15% by weight.

  12. Performance of Alumina-Forming Austenitic Steels, Fe-base and Ni-base alloys exposed to metal dusting environments

    SciTech Connect

    Vande Put Ep Rouaix, Aurelie; Unocic, Kinga A; Pint, Bruce A; Brady, Michael P

    2011-01-01

    A series of conventional Fe- and Ni- base, chromia- and alumina- forming alloys, and a newly developed creep-resistant, alumina-forming austenitic steel were developed and its performance relative to conventional Fe- and Ni-based chromia-forming alloys was evaluated in metal dusting environments with a range of water vapor contents. Five 500h experiments have been performed at 650 C with different water vapor contents and total pressures. Without water vapor, the Ni-base alloys showed greater resistance to metal dusting than the Fe-base alloys, including AFA. However, with 10-28% water vapor, more protective behavior was observed with the higher-alloyed materials and only small mass changes were observed. Longer exposure times are in progress to further differentiate performance.

  13. The erosion-corrosion of copper-based and nickel-based alloys in warm polluted Arabian Gulf seawater

    SciTech Connect

    Carew, J.A.; Islam, M.

    1994-12-31

    This paper presents the results of an investigation of the erosion-corrosion behavior of copper-nickel alloys (90:10 Cu/Ni and 7030 Cu/Ni), nickel-copper alloy UNS N04400 and nickel-based alloys (UNS N06022, N06030 and UNS S32550) used as heat exchanger tubes, in warm flowing Arabian Gulf seawater containing up to 5 ppm of sulphide ions. Visual and optical examinations of the internal surfaces of the tubes were carried out to compare the susceptibilities to erosion-corrosion attack of the different alloys, taking into consideration the nature of the product films formed.

  14. Scale formation on Ni-based alloys in simulated solid oxide fuel cell interconnect environments

    SciTech Connect

    Ziomek-Moroz, Margaret; Cramer, Stephen D.; Holcomb, Gordon R.; Covino, Bernard S., Jr.; Bullard, Sophie J.; Singh, P.; Windisch, C.F.; Johnson, C.D.; Schaeffer, C.

    2004-11-01

    Recent publications suggest that the environment on the fuel side of the bi-polar stainless steel SOFC interconnects changes the oxidation behavior and morphology of the scale formed on the air side. The U.S. Department of Energy Albany Research Center (ARC), has examined the role of such exposure conditions on advanced nickel base alloys. Alloy formulations developed at ARC and commercial alloys were studied using X-ray diffraction (XRD) and Raman spectroscopy. The electrical property of oxide scales formed on selected alloys was determined in terms of areaspecific resistance (ASR). The corrosion behavior of ARC nickel-based alloys exposed to a dual environment of air/ H2 were compared to those of Crofer 22APU and Haynes 230.

  15. Development and study of chemical vapor deposited tantalum base alloys

    NASA Technical Reports Server (NTRS)

    Meier, G. H.; Bryant, W. A.

    1976-01-01

    A technique for the chemical vapor deposition of alloys was developed. The process, termed pulsing, involves the periodic injection of reactant gases into a previously-evacuated reaction chamber where they blanket the substrate almost instantaneously. Formation of alternating layers of the alloy components and subsequent homogenization allows the formation of an alloy of uniform composition with the composition being determined by the duration and relative numbers of the various cycles. The technique has been utilized to produce dense alloys of uniform thickness and composition (Ta- 10 wt % W) by depositing alternating layers of Ta and W by the hydrogen reduction of TaCl5 and WCl6. A similar attempt to deposit a Ta - 8 wt % W - 2 wt% Hf alloy was unsuccessful because of the difficulty in reducing HfCl4 at temperatures below those at which gas phase nucleation of Ta and W occurred.

  16. Cr{sub 2}Nb-based alloy development

    SciTech Connect

    Liu, C.T.; Horton, J.A.; Carmichael, C.A.

    1996-05-01

    This paper summarizes recent progress in developing Cr{sub 2}Nb/Cr(Nb) alloys for structural use in advanced fossil energy conversion systems. Alloy additions were added to control the microstructure and mechanical properties. Two beneficial elements have been identified among all alloying additions added to the alloys. One element is effective in refining the coarse eutectic structure and thus substantially improves the compressive strength and ductility of the alloys. The other element enhances oxidation resistance without sacrificing the ductility. The tensile properties are sensitive to cast defects, which can not be effectively reduced by HIPping at 1450-1580{degrees}C and/or directionally solidifying via a floating zone remelting method.

  17. Nonlocal anomalous Hall effect in ternary alloys based on noble metals

    NASA Astrophysics Data System (ADS)

    Töpler, Franziska; Hönemann, Albert; Tauber, Katarina; Fedorov, Dmitry V.; Gradhand, Martin; Mertig, Ingrid; Fert, Albert

    2016-10-01

    We present a theoretical study of the nonlocal anomalous Hall effect induced by heavy-metal impurities in dilute magnetic alloys based on noble metals. The results of our first-principles calculations are shown in comparison to those obtained within a model consideration via Matthiessen's rule. Based on the transport properties of the constituent binary alloys, we reveal optimal host-impurity combinations to enhance the phenomenon. In particular, this allows us to explain experimental findings showing a strong effect in Cu-based alloys but a vanishing effect in the case of the Au host.

  18. Solidification Behavior in Newly Designed Ni-Rich Ni-Ti-Based Alloys

    NASA Astrophysics Data System (ADS)

    Samal, Sumanta; Biswas, Krishanu; Phanikumar, Gandham

    2016-12-01

    The present investigation reports phase and microstructure evolution during solidification of novel Ni-rich Ni-Ti-based alloys, Ni60Ti40, Ni50Cu10Ti40, Ni48Cu10Co2Ti40, and Ni48Cu10Co2Ti38Ta2 during suction casting. The design philosophy of the multicomponent alloys involves judicious selection of alloying elements such as Cu, Co, and Ta in the near Ni60Ti40 eutectic alloy by replacing both Ni and Ti so that phase mixture in the microstructure remains the same from the binary to quinary alloy. The basic objective is to study the effect of addition of Cu, Co, and Ta on the phase evolution and transformation in the Ni-rich Ni-Ti-based alloys. The detailed electron microscopic studies on these suction cast alloys reveal the presence of ultrafine eutectic lamellae between NiTi and Ni3Ti phases along with dendritic NiTi and Ti2Ni phases. It has also been observed that in the binary (Ni60Ti40) alloy, the ordered NiTi (B2) phase transforms to trigonal (R) phase followed by NiTi martensitic phase (M-phase), i.e., B2 → R-phase → M-phase during solid-state cooling. However, the addition of alloying elements such as Cu, Co to the binary (Ni60Ti40) alloy suppresses the martensitic transformation of the ordered NiTi (B2) dendrite. Thus, in the ternary and quaternary alloys, the ordered NiTi (B2) phase is transformed to only trigonal (R) phase, i.e., B2 → R-phase. The secondary precipitate of Ti2Ni has been observed in all of the studied alloys. Interestingly, Ni48Cu10Co2Ti38Ta2 quinary alloy shows the disordered nature of NiTi dendrites. The experimentally observed solidification path is in good agreement with Gulliver-Scheil simulated path for binary alloy, whereas simulated solidification path deviates from the experimental results in case of ternary, quaternary, and quinary alloys.

  19. Recent progress in high Bs Fe-based nanocrystalline soft magnetic alloys

    NASA Astrophysics Data System (ADS)

    Ohta, M.; Yoshizawa, Y.

    2011-02-01

    High saturation magnetic flux density (high-Bs) alloy has been developed in an Fe-based nanocrystalline alloy system. A nanocrystalline phase with an average grain size of about 20 nm is obtained by annealing Cu-substituted and/or Cu-and-Si-complex-substituted Fe-B amorphous alloys. The alloy exhibits low coercivity of less than 7 A m-1 and a high Bs of more than 1.8 T. The iron loss at 50 Hz and 1.6 T for a toroidal core made of Fe80.5Cu1.5Si4B14 nanocrystalline alloy is 0.46 W kg-1, which is about 2/3 of that of grain-oriented Si steel. Moreover, the iron loss at 10 kHz and 0.2 T for a wound core made of this alloy is 7.5 W kg-1, which is about 25% of that of non-grain-oriented Si steel and about 60% of that of an Fe-based amorphous alloy. In addition, the cut cores made of the alloy show good superimposed dc-current characteristics and appear promising in applications such as power choke coils (at the high-frequency region).

  20. Imprecise knowledge based design and development of titanium alloys for prosthetic applications.

    PubMed

    Datta, S; Mahfouf, M; Zhang, Q; Chattopadhyay, P P; Sultana, N

    2016-01-01

    Imprecise knowledge on the composition-processing-microstructure-property correlation of titanium alloys combined with experimental data are used for developing rule based models for predicting the strength and elastic modulus of titanium alloys. The developed models are used for designing alloys suitable for orthopedic and dental applications. Reduced Space Searching Algorithm is employed for the multi-objective optimization to find composition, processing and microstructure of titanium alloys suitable for orthopedic applications. The conflicting requirements attributes of the alloys for this particular purpose are high strength with low elastic modulus, along with adequate biocompatibility and low costs. The 'Pareto' solutions developed through multi-objective optimization show that the preferred compositions for the fulfilling the above objectives lead to β or near β-alloys. The concept of decision making employed on the solutions leads to some compositions, which should provide better combination of the required attributes. The experimental development of some of the alloys has been carried out as guided by the model-based design methodology presented in this research. Primary characterizations of the alloys show encouraging results in terms of the mechanical properties.

  1. Research into Oil-based Colloidal-Graphite Lubricants for Forging of Al-based Alloys

    SciTech Connect

    Petrov, A.; Petrov, P.; Petrov, M.

    2011-05-04

    The presented paper describes the topical problem in metal forging production. It deals with the choice of an optimal lubricant for forging of Al-based alloys. Within the scope of the paper, the properties of several oil-based colloidal-graphite lubricants were investigated. The physicochemical and technological properties of these lubricants are presented. It was found that physicochemical properties of lubricant compositions have an influence on friction coefficient value and quality of forgings.The ring compression method was used to estimate the friction coefficient value. Hydraulic press was used for the test. The comparative analysis of the investigated lubricants was carried out. The forging quality was estimated on the basis of production test. The practical recommendations were given to choose an optimal oil-based colloidal-graphite lubricant for isothermal forging of Al-based alloy.

  2. Octonary resistance states in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 multiferroic tunnel junctions

    SciTech Connect

    Yue -Wei Yin; Tao, Jing; Huang, Wei -Chuan; Liu, Yu -Kuai; Yang, Sheng -Wei; Dong, Si -Ning; Zhu, Yi -Mei; Li, Qi; Li, Xiao -Guang

    2015-10-06

    General drawbacks of current electronic/spintronic devices are high power consumption and low density storage. A multiferroic tunnel junction (MFTJ), employing a ferroelectric barrier layer sandwiched between two ferromagnetic layers, presents four resistance states in a single device and therefore provides an alternative way to achieve high density memories. Here, an MFTJ device with eight nonvolatile resistance states by further integrating the design of noncollinear magnetization alignments between the ferromagnetic layers is demonstrated. Through the angle-resolved tunneling magnetoresistance investigations on La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 junctions, it is found that, besides collinear parallel/antiparallel magnetic configurations, the MFTJ shows at least two other stable noncollinear (45° and 90°) magnetic configurations. As a result, combining the tunneling electroresistance effect caused by the ferroelectricity reversal of the BaTiO3 barrier, an octonary memory device is obtained, representing potential applications in high density nonvolatile storage in the future.

  3. Evaluation of Surface Roughness and Tensile Strength of Base Metal Alloys Used for Crown and Bridge on Recasting (Recycling)

    PubMed Central

    Hashmi, Syed W.; Rao, Yogesh; Garg, Akanksha

    2015-01-01

    Background Dental casting alloys play a prominent role in the restoration of the partial dentition. Casting alloys have to survive long term in the mouth and also have the combination of structure, molecules, wear resistance and biologic compatibility. According to ADA system casting alloys were divided into three groups (wt%); high noble, Noble and predominantly base metal alloys. Aim To evaluate the mechanical properties such as tensile strength and surface roughness of the new and recast base metal (nickel-chromium) alloys. Materials and Methods Recasting of the base metal alloys derived from sprue and button, to make it reusable has been done. A total of 200 test specimens were fabricated using specially fabricated jig of metal and divided into two groups- 100 specimens of new alloy and 100 specimens of recast alloys, which were tested for tensile strength on universal testing machine and surface roughness on surface roughness tester. Results Tensile strength of new alloy showed no statistically significant difference (p-value>0.05) from recast alloy whereas new alloy had statistically significant surface roughness (Maximum and Average surface roughness) difference (p-value<0.01) as compared to recast alloy. Conclusion Within the limitations of the study it is concluded that the tensile strength will not be affected by recasting of nickel-chromium alloy whereas surface roughness increases markedly. PMID:26393194

  4. MECHANICAL BEHAVIOR OF MOLYBDENUM DISILICIDE-BASED ALLOYS

    SciTech Connect

    A. MISRA; A. SHARIF; ET AL

    2000-12-01

    We have investigated the mechanical behavior of the following single-phase polycrystalline alloys with the MoSi{sub 2} body-center tetragonal structure: MoSi{sub 2} alloyed with {approximately}2.5 at.% Re, MoSi{sub 2} alloyed with 2 at.% Al, MoSi{sub 2} alloyed with 1 at.% Nb, and MoSi{sub 2} alloyed with 1 at.% Re and 2 at.% Al. Several anomalies in the mechanical behavior of alloyed materials were observed. For example, (1) addition of only {approximately}2.5 at. % Re results in an order of magnitude increase in compressive strength at 1600 C, (2) additions of Nb and Al cause solution softening at near-ambient temperatures, and (3) quaternary MoSi{sub 2}-Re-Al alloys show strengthening at elevated temperatures and reduction in flow stress with enhanced plasticity at near-ambient temperatures in compression. The mechanisms of anomalous solution hardening and softening are discussed.

  5. Cr{sub 2}Nb-based alloy development

    SciTech Connect

    Liu, C.T.; Tortorelli, P.F.; Horton, J.A.; Easton, D.S.; Schneibel, J.H.; Heatherly, L.; Carmichael, C.A.; Howell, M.; Wright, J.L.

    1995-07-01

    Two-phase Cr-Cr{sub 2}Nb alloys (designated as CN alloys) were prepared by arc melting, followed by directional solidification, HIPping, or hot extrusion at 1450 to 1500C. The microstructure of CN alloys containing 6 to 12 at.% Nb depended strongly on alloying additions, heat treatment, and material processing. Tensile properties were sensitive to defects. Hot extrusion at 1480C was most effective in reducing as-cast defects and refining the cast Cr-Cr{sub 2}Nb eutectic structure and thus improving ductility. Beneficial alloying elements that modified the eutectic microstructure, improved oxidation resistance, or increased high-temperature strength were identified. One particular composition had a room-temperature fracture strength of 548 MPa and an ultimate tensile strength of 388 MPa, and 23% elongation at 1200C. Another CN alloy showed a fracture toughness of 7.6 MPa{radical}m at room temperature and 24.4 MPa{radical}m at 1100C. Silicide coatings applied by a pack cementation process substantially improved the oxidation resistance of the Cr-Cr{sub 2}Nb alloys at 950 and 1100C.

  6. Ignition characteristics of the nickel-based alloy UNS N07718 in pressurized oxygen

    NASA Technical Reports Server (NTRS)

    Bransford, James W.; Billiard, Phillip A.; Hurley, James A.; Mcdermott, Kathleen M.; Vazquez, Isaura

    1989-01-01

    The development of ignition and combustion in pressurized oxygen atmospheres was studied for the nickel based alloy UNS N07718. Ignition of the alloy was achieved by heating the top. It was found that the alloy would autoheat to destruction from temperatures below the solidus temperature. In addition, endothermic events occurred as the alloy was heated, many at reproducible temperatures. Many endothermic events occurred prior to abrupt increases in surface temperature and appeared to accelerate the rate of increase in specimen temperature. It appeared that the source of some endotherms may increase the oxidation rate of the alloy. Ignition parameters are defined and the temperatures at which these parameters occur are given for the oxygen pressure range of 1.72 to 13.8 MPa (250 to 2000 psia).

  7. Welding and mechanical properties of cast FAPY (Fe-16 at. % Al-based) alloy slabs

    SciTech Connect

    Sikka, V.K.; Goodwin, G.M.; Alexander, D.J.; Howell, C.R.

    1995-08-01

    The low-aluminum-content iron-aluminum program deals with the development of a Fe-Al alloy with aluminum content such as a produce the minimum environmental effect at room temperature. The FAPY is an Fe-16 at. % Al-based alloy developed at the Oak Ridge National Laboratory as the highest aluminum-containing alloy with essentially no environmental effect. The chemical composition for FAPY in weight percent is: aluminum = 8.46, chromium = 5.50, zirconium = 0.20, carbon = 0.03, molybdenum = 2.00, yttrium = 0.10, and iron = 83.71. The cast ingots of the alloy can be hot worked by extrusion, forging, and rolling processes. The hot- worked cast structure can be cold worked with intermediate anneals at 800{degrees}C. Typical room-temperature ductility of the fine-grained wrought structure is 20 to 25% for this alloy. In contrast to the wrought structure, the cast ductility at room temperature is approximately 1% with a transition temperature of approximately 100 to 150{degrees}C, above which ductility values exceed 20%. The alloy has been melted and processed into bar, sheet, and foil. The alloy has also been cast into slabs, step-blocks of varying thicknesses, and shapes. The purpose of this section is to describe the welding response of cast slabs of three different thicknesses of FAPY alloy. Tensile, creep, and Charpy-impact data of the welded plates are also presented.

  8. Atomic-scale properties of Ni-based FCC ternary, and quaternary alloys

    DOE PAGES

    Tamm, Artur; Aabloo, Alvo; Klintenberg, Mattias; ...

    2015-08-26

    The aim of our study is to characterize some atomic-scale properties of Ni-based FCC multicomponent alloys. For this purpose, we use Monte Carlo method combined with density functional theory calculations to study short-range order (SRO), atomic displacements, electronic density of states, and magnetic moments in equimolar ternary NiCrCo, and quaternary NiCrCoFe alloys. The salient features for the ternary alloy are a negative SRO parameter between Ni Cr and a positive between Cr Cr pairs as well as a weakly magnetic state. For the quaternary alloy we predict negative SRO parameter for Ni Cr and Ni Fe pairs and positive formore » Cr Cr and Fe Fe pairs. Atomic displacements for both ternary and quaternary alloys are negligible. In contrast to the ternary, the quaternary alloy shows a complex magnetic structure. The electronic structure of the ternary and quaternary alloys shows differences near the Fermi energy between a random solid solution and the predicted structure with SRO. Despite that, the calculated EXAFS spectra does not show enough contrast to discriminate between random and ordered structures. Finally, the predicted SRO has an impact on point-defect energetics, electron phonon coupling and thermodynamic functions and thus, SRO should not be neglected when studying properties of these two alloys.« less

  9. Atomic-scale properties of Ni-based FCC ternary, and quaternary alloys

    SciTech Connect

    Tamm, Artur; Aabloo, Alvo; Klintenberg, Mattias; Stocks, Malcolm; Caro, Alfredo

    2015-08-26

    The aim of our study is to characterize some atomic-scale properties of Ni-based FCC multicomponent alloys. For this purpose, we use Monte Carlo method combined with density functional theory calculations to study short-range order (SRO), atomic displacements, electronic density of states, and magnetic moments in equimolar ternary NiCrCo, and quaternary NiCrCoFe alloys. The salient features for the ternary alloy are a negative SRO parameter between Ni Cr and a positive between Cr Cr pairs as well as a weakly magnetic state. For the quaternary alloy we predict negative SRO parameter for Ni Cr and Ni Fe pairs and positive for Cr Cr and Fe Fe pairs. Atomic displacements for both ternary and quaternary alloys are negligible. In contrast to the ternary, the quaternary alloy shows a complex magnetic structure. The electronic structure of the ternary and quaternary alloys shows differences near the Fermi energy between a random solid solution and the predicted structure with SRO. Despite that, the calculated EXAFS spectra does not show enough contrast to discriminate between random and ordered structures. Finally, the predicted SRO has an impact on point-defect energetics, electron phonon coupling and thermodynamic functions and thus, SRO should not be neglected when studying properties of these two alloys.

  10. Electron-ion plasma modification of Al-based alloys

    SciTech Connect

    Ivanov, Yurii; Rygina, Mariya; Petrikova, Elizaveta Krysina, Olga Teresov, Anton; Ivanova, Olga Ikonnikova, Irina

    2016-01-15

    The paper reports on the study where we analyzed the surface structure and strength properties of coated Al alloys modified by electron-ion plasma treatment. The Al alloys were deposited with a thin (≈0.5 μm) TiCu film coating (TiCu-Al system) and with a hard TiCuN coating (TiCuN–AlSi system) on a TRIO vacuum setup in the plasma of low-pressure arc discharges. The temperature fields and phase transformations in the film–substrate system were estimated by numerical simulation in a wide range of electron energy densities (5–30 J/cm{sup 2}) and pulse durations (50–200 μs). The calculations allowed us to determine the threshold energy density and pulse duration at which the surface structure of the irradiated Al-based systems is transformed in a single-phase state (solid or liquid) and in a two-phase state (solid plus liquid). The elemental composition, defect structure, phase state, and lattice state in the modified surface layers were examined by optical, scanning, and transmission electron microscopy, and by X-ray diffraction analysis. The mechanical characteristics of the modified layers were studied by measuring the hardness and Young’s modulus. The tribological properties of the modified layers were analyzed by measuring the wear resistance and friction coefficient. It is shown that melting and subsequent high-rate crystallization of the TiCu–Al system makes possible a multiphase Al-based surface structure with the following characteristics: crystallite size ranging within micrometer, microhardness of more than 3 times that in the specimen bulk, and wear resistance ≈1.8 times higher compared to the initial material. Electron beam irradiation of the TiCuN–AlSi system allows fusion of the coating into the substrate, thus increasing the wear resistance of the material ≈2.2 times at a surface hardness of ∼14 GPa.

  11. Alloy catalysts for fuel cell-based alcohol sensors

    NASA Astrophysics Data System (ADS)

    Ghavidel, Mohammadreza Zamanzad

    Direct ethanol fuel cells (DEFCs) are attractive from both economic and environmental standpoints for generating renewable energy and powering vehicles and portable electronic devices. There is a great interest recently in developing DEFC systems. The cost and performance of the DEFCs are mainly controlled by the Pt-base catalysts used at each electrode. In addition to energy conversion, DEFC technology is commonly employed in the fuel-cell based breath alcohol sensors (BrAS). BrAS is a device commonly used to measure blood alcohol concentration (BAC) and enforce drinking and driving laws. The BrAS is non-invasive and has a fast respond time. However, one of the most important drawback of the commercially available BrAS is the very high loading of Pt employed. One well-known and cost effective method to reduce the Pt loading is developing Pt-alloy catalysts. Recent studies have shown that Pt-transition metal alloy catalysts enhanced the electroactivity while decreasing the required loadings of the Pt catalysts. In this thesis, carbon supported Pt-Mn and Pt-Cu electrocatalysts were synthesized by different methods and the effects of heat treatment and structural modification on the ethanol oxidation reaction (EOR) activity, oxygen reduction reaction (ORR) activity and durability of these samples were thoroughly studied. Finally, the selected Pt-Mn and Pt-Cu samples with the highest EOR activity were examined in a prototype BrAS system and compared to the Pt/C and Pt 3Sn/C commercial electrocatalysts. Studies on the Pt-Mn catalysts produced with and without additives indicate that adding trisodium citrate (SC) to the impregnation solution improved the particle dispersion, decreased particle sizes and reduced the time required for heat treatment. Further studies show that the optimum weight ratio of SC to the metal loading in the impregnation solution was 2:1 and optimum results achieved at pH lower than 4. In addition, powder X-ray diffraction (XRD) analyses indicate

  12. Thermal expansion measurements in Fe-base invar alloys

    NASA Astrophysics Data System (ADS)

    Ono, F.; Kittaka, T.; Maeta, H.

    1983-04-01

    By using the X-ray Bond method, measurements of thermal expansion curves have been made in Fe-Ni and Fe-Pd Invar alloys in the temperature range between 4.2 K and room temperatures. A minimum in the thermal expansion curve was observed for each alloy. This anomaly could be explained by considering the magnetovolume coupling term caused by the longitudinal spin fluctuation and the contribution due to the anharmonic terms in the normal lattice vibration energy. In 34.2 at% Pd-Fe alloy an abnormal increase of the linewidth of the (400) X-ray peak was observed with decreasing temperature from room temperature down to 4.2 K, while in Fe-Ni and Fe-Pt Invar alloys no such increase in linewidth was observed.

  13. HIGH-TEMPERATURE OXIDATION PROTECTIVE COATINGS FOR VANADIUM-BASE ALLOYS

    DTIC Science & Technology

    SILICIDES , SILICON COATINGS , THIN FILM STORAGE DEVICES, TITANIUM ALLOYS, VAPOR PLATING, YTTRIUM COMPOUNDS, ZINC ALLOYS, ZINC COATINGS ....ANTIOXIDANTS, *METAL COATINGS , *REFRACTORY COATINGS , *VANADIUM ALLOYS, ALUMINUM ALLOYS, CERAMIC COATINGS , CHROMIUM ALLOYS, CLADDING, FLAME SPRAYING...HIGH TEMPERATURE, INTERMETALLIC COMPOUNDS, IODINE COMPOUNDS, IRON ALLOYS, MAGNESIUM ALLOYS, NICKEL ALLOYS, NICKEL COMPOUNDS, NIOBIUM ALLOYS, OXIDES

  14. Development of Advanced Carbide for Nickel-Based Alloy Machining for Turbine Engines

    DTIC Science & Technology

    2006-06-20

    based alloys such as Inconel 718 with 40% higher machining productivity. 15. SUBJECT TERMS NCDMM; Success Stories; Kennametal, Inc.; Inconel 718 ...Inc. involved developing an advanced coated carbide cutting tool for turning nickel-based alloys such as Inconel 718 with 40% higher machining...nd DOC constant for the ng of six (6) cutting tools t 180 and 250 SFM led to l performance goal. It was r resulting from premature e in Inconel

  15. Environmental Effects in Niobium Base Alloys and Other Selected Intermetallic Compounds

    DTIC Science & Technology

    1988-12-15

    Niobium aluminides and silicides as well as other intermetallic corn unds have potential for use in advanced gas turbines where increased operating...diffusion aluminide coatings on Ni-base alloys(10), Fe- silicides (l 1), and Ni- ’ silicides (12) indicate similar behavior to that in Figure 8. Typical... Niobium W MAR- 2 7 1983 Base Alloys and Other Selected Intermetallic Compounds &Simukx Defense Advanced Research Projects Agency . DARPA Order No. 6155

  16. Mn-Fe base and Mn-Cr-Fe base austenitic alloys

    DOEpatents

    Brager, Howard R.; Garner, Francis A.

    1987-01-01

    Manganese-iron base and manganese-chromium-iron base austenitic alloys designed to have resistance to neutron irradiation induced swelling and low activation have the following compositions (in weight percent): 20 to 40 Mn; up to about 15 Cr; about 0.4 to about 3.0 Si; an austenite stabilizing element selected from C and N, alone or in combination with each other, and in an amount effective to substantially stabilize the austenite phase, but less than about 0.7 C, and less than about 0.3 N; up to about 2.5 V; up to about 0.1 P; up to about 0.01 B; up to about 3.0 Al; up to about 0.5 Ni; up to about 2.0 W; up to about 1.0 Ti; up to about 1.0 Ta; and with the remainder of the alloy being essentially iron.

  17. Mn-Fe base and Mn-Cr-Fe base austenitic alloys

    DOEpatents

    Brager, Howard R.; Garner, Francis A.

    1987-09-01

    Manganese-iron base and manganese-chromium-iron base austenitic alloys designed to have resistance to neutron irradiation induced swelling and low activation have the following compositions (in weight percent): 20 to 40 Mn; up to about 15 Cr; about 0.4 to about 3.0 Si; an austenite stabilizing element selected from C and N, alone or in combination with each other, and in an amount effective to substantially stabilize the austenite phase, but less than about 0.7 C, and less than about 0.3 N; up to about 2.5 V; up to about 0.1 P; up to about 0.01 B; up to about 3.0 Al; up to about 0.5 Ni; up to about 2.0 W; up to about 1.0 Ti; up to about 1.0 Ta; and with the remainder of the alloy being essentially iron.

  18. Shape Memory Alloy (SMA)-Based Launch Lock

    NASA Technical Reports Server (NTRS)

    Badescu, Mircea; Bao, Xiaoqi; Bar-Cohen, Yoseph

    2014-01-01

    Most NASA missions require the use of a launch lock for securing moving components during the launch or securing the payload before release. A launch lock is a device used to prevent unwanted motion and secure the controlled components. The current launch locks are based on pyrotechnic, electro mechanically or NiTi driven pin pullers and they are mostly one time use mechanisms that are usually bulky and involve a relatively high mass. Generally, the use of piezoelectric actuation provides high precession nanometer accuracy but it relies on friction to generate displacement. During launch, the generated vibrations can release the normal force between the actuator components allowing shaft's free motion which could result in damage to the actuated structures or instruments. This problem is common to other linear actuators that consist of a ball screw mechanism. The authors are exploring the development of a novel launch lock mechanism that is activated by a shape memory alloy (SMA) material ring, a rigid element and an SMA ring holding flexure. The proposed design and analytical model will be described and discussed in this paper.

  19. Deployable aerospace PV array based on amorphous silicon alloys

    NASA Technical Reports Server (NTRS)

    Hanak, Joseph J.; Walter, Lee; Dobias, David; Flaisher, Harvey

    1989-01-01

    The development of the first commercial, ultralight, flexible, deployable, PV array for aerospace applications is discussed. It is based on thin-film, amorphous silicon alloy, multijunction, solar cells deposited on a thin metal or polymer by a proprietary, roll-to-roll process. The array generates over 200 W at AM0 and is made of 20 giant cells, each 54 cm x 29 cm (1566 sq cm in area). Each cell is protected with bypass diodes. Fully encapsulated array blanket and the deployment mechanism weigh about 800 and 500 g, respectively. These data yield power per area ratio of over 60 W/sq m specific power of over 250 W/kg (4 kg/kW) for the blanket and 154 W/kg (6.5 kg/kW) for the power system. When stowed, the array is rolled up to a diameter of 7 cm and a length of 1.11 m. It is deployed quickly to its full area of 2.92 m x 1.11 m, for instant power. Potential applications include power for lightweight space vehicles, high altitude balloons, remotely piloted and tethered vehicles. These developments signal the dawning of a new age of lightweight, deployable, low-cost space arrays in the range from tens to tens of thousands of watts for near-term applications and the feasibility of multi-100 kW to MW arrays for future needs.

  20. Shape-Memory-Alloy-Based Deicing System Developed

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Ice buildup on aircraft leading edge surfaces has historically been a problem. Most conventional deicing systems rely either on surface heating to melt the accreted ice or pneumatic surface inflation to mechanically debond the ice. Deicers that rely solely on surface heating require large amounts of power. Pneumatic deicers usually cannot remove thin layers of ice and lack durability. Thus, there is a need for an advanced, low-power ice protection system. As part of the NASA Small Business and Innovation Research (SBIR) program, Innovative Dynamics, Inc., developed an aircraft deicing system that utilizes the properties of Shape Memory Alloys (SMA). The SMA-based system has achieved promising improvements in energy efficiency and durability over more conventional deicers. When they are thermally activated, SMA materials change shape; this is analogous to a conventional thermal expansion. The thermal input is currently applied via conventional technology, but there are plans to implement a passive thermal input that is supplied from the energy transfer due to the formation of the ice itself. The actively powered deicer was tested in the NASA Lewis Icing Research Tunnel on a powered rotating rig in early 1995. The system showed promise, deicing both rime and glaze ice shapes as thin as 1/8 in. The first prototype SMA deicer reduced power usage by 45 percent over existing electrothermal systems. This prototype system was targeted for rotorcraft system development. However, there are current plans underway to develop a fixed-wing version of the deicer.

  1. Deployable aerospace PV array based on amorphous silicon alloys

    NASA Astrophysics Data System (ADS)

    Hanak, Joseph J.; Walter, Lee; Dobias, David; Flaisher, Harvey

    1989-04-01

    The development of the first commercial, ultralight, flexible, deployable, PV array for aerospace applications is discussed. It is based on thin-film, amorphous silicon alloy, multijunction, solar cells deposited on a thin metal or polymer by a proprietary, roll-to-roll process. The array generates over 200 W at AM0 and is made of 20 giant cells, each 54 cm x 29 cm (1566 sq cm in area). Each cell is protected with bypass diodes. Fully encapsulated array blanket and the deployment mechanism weigh about 800 and 500 g, respectively. These data yield power per area ratio of over 60 W/sq m specific power of over 250 W/kg (4 kg/kW) for the blanket and 154 W/kg (6.5 kg/kW) for the power system. When stowed, the array is rolled up to a diameter of 7 cm and a length of 1.11 m. It is deployed quickly to its full area of 2.92 m x 1.11 m, for instant power. Potential applications include power for lightweight space vehicles, high altitude balloons, remotely piloted and tethered vehicles. These developments signal the dawning of a new age of lightweight, deployable, low-cost space arrays in the range from tens to tens of thousands of watts for near-term applications and the feasibility of multi-100 kW to MW arrays for future needs.

  2. Processing and Characterization of Mechanically Alloyed NiAl-Based Alloys

    DTIC Science & Technology

    1994-07-20

    50.1 49.9 - - - 0.007 * 5 00 0E 4 CD C o E * 0 0 L 00000i,_ 0 • 4- -. 0 * CCL 6.2 6- Three types of alloys were produced, NiAI with a brittle, Heusler ...16): -e - h where 7’ is the Orowan stress, h is particle height (usually, particle radius), and X is half the mean interparticle spacing. By

  3. Application of STEM characterization for investigating radiation effects in BCC Fe-based alloys

    DOE PAGES

    Parish, Chad M.; Field, Kevin G.; Certain, Alicia G.; ...

    2015-04-20

    This paper provides a general overview of advanced scanning transmission electron microscopy (STEM) techniques used for characterization of irradiated BCC Fe-based alloys. Advanced STEM methods provide the high-resolution imaging and chemical analysis necessary to understand the irradiation response of BCC Fe-based alloys. The use of STEM with energy dispersive x-ray spectroscopy (EDX) for measurement of radiation-induced segregation (RIS) is described, with an illustrated example of RIS in proton- and self-ion irradiated T91. Aberration-corrected STEM-EDX for nanocluster/nanoparticle imaging and chemical analysis is also discussed, and examples are provided from ion-irradiated oxide dispersion strengthened (ODS) alloys. In conclusion, STEM techniques for void,more » cavity, and dislocation loop imaging are described, with examples from various BCC Fe-based alloys.« less

  4. Application of STEM characterization for investigating radiation effects in BCC Fe-based alloys

    SciTech Connect

    Parish, Chad M.; Field, Kevin G.; Certain, Alicia G.; Wharry, Janelle P.

    2015-04-20

    This paper provides a general overview of advanced scanning transmission electron microscopy (STEM) techniques used for characterization of irradiated BCC Fe-based alloys. Advanced STEM methods provide the high-resolution imaging and chemical analysis necessary to understand the irradiation response of BCC Fe-based alloys. The use of STEM with energy dispersive x-ray spectroscopy (EDX) for measurement of radiation-induced segregation (RIS) is described, with an illustrated example of RIS in proton- and self-ion irradiated T91. Aberration-corrected STEM-EDX for nanocluster/nanoparticle imaging and chemical analysis is also discussed, and examples are provided from ion-irradiated oxide dispersion strengthened (ODS) alloys. In conclusion, STEM techniques for void, cavity, and dislocation loop imaging are described, with examples from various BCC Fe-based alloys.

  5. Hot Workability of CuZr-Based Shape Memory Alloys for Potential High-Temperature Applications

    NASA Astrophysics Data System (ADS)

    Biffi, Carlo Alberto; Tuissi, Ausonio

    2014-07-01

    The research on high-temperature shape memory alloys has been growing because of the interest of several potential industrial fields, such as automotive, aerospace, mechanical, and control systems. One suitable candidate is given by the CuZr system, because of its relative low price in comparison with others, like the NiTi-based one. In this context, the goal of this work is the study of hot workability of some CuZr-based shape memory alloys. In particular, this study addresses on the effect of hot rolling process on the metallurgical and calorimetric properties of the CuZr system. The addition of some alloying elements (Cr, Co, Ni, and Ti) is taken into account and their effect is also put in comparison with each other. The alloys were produced by means of an arc melting furnace in inert atmosphere under the shape of cigars. Due to the high reactivity of these alloys at high temperature, the cigars were sealed in a stainless steel can before the processing and two different procedures of hot rolling were tested. The characterization of the rolled alloys is performed using discrete scanning calorimetry in terms of evolution of the martensitic transformation and scanning electron microscopy for the microstructural investigations. Additionally, preliminary tests of laser interaction has been also proposed on the alloy more interesting for potential applications, characterized by high transformation temperatures and its good thermal stability.

  6. Development of tough, strong, iron-base alloy for cryogenic applications

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.

    1983-01-01

    The development of an iron-base alloy that combines the normally divergent properties of high toughness and high strength at cryogenic temperatures is discussed. Specifically, alloy properties were sought which at -196 C would exhibit a fracture toughness of 220 MPa-m(1/2) with a corresponding yield strength of 1.4 GPa (200 ksi). Early work showed that high toughness could be achieved in Fe-12Ni alloys containing reactive metal additions such as Al, Nb, Ti, and V. Further research emphasized strengthening of these tough alloys by thermomechanical processing and the addition of Cu. Results showed that high strength and high toughness could be achieved in a single alloy at temperatures as low as -196 C. An alloy with composition Fe-12Ni-9.5Al-2Cu exhibited a yield strength of 1.65 GPa with a corresponding fracture toughness of 220 MPa-m(1/2) at -196 C. Strengthening due to Cu additions to the Fe-12Ni base alloys results primarily from precipitation of Cu-rich epsilon particles approximately 20 nm in diameter. Strengthening mechanisms are discussed in terms of an elastic modulus hardening model and are supported by transimission electron microscopy examinations of selected test specimens.

  7. The effects of remelting on the mechanical properties of a nickel base partial denture casting alloy.

    PubMed

    Lewis, A J

    1975-04-01

    Three series of tensile test pieces were produced using a nickel base partial denture casting alloy. For the first series induction heating was employed, for the second a resistance crucible, and for the third, an oxy-acetylene torch. In each series the same metal was cast sequentially a number of times and all test pieces so produced were subjected to mechanical testing. The mechanical properties were found to vary according to both the number of times the alloy was cast and the method of heating used to render the alloy molten.

  8. Interstitial-phase precipitation in iron-base alloys: a comparative study

    SciTech Connect

    Pelton, A.R.

    1982-06-01

    Recent developments have elucidated the atomistic mechanisms of precipitation of interstitial elements in simple alloy systems. However, in the more technologically important iron base alloys, interstitial phase precipitation is generally not well understood. The present experimental study was therefore designed to test the applicability of these concepts to more complex ferrous alloys. Hence, a comparative study was made of interstitial phase precipitation in ferritic Fe-Si-C and in austenitic phosphorus-containing Fe-Cr-Ni steels. These systems were subjected to a variety of quench-age thermal treatments, and the microstructural development was subsequently characterized by transmission electron microscopy.

  9. Biocompatibility of new Ti-Nb-Ta base alloys.

    PubMed

    Hussein, Abdelrahman H; Gepreel, Mohamed A-H; Gouda, Mohamed K; Hefnawy, Ahmad M; Kandil, Sherif H

    2016-04-01

    β-type titanium alloys are promising materials in the field of medical implants. The effect of β-phase stability on the mechanical properties, corrosion resistance and cytotoxicity of a newly designed β-type (Ti77Nb17Ta6) biocompatible alloys are studied. The β-phase stability was controlled by the addition of small quantities of Fe and O. X-ray diffraction and microstructural analysis showed that the addition of O and Fe stabilized the β-phase in the treated solution condition. The strength and hardness have increased with the increase in β-phase stability while ductility and Young's modulus have decreased. The potentio-dynamic polarization tests showed that the corrosion resistance of the new alloys is better than Ti-6Al-4V alloy by at least ten times. Neutral red uptake assay cytotoxicity test showed cell viability of at least 95%. The new alloys are promising candidates for biomedical applications due to their high mechanical properties, corrosion resistance, and reduced cytotoxicity.

  10. Tailoring Fe-Base Alloys for Intermediate Temperature SOFC Interconnect Application

    SciTech Connect

    J.H. Zhu; M.P. Brady; H.U. Anderson

    2007-12-31

    This report summarized the research efforts and major conclusions for our SECA Phase I and II project focused on Cr-free or low Cr Fe-Ni based alloy development for intermediate temperature solid oxide fuel cell (SOFC) interconnect application. Electrical conductivity measurement on bulk (Fe,Ni){sub 3}O{sub 4} coupons indicated that this spinel phase possessed a higher electrical conductivity than Cr{sub 1.5}Mn{sub 1.5}O{sub 4} spinel and Cr{sub 2}O{sub 3}, which was consistent with the low area specific resistance (ASR) of the oxide scale formed on these Fe-Ni based alloys. For Cr-free Fe-Ni binary alloys, although the increase in Ni content in the alloys improved the oxidation resistance, and the Fe-Ni binary alloys exhibited adequate CTE and oxide scale ASR, their oxidation resistance needs to be further improved. Systematic alloy design efforts have led to the identification of one low-Cr (6wt.%) Fe-Ni-Co based alloy which formed a protective, electrically-conductive Cr{sub 2}O{sub 3} inner layer underneath a Cr-free, highly conductive spinel outer layer. This low-Cr, Fe-Ni-Co alloy has demonstrated a good CTE match with other cell components; high oxidation resistance comparable to that of Crofer; low oxide scale ASR with the formation of electrically-insulating phases in the oxide scale; no scale spallation during thermal cycling; adequate compatibility with cathode materials; and comparable mechanical properties with Crofer. The existence of the Cr-free (Fe,Co,Ni){sub 3}O{sub 4} outer layer effectively reduced the Cr evaporation and in transpiration testing resulted in a 6-fold decrease in Cr evaporation as compared to a state-of-the-art ferritic interconnect alloy. In-cell testing using an anode supported cell with a configuration of Alloy/Pt/LSM/YSZ/Ni+YSZ indicates that the formation of the Cr-free spinel layer via thermal oxidation was effective in blocking the Cr migration and thus improving the cell performance stability. Electroplating of the Fe

  11. Antiferromagnetic FeMn alloys electrodeposited from chloride-based electrolytes.

    PubMed

    Ruiz-Gómez, Sandra; Ranchal, Rocío; Abuín, Manuel; Aragón, Ana María; Velasco, Víctor; Marín, Pilar; Mascaraque, Arantzazu; Pérez, Lucas

    2016-03-21

    The capability of synthesizing Fe-based antiferromagnetic metal alloys would fuel the use of electrodeposition in the design of new magnetic devices such as high-aspect-ratio spin valves or new nanostructured hard magnetic composites. Here we report the synthesis of high quality antiferromagnetic FeMn alloys electrodeposited from chloride-based electrolytes. We have found that in order to grow homogeneous FeMn films it is necessary to incorporate a large concentration of NH4Cl as an additive in the electrolyte. The study of the structure and magnetic properties shows that films with composition close to Fe50Mn50 are homogeneous antiferromagnetic alloys. We have established a parameter window for the synthesis of FeMn alloys that show antiferromagnetism at room temperature.

  12. Tool wear mechanisms in the machining of Nickel based super-alloys: A review

    NASA Astrophysics Data System (ADS)

    Akhtar, Waseem; Sun, Jianfei; Sun, Pengfei; Chen, Wuyi; Saleem, Zawar

    2014-06-01

    Nickel based super-alloys are widely employed in aircraft engines and gas turbines due to their high temperature strength, corrosion resistance and, excellent thermal fatigue properties. Conversely, these alloys are very difficult to machine and cause rapid wear of the cutting tool, frequent tool changes are thus required resulting in low economy of the machining process. This study provides a detailed review of the tool wear mechanism in the machining of nickel based super-alloys. Typical tool wear mechanisms found by different researchers are analyzed in order to find out the most prevalent wear mechanism affecting the tool life. The review of existing works has revealed interesting findings about the tool wear mechanisms in the machining of these alloys. Adhesion wear is found to be the main phenomenon leading to the cutting tool wear in this study.

  13. Simulated characteristics of a heterojunction phototransistor with Ge1-xSnx alloy as base

    NASA Astrophysics Data System (ADS)

    Kumar, Dur Vesh; Pandey, Ankit Kumar; Basu, Rikmantra; Sharma, Anuj K.

    2016-12-01

    Groups III-V compound semiconductors and their alloys are the main photodetecting elements for the entire fiber optic telecommunication band. However, the recent successful growth of GeSnx alloy on Ge virtual substrates on Si platform makes the group IV alloys a potential competitor. GeSnx alloy shows direct band gap and has an absorption coefficient almost 10 times higher than that of Ge. The photonic devices are complementary metal-oxide-semiconductor compatible. We have considered an n-Ge/p+-GeSnx/n-GeSnx heterojunction phototransistor (HPT) and studied the variations of terminal currents by considering the Gummel Poon model of HPT, and values of optical and current gains, photocurrent, and responsivity have been obtained. The performance of the device as a photodetector at fiber optic communication wavelengths seems quite encouraging to justify the use of GeSn-based HPTs as a replacement of III-IV semiconductor-based photodetectors.

  14. Iron-based alloy and nitridation treatment for PEM fuel cell bipolar plates

    DOEpatents

    Brady, Michael P [Oak Ridge, TN; Yang, Bing [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN

    2010-11-09

    A corrosion resistant electrically conductive component that can be used as a bipolar plate in a PEM fuel cell application is composed of an alloy substrate which has 10-30 wt. % Cr, 0.5 to 7 wt. % V, and base metal being Fe, and a continuous surface layer of chromium nitride and vanadium nitride essentially free of base metal. A oxide layer of chromium vanadium oxide can be disposed between the alloy substrate and the continuous surface nitride layer. A method to prepare the corrosion resistant electrically conductive component involves a two-step nitridization sequence by exposing the alloy to a oxygen containing gas at an elevated temperature, and subsequently exposing the alloy to an oxygen free nitrogen containing gas at an elevated temperature to yield a component where a continuous chromium nitride layer free of iron has formed at the surface.

  15. Heat-resistant coatings for niobium and niobium-base alloys (review)

    SciTech Connect

    Dzyadykevich, Y.V.

    1986-06-01

    The author shows that it is possible to formulate the directions in developments whose purpose is to increase the heat resistance of niobium and niobium-base alloys. These include the creation of a barrier layer for retarding undesirable diffusion processes at the coating-base interface, the formation on niobium alloy parts of alloy silicide layers, the obtaining on parts operating at temperatures above 1300 C of a coating of molybdenum disilicide, the application to previously siliconized niobium alloys of a barrier layer of heterophase coatings, the matrix of which is a low-melting component and the filler refractory compounds, and the addition to the oxidizing gaseous medium of various additions increasing the service life of the protective coating.

  16. Burner Rig Hot Corrosion of Five Ni-Base Alloys Including Mar-M247

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.; Helmink, R.; Harris, K.; Erickson, G.

    2000-01-01

    The hot corrosion resistance of four new Ni-base superalloys was compared to that of Mar-M247 by testing in a Mach 0.3 burner rig at 900 C for 300 1-hr cycles. While the Al content was held the same as in the Mar-M247, the Cr and Co levels in the four new alloys were decreased while other strengthening elements (Re, Ta) were increased. Surprisingly, despite their lower Cr and Co contents, the hot corrosion behavior of all four new alloys was superior to that of the Mar-M247 alloy. The Mar-M247 alloy began to lose weight almost immediately whereas the other four alloys appeared to undergo an incubation period of 50-150 1-hr cycles. Examination of the cross-sectional microstructures showed regions of rampant corrosion attack (propagation stage) in all five alloys after 300 1-hr cycles . This rampant corrosion morphology was similar for each of the alloys with Ni and Cr sulfides located in an inner subscale region. The morphology of the attack suggests a classic "Type I", or high temperature, hot corrosion attack.

  17. Plasma sprayed ceramic thermal barrier coating for NiAl-based intermetallic alloys

    NASA Technical Reports Server (NTRS)

    Miller, Robert A. (Inventor); Doychak, Joseph (Inventor)

    1994-01-01

    A thermal barrier coating system consists of two layers of a zirconia-yttria ceramic. The first layer is applied by low pressure plasma spraying. The second layer is applied by conventional atmospheric pressure plasma spraying. This facilitates the attachment of a durable thermally insulating ceramic coating directly to the surface of a highly oxidation resistant NiAl-based intermetallic alloy after the alloy has been preoxidized to promote the formation of a desirable Al2O3 scale.

  18. Alloy Development, Processing and Characterization of Devitrified Titanium Base Microcrystalline Alloys.

    DTIC Science & Technology

    1983-12-01

    different I" Report) 10. SUPPLEMENTARY NOTES i. K~EY O fDSJ C dlutatopb~ oc uDevitrifie Ti al"I󈨇’a~V1 y’oTi’le mf~ icrorsalline alloy, arc plasma melt...relationships have been found. WTIocession For DTIC TAB Unannounced 0 JustIficati By I Distribution/ Availability Codes " a i l AV a n d / o r IL, I ..’" " 1...largely are divided into two categories: 1) Solid solution forming elements such as Zr, Hf, V. Mo, Cr , Al, Sn, etc., to provide solid solution

  19. Chromium boron surfaced nickel-iron base alloys

    NASA Technical Reports Server (NTRS)

    Rashid, James M. (Inventor); Friedrich, Leonard A. (Inventor); Freling, Melvin (Inventor)

    1984-01-01

    Chromium boron diffusion coatings on nickel iron alloys uniquely provide them with improvement in high cycle fatigue strength (up to 30%) and erosion resistance (up to 15 times), compared to uncoated alloy. The diffused chromium layer extends in two essential concentration zones to a total depth of about 40.times.10.sup.-6 m, while the succeeding boron layer is limited to 50-90% of the depth of the richest Cr layer nearest the surface. Both coatings are applied using conventional pack diffusion processes.

  20. Creep behavior of uranium carbide-based alloys

    NASA Technical Reports Server (NTRS)

    Seltzer, M. S.; Wright, T. R.; Moak, D. P.

    1975-01-01

    The present work gives the results of experiments on the influence of zirconium carbide and tungsten on the creep properties of uranium carbide. The creep behavior of high-density UC samples follows the classical time-dependence pattern of (1) an instantaneous deformation, (2) a primary creep region, and (3) a period of steady-state creep. Creep rates for unalloyed UC-1.01 and UC-1.05 are several orders of magnitude greater than those measured for carbide alloys containing a Zr-C and/or W dispersoid. The difference in creep strength between alloyed and unalloyed materials varies with temperature and applied stress.

  1. Casting alloys.

    PubMed

    Wataha, John C; Messer, Regina L

    2004-04-01

    Although the role of dental casting alloys has changed in recent years with the development of improved all-ceramic materials and resin-based composites, alloys will likely continue to be critical assets in the treatment of missing and severely damaged teeth. Alloy shave physical, chemical, and biologic properties that exceed other classes of materials. The selection of the appropriate dental casting alloy is paramount to the long-term success of dental prostheses,and the selection process has become complex with the development of many new alloys. However, this selection process is manageable if the practitioner focuses on the appropriate physical and biologic properties, such as tensile strength, modulus of elasticity,corrosion, and biocompatibility, and avoids dwelling on the less important properties of alloy color and short-term cost. The appropriate selection of an alloy helps to ensure a longer-lasting restoration and better oral health for the patient.

  2. Subtask 12D5: Thermal creep properties of vanadium-base alloys

    SciTech Connect

    Chung, H.M.; Loomis, B.A.; Smith, D.L.

    1995-03-01

    The objective of this work is to provide baseline data on the thermal creep properties of candidate vanadium base alloys. Vanadium-base alloys are promising candidate materials for application in fusion reactor structural components because of several important advantages. V-4Cr-4Ti has been identified as one of the most promising candidate alloys and was selected for comprehensive tests and examination. In the present investigation, thermal creep rates and stress-rupture life of V-4Cr-4Ti and V-10Cr-5Ti alloys were determined at 600{degrees}C. The impurity composition and microstructural characteristics of creep-tested specimens were analyzed and correlated with the measured creep properties. The results of these tests show that V-4Cr-4Ti, which contains impurity compositions typical of a commercially fabricated vanadium-based alloy, exhibits creep strength substantially superior to that of V-20Ti, HT-9, or Type 316 stainless steel. The V-10Cr-5Ti alloy exhibits creep strength somewhat higher than that of V-4Cr-4Ti. 9 refs., 7 figs., 2 tabs.

  3. SYNTHESIS AND PERFORMANCE OF FE-BASED AMORPHOUS ALLOYS FOR NUCLEAR WASTE REPOSITORY APPLICATIONS

    SciTech Connect

    Kaufman, L; Perepezko, J; Hildal, K

    2007-02-08

    In several Fe-based alloy systems it is possible to produce glasses with cooling rates as low as 100 K/s that exhibit outstanding corrosion resistance compared to typical crystalline alloys such as high-performance stainless steels and Ni-based C-22 alloy. Moreover, novel alloy compositions can be synthesized to maximize corrosion resistance (i.e. adding Cr and Mo) and to improve radiation compatibility (adding B) and still maintain glass forming ability. The applicability of Fe-based amorphous coatings in typical environments where corrosion resistance and thermal stability are critical issues has been examined in terms of amorphous phase stability and glass-forming ability through a coordinated computational analysis and experimental validation. Similarly, a novel computational thermodynamics approach has been developed to explore the compositional sensitivity of glass-forming ability and thermal stability. Also, the synthesis and characterization of alloys with increased cross-section for thermal neutron capture will be outlined to demonstrate that through careful design of alloy composition it is possible to tailor the material properties of the thermally spray-formed amorphous coating to accommodate the challenges anticipated in typical nuclear waste storage applications over tens of thousands of years in a variety of corrosive environments.

  4. Elastic anharmonicity of bcc Fe and Fe-based random alloys from first-principles calculations

    NASA Astrophysics Data System (ADS)

    Li, Xiaoqing; Schönecker, Stephan; Zhao, Jijun; Vitos, Levente; Johansson, Börje

    2017-01-01

    We systematically investigate elastic anharmonic behavior in ferromagnetic body-centered cubic (bcc) Fe and Fe1 -xMx (M =Al , V, Cr, Co, or Ni) random alloys by means of density-functional simulations. To benchmark computational accuracy, three ab initio codes are used to obtain the complete set of second- and third-order elastic constants (TOECs) for bcc Fe. The TOECs of Fe1 -xMx alloys are studied employing the first-principles alloy theory formulated within the exact muffin-tin orbital method in combination with the coherent-potential approximation. It is found that the alloying effects on C111,C112 , and C123, which are governed by normal strains only, are more pronounced than those on C144,C166 , and C456, which involve shear strains. Remarkably, the magnitudes of all TOECs but C123 decrease upon alloying with Al, V, Cr, Co, or Ni. Using the computed TOECs, we study compositional effects on the pressure derivatives of the effective elastic constants (d Bi j/d P ), bulk (d K /d P ), and shear moduli (d G /d P ) and derive longitudinal acoustic nonlinearity parameters (β ). Our predictions show that the pressure derivatives of K and G decrease with x for all solute elements and reveal a strong correlation between the compositional trends on d K /d P and d G /d P arising from the fact that alloying predominantly alters d B11/d P . The sensitivity of d B11/d P to composition is attributed to intrinsic alloying effects as opposed to lattice parameter changes accompanying solute addition. For Fe and the considered Fe-based alloys, β along high-symmetry directions orders as β [111 ]>β [100 ]>β [110 ] , and alloying increases the directional anisotropy of β but reduces its magnitude.

  5. Bond Strength of Resin Cements to Noble and Base Metal Alloys with Different Surface Treatments

    PubMed Central

    Raeisosadat, Farkhondeh; Ghavam, Maryam; Hasani Tabatabaei, Masoomeh; Arami, Sakineh; Sedaghati, Maedeh

    2014-01-01

    Objectives: The bond strength of resin cements to metal alloys depends on the type of the metal, conditioning methods and the adhesive resins used. The purpose of this study was to evaluate the bond strength of resin cements to base and noble metal alloys after sand blasting or application of silano-pen. Materials and Method: Cylinders of light cured Z 250 composite were cemented to “Degubond 4” (Au Pd) and “Verabond” (Ni Cr) alloys by either RelyX Unicem or Panavia F2, after sandblasting or treating the alloys with Silano-Pen. The shear bond strengths were evaluated. Data were analyzed by three-way ANOVA and t tests at a significance level of P<0.05. Results: When the alloys were treated by Silano-Pen, RelyX Unicem showed a higher bond strength for Degubond 4 (P=0.021) and Verabond (P< 0.001). No significant difference was observed in the bond strength of Panavia F2 to the alloys after either of surface treatments, Degubond 4 (P=0.291) and Verabond (P=0.899). Panavia F2 showed a higher bond strength to sandblasted Verabond compared to RelyX Unicem (P=0.003). The bond strength of RelyX Unicem was significantly higher to Silano-Pen treated Verabond (P=0.011). The bond strength of the cements to sandblasted Degubond 4 showed no significant difference (P=0.59). RelyX Unicem had a higher bond strength to Silano-Pen treated Degubond 4 (P=0.035). Conclusion: The bond strength of resin cements to Verabond alloy was significantly higher than Degubond 4. RelyX Unicem had a higher bond strength to Silano-Pen treated alloys. Surface treatments of the alloys did not affect the bond strength of Panavia F2. PMID:25628687

  6. Application of Laser Design of Amorphous Feco-Based Alloys for the Formation of Amorphous-Crystalline Composites

    NASA Astrophysics Data System (ADS)

    Permyakova, I. E.; Glezer, A. M.; Ivanov, A. A.; Shelyakov, A. V.

    2016-01-01

    Morphological and fractographic features of change of FeCo-based amorphous alloy surfaces after laser treatment are studied in detail. Regimes of laser treatment that allow various degrees of crystallization of the examined alloys to be obtained, including thin (<1 •m) crystal layers on amorphous alloy surfaces, amorphous-crystalline composites, and completely crystalline alloys are adjusted. The Vickers hardness is estimated in zones of selective laser irradiation. The structure of the examined alloys attendant to the change of their mechanical properties is analyzed.

  7. First-principle study on some new spin-gapless semiconductors: The Zr-based quaternary Heusler alloys

    NASA Astrophysics Data System (ADS)

    Gao, Qiang; Xie, Huan-Huan; Li, Lei; Lei, Gang; Deng, Jian-Bo; Hu, Xian-Ru

    2015-09-01

    Employing first-principle calculations, we have investigated electronic and magnetic properties of the Zr-based quaternary Heusler alloys: ZrCoVIn, ZrFeVGe, ZrCoFeP, ZrCoCrBe and ZrFeCrZ (Z = In and Ga). Our calculation results show that all the alloys are (or nearly) spin-gapless semiconductors. The Slater-Pauling behaviours of these alloys are discussed as well. The cohesion energy and formation energy of these alloys have also been discussed, and the results indicate the studied alloys are stable.

  8. Optimization of Iron Cobalt-based Nanocomposite Alloys for High Induction and Increased Resistivity

    NASA Astrophysics Data System (ADS)

    Shen, Shen

    FeCo-based nanocrystalline soft magnetic materials are promising to provide high saturation induction, high Curie temperature and excellent soft magnetic properties for electric vehicle and high frequency power conversion applications. The increasing operation frequency of various inductive applications requires nanocomposite alloys with higher resistivity to suppress power losses. In this thesis, the method of measuring as-cast and annealed resistivity of melt-spun ribbon alloys by obtaining alloy densities was established. Archimedes method with deionized water as a medium was used to determine the density of crystalline alloys. A gas pycnometer using dry Helium gas as the medium exhibited improved accuracy in measuring the density of amorphous ribbon alloys compared to the conventional Archimedes method using a liquid medium. This method was applied to previously developed HITPERM (FeCoZrBCu) and HTX002 (FeCoBSiCu) type of alloys as well as carbon-containing (FeCoBCCu) alloys to guide composition adjustments pursuing for improved magnetic properties. In the HITPERM type of alloys, the composition dependence of as-cast resistivity was studied and simulated by Mott's two-current model with a rigid-band assumption which provided guidance for further adjusting alloy composition looking for higher resistivity. An alloy designed with the Fe:Co ratio for maximum as-cast resistivity and Hf as glass former exhibits low power loss values being approximately 1/4 of those measured on the alloy with the original HITPERM composition for a range of frequencies. The Al and Si additions were found effective to achieve a high resistivity of 151.9 muO·cm in the as-cast alloys but also lead to embrittlement of melt-spun ribbons. Composition adjustments on the HTX002 type of alloys which are castable in air and available for larger-scale production were also explored. Increasing the ferromagnetic late transition metal content by reducing glass formers was found effective to achieve

  9. Vacuum thermal-mechanical fatigue behavior of two iron-base alloys

    NASA Technical Reports Server (NTRS)

    Sheffler, K. D.

    1976-01-01

    The present study extends the concept of in-phase grain boundary ratcheting to two iron-base alloys (Type 304 stainless steel and A286 alloy) and provides a clearer interpretation of out-of-phase grain boundary ratcheting effects observed in the A286 alloy which does not exhibit geometric instability. Elevated-temperature low-cycle thermal-mechanical fatigue tests in an ion-pumped ultrahigh vacuum chamber revealed significant effects of frequency and combined temperature-strain cycling on fatigue life. In-phase thermal cycling (tension at high temperature and compression at low temperature) caused large life reductions in both materials due to grain boundary cavitation caused by unreversed grain boundary sliding (grain boundary ratcheting). Out-of-phase thermal cycling (tension at low temperature and compression at high temperature) also caused large cyclic life reductions in both materials. In the A286 alloy, out-of-phase life reductions are attributed to compressive ratcheting.

  10. Effect of High Temperature Aging on the Corrosion Resistance of Iron Based Amorphous Alloys

    SciTech Connect

    Day, S D; Haslam, J J; Farmer, J C; Rebak, R B

    2007-08-10

    Iron-based amorphous alloys can be more resistant to corrosion than polycrystalline materials of similar compositions. However, when the amorphous alloys are exposed to high temperatures they may recrystallize (or devitrify) thus losing their resistance to corrosion. Four different types of amorphous alloys melt spun ribbon specimens were exposed to several temperatures for short periods of time. The resulting corrosion resistance was evaluated in seawater at 90 C and compared with the as-prepared ribbons. Results show that the amorphous alloys can be exposed to 600 C for 1-hr. without losing the corrosion resistance; however, when the ribbons were exposed at 800 C for 1-hr. their localized corrosion resistance decreased significantly.

  11. Computational design of precipitation-strengthened titanium-nickel-based shape memory alloys

    NASA Astrophysics Data System (ADS)

    Bender, Matthew D.

    Motivated by performance requirements of future medical stent applications, experimental research addresses the design of novel TiNi-based, superelastic shape-memory alloys employing nanoscale precipitation strengthening to minimize accommodation slip for cyclic stability and to increase output stress capability for smaller devices. Using a thermodynamic database describing the B2 and L21 phases in the Al-Ni-Ti-Zr system, Thermo-Calc software was used to assist modeling the evolution of phase composition during 600°C isothermal evolution of coherent L21 Heusler phase precipitation from supersaturated TiNi-based B2 phase matrix in an alloy experimentally characterized by atomic-scale Local Electrode Atom Probe (LEAP) microanalysis. Based on measured evolution of the alloy hardness (under conditions stable against martensitic transformation) a model for the combined effects of solid solution strengthening and precipitation strengthening was calibrated, and the optimum particle size for efficient strengthening was identified. Thermodynamic modeling of the evolution of measured phase fractions and compositions identified the interfacial capillary energy enabling thermodynamic design of alloy microstructure with the optimal strengthening particle size. Extension of alloy designs to incorporate Pt and Pd for reducing Ni content, enhancing radiopacity, and improving manufacturability were considered using measured Pt and Pd B2/L2 1 partitioning coefficients. After determining that Pt partitioning greatly increases interphase misfit, full attention was devoted to Pd alloy designs. A quantitative approach to radiopacity was employed using mass attenuation as a metric. Radiopacity improvements were also qualitatively observed using x-ray fluoroscopy. Transformation temperatures were experimentally measured as a function of Al and Pd content. Redlich-Kister polynomial modeling was utilized for the dependence of transformation reversion Af temperature on B2 matrix phase

  12. Eutectic alloys. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Moore, P.

    1980-01-01

    These 250 abstracts from the international literature provide summaries of the preparation, treatments, composition and structure, and properties of eutectic alloys. Techniques for directional solidification and treatments including glazing, coating, and fiber reinforcement are discussed. In addition to the mechanical and thermal properties, the superconducting, corrosion, resistance, and thermionic emission and adsorption properties are described.

  13. Fracture behavior of nickel-based alloys in water

    SciTech Connect

    Mills, W.J.; Brown, C.M.

    1999-08-01

    The cracking resistance of Alloy 600, Alloy 690 and their welds, EN82H and EN52, was characterized by conducting J{sub IC} tests in air and hydrogenated water. All test materials displayed excellent toughness in air and high temperature water, but Alloy 690 and the two welds were severely embrittled in low temperature water. In 54 C water with 150 cc H{sub 2}/kg H{sub 2}O, J{sub IC} values were typically 70% to 95% lower than their air counterparts. The toughness degradation was associated with a fracture mechanism transition from microvoid coalescence to intergranular fracture. Comparison of the cracking response in water with that for hydrogen-precharged specimens tested in air demonstrated that susceptibility to low temperature cracking is due to hydrogen embrittlement of grain boundaries. The effects of water temperature, hydrogen content and loading rate on low temperature crack propagation were studied. In addition, testing of specimens containing natural weld defects and as-machined notches was performed to determine if low temperature cracking can initiate at these features. Unlike the other materials, Alloy 600 is not susceptible to low temperature cracking as the toughness in 54 C water remained high and a microvoid coalescence mechanism was operative in both air and water.

  14. Corrosion Mechanisms in Brazed Al-Base Alloy Sandwich Structures as a Function of Braze Alloy and Process Variables

    DTIC Science & Technology

    2013-02-01

    aeration solution for 8 hours. A concentrated Nitric acid (HNO3) dip for 15 seconds removed corrosion products prior to post-exposure SEM imaging [25...32 to -37°C under a liquid nitrogen chill at 11.2 V for one minute [10]. The electropolishing solution was a mixture of 1/3 concentrated Nitric acid ...DATES COVERED (From - To) 03/27/06-12/31/12 4. TITLE AND SUBTITLE Corrosion Mechanisms in Brazed Al-Base Alloy Sandwich Structures as a Function

  15. Pack cementation diffusion coatings for Fe-base and refractory alloys. Final report

    SciTech Connect

    Rapp, R.A.

    1998-03-10

    With the aid of computer-assisted calculations of the equilibrium vapor pressures in halide-activated cementation packs, processing conditions have been identified and experimentally verified for the codeposition of two or more alloying elements in a diffusion coating on a variety of steels and refractory metal alloys. A new comprehensive theory to treat the multi-component thermodynamic equilibria in the gas phase for several coexisting solid phases was developed and used. Many different processes to deposit various types of coatings on several types of steels were developed: Cr-Si codeposition for low- or medium-carbon steels, Cr-Al codeposition on low-carbon steels to yield either a Kanthal-type composition (Fe-25Cr-4Al in wt.%) or else a (Fe, Cr){sub 3}Al surface composition. An Fe{sub 3}Al substrate was aluminized to achieve an FeAl surface composition, and boron was also added to ductilize the coating. The developmental Cr-lean ORNL alloys with exceptional creep resistance were Cr-Al coated to achieve excellent oxidation resistance. Alloy wires of Ni-base were aluminized to provide an average composition of Ni{sub 3}Al for use as welding rods. Several different refractory metal alloys based on Cr-Cr{sub 2}Nb have been silicided, also with germanium additions, to provide excellent oxidation resistance. A couple of developmental Cr-Zr alloys were similarly coated and tested.

  16. Development and commercialization status of Fe{sub 3}Al-based intermetallic alloys

    SciTech Connect

    Sikka, V.K.; Viswanathan, S.; McKamey, C.G.

    1993-06-01

    The Fe{sub 3}Al-based intermetallic alloys offer unique benefits of excellent oxidation and sulfidation resistance, limited by poor room-temperature (RT) ductility and low high-temperature strength. Recent understanding of environmental effects on RT ductility of these alloys has led to progress toward taking commercial advantage of Fe{sub 3}Al-based materials. Cause of low ductility appears to be related to hydrogen formed from reaction with moisture. The environmental effect has been reduced in these intermetallic alloys by two methods. The first deals with producing a more hydrogen-resistant microstructure through thermomechanical processing, and the second dealed with compositional modification. The alloys showing reduced environmental effect have been melted and processed by many different methods. Laboratory and commercial heats have been characterized. Tests have been conducted in both air and controlled environments to quantify environmental effects on these properties. These materials were also tested for aqueous corrosion and resistance to stress corrosion cracking. Oxidation and sulfidation data were generated and effects of minor alloying elements on were also investigated. Several applications have been identified for the newly developed iron aluminides. Commercialization status of these alloys is described.

  17. Subtask 12F1: Effect of neutron irradiation on swelling of vanadium-base alloys

    SciTech Connect

    Chung, H.M.; Loomis, B.A.; Smith, D.L.

    1995-03-01

    The objective of this work is to determine the effects of neutron irradiation on the density change, void distribution, and microstructural evolution of vanadium-base alloys. Swelling behavior and microstructural evolution of V-Ti, V-Cr-Ti, and V-Ti-Si alloys were investigated after irradiation at 420-600{degrees}C up to 114 dpa. The alloys exhibited swelling maxima between 30 and 80 dpa and swelling decreased on irradiation to higher dpa. This is in contrast to the monotonically increasing swelling of binary alloys that contain Fe, Ni, Cr, Mo, W, and Si. Precipitation of dense Ti{sub 5}Si{sub 3} promotes good resistance to swelling of the Ti-containing alloys, and it was concluded that Ti of >3 wt.% and 400-1000 wppm Si are necessary to effectively suppress swelling. Swelling was minimal in V-4Cr-4Ti, identified as the most promising alloy based on good mechanical properties and superior resistance to irradiation embrittlement. 18 refs., 6 figs., 1 tab.

  18. Subtask 12F3: Effects of neutron irradiation on tensile properties of vanadium-base alloys

    SciTech Connect

    Loomis, B.A.; Chung, H.M.; Smith, D.L.

    1995-03-01

    The objective of this work is to determine the effects of neutron irradiation on the tensile properties of candidate vanadium-base alloys. Vanadium-base alloys of the V-Cr-Ti system are attractive candidates for use as structural materials in fusion reactors. The current focus of the U.S. program of research on these alloys is on the V-(4-6)Cr-(3-6)Ti-(0.05-0.1)Si (in wt.%) alloys. In this paper, we present experimental results on the effects of neutron irradiation on tensile properties of selected candidate alloys after irradiation at 400{degrees}C-600{degrees}C in lithium in fast fission reactors to displacement damages of up to {approx}120 displacement per atom (dpa). Effects of irradiation temperature and dose on yield and ultimate tensile strengths and uniform and total elongations are given for tensile test temperatures of 25{degrees}C, 420{degrees}C, 500{degrees}, and 600{degrees}C. Effects of neutron damage on tensile properties of the U.S. reference alloy V-4Cr-4Ti are examined in detail. 7 refs., 10 figs., 1 tab.

  19. Corrosion Performance of Fe-Based Alloys in Simulated Oxy-Fuel Environment

    NASA Astrophysics Data System (ADS)

    Zeng, Zuotao; Natesan, Ken; Cai, Zhonghou; Rink, David L.

    2017-02-01

    The long-term corrosion of Fe-based alloys in simulated oxy-fuel environment at 1023 K (750 °C) was studied. Detailed results are presented on weight change, scale thickness, internal penetration, microstructural characteristics of the corrosion products, and the cracking of scales for the alloys after exposure at 1023 K (750 °C) for up to 3600 hours. An incubation period during which the corrosion rate was low was observed for the alloys. After the incubation period, the corrosion accelerated, and the corrosion process followed linear kinetics. Effects of alloy, CaO-containing ash, and gas composition on the corrosion rate were also studied. In addition, synchrotron nanobeam X-ray analysis was employed to determine the phase and chemical composition of the oxide layers on the alloy surface. Results from these studies are being used to address the long-term corrosion performance of Fe-based alloys in various coal-ash combustion environments and to develop methods to mitigate high-temperature ash corrosion.

  20. Ni-Cr based dental alloys; Ni release, corrosion and biological evaluation.

    PubMed

    Reclaru, L; Unger, R E; Kirkpatrick, C J; Susz, C; Eschler, P-Y; Zuercher, M-H; Antoniac, I; Lüthy, H

    2012-08-01

    In the last years the dental alloy market has undergone dramatic changes for reasons of economy and biocompatibility. Nickel based alloys have become widely used substitute for the much more expensive precious metal alloys. In Europe the prevalence of nickel allergy is 10-15% for female adults and 1-3% for male adults. Despite the restrictions imposed by the EU for the protection of the general population in contact dermatitis, the use of Ni-Cr dental alloys is on the increase. Some questions have to be faced regarding the safety risk of nickel contained in dental alloys. We have collected based on many EU markets, 8 Ni-Cr dental alloys. Microstructure characterization, corrosion resistance (generalized, crevice and pitting) in saliva and the quantities of cations released in particular nickel and CrVI have been evaluated. We have applied non parametric classification tests (Kendall rank correlation) for all chemical results. Also cytotoxicity tests and an evaluation specific to TNF-alpha have been conducted. According to the obtained results, it was found that their behavior to corrosion was weak but that nickel release was high. The quantities of nickel released are higher than the limits imposed in the EU concerning contact with the skin or piercing. Surprisingly the biological tests did not show any cytotoxic effect on Hela and L929 cells or any change in TNF-alpha expression in monocytic cells. The alloys did not show any proinflammatory response in endothelial cells as demonstrated by the absence of ICAM-1 induction. We note therefore that there is really no direct relationship between the in vitro biological evaluation tests and the physico-chemical characterization of these dental alloys. Clinical and epidemiological studies are required to clarify these aspects.

  1. Coating of 6028 Aluminum Alloy Using Aluminum Piston Alloy and Al-Si Alloy-Based Nanocomposites Produced by the Addition of Al-Ti5-B1 to the Matrix Melt

    NASA Astrophysics Data System (ADS)

    El-Labban, Hashem F.; Abdelaziz, M.; Mahmoud, Essam R. I.

    2014-10-01

    The Al-12 pctSi alloy and aluminum-based composites reinforced with TiB2 and Al3Ti intermetallics exhibit good wear resistance, strength-to-weight ratio, and strength-to-cost ratio when compared to equivalent other commercial Al alloys, which make them good candidates as coating materials. In this study, structural AA 6028 alloy is used as the base material. Four different coating materials were used. The first one is Al-Si alloy that has Si content near eutectic composition. The second, third, and fourth ones are Al-6 pctSi-based reinforced with TiB2 and Al3Ti nano-particles produced by addition of Al-Ti5-B1 master alloy with different weight percentages (1, 2, and 3 pct). The coating treatment was carried out with the aid of GTAW process. The microstructures of the base and coated materials were investigated using optical microscope and scanning electron microscope equipped with EDX analyzer. Microhardness of the base material and the coated layer were evaluated using a microhardness tester. GTAW process results in almost sound coated layer on 6028 aluminum alloy with the used four coating materials. The coating materials of Al-12 pct Si alloy resulted in very fine dendritic Al-Si eutectic structure. The interface between the coated layer and the base metal was very clean. The coated layer was almost free from porosities or other defects. The coating materials of Al-6 pct Si-based mixed with Al-Ti5-B1 master alloy with different percentages (1, 2, and 3 pct), results in coated layer consisted of matrix of fine dendrite eutectic morphology structure inside α-Al grains. Many fine in situ TiAl3 and TiB2 intermetallics were precipitated almost at the grain boundary of α-Al grains. The amounts of these precipitates are increased by increasing the addition of Al-Ti5-B1 master alloy. The surface hardness of the 6028 aluminum alloy base metal was improved with the entire four used surface coating materials. The improvement reached to about 85 pct by the first type of

  2. Computer-Aided Design of Manufacturing Chain Based on Closed Die Forging for Hardly Deformable Cu-Based Alloys

    NASA Astrophysics Data System (ADS)

    Pietrzyk, Maciej; Kuziak, Roman; Pidvysots'kyy, Valeriy; Nowak, Jarosław; Węglarczyk, Stanisław; Drozdowski, Krzysztof

    2013-07-01

    Two copper-based alloys were considered, Cu-1 pct Cr and Cu-0.7 pct Cr-1 pct Si-2 pct Ni. The thermal, electrical, and mechanical properties of these alloys are given in the paper and compared to pure copper and steel. The role of aging and precipitation kinetics in hardening of the alloys is discussed based upon the developed model. Results of plastometric tests performed at various temperatures and various strain rates are presented. The effect of the initial microstructure on the flow stress was investigated. Rheologic models for the alloys were developed. A finite element (FE) model based on the Norton-Hoff visco-plastic flow rule was applied to the simulation of forging of the alloys. Analysis of the die wear for various processes of hot and cold forging is presented as well. A microstructure evolution model was implemented into the FE code, and the microstructure and mechanical properties of final products were predicted. Various variants of the manufacturing cycles were considered. These include different preheating schedules, hot forging, cold forging, and aging. All variants were simulated using the FE method and loads, die filling, tool wear, and mechanical properties of products were predicted. Three variants giving the best combination of forging parameters were selected and industrial trials were performed. The best manufacturing technology for the copper-based alloys is proposed.

  3. Fatigue properties of MA 6000E, a gamma-prime strengthened ODS alloy. [Oxide Dispersion Strengthened Ni-base alloy for gas turbine blade applications

    NASA Technical Reports Server (NTRS)

    Kim, Y. G.; Merrick, H. F.

    1980-01-01

    MA 6000E is a corrosion resistant, gamma-prime strengthened ODS alloy under development for advanced turbine blade applications. The high temperature, 1093 C, rupture strength is superior to conventional nickel-base alloys. This paper addresses the fatigue behavior of the alloy. Excellent properties are exhibited in low and high cycle fatigue and also thermal fatigue. This is attributed to a unique combination of microstructural features, i.e., a fine distribution of dispersed oxides and other nonmetallics, and the highly elongated grain structure which advantageously modify the deformation characteristics and crack initiation and propagation modes from that characteristic of conventional gamma-prime hardened superalloys.

  4. Wear Behavior Characterization for the Screening of Magnesium-based Alloys

    NASA Astrophysics Data System (ADS)

    McGhee, Paul R.

    This research is focused on the development of a systematic approach to evaluate the selection of materials for Mg-based alloys under wear conditions for biomedical applications. A pilot study was carried out in order to establish an accurate and reliable wear testing technique for magnesium and its alloys. This pilot study was conducted on aluminum (Al) and pure Mg, and showed that aluminum has a lower wear rate compared to Mg. The technique displayed good repeatability and high precision. For the main study, an ERC Mg-based alloy was to be compared with pure Mg. The same technique, when applied to pure Mg from a different vendor, produced up to 90% scatter in the data. Microstructure was studied to see if it had any correlation with the scatter. It was discovered that Mg ingot from the second vendor had outsized grains that contributed to the disproportional scatter in the wear data. Increasing the stroke length during wear testing was required so that the wear data would be averaged over multiple grains and reduces the variation in computed wear rates. In the main study, wear behavior and friction properties were analyzed using microtribometery, mechanical stylus profilometry, and microindentation. Surface morphology and microstructure were characterized using optical microscopy, scanning electron microscopy, and optical profilometry. For the main study, pure Mg and the ERC alloy as-cast and extruded conditions were compared. Pure Mg and MZCR alloys were extruded at 350°C and 400°C, respectively. Mg and MZCR alloy were cast at 350°C and heat treated at 510°C. The extruded specimens were divided into two sections, cross-section and longitudinal section. Wear tests were carried out under the applied normal load 0.5 N - 2.5 N in 0.5 N increments sliding at a rate of 0.2 Hz for 240 passes. The results show that the alloying and extrusion processes increase the hardness of the MZCR alloy significantly up to 80%. The as-cast MZCR has a lower resistance to wear

  5. Role of electronic perturbation in stability and activity of Pt-based alloy nanocatalysts for oxygen reduction.

    PubMed

    Hwang, Seung Jun; Kim, Soo-Kil; Lee, June-Gunn; Lee, Seung-Cheol; Jang, Jong Hyun; Kim, Pil; Lim, Tae-Hoon; Sung, Yung-Eun; Yoo, Sung Jong

    2012-12-05

    The design of electrocatalysts for polymer electrolyte membrane fuel cells must satsify two equally important fundamental principles: optimization of electrocatalytic activity and long-term stability in acid media (pH <1) at high potential (0.8 V). We report here a solution-based approach to the preparation of Pt-based alloy with early transition metals and realistic parameters for the stability and activity of Pt(3)M (M = Y, Zr, Ti, Ni, and Co) nanocatalysts for oxygen reduction reaction (ORR). The enhanced stability and activity of Pt-based alloy nanocatalysts in ORR and the relationship between electronic structure modification and stability were studied by experiment and DFT calculations. Stability correlates with the d-band fillings and the heat of alloy formation of Pt(3)M alloys, which in turn depends on the degree of the electronic perturbation due to alloying. This concept provides realistic parameters for rational catalyst design in Pt-based alloy systems.

  6. Challenges in Developing Oxidation-Resistant Chromium-Based Alloys for Applications Above 900°C

    NASA Astrophysics Data System (ADS)

    Dorcheh, Ali S.; Galetz, Mathias C.

    2016-11-01

    Chromium-based alloys are potential candidates for high-temperature structural applications. This article reviews the challenges of chromium and Cr-alloys used at temperatures higher than 900°C with the focus on their oxidation behavior. First, latest findings on the key environmental factors affecting the oxidation resistance such as volatilization and the impact of nitrogen in air are summarized. Oxidation resistance is addressed with regards to the effects of major alloying elements and reactive elements as well as its correlation with microstructure in multi-phase alloys. Secondly, the existing challenges to develop chromium alloys with enhanced high-temperature oxidation resistance are discussed. It is shown that volatilization and nitridation, the two major obstacles for the use of chromium alloys in air, can be significantly improved by alloy design.

  7. Computational studies of physical properties of Nb-Si based alloys

    SciTech Connect

    Ouyang, Lizhi

    2015-04-16

    The overall goal is to provide physical properties data supplementing experiments for thermodynamic modeling and other simulations such as phase filed simulation for microstructure and continuum simulations for mechanical properties. These predictive computational modeling and simulations may yield insights that can be used to guide materials design, processing, and manufacture. Ultimately, they may lead to usable Nb-Si based alloy which could play an important role in current plight towards greener energy. The main objectives of the proposed projects are: (1) developing a first principles method based supercell approach for calculating thermodynamic and mechanic properties of ordered crystals and disordered lattices including solid solution; (2) application of the supercell approach to Nb-Si base alloy to compute physical properties data that can be used for thermodynamic modeling and other simulations to guide the optimal design of Nb-Si based alloy.

  8. Metallurgical investigation into ductility dip cracking in nickel based alloys

    NASA Astrophysics Data System (ADS)

    Noecker, Fredrick F., II

    A690 is a Ni-Cr-Fe alloy with excellent resistance to general corrosion, localized corrosion and stress corrosion cracking. However, the companion filler metal for A690, EN52, has been shown by several researchers to be susceptible to ductility dip cracking (DDC), which limits its widespread use in joining applications. The Gleeble hot ductility test was used to evaluate the DDC susceptibility of A600 and A690, along with their filler metals, EN82H and EN52, throughout the heating and cooling portions of a simulated weld reheat thermal cycle. Both macroscopic mechanical measures and microscopic measures of DDC were quantified and compared. Water quenching was conducted at select temperatures for subsequent microstructural characterization. Microstructural and microchemical characterization was carried out using scanning electron microscopy, transmission electron microscopy and analytical electron microscopy (AEM) techniques. The greatest resistance to DDC was observed in A600 and A690 during heating, where no DDC cracks formed even when the samples were fractured. Both A690 and EN52 were found to form an intermediate on-cooling dip in ductility and UTS, which corresponded to an increase in ductility dip crack length. The hot ductility and cracking resistance of EN82H remained high throughout the entire thermal cycle. DDC susceptibility in both EN52 and EN82H decreased when the thermal cycle was modified to promote coarsening/precipitation of intergranular carbides prior to straining. AEM analysis did not reveal any sulfur or phosphorous intergranular segregation in EN52 at 1600°F on-heating, on-cooling or after a 60 second hold. The ductility dip cracks were preferentially oriented at a 45° to the tensile axis and were of a wedge type appearance, both of which are characteristic of grain boundary sliding (GBS). Samples with microstructures that consisted of coarsened carbides and/or serrated grain boundaries, which are expected to decrease GBS, were found to be

  9. PROCESS OF COATING METALS WITH BISMUTH OR BISMUTH-BASE ALLOYS

    DOEpatents

    Beach, J.G.

    1958-01-28

    A method is described for producing coatings of bismuth or bismuth alloys on a metal base. This is accomplished by electrodepositing the bismuth from an aqueous solution of BiCl/sub 3/, and by making the metal base alternately the cathode and the anode, the cathode periods being twice as long as the anode periods. In one embodiment a nickel coating is first electrodeposited in a known way, and this nickel plated piece is tae base upon which tae bismuth is deposited by the process of this patent. The coated piece is then heat treated to produce a homogeneous Ni--Bi alloy by diffusion.

  10. Joint effect of scandium and zirconium on the structure and the strength properties of Al-Mg2Si-Based alloys

    NASA Astrophysics Data System (ADS)

    Rokhlin, L. L.; Bochvar, N. R.; Tarytina, I. E.

    2015-09-01

    The joint effect of scandium and zirconium on the strength properties and the electrical resistivity of industrial Al-Mg2Si-based alloys has been studied. The additional alloying of Al-Mg2Si alloys with transition metals leads to substantial grain refinement of the aluminum solid-solution and, therefore, an increase in the strength properties of the industrial alloys.

  11. Microstructure Evaluation of Fe-BASED Amorphous Alloys Investigated by Doppler Broadening Positron Annihilation Technique

    NASA Astrophysics Data System (ADS)

    Lu, Wei; Huang, Ping; Wang, Yuxin; Yan, Biao

    2013-07-01

    Microstructure of Fe-based amorphous and nanocrystalline soft magnetic alloy has been investigated by X-ray diffraction (XRD), transmission electronic microscopy (TEM) and Doppler broadening positron annihilation technique (PAT). Doppler broadening measurement reveals that amorphous alloys (Finemet, Type I) which can form a nanocrystalline phase have more defects (free volume) than alloys (Metglas, Type II) which cannot form this microstructure. XRD and TEM characterization indicates that the nanocrystallization of amorphous Finemet alloy occurs at 460°C, where nanocrystallites of α-Fe with an average grain size of a few nanometers are formed in an amorphous matrix. With increasing annealing temperature up to 500°C, the average grain size increases up to around 12 nm. During the annealing of Finemet alloy, it has been demonstrated that positron annihilates in quenched-in defect, crystalline nanophase and amorphous-nanocrystalline interfaces. The change of line shape parameter S with annealing temperature in Finemet alloy is mainly due to the structural relaxation, the pre-nucleation of Cu nucleus and the nanocrystallization of α-Fe(Si) phase during annealing. This study throws new insights into positron behavior in the nanocrystallization of metallic glasses, especially in the presence of single or multiple nanophases embedded in the amorphous matrix.

  12. Nanostructure Characterization of Bismuth Telluride-Based Powders and Extruded Alloys by Various Experimental Methods

    NASA Astrophysics Data System (ADS)

    Vasilevskiy, D.; Bourbia, O.; Gosselin, S.; Turenne, S.; Masut, R. A.

    2011-05-01

    High-resolution transmission electron microscopy (HRTEM) observations of mechanically alloyed powders and bulk extruded alloys give experimental evidence of nanosized grains in bismuth telluride-based materials. In this study we combine HRTEM observations and x-ray diffraction (XRD) measurements, of both mechanically alloyed powders and extruded samples, with mechanical spectroscopy (MS) of extruded rods. Both HRTEM and XRD show that nanostructures with an average grain size near 25 nm can be achieved within 2 h of mechanical alloying from pure elements in an attritor-type milling machine. Residual strain orthogonal to the c-axis of powder nanoparticles has been evaluated at about 1.2% by XRD peak broadening. In contrast, XRD has been found unreliable for evaluation of grain size in highly textured extruded materials for which diffraction conditions are similar to those of single crystals, while MS appears promising for study of bulk extruded samples. Nanostructured extruded alloys at room temperature exhibit an internal friction (IF) background that is one order of magnitude higher than that of conventional zone-melted material with a grain size of several millimeters. IF as a function of sample temperature gives activation energies that are also different between bulk materials having nano- and millimeter-size grains, a result that is attributed to different creep mechanisms. Nanograin size, as well as orientation and volumetric proportion, provide valuable information for optimization of technological parameters of thermoelectric alloys and should be carefully cross-examined by various independent methods.

  13. Hot Corrosion of Nickel-Base Alloys in Biomass-Derived Fuel Simulated Atmosphere

    SciTech Connect

    Leyens, C.; Pint, B.A.; Wright, I.G.

    1999-02-28

    Biomass fuels are considered to be a promising renewable source of energy. However, impurities present in the fuel may cause corrosion problems with the materials used in the hot sections of gas turbines and only limited data are available so far. As part of the Advanced Turbine Systems Program initiated by the U.S. Department of Energy, the present study provides initial data on the hot corrosion resistance of different nickel-base alloys against sodium sulfate-induced corrosion as a baseline, and against salt compositions simulating biomass-derived fuel deposits. Single crystal nickel-superalloy Rene N5, a cast NiCrAlY alloy, a NiCoCrAlY alloy representing industrially used overlay compositions, and a model {beta}NiAl+Hf alloy were tested in 1h thermal cycles at 950 C with different salt coatings deposited onto the surfaces. Whereas the NiCoCrAlY alloy exhibited reasonable resistance against pure sodium sulfate deposits, the NiCrAiY alloy and Rene N5 were attacked severely. Although considered to be an ideal alumina former in air and oxygen at higher temperatures, {beta}NiAl+Hf also suffered from rapid corrosion attack at 950 C when coated with sodium sulfate. The higher level of potassium present in biomass fuels compared with conventional fuels was addressed by testing a NiCoCrAlY alloy coated with salts of different K/Na atomic ratios. Starting at zero Na, the corrosion rate increased considerably when sodium was added to potassium sulfate. In an intermediate region the corrosion rate was initially insensitive to the K/Na ratio but accelerated when very Na-rich compositions were deposited. The key driver for corrosion of the NiCoCrAlY alloy was sodium sulfate rather than potassium sulfate, and no simple additive or synergistic effect of combining sodium and potassium was found.

  14. Room temperature synthesis of Ni-based alloy nanoparticles by radiolysis.

    SciTech Connect

    Nenoff, Tina Maria; Berry, Donald T.; Lu, Ping; Leung, Kevin; Provencio, Paula Polyak; Stumpf, Roland Rudolph; Huang, Jian Yu; Zhang, Zhenyuan

    2009-09-01

    Room temperature radiolysis, density functional theory, and various nanoscale characterization methods were used to synthesize and fully describe Ni-based alloy nanoparticles (NPs) that were synthesized at room temperature. These complementary methods provide a strong basis in understanding and describing metastable phase regimes of alloy NPs whose reaction formation is determined by kinetic rather than thermodynamic reaction processes. Four series of NPs, (Ag-Ni, Pd-Ni, Co-Ni, and W-Ni) were analyzed and characterized by a variety of methods, including UV-vis, TEM/HRTEM, HAADF-STEM and EFTEM mapping. In the first focus of research, AgNi and PdNi were studied. Different ratios of Ag{sub x}- Ni{sub 1-x} alloy NPs and Pd{sub 0.5}- Ni{sub 0.5} alloy NP were prepared using a high dose rate from gamma irradiation. Images from high-angle annular dark-field (HAADF) show that the Ag-Ni NPs are not core-shell structure but are homogeneous alloys in composition. Energy filtered transmission electron microscopy (EFTEM) maps show the homogeneity of the metals in each alloy NP. Of particular interest are the normally immiscible Ag-Ni NPs. All evidence confirmed that homogeneous Ag-Ni and Pd-Ni alloy NPs presented here were successfully synthesized by high dose rate radiolytic methodology. A mechanism is provided to explain the homogeneous formation of the alloy NPs. Furthermore, studies of Pd-Ni NPs by in situ TEM (with heated stage) shows the ability to sinter these NPs at temperatures below 800 C. In the second set of work, CoNi and WNi superalloy NPs were attempted at 50/50 concentration ratios using high dose rates from gamma irradiation. Preliminary results on synthesis and characterization have been completed and are presented. As with the earlier alloy NPs, no evidence of core-shell NP formation occurs. Microscopy results seem to indicate alloying occurred with the CoNi alloys. However, there appears to be incomplete reduction of the Na{sub 2}WO{sub 4} to form the W

  15. Development of Al sbnd Ge base rheocast brazing alloys

    NASA Astrophysics Data System (ADS)

    Saint-Antonin, F.; Suéry, M.; Meneses, P.; Le Marois, G.; Moret, F.

    1996-10-01

    This study concerns the development of an aluminium—germanium rheocast brazing alloy able to join replaceable sacrificial protections onto permanently cooled substrates in the ITER divertor. The rheocast alloy must be solid at the in-service temperature (up to 350°C) and semi-solid, with a viscosity close to that of grease, in a wide range of temperature above: this last property will allow the in-situ replacement of the sacrificial components even on vertical surfaces. This paper describes the fabrication route of the rheocast and reports the mechanical characterisation both up to 400°C and in the semi-solid region. Moreover, the brazing process has been optimized to obtain sound joints. The surface, mechanical resistance and thermal stability of the Al sbnd Ge/Cu joint are presented. Successive brazing tests have been performed to show the feasibility to sacrificial parts removal and replacement.

  16. VANADIUM ALLOYS

    DOEpatents

    Smith, K.F.; Van Thyne, R.J.

    1959-05-12

    This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

  17. Crystallization in Fe- and Co-Based Amorphous Alloys Studied by In-Situ X-Ray Diffraction

    NASA Astrophysics Data System (ADS)

    Zhang, L. J.; Yu, P. F.; Cheng, H.; Zhang, M. D.; Liu, D. J.; Zhou, Z.; Jin, Q.; Liaw, P. K.; Li, G.; Liu, R. P.

    2016-12-01

    The amorphous alloys, Fe80Si20, Fe78Si9B13, and Fe4Co67Mo1.5Si16.5B11, were prepared by the spinning method in pure argon. The crystallization behaviors of the three amorphous alloys were researched by in-situ X-ray diffraction (XRD), and the crystallization activation energy was calculated, based on the results of differential scanning calorimetry. The crystallization mechanism of the Fe- and Co-based alloys was analyzed, based on the experimental data. The transformation kinetics was described in terms of Johnson-Mehl-Avrami kinetics, except that the Avrami exponent of the Fe78Si9B13 amorphous alloy annealed at 753 K (480 °C) was 4.12; the obtained values for the overall Avrami exponents of the other three amorphous alloys were below 1, as usually found for the Fe-Si amorphous alloys.

  18. Degradation mode survey of titanium-base alloys

    SciTech Connect

    Gdowski, G.E.; Ahluwalia, H.S.

    1995-01-30

    Of the materials reviewed, commercially pure titanium, Ti Gr 2, is the most susceptible to crevice corrosion. Ti Gr 7, 12, and 16 are likely to be resistant to crevice corrosion under the current expected Yucca Mountain repository conditions. Although Grade 7 has the greatest resistance to crevice corrosion it is also the most expensive. Although the possibility of sustained loads cracking exists, it has not yet been observed in a Ti alloys. For hydride precipitation to occur 100{degrees}C, the hydrogen concentration would need to be relatively high, much higher than the maximum amount of hydrogen allowed during the manufacture of ({alpha} Ti alloys (0.0 15 wt%). A large amount of (SCC) stress corrosion cracking data accumulated at SNL and BNL for the WIPP program and by the Canadian Waste Management Program on titanium grades 2 and 12 indicates that there is no SCC at naturally occurring potentials in various brines. Hydride-induced cracking of titanium is a possibility and therefore, further investigation of this phenomenon under credible repository conditions is warranted. One disadvantage of titanium and its alloys is that their strengths decrease rather rapidly with temperature. This is due to the strong temperature dependence of interstitial solute strengthening mechanisms. Ti Gr 12 and 16 are recommended for further consideration as candidate materials for high level nuclear waste containers.

  19. Mechanisms of cavitation erosion of TiAl-based titanium aluminide intermetallic alloys

    SciTech Connect

    Howard, R.L.; Ball, A.

    1996-08-01

    The modes and controlling mechanisms of cavitation erosion of plasma arc-melted TiAl-based titanium aluminide intermetallic alloys, Ti-52Al (at.%) and Ti-48Al-2Mn-2Nb (at.%) were studied and compared to those of the Ti{sub 3}Al-based alloy, Ti-25Al-10Nb-3V-1Mo (at.%) and other comparative materials. The accumulation of cavitation damage during the initial stages of cavitation erosion was monitored and the work hardening produced in steady state erosion conditions was measured on 5{degree} taper sections. The cavitation erosion resistance of the titanium cavitation erosion resistance of the TiAl-based titanium aluminide alloys compared to Ti-25Al-10Nb-3V-1Mo (at.%) is ascribed to their ability to twin and their greater work hardening ability during cavitation erosion.

  20. The strengthening mechanism of a nickel-based alloy after laser shock processing at high temperatures

    PubMed Central

    Li, Yinghong; Zhou, Liucheng; He, Weifeng; He, Guangyu; Wang, Xuede; Nie, Xiangfan; Wang, Bo; Luo, Sihai; Li, Yuqin

    2013-01-01

    We investigated the strengthening mechanism of laser shock processing (LSP) at high temperatures in the K417 nickel-based alloy. Using a laser-induced shock wave, residual compressive stresses and nanocrystals with a length of 30–200 nm and a thickness of 1 μm are produced on the surface of the nickel-based alloy K417. When the K417 alloy is subjected to heat treatment at 900 °C after LSP, most of the residual compressive stress relaxes while the microhardness retains good thermal stability; the nanocrystalline surface has not obviously grown after the 900 °C per 10 h heat treatment, which shows a comparatively good thermal stability. There are several reasons for the good thermal stability of the nanocrystalline surface, such as the low value of cold hardening of LSP, extreme high-density defects and the grain boundary pinning of an impure element. The results of the vibration fatigue experiments show that the fatigue strength of K417 alloy is enhanced and improved from 110 to 285 MPa after LSP. After the 900 °C per 10 h heat treatment, the fatigue strength is 225 MPa; the heat treatment has not significantly reduced the reinforcement effect. The feature of the LSP strengthening mechanism of nickel-based alloy at a high temperature is the co-working effect of the nanocrystalline surface and the residual compressive stress after thermal relaxation. PMID:27877617

  1. Development of Sn-based, low melting temperature Pb-free solder alloys.

    SciTech Connect

    Grant, Richard L.; Vianco, Paul Thomas; Rejent, Jerome Andrew

    2003-09-01

    Low temperature, Sn-based Pb-free solders were developed by making alloy additions to the starting material, 96.5Sn-3.5Ag (mass%). The melting behavior was determined using Differential Scanning Calorimetry (DSC). The solder microstructure was evaluated by optical microscopy and electron probe microanalysis (EPMA). Shear strength measurements, hardness tests, intermetallic compound (IMC) layer growth measurements, and solderability tests were performed on selected alloys. Three promising ternary alloy compositions and respective solidus temperatures were: 91.84Sn-3.33Ag-4.83Bi, 212 C; 87.5Sn-7.5Au-5.0Bi, 200 C; and 86.4Sn-5.1 Ag-8.5Au, 205 C. A quaternary alloy had the composition 86.8Sn-3.2Ag-5.0Bi-5.0Au and solidus temperature of 194 C The shear strength of this quaternary alloy was nearly twice that of the eutectic Sn-Pb solder. The 66Sn-5.0Ag-10Bi-5.0Au-101n-4.0Cu alloy had a solidus temperature of 178 C and good solderability on Cu. The lowest solidus temperature of 159 C was realized with the alloy 62Sn-5.0Ag-10Bi-4.0Au-101n-4.0Cu-5.0Ga. The contributing factor towards the melting point depression was the composition of the solid solution, Sn-based matrix phase of each solder.

  2. Novel Zn-based alloys for biodegradable stent applications: Design, development and in vitro degradation.

    PubMed

    Mostaed, E; Sikora-Jasinska, M; Mostaed, A; Loffredo, S; Demir, A G; Previtali, B; Mantovani, D; Beanland, R; Vedani, M

    2016-07-01

    The search for a degradable metal simultaneously showing mechanical properties equal or higher to that of stainless steel and uniform degradation is still an open challenge. Several magnesium-based alloys have been studied, but their degradation rate has proved to be too fast and rarely homogeneous. Fe-based alloys show appropriate mechanical properties but very low degradation rate. In the present work, four novel Zn-Mg and two Zn-Al binary alloys were investigated as potential biodegradable materials for stent applications. The alloys were developed by casting process and homogenized at 350°C for 48h followed by hot extrusion at 250°C. Tube extrusion was performed at 300°C to produce tubes with outer/inner diameter of 4/1.5mm as precursors for biodegradable stents. Corrosion tests were performed using Hanks׳ modified solution. Extruded alloys exhibited slightly superior corrosion resistance and slower degradation rate than those of their cast counterparts, but all had corrosion rates roughly half that of a standard purity Mg control. Hot extrusion of Zn-Mg alloys shifted the corrosion regime from localized pitting to more uniform erosion, mainly due to the refinement of second phase particles. Zn-0.5Mg is the most promising material for stent applications with a good combination of strength, ductility, strain hardening exponent and an appropriate rate of loss of mechanical integrity during degradation. An EBSD analysis in the vicinity of the laser cut Zn-0.5Mg tube found no grain coarsening or texture modification confirming that, after laser cutting, the grain size and texture orientation of the final stent remains unchanged. This work shows the potential for Zn alloys to be considered for stent applications.

  3. Irradiation effects in oxide dispersion strengthened (ODS) Ni-base alloys for Gen. IV nuclear reactors

    NASA Astrophysics Data System (ADS)

    Oono, Naoko; Ukai, Shigeharu; Kondo, Sosuke; Hashitomi, Okinobu; Kimura, Akihiko

    2015-10-01

    Oxide particle dispersion strengthened (ODS) Ni-base alloys are irradiated by using simulation technique (Fe/He dual-ion irradiation) to investigate the reliability to Gen. IV high-temperature reactors. The fine oxide particles with less than 10 nm in average size and approximately 8.0 × 1022 m-3 in number density remained after 101 dpa irradiation. The tiny helium bubbles were inside grains, not at grain-boundaries; it is advantageous effect of oxide particles which trap the helium atoms at the particle-matrix interface. Ni-base ODS alloys demonstrated their great ability to overcome He embrittlement.

  4. Theoretical study of surface plasmon resonance sensors based on 2D bimetallic alloy grating

    NASA Astrophysics Data System (ADS)

    Dhibi, Abdelhak; Khemiri, Mehdi; Oumezzine, Mohamed

    2016-11-01

    A surface plasmon resonance (SPR) sensor based on 2D alloy grating with a high performance is proposed. The grating consists of homogeneous alloys of formula MxAg1-x, where M is gold, copper, platinum and palladium. Compared to the SPR sensors based a pure metal, the sensor based on angular interrogation with silver exhibits a sharper (i.e. larger depth-to-width ratio) reflectivity dip, which provides a big detection accuracy, whereas the sensor based on gold exhibits the broadest dips and the highest sensitivity. The detection accuracy of SPR sensor based a metal alloy is enhanced by the increase of silver composition. In addition, the composition of silver which is around 0.8 improves the sensitivity and the quality of SPR sensor of pure metal. Numerical simulations based on rigorous coupled wave analysis (RCWA) show that the sensor based on a metal alloy not only has a high sensitivity and a high detection accuracy, but also exhibits a good linearity and a good quality.

  5. Effect of chromium and phosphorus on the physical properties of iron and titanium-based amorphous metallic alloy films

    NASA Technical Reports Server (NTRS)

    Distefano, S.; Rameshan, R.; Fitzgerald, D. J.

    1991-01-01

    Amorphous iron and titanium-based alloys containing various amounts of chromium, phosphorus, and boron exhibit high corrosion resistance. Some physical properties of Fe and Ti-based metallic alloy films deposited on a glass substrate by a dc-magnetron sputtering technique are reported. The films were characterized using differential scanning calorimetry, stress analysis, SEM, XRD, SIMS, electron microprobe, and potentiodynamic polarization techniques.

  6. Hydrogen absorption in uranium-based alloys with cubic γ -U structure

    NASA Astrophysics Data System (ADS)

    Havela, L.; Kim-Ngan, N.-T. H.

    2017-03-01

    UH3-type hydrides were formed by hydrogenation of splat-cooled U-based alloys upon applying high H2 pressures (>2.5 bar). Hydrogenation of U1‑x Mo x alloys (with x  ⩾  0.12 (12 at.% Mo) containing the cubic γ-U phase leads to a formation of nanocrystalline β-UH3, why those of U1‑x Zr x alloys (with x  ⩾15 at.% Zr) implies a pure α-UH3. The Curie temperature of hydride (UH3)0.85Mo0.15 reaches 200 K it may be the first U-based ferromagnet with such high T C. The results reflect the dominant U–H interaction. Invited talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8–12 November 2016, Ha Long City, Vietnam.

  7. Ti-based glassy alloys in Ti-Cu-Zr-Sn system

    NASA Astrophysics Data System (ADS)

    Wang, ZengRui; Dong, DanDan; Qiang, JianBing; Wang, Qing; Wang, YingMin; Dong, Chuang

    2013-07-01

    Bulk amorphous formation in Ti-Cu-based multicomponent alloys, free of Ni, Pd and Be elements, were studied using the cluster-plus-glue-atom model. The basic cluster formula was revealed as [Ti9Cu6]Cu3 to explain the best binary glass forming composition Ti50Cu50=Ti9Cu9, where the CN14 rhombi-dodecahedron Ti9Cu6 was the principal cluster in the devitrification phase CuTi. This basic cluster formula was further alloyed with Zr and Sn and a critical glass forming ability was reached at (Ti7.2Zr1.8)(Cu8.72Sn0.28) and (Ti7.2Zr1.8)(Cu8.45Sn0.55) up to 5 mm in diameter by suction casting, which was the largest in Ti-Cu-based and Ni-, Pd- and Be-free alloys.

  8. Laboratory evaluations of iron-based hard-facing alloys: A European study: Final report

    SciTech Connect

    Hofmann, P.J.; Friedrich, B.C.

    1988-06-01

    In order to identify suitable alternative materials for cobalt-base alloys used as hardfacing material for nuclear valves, three corrosion and wear-resistant iron-base alloys were investigated. In detail, comparisons were performed between Everit 50, Antinit DUR 300, Cenium Z 20 and Stellite 6 as to metallurgy, manufacturing properties, corrosive properties in simulated PWR and BWR coolant ( under no-flow and high-flow conditions with and without contamination), tribological properties (at different temperatures, contact pressure levels and for different material combinations) and mechanical properties. Data are given on suitable heat treatment, welding parameters and areas of application for each alloy under consideration. 24 refs., 87 figs., 4 tabs.

  9. Thermo-mechanical processing (TMP) of Ti-48Al-2Nb-2Cr based alloys

    SciTech Connect

    Fuchs, G.E.

    1995-02-01

    The effects of heat treatment and deformation processing on the microstructures and properties of {gamma}-TiAl based alloys produced by ingot metallurgy (I/M) and powder metallurgy (P/M) techniques were examined. The alloy selected for this work is the second generation {gamma}-TiAl based alloy -- Ti-48Al-2Nb-2Cr (at %). Homogenization of I/M samples was performed at a variety of temperatures, followed by hot working by isothermal forging. P/M samples were prepared from gas atomized powders, consolidated by both HIP and extrusion and some of the HIPed material was then hot worked by isothermal forging. The effects of processing, heat treatment and hot working on the microstructures and properties will be discussed.

  10. Indoor environmental corrosion of Ag-based alloys in the Egyptian Museum (Cairo, Egypt)

    NASA Astrophysics Data System (ADS)

    Ingo, G. M.; Angelini, E.; Riccucci, C.; de Caro, T.; Mezzi, A.; Faraldi, F.; Caschera, D.; Giuliani, C.; Di Carlo, G.

    2015-01-01

    In this study, we have investigated the indoor environmental corrosion of Ag-based alloys after long-term exposure in a showcase of an exhibition room and in the open atmosphere at the Egyptian Museum of Cairo (Egypt). In order to simulate the corrosion processes that occur at the surface of archaeological artefacts, Ag-based alloys with chemical composition, metallurgical features and micro-chemical structure similar to those of ancient alloys have been purposely produced as sacrificial reference samples. Our findings show that corrosion phenomena on alloy surface are mainly caused by environmental sulphur and chlorine containing species that react in different ways depending on the exhibition conditions and on the alloy composition. This approach allows to identify the degradation agents and mechanisms that really take place at the surface of objects similar to ancient artefacts without the necessity of sampling them. Moreover, it is possible to get useful indications for the safe storage or exhibition of silver archaeological artefacts, their cleaning and conservation.

  11. Cerium-Based, Intermetallic-Strengthened Aluminum Casting Alloy: High-Volume Co-product Development

    NASA Astrophysics Data System (ADS)

    Sims, Zachary C.; Weiss, D.; McCall, S. K.; McGuire, M. A.; Ott, R. T.; Geer, Tom; Rios, Orlando; Turchi, P. A. E.

    2016-07-01

    Several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanical properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.

  12. Cerium-based, intermetallic-strengthened aluminum casting alloy: High-volume co-product development

    DOE PAGES

    Sims, Zachary C.; Weiss, David; McCall, S. K.; ...

    2016-05-23

    Here, several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanicalmore » properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.« less

  13. Oral keratinocyte responses to nickel-based dental casting alloys in vitro.

    PubMed

    Wylie, C M; Davenport, A J; Cooper, P R; Shelton, R M

    2010-09-01

    Adverse reactions of oral mucosa to nickel-based dental casting alloys are probably due to corrosion metal ion release. We exposed H400 oral keratinocytes to two Ni-based dental alloys (Matchmate and Dsign10) as well as NiCl( 2) (1-40 microg/mL Ni(2+)). Alloy derived Ni(2+) media concentrations were determined. Direct culture on both alloys resulted in inhibited growth with a greater effect observed for Dsign10 (higher ion release). Indirect exposure of cells to conditioned media from Dsign10 negatively affected cell numbers (approximately 64% of control by 6 days) and morphology while Matchmate-derived media did not. Exposure to increasing NiCl(2) negatively affected cell growth and morphology, and the Granulocyte-macrophage colony-stimulating factor (GM-CSF) transcript was significantly up-regulated in cells following direct and indirect exposure to Dsign10. NiCl(2) exposure up-regulated all cytokine transcripts at 1 day. At day 6, IL-1beta and IL-8 transcripts were suppressed while GM-CSF and IL-11 increased with Ni(2+) dose. Accumulation of Ni(2+) ions from alloys in oral tissues may affect keratinocyte viability and chronic inflammation.

  14. Electron phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    DOE PAGES

    Samolyuk, German D.; Stocks, George Malcolm; Stoller, Roger E.

    2016-04-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states atmore » the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.« less

  15. Application of an alternative current in the processing of cobalt-containing nickel-based alloys

    NASA Astrophysics Data System (ADS)

    Kuznetsova, O. G.; Bryukvin, V. A.; Ermuratskii, P. V.; Paretskii, V. M.

    2010-06-01

    The versions of electrochemical processing of multialloyed nickel-based alloys are studied. These are the processing of the compositions (wt %) 57.0-70.0 Ni, 5.0-10.5 Co, 8.0-20.0 Cr, 1.2-5.0 Mo, 5.0-11.0 W, 2.0-2.9 Ti, 0.8-1.2 Nb, and 5.1-6.0 Al using an industrial-frequency alternating current and sulfuric acid electrolytes, namely, the dissolution of Ni-(10.0-15.0 wt %) Co alloys resulting from primary pyrometallurgical refining and direct dissolution. The rates of electrochemical dissolution of multialloyed nickel-based alloys under the action of a direct current and an industrial frequency (50 Hz) alternating current and the current efficiencies of the processes as functions of the temperatures and concentrations of sulfuric acid in electrolytes are compared. The optimum conditions of alloy dissolution are determined, and large laboratory studies are performed. A principal scheme of ac processing of the alloys is suggested.

  16. Neutronics Evaluation of Lithium-Based Ternary Alloys in IFE Blankets

    SciTech Connect

    Jolodosky, A.; Fratoni, M.

    2014-11-20

    Pre-conceptual fusion blanket designs require research and development to reflect important proposed changes in the design of essential systems, and the new challenges they impose on related fuel cycle systems. One attractive feature of using liquid lithium as the breeder and coolant is that it has very high tritium solubility and results in very low levels of tritium permeation throughout the facility infrastructure. However, lithium metal vigorously reacts with air and water and presents plant safety concerns. If the chemical reactivity of lithium could be overcome, the result would have a profound impact on fusion energy and associated safety basis. The overriding goal of this project is to develop a lithium-based alloy that maintains beneficial properties of lithium (e.g. high tritium breeding and solubility) while reducing overall flammability concerns. To minimize the number of alloy combinations that must be explored, only those alloys that meet certain nuclear performance metrics will be considered for subsequent thermodynamic study. The specific scope of this study is to evaluate the neutronics performance of lithium-based alloys in the blanket of an inertial confinement fusion (ICF) engine. The results of this study will inform the development of lithium alloys that would guarantee acceptable neutronics performance while mitigating the chemical reactivity issues of pure lithium.

  17. Cerium-based, intermetallic-strengthened aluminum casting alloy: High-volume co-product development

    SciTech Connect

    Sims, Zachary C.; Weiss, David; McCall, S. K.; McGuire, Michael A.; Ott, Ryan T.; Geer, Tom; Rios, Orlando; Turchi, P. A. E.

    2016-05-23

    Here, several rare earth elements are considered by-products to rare earth mining efforts. By using one of these by-product elements in a high-volume application such as aluminum casting alloys, the supply of more valuable rare earths can be globally stabilized. Stabilizing the global rare earth market will decrease the long-term criticality of other rare earth elements. The low demand for Ce, the most abundant rare earth, contributes to the instability of rare earth extraction. In this article, we discuss a series of intermetallic-strengthened Al alloys that exhibit the potential for new high-volume use of Ce. The castability, structure, and mechanical properties of binary, ternary, and quaternary Al-Ce based alloys are discussed. We have determined Al-Ce based alloys to be highly castable across a broad range of compositions. Nanoscale intermetallics dominate the microstructure and are the theorized source of the high ductility. In addition, room-temperature physical properties appear to be competitive with existing aluminum alloys with extended high-temperature stability of the nanostructured intermetallic.

  18. Fabrication methods and applications of microstructured gallium based liquid metal alloys

    NASA Astrophysics Data System (ADS)

    Khondoker, M. A. H.; Sameoto, D.

    2016-09-01

    This review contains a comparative study of reported fabrication techniques of gallium based liquid metal alloys embedded in elastomers such as polydimethylsiloxane or other rubbers as well as the primary challenges associated with their use. The eutectic gallium-indium binary alloy (EGaIn) and gallium-indium-tin ternary alloy (galinstan) are the most common non-toxic liquid metals in use today. Due to their deformability, non-toxicity and superior electrical conductivity, these alloys have become very popular among researchers for flexible and reconfigurable electronics applications. All the available manufacturing techniques have been grouped into four major classes. Among them, casting by needle injection is the most widely used technique as it is capable of producing features as small as 150 nm width by high-pressure infiltration. One particular fabrication challenge with gallium based liquid metals is that an oxide skin is rapidly formed on the entire exposed surface. This oxide skin increases wettability on many surfaces, which is excellent for keeping patterned metal in position, but is a drawback in applications like reconfigurable circuits, where the position of liquid metal needs to be altered and controlled accurately. The major challenges involved in many applications of liquid metal alloys have also been discussed thoroughly in this article.

  19. A new approach to the hazard classification of alloys based on transformation/dissolution.

    PubMed

    Skeaff, James M; Hardy, David J; King, Pierrette

    2008-01-01

    . For the other alloys, we developed a new critical surface area-toxic units (CSA-TU) approach to derive their GHS classification proposals. The CSA-TU approach can be readily applied to other multicomponent alloy systems, without the need to arbitrarily select a particular component among several as the determinant of toxicity. This paper shows how regulatory obligations, such as those mandated by REACH, can be met with a laboratory-based CSA-TU method for deriving hazard classification proposals for alloys, linking to attendant environmental protection management decisions. Drawing on T/D data derived from laboratory testing of the alloy itself, the CSA-TU approach can be applied to establish scientifically defensible decisions on hazard classification proposals for an alloy of interest. The resulting decisions can then be incorporated into environmental management measures in such jurisdictions as the European Union. Based on an approach developed specifically for alloys, the hazard classification decisions can be regarded as relevant, credible, and protective of the environment. Since alloys are usually more resistant to chemical attack than their components, this approach is a considerable improvement over the possibility provided for in the GHS of calculating a hazard classification level for an alloy from the classification levels of its components.

  20. Changes in the composition of a nickel-base partial denture casting alloy upon fusion and casting.

    PubMed

    Lewis, A J

    1975-02-01

    Three series of tensile test pieces were produced using a nickel-base partial denture casting alloy. For the first series induction heating was employed for melting the alloy, for the second a resistance crucible, and for the third an oxy-acetylene torch. In each series the same metal was cast sequentially five times, following which samples of the alloy were subjected to a ten element quantitative analysis to ascertain compositional changes associated with the three methods of fusion.

  1. Tensile and stress-rupture behavior of hafnium carbide dispersed molybdenum and tungsten base alloy wires

    NASA Technical Reports Server (NTRS)

    Yun, Hee Mann; Titran, Robert H.

    1993-01-01

    The tensile strain rate sensitivity and the stress-rupture strength of Mo-base and W-base alloy wires, 380 microns in diameter, were determined over the temperature range from 1200 K to 1600 K. Three molybdenum alloy wires; Mo + 1.1w/o hafnium carbide (MoHfC), Mo + 25w/o W + 1.1w/o hafnium carbide (MoHfC+25W) and Mo + 45w/o W + 1.1w/o hafnium carbide (MoHfC+45W), and a W + 0.4w/o hafnium carbide (WHfC) tungsten alloy wire were evaluated. The tensile strength of all wires studied was found to have a positive strain rate sensitivity. The strain rate dependency increased with increasing temperature and is associated with grain broadening of the initial fibrous structures. The hafnium carbide dispersed W-base and Mo-base alloys have superior tensile and stress-rupture properties than those without HfC. On a density compensated basis the MoHfC wires exhibit superior tensile and stress-rupture strengths to the WHfC wires up to approximately 1400 K. Addition of tungsten in the Mo-alloy wires was found to increase the long-term stress rupture strength at temperatures above 1400 K. Theoretical calculations indicate that the strength and ductility advantage of the HfC dispersed alloy wires is due to the resistance to recrystallization imparted by the dispersoid.

  2. Gamma prime precipitation mechanisms and solute partitioning in Ni-base alloys

    NASA Astrophysics Data System (ADS)

    Rojhirunsakool, Tanaporn

    Nickel-base superalloys have been emerged as materials for gas turbines used for jet propulsion and electricity generation. The strength of the superalloys depends mainly from an ordered precipitates of L12 structure, so called gamma prime (gamma') dispersed within the disorder gamma matrix. The Ni-base alloys investigated in this dissertation comprise both model alloy systems based on Ni-Al-Cr and Ni-Al-Co as well as the commercial alloy Rene N5. Classical nucleation and growth mechanism dominates the gamma' precipitation process in slowed-cooled Ni-Al-Cr alloys. The effect of Al and Cr additions on gamma' precipitate size distribution as well as morphological and compositional development of gamma' precipitates were characterized by coupling transmission electron microscopy (TEM) and 3D atom probe (3DAP) techniques. Rapid quenching Ni-Al-Cr alloy experiences a non-classical precipitation mechanism. Structural evolution of the gamma' precipitates formed and subsequent isothermal annealing at 600 °C were investigated by coupling TEM and synchrotron-based high-energy xray diffraction (XRD). Compositional evolution of the non-classically formed gamma' precipitates was determined by 3DAP and Langer, Bar-on and Miller (LBM) method. Besides homogeneous nucleation, the mechanism of heterogeneous gamma' precipitation involving a discontinuous precipitation mechanism, as a function of temperature, was the primary focus of study in case of the Ni-Al-Co alloy. This investigation coupled SEM, SEM-EBSD, TEM and 3DAP techniques. Lastly, solute partitioning and enrichment of minor refractory elements across/at the gamma/ gamma' interfaces in the commercially used single crystal Rene N5 superalloy was investigated by using an advantage of nano-scale composition investigation of 3DAP technique.

  3. Creep rupture testing of alloy 617 and A508/533 base metals and weldments.

    SciTech Connect

    Natesan, K.; Li, M.; Soppet, W.K.; Rink, D.L.

    2012-01-17

    The NGNP, which is an advanced HTGR concept with emphasis on both electricity and hydrogen production, involves helium as the coolant and a closed-cycle gas turbine for power generation with a core outlet/gas turbine inlet temperature of 750-1000 C. Alloy 617 is a prime candidate for VHTR structural components such as reactor internals, piping, and heat exchangers in view of its resistance to oxidation and elevated temperature strength. However, lack of adequate data on the performance of the alloy in welded condition prompted to initiate a creep test program at Argonne National Laboratory. In addition, Testing has been initiated to evaluate the creep rupture properties of the pressure vessel steel A508/533 in air and in helium environments. The program, which began in December 2009, was certified for quality assurance NQA-1 requirements during January and February 2010. Specimens were designed and fabricated during March and the tests were initiated in April 2010. During the past year, several creep tests were conducted in air on Alloy 617 base metal and weldment specimens at temperatures of 750, 850, and 950 C. Idaho National Laboratory, using gas tungsten arc welding method with Alloy 617 weld wire, fabricated the weldment specimens. Eight tests were conducted on Alloy 617 base metal specimens and nine were on Alloy 617 weldments. The creep rupture times for the base alloy and weldment tests were up to {approx}3900 and {approx}4500 h, respectively. The results showed that the creep rupture lives of weld specimens are much longer than those for the base alloy, when tested under identical test conditions. The test results also showed that the creep strain at fracture is in the range of 7-18% for weldment samples and were much lower than those for the base alloy, under similar test conditions. In general, the weldment specimens showed more of a flat or constant creep rate region than the base metal specimens. The base alloy and the weldment exhibited tertiary creep

  4. Effect of CeO{sub 2} addition on the properties of FeAl based alloy produced by mechanical alloying technique

    SciTech Connect

    Khaerudini, Deni S.; Muljadi,; Sardjono, P.; Tetuko, Anggito P.; Sebayang, P.; Ginting, M.

    2013-09-03

    Iron aluminides based on FeAl is notable for their low materials cost, ease of fabrication and good corrosion, suffixation and oxidation resistance. However, the application based on these unique properties still require the development of Fe-Al based alloy since it shows some drawbacks such as a lack of high temperature strength and low ductility. To improve the mechanical properties of FeAl based alloy, ceria (CeO{sub 2}) will be added to this compound. FeAl based alloy produced by the mechanical alloying (MA) technique. The developed specimens then assessed with respect to oxidation behaviour in high temperature, scale microstructure and hardness. The surface morphologies of the alloy evaluated and observed using scanning electron microscopy (SEM) with an energy dispersive X-ray spectroscopy (EDX). The phase structures of oxide scale formed on them were identified by X-ray diffraction (XRD). The results found that the FeAl intermetallic compound containing CeO{sub 2} 0.5 wt.% is less pores and CeO{sub 2} 1.0 wt.% is more homogen in powder and solid form, higher hardness and increase in their resistance to oxidation behaviour in high temperature compared with another percentage of CeO{sub 2}.

  5. Thermodynamics-Based Selection and Design of Creep-Resistant Cast Mg Alloys

    NASA Astrophysics Data System (ADS)

    Abaspour, Saeideh; Cáceres, Carlos H.

    2015-12-01

    Atomic level thermodynamics arguments that account for the generally weak age hardening response while suggesting that extending the athermal regime through short-range order (SRO) is a most feasible path to increasing the creep strength of many current alloys are presented. The tendency, or otherwise, of many solutes to develop SRO in dilute solid solutions rationalizes a number of observations in current multicomponent Mg alloys, and in particular the retention of linear strain hardening at high temperatures, while it disputes the viability of several micromechanisms often considered active, such as pinning of edge dislocations by mobile solute clouds, dynamic precipitation of thermally stable precipitates, or atomic size effects on the diffusivity. Potential solutes are sorted out and ranked based on the sign and value of the enthalpy of mixing of binary solid solutions using the Miedema phenomenological scheme. Due to their large negative energy of mixing and reasonable solubility (>1 at. pct) at ~473 K (~200 °C), Y and Gd appear as the best candidates to increase the creep strength through SRO, followed by Nd and Ca, in close agreement with data reported in the literature. The feasibility of enhancing the age hardening response through homogeneously nucleated, coherent precipitates, in some cases despite the negative energy of mixing of the alloy, or via internally ordered precipitates mimicking those present in Mg-Th alloys is considered by making parallels with the Al-Zn and the Al-Cu alloy systems. The possible optimization of the strengthening of high pressure die cast alloys combining SRO and intergranular eutectics or of heat-treatable cast alloys through internally ordered precipitates and SRO is discussed.

  6. Grain refinement of permanent mold cast copper base alloys. Final report

    SciTech Connect

    Sadayappan, M.; Thomson, J. P.; Elboujdaini, M.; Gu, G. Ping; Sahoo, M.

    2004-04-29

    control tool was proved in two foundries. The method can also correctly predict the onset of fading. The corrosion resistance of the grain refined alloys was measured in two solutions having different hydrogen activities, pH 6 and pH8, and compared with the base alloys. Potentiodynamic polarization and long term weight loss experiments were conducted to evaluate the corrosion resistance. Cu-Zn alloys were evaluated for dezincification. In general, the grain refined alloys performed marginally better than the base alloys.

  7. Dual Microstructure Heat Treatment of a Nickel-Base Disk Alloy Assessed

    NASA Technical Reports Server (NTRS)

    Gayda, John

    2002-01-01

    Gas turbine engines for future subsonic aircraft will require nickel-base disk alloys that can be used at temperatures in excess of 1300 F. Smaller turbine engines, with higher rotational speeds, also require disk alloys with high strength. To address these challenges, NASA funded a series of disk programs in the 1990's. Under these initiatives, Honeywell and Allison focused their attention on Alloy 10, a high-strength, nickel-base disk alloy developed by Honeywell for application in the small turbine engines used in regional jet aircraft. Since tensile, creep, and fatigue properties are strongly influenced by alloy grain size, the effect of heat treatment on grain size and the attendant properties were studied in detail. It was observed that a fine grain microstructure offered the best tensile and fatigue properties, whereas a coarse grain microstructure offered the best creep resistance at high temperatures. Therefore, a disk with a dual microstructure, consisting of a fine-grained bore and a coarse-grained rim, should have a high potential for optimal performance. Under NASA's Ultra-Safe Propulsion Project and Ultra-Efficient Engine Technology (UEET) Program, a disk program was initiated at the NASA Glenn Research Center to assess the feasibility of using Alloy 10 to produce a dual-microstructure disk. The objectives of this program were twofold. First, existing dual-microstructure heat treatment (DMHT) technology would be applied and refined as necessary for Alloy 10 to yield the desired grain structure in full-scale forgings appropriate for use in regional gas turbine engines. Second, key mechanical properties from the bore and rim of a DMHT Alloy 10 disk would be measured and compared with conventional heat treatments to assess the benefits of DMHT technology. At Wyman Gordon and Honeywell, an active-cooling DMHT process was used to convert four full-scale Alloy 10 disks to a dual-grain microstructure. The resulting microstructures are illustrated in the

  8. Magnetostriction and texture development in binary and ternary iron-gallium-based alloys

    NASA Astrophysics Data System (ADS)

    Mungsantisuk, Pinai

    2005-07-01

    The rare earth-free bcc FeGa-based alloys have an excellent combination of large low-field magnetostriction at room temperature, good mechanical properties, low hysteresis, and relatively low cost. These alloys are attractive for use in numerous sensor and actuator devices. The first part of this dissertation examines the influence of partial substitutions of Ga with Al, Be, Si, Ge, and Sn and partial substitutions of Fe with Co and Ni. The work involved directional growth of [001] textured rods of these ternary alloys using a Vertical Bridgman process, X-ray diffraction analysis, magnetic property measurements using vibrating sample magnetometry, and magnetostriction measurements. It is shown that substitution of Ga with Al can be made in FeGa alloys in certain composition ranges without a reduction in magnetostriction, and the additions of Si, Ge, and Sn results in a sharp decrease of magnetostriction. The addition or substitute of Be, due to its smaller size than Fe, resulted in only a slight decrease of magnetostriction. Substitution of Fe with Ni and Co results in a significant decrease of the magnetostriction. The work also evaluated the elastic properties of Fe-x at. % Ga and Fe-(20-y) at. % Ga-y at. % Al polycrystalline alloys using resonant ultrasound spectroscopy. Young's modulus obtained for FeGa and FeGaAl alloys were in the range of 110 to 170 GPa which are several times that for Terfenol-D alloys. Thus, large-force delivery is possible from FeGa alloy based actuators even though saturation strain values are smaller than that of Terfenol-D. The second part of this work examined the development of an inexpensive thermomechanical processing method to obtain [001] textured polycrystalline Fe-15 at. % Ga alloys. The processing involved a sequence of controlled hot rolling, two-stage warm rolling with intermediate anneal, and texture anneal. Roll forces measured and the extent of reductions feasible indicated an excellent processability. Texture evolution

  9. Superior Ballistic Impact Resistance Achieved by the Co-Base Alloy Haynes 25

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.; Noebe, Ronald D.; Revilock, Duane M.

    2003-01-01

    The fan case in a jet engine is required to contain a fan blade in the rare event of a blade loss during operation. Because of its function, the fan case is the largest structural component in high-bypass-ratio turbofan engines used in commercial aircraft. Therefore, the use of lighter and stronger materials would be advantageous in most engines and is practically a necessity in the latest generation of high-bypass engines. Small panels, 7 in. wide by 7 in. long, of a number of metallic alloys were impact tested at room temperature with a 0.50-caliber blunt-nose titanium alloy projectile at the NASA Glenn Research Center (ref. 1). These metallic systems included several high-strength aluminum (Al) alloys, Al-based laminates, aluminum metal matrix composites (Al-MMCs), nickel-base superalloys (Inconel 718 and 625), several titanium (Ti) alloys in different heat treated conditions, 304L stainless steel, a stainless-steel-based laminate, and a high strength steel (Nitronic 60). It was determined that a simple Co-base alloy (Haynes 25) had the best impact resistance on an areal weight basis. Haynes 25 was at least 10 percent better than IMI 550, the best titanium alloy tested to date, and it was far superior to other metals, especially at higher impact velocities (greater than 1100 ft/sec). Because this material could be ideal for fan containment applications in supersonic aircraft as a replacement for titanium, impact tests were also conducted at 371 oC and compared with results from alloys tested at elevated temperature under previous programs (i.e., Inconel 718, Ti-6242, M-152, Timetal 21S, and Aeromet 100). Although cobalt-base alloys are used in some high-temperature engine applications, to our knowledge they are not used in any containment systems. Advantages of cobalt over titanium include lower cost, easier processing, better high-temperature strength, and no fire hazard if tip rub occurs. Future plans include testing of lightweight sandwich panels with Haynes

  10. Gilbert damping and anisotropic magnetoresistance in iron-based alloys

    NASA Astrophysics Data System (ADS)

    Berger, L.

    2016-07-01

    We use the two-current model of Campbell and Fert to understand the compositional dependence of the Gilbert damping parameter in certain iron alloys. In that model, spin-up and spin-down carriers have different resistivities ρ↑ and ρ↓. We emphasize the part of the Gilbert parameter, called Gsf, generated by spin-flip interband processes. Both Gsf and the anisotropic magnetoresistance Δρ are proportional to the square of the spin-orbit parameter, and also proportional to ρ↑. In bcc alloys of iron with V, Cr, Mo, etc. solutes on the left of iron in the periodic table, ρ↑ is increased by a scattering resonance (Gomes and Campbell, 1966, 1968). Then ρ↑, Δρ, and Gsf all exhibit a peak at the same moderate concentration of the solute. We find the best fit between this theory and existing experimental data of Gilbert damping for Fe-V epitaxial films at room temperature (Cheng, 2006; Scheck et al., 2007). At room temperature, the predicted Gsf peak is masked by a background arising from non-flip intraband processes. At elevated temperatures, the peak is expected to become more prominent, and less hidden in the background.

  11. Intergranular tellurium cracking of nickel-based alloys in molten Li, Be, Th, U/F salt mixture

    NASA Astrophysics Data System (ADS)

    Ignatiev, Victor; Surenkov, Alexander; Gnidoy, Ivan; Kulakov, Alexander; Uglov, Vadim; Vasiliev, Alexander; Presniakov, Mikhail

    2013-09-01

    In Russia, R&D on Molten Salt Reactor (MSR) are concentrated now on fast/intermediate spectrum concepts which were recognized as long term alternative to solid fueled fast reactors due to their attractive features: strong negative feedback coefficients, easy in-service inspection, and simplified fuel cycle. For high-temperature MSR corrosion of the metallic container alloy in primary circuit is the primary concern. Key problem receiving current attention include surface fissures in Ni-based alloys probably arising from fission product tellurium attack. This paper summarizes results of corrosion tests conducted recently to study effect of oxidation state in selected fuel salt on tellurium attack and to develop means of controlling tellurium cracking in the special Ni-based alloys recently developed for molten salt actinide recycler and tranforming (MOSART) system. Tellurium corrosion of Ni-based alloys was tested at temperatures up to 750 °C in stressed and unloaded conditions in molten LiF-BeF2 salt mixture fueled by about 20 mol% of ThF4 and 2 mol% of UF4 at different [U(IV)]/[U(III)] ratios: 0.7, 4, 20, 100 and 500. Following Ni-based alloys (in mass%): HN80М-VI (Mo—12, Cr—7.6, Nb—1.5), HN80МТY (Mo—13, Cr—6.8, Al—1.1, Ti—0.9), HN80МТW (Mo—9.4, Cr—7.0, Ti—1.7, W—5.5) and ЕМ-721 (W—25.2, Cr—5.7, Ti—0.17) were used for the study in the corrosion facility. If the redox state the fuel salt is characterized by uranium ratio [U(IV)]/[U(III)] < 1 the alloys' specimens get a more negative stationary electrode potential than equilibrium electrode potentials of some uranium intermetallic compounds and alloys with nickel and molybdenum. This leads to spontaneous behavior of alloy formation processes on the specimens' surface and further diffusion of uranium deep into the metallic phase. As consequence of this films of intermetallic compounds and alloys of nickel, molybdenum, tungsten with uranium are formed on the alloys specimens' surface

  12. Boundary Engineering for the Thermoelectric Performance of Bulk Alloys Based on Bismuth Telluride.

    PubMed

    Mun, Hyeona; Choi, Soon-Mok; Lee, Kyu Hyoung; Kim, Sung Wng

    2015-07-20

    Thermoelectrics, which transports heat for refrigeration or converts heat into electricity directly, is a key technology for renewable energy harvesting and solid-state refrigeration. Despite its importance, the widespread use of thermoelectric devices is constrained because of the low efficiency of thermoelectric bulk alloys. However, boundary engineering has been demonstrated as one of the most effective ways to enhance the thermoelectric performance of conventional thermoelectric materials such as Bi2 Te3 , PbTe, and SiGe alloys because their thermal and electronic transport properties can be manipulated separately by this approach. We review our recent progress on the enhancement of the thermoelectric figure of merit through boundary engineering together with the processing technologies for boundary engineering developed most recently using Bi2 Te3 -based bulk alloys. A brief discussion of the principles and current status of boundary-engineered bulk alloys for the enhancement of the thermoelectric figure of merit is presented. We focus mainly on (1) the reduction of the thermal conductivity by grain boundary engineering and (2) the reduction of thermal conductivity without deterioration of the electrical conductivity by phase boundary engineering. We also discuss the next potential approach using two boundary engineering strategies for a breakthrough in the area of bulk thermoelectric alloys.

  13. Superplasticity of nickel-based alloys with micro- and sub-microcrystalline structures

    SciTech Connect

    Valitov, V.A.; Bewlay, B.P.; Mukhtarov, S.K.; Kaibyshev, O.A.; Gigliotti, M.F.X.

    2000-07-01

    This paper describes the generation of micro- and sub-microcrystalline structures in two Ni-based alloys that are typically strengthened by phases, such as {gamma}{prime} and {gamma}{double_prime}+{delta}. The relationship between the superplastic behavior and microstructure is discussed. High strain deformation processing in the temperature range of 0.9T{sub m} to 0.6T{sub m} results in reduction of the initial coarse-grained structure (> 100 {micro}m) to a range of structures including microcrystalline (MC) (grain size < 10 {micro}m) and sub-microcrystalline (SMC) (grain size < 1 {micro}m) with increasing deformation. The influence of alloy chemistry and constituent phases on dynamic and static recrystallization is considered, and their effect on grain refinement is described. Low-temperature and high strain rate superplasticity can be observed in dispersion-strengthened alloys with SMC structures. it was established that in dispersion-hardened Ni alloys with SMC structures, superplasticity can be observed at temperatures 200--250 C lower than in alloys with MC structure.

  14. Ignition characteristics of the iron-based alloy UNS S66286 in pressurized oxygen

    NASA Technical Reports Server (NTRS)

    Bransford, James W.; Billard, Phillip A.; Hurley, James A.; Mcdermott, Kathleen M.; Vazquez, Isaura

    1988-01-01

    The development of ignition and combustion in pressurized oxygen atmospheres was studied for the iron based alloy UNS S66286. Ignition of the alloy was achieved by heating the top surface of a cylindrical specimen with a continuous-wave CO2 laser. Two heating procedures were used. In the first, laser power was adjusted to maintain an approximately linear increase in surface temperature. In the second, laser power was periodically increased until autoheating (self-heating) was established. It was found that the alloy would autoheat to destruction from temperatures below the solidus temperature. In addition endothermic events occurred as the alloy was heated, many at reproducible temperatures. Many endothermic events occurred prior to abrupt increases in surface temperature and appeared to accelerate the rate of increase in specimen temperature to rates greater than what would be expected from increased temperature alone. It is suggested that the source of these endotherms may increase the oxidation rate of the alloy. Ignition parameters are defined and the temperatures at which these parameters occur are given for the oxygen pressure range of 1.72 to 13.8 MPa (25 to 2000 psia).

  15. The effects of seven alloying elements on the microstructure and stress-rupture behavior of nickle-base superalloys

    NASA Technical Reports Server (NTRS)

    Hull, D. R.; Miner, R. V.; Barrett, C. A.

    1984-01-01

    Seven alloying elements: Al, Cr, Ti, Nb, Ta, Mo, and W were added at two levels of concentration to produce a series of experimental nickel-base superalloys. Fifty alloys, representing a fraction of a 2 to the 7th power factorial design, were cast, tested, and analyzed. Each alloy's microstructure was characterized by phase extractions, X-ray diffraction, metallography and energy dispersive X-ray spectroscopy. Regression analysis was used to determine the effect of alloying element content on microstructure and stress-rupture life.

  16. Chemical durability and degradation mechanisms of HT9 based alloy waste forms with variable Zr content

    SciTech Connect

    Olson, L. N.

    2015-10-30

    In Corrosion studies were undertaken on alloy waste forms that can result from advanced electrometallurgical processing techniques to better classify their durability and degradation mechanisms. The waste forms were based on the RAW3-(URe) composition, consisting primarily of HT9 steel and other elemental additions to simulate nuclear fuel reprocessing byproducts. The solution conditions of the corrosion studies were taken from an electrochemical testing protocol, and meant to simulate conditions in a repository. The alloys durability was examined in alkaline and acidic brines.

  17. Microstructural and Mechanical Property Changes in the Ta-base T-111 Alloy with Aging

    SciTech Connect

    Leonard, Keith J; Busby, Jeremy T; Zinkle, Steven J

    2007-01-01

    The microstructural changes occurring in the Ta-base T-111 (Ta-8W-2Hf) alloy following 1100 h of aging at 1098, 1248 and 1398 K under inert atmosphere and its influence on the mechanical properties are reported. Microstructural evaluations were performed by optical, scanning electron microscopy and, for the first time, transmission electron microscopy. Electrical resistivity, hardness and tensile properties are compared between the as-annealed and aged samples. An increase in the amount of grain boundary precipitation with increasing aging temperature was found to decrease the electrical resistivity and material strength, leading to the eventual embrittlement of the alloy following aging at 1398 K.

  18. Niobium-aluminum base alloys having improved, high temperature oxidation resistance

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G. (Inventor); Stephens, Joseph R. (Inventor)

    1991-01-01

    A niobium-aluminum base alloy having improved oxidation resistance at high temperatures and consisting essentially of 48%-52% niobium, 36%-42% aluminum, 4%-10% chromium, 0%-2%, more preferably 1%-2%, silicon and/or tungsten with tungsten being preferred, and 0.1%-2.0% of a rare earth selected from the group consisting of yttrium, ytterbium and erbium. Parabolic oxidation rates, k.sub.p, at 1200.degree. C. range from about 0.006 to 0.032 (mg/cm.sup.2).sup.2 /hr. The new alloys also exhibit excellent cyclic oxidation resistance.

  19. Integrated Design and Rapid Development of Refractory Metal Based Alloys for Fossil Energy Applications

    SciTech Connect

    Dogan, O.N.; King, P.E.; Gao, M.C.

    2008-07-01

    One common barrier in the development of new technologies for future energy generating systems is insufficiency of existing materials at high temperatures (>1150oC) and aggressive atmospheres (e.g., steam, oxygen, CO2). To overcome this barrier, integrated design methodology will be applied to the development of refractory metal based alloys. The integrated design utilizes the multi-scale computational methods to design materials for requirements of processing and performance. This report summarizes the integrated design approach to the alloy development and project accomplishments in FY 2008.

  20. Void growth in high strength aluminium alloy single crystals: a CPFEM based study

    NASA Astrophysics Data System (ADS)

    Asim, Umair; Siddiq, M. Amir; Demiral, Murat

    2017-04-01

    High strength aluminium alloys that are produced through forming and joining processes are widely used in aerospace components. The ductile failure in these metals occurs due to the evolution and accumulation of microscopic defects, such as microvoids and shear bands. The present work investigates the underlying physical mechanisms during ductile failure by performing a rigorous, fully-validated, three-dimensional crystal plasticity, finite element study with aluminium alloy single crystals. Representative volume element (RVE) based simulations of single crystalline aluminium alloys (AA-5xxx) with different void geometries and orientations have been performed. Both local and nonlocal crystal plasticity constitutive models have been implemented in a finite element framework and are used to seek new insights into the interrelationships among void growth, initial porosity, initial void size, plastic anisotropy, and local/nonlocal size effects.

  1. First-principles based calculation of phonon spectrain substitutionally disordered alloys

    NASA Astrophysics Data System (ADS)

    Ghosh, Subhradip

    2013-02-01

    A first-principles based solution to the longstanding problem of calculating the phonon spectra in substitutional disordered alloys where strong force-constant disorder plays a significantrole is provided by a combination of first-principles electronicstructure tools, physically reasonable models of force-constant in alloyenvironments, and the Itinerant Coherent-Potntial Approximation (ICPA) by Ghosh and co-workers (S. Ghosh et. al., Physical Review B 66, 214206 (2002)). Wehere present the salient features of such hybrid formalism and illustrate its capability by the computation of phonon spectrafor disordered alloys with large size mismatch of end point components. We demonstrate that the consideration of local environments insize-mismatched alloys is crucial in understanding the microscopicinterplay of forces between various pairs of chemical specie and a correctdepiction of these is important for computation of accurate phonondispersions in these systems.

  2. The Degradation Interface of Magnesium Based Alloys in Direct Contact with Human Primary Osteoblast Cells

    PubMed Central

    Willumeit-Römer, Regine; Laipple, Daniel; Luthringer, Bérengère; Feyerabend, Frank

    2016-01-01

    Magnesium alloys have been identified as a new generation material of orthopaedic implants. In vitro setups mimicking physiological conditions are promising for material / degradation analysis prior to in vivo studies however the direct influence of cell on the degradation mechanism has never been investigated. For the first time, the direct, active, influence of human primary osteoblasts on magnesium-based materials (pure magnesium, Mg-2Ag and Mg-10Gd alloys) is studied for up to 14 days. Several parameters such as composition of the degradation interface (directly beneath the cells) are analysed with a scanning electron microscope equipped with energy dispersive X-ray and focused ion beam. Furthermore, influence of the materials on cell metabolism is examined via different parameters like active mineralisation process. The results are highlighting the influences of the selected alloying element on the initial cells metabolic activity. PMID:27327435

  3. Microstructures and Mechanical Properties of Two-Phase Alloys Based on NbCr(2)

    SciTech Connect

    Cady, C.M.; Chen, K.C.; Kotula, P.G.; Mauro, M.E.; Thoma, D.J.

    1998-12-07

    A two-phase, Nb-Cr-Ti alloy (bee+ C15 Laves phase) has been developed using several alloy design methodologies. In effort to understand processing-microstructure-property relationships, diffment processing routes were employed. The resulting microstructure and mechanical properties are discussed and compared. Plasma arc-melted samples served to establish baseline, . . . as-cast properties. In addition, a novel processing technique, involving decomposition of a supersaturated and metastable precursor phase during hot isostatic pressing (HIP), was used to produce a refined, equilibrium two-phase microstructure. Quasi-static compression tests as a ~ function of temperature were performed on both alloy types. Different deformation mechanisms were encountered based upon temperature and microstructure.

  4. Micromechanics-Based Damage Analysis of Fracture in Ti5553 Alloy with Application to Bolted Sectors

    NASA Astrophysics Data System (ADS)

    Bettaieb, Mohamed Ben; Van Hoof, Thibaut; Minnebo, Hans; Pardoen, Thomas; Dufour, Philippe; Jacques, Pascal J.; Habraken, Anne Marie

    2015-03-01

    A physics-based, uncoupled damage model is calibrated using cylindrical notched round tensile specimens made of Ti5553 and Ti-6Al-4V alloys. The fracture strain of Ti5553 is lower than for Ti-6Al-4V in the full range of stress triaxiality. This lower ductility originates from a higher volume fraction of damage sites. By proper heat treatment, the fracture strain of Ti5553 increases by almost a factor of two, as a result of a larger damage nucleation stress. This result proves the potential for further optimization of the damage resistance of the Ti5553 alloy. The damage model is combined with an elastoviscoplastic law in order to predict failure in a wide range of loading conditions. In particular, a specific application involving bolted sectors is addressed in order to determine the potential of replacing the Ti-6Al-4V by the Ti5553 alloy.

  5. Improved Warm-Working Process For An Iron-Base Alloy

    NASA Technical Reports Server (NTRS)

    Cone, Fred P.; Cryns, Brendan J.; Miller, John A.; Zanoni, Robert

    1992-01-01

    Warm-working process produces predominantly unrecrystallized grain structure in forgings of iron-base alloy A286 (PWA 1052 composition). Yield strength and ultimate strength increased, and elongation and reduction of area at break decreased. Improved process used on forgings up to 10 in. thick and weighing up to 900 lb.

  6. Heterogeneous Nb-Based Nuclei for the Grain Refinement of Al-Si Alloys

    NASA Astrophysics Data System (ADS)

    Bolzoni, L.; Hari Babu, N.

    2016-05-01

    Nb-based intermetallics are, generally, low-density high-temperature materials used for structural applications or cryogenic superconductors. In this work, we report the development of an Al(96)-Nb(2)-B(2) master alloy where in situ-formed micrometric Nb-based intermetallics (i.e. NbB2 and Al3Nb) are used for a completely different purpose: to promote the refinement of Al-Si alloys by taking advantage of enhanced heterogeneous nucleation. Nb-based intermetallics have the right characteristics, like low density, stability at high temperature and good lattice match, to be used as heterogeneous nucleation substrates. It was found that the addition of these Nb-based intermetallics permits the significant refinement of the microstructural features of the Al-Si alloy studied. The enhanced heterogeneous nucleation makes the grain size of the material far less dependent on the cooling rate, which is one of the critical parameters influencing the variation of the properties of the alloy.

  7. Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants

    PubMed Central

    Uddin, M S; Hall, Colin; Murphy, Peter

    2015-01-01

    Due to their excellent biodegradability characteristics, Mg and Mg-based alloys have become an emerging material in biomedical implants, notably for repair of bone as well as coronary arterial stents. However, the main problem with Mg-based alloys is their rapid corrosion in aggressive environments such as human bodily fluids. Previously, many approaches such as control of alloying materials, composition and surface treatments, have been attempted to regulate the corrosion rate. This article presents a comprehensive review of recent research focusing on surface treatment techniques utilised to control the corrosion rate and surface integrity of Mg-based alloys in both in vitro and in vivo environments. Surface treatments generally involve the controlled deposition of thin film coatings using various coating processes, and mechanical surfacing such as machining, deep rolling or low plasticity burnishing. The aim is to either make a protective thin layer of a material or to change the micro-structure and mechanical properties at the surface and sub-surface levels, which will prevent rapid corrosion and thus delay the degradation of the alloys. We have organised the review of past works on coatings by categorising the coatings into two classes—conversion and deposition coatings—while works on mechanical treatments are reviewed based on the tool-based processes which affect the sub-surface microstructure and mechanical properties of the material. Various types of coatings and their processing techniques under two classes of coating and mechanical treatment approaches have been analysed and discussed to investigate their impact on the corrosion performance, biomechanical integrity, biocompatibility and cell viability. Potential challenges and future directions in designing and developing the improved biodegradable Mg/Mg-based alloy implants were addressed and discussed. The literature reveals that no solutions are yet complete and hence new and innovative approaches

  8. Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants.

    PubMed

    Uddin, M S; Hall, Colin; Murphy, Peter

    2015-10-01

    Due to their excellent biodegradability characteristics, Mg and Mg-based alloys have become an emerging material in biomedical implants, notably for repair of bone as well as coronary arterial stents. However, the main problem with Mg-based alloys is their rapid corrosion in aggressive environments such as human bodily fluids. Previously, many approaches such as control of alloying materials, composition and surface treatments, have been attempted to regulate the corrosion rate. This article presents a comprehensive review of recent research focusing on surface treatment techniques utilised to control the corrosion rate and surface integrity of Mg-based alloys in both in vitro and in vivo environments. Surface treatments generally involve the controlled deposition of thin film coatings using various coating processes, and mechanical surfacing such as machining, deep rolling or low plasticity burnishing. The aim is to either make a protective thin layer of a material or to change the micro-structure and mechanical properties at the surface and sub-surface levels, which will prevent rapid corrosion and thus delay the degradation of the alloys. We have organised the review of past works on coatings by categorising the coatings into two classes-conversion and deposition coatings-while works on mechanical treatments are reviewed based on the tool-based processes which affect the sub-surface microstructure and mechanical properties of the material. Various types of coatings and their processing techniques under two classes of coating and mechanical treatment approaches have been analysed and discussed to investigate their impact on the corrosion performance, biomechanical integrity, biocompatibility and cell viability. Potential challenges and future directions in designing and developing the improved biodegradable Mg/Mg-based alloy implants were addressed and discussed. The literature reveals that no solutions are yet complete and hence new and innovative approaches are

  9. Exploring Half Metals in Li-based Half Heusler Alloys

    NASA Astrophysics Data System (ADS)

    Busemeyer, B.; Shaughnessy, M.; Fong, C. Y.

    2011-11-01

    We examine the electronic and magnetic properties of three Li-related half Heusler alloys, namely LiMnN, LiMnP, and LiMnSi in a structure close to the well-known zinc-blende structure in the attempt to search for new half metallic materials. If they do demonstrate half metallic properties, this will open new grounds for finding half metallic spintronic materials. Our results will furnish guidelines for future exploration of alkali-related half metals. Using the primitive cell LiMnSi is a half metal, while the pnictides are not. However when the conventional cell is used, we find that Li3Mn4P4 and Li3Mn4N4 are half metals. The physical reason for these two pnictides to be half metallic and for their magnetic moment per unit cell will be presented.

  10. Welding of NOREM iron-base hardfacing alloy wire products: Procedures for gas tungsten arc welding. Interim report

    SciTech Connect

    Phillps, M.K.; Findlan, S.J.

    1992-09-01

    New wire products have been successfully fabricated and procedures developed for automatic gas tungsten arc welding of wear-resistant NOREM iron-base alloys. Research demonstrated that sound multilayer welds on carbon and stainless steel substrates can be obtained without the use of preheating. These developments point to the advantages of NOREM alloys for field applications, such as valve refurbishing.

  11. Investigation of the Structure and Hardness of Quenched Sintered Materials Produced from Iron-Base Alloyed Powders (Astaloy E)

    NASA Astrophysics Data System (ADS)

    Ostovan, Farhad; Matori, Khamirul Amin; Yusoff, Hamdan Mohamed; Yunus, Robiah; Ariff, Azmah Hanim Mohamed; Toozandehjani, Meysam; Meschian, Mohammad Reza

    2016-11-01

    The effect of heat treatment on the microstructure, hardness and density of sintered (1129°C, 45 min) specimens of iron-base powder alloys containing 0.8 - 2.5% C, 2% Cu and additives of chromium- and molybdenum-alloyed Astaloy E iron powder is studied.

  12. 4-d magnetism: Electronic structure and magnetism of some Mo-based alloys

    NASA Astrophysics Data System (ADS)

    Liu, Yong; Bose, S. K.; Kudrnovský, J.

    2017-02-01

    We report results of a first-principles density-functional study of alloys of the 4 d -element Mo with group IV elements Si, Ge and Sn in zinc blende (ZB) and rock salt (RS) structures. The study was motivated by a similar study of ours based on the 4 d -element Tc, which showed the presence of half-metallic states with integer magnetic moment (1μB) per formula unit in TcX (X=C, Si, Ge) alloys. The calculated Curie temperatures for the ferromagnetic (FM) phases were low, around or less than 300 K. Searching for the possibility of 4 d -based alloys with higher Curie temperatures we have carried out the study involving the elements Mo, Ru and Rh. Among these the most promising case appears to be that involving the element Mo. Among the MoX (X=Si, Ge, Sn) alloys in ZB and RS structures, both MoGe and MoSn in ZB structures are found to possess an integer magnetic moment of 2μB per formula unit. ZB MoSn can be classified as a marginal/weak half-metal or a spin gapless semiconductor, while ZB MoGe would be best described as a gapless magnetic semiconductor. The calculated Curie temperatures are in the range 300-700 K. Considering the theoretical uncertainty in the band gaps due not only to the treatment of exchange and correlation effects, but density functional theory itself, these classifications may change somewhat, but both merit investigation from the viewpoint of potential spintronic application. Based on their higher Curie temperatures, Mo-based alloys would serve such purpose better than the previously reported Tc-based ones.

  13. Comparison of methanol and ethylene glycol oxidation by alloy and Core-Shell platinum based catalysts

    NASA Astrophysics Data System (ADS)

    Kaplan, D.; Burstein, L.; Rosenberg, Yu.; Peled, E.

    2011-10-01

    Two Core-Shell, RuCore-PtShell and IrNiCore-PtRuShell, XC72-supported catalyst were synthesized in a two-step deposition process with NaBH4 as reducing agent. The structure and composition of the Core-Shell catalysts were determined by EDS, XPS and XRD. Electrochemical characterization was performed with the use of cyclic voltammetry. Methanol and ethylene glycol oxidation activities of the Core-Shell catalysts (in terms of surface and mass activities) were studied at 80 °C and compared to those of a commercial Pt-Ru alloy catalyst. The surface activity of the alloy based catalyst, in the case of methanol oxidation, was found to be superior as a result of optimized surface Pt:Ru composition. However, the mass activity of the PtRu/IrNi/XC72 was higher than that of the alloy based catalyst by ∼50%. Regarding ethylene glycol oxidation, while the surface activity of the alloy based catalyst was slightly higher than that of the Pt/Ru/XC72 catalyst, the latter showed ∼66% higher activities in terms of A g-1 of Pt. These results show the potential of Core-Shell catalysts for reducing the cost of catalysts for DMFC and DEGFC.

  14. Evaluation of thiouracil-based adhesive systems for bonding cast silver-palladium-copper-gold alloy.

    PubMed

    Yamashita, Miyuki; Koizumi, Hiroyasu; Ishii, Takaya; Furuchi, Mika; Matsumura, Hideo

    2010-09-01

    This study aimed to evaluate the effect of adhesive systems based on a thiouracil monomer on bonding to silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy (Castwell M.C.12). Disk specimens were cast from the alloy and then air-abraded with alumina. The disks were bonded using six bonding systems selected from four primers and three luting materials. Shear bond strengths were determined both before and after thermocycling. Bond strength varied from 2.7 MPa to 32.0 MPa. Three systems based on a thiouracil monomer (MTU-6) showed durable bonding to the alloy, with post-thermocycling bond strengths of 22.4 MPa for the Metaltite (MTU-6) primer and Super-Bond, a tri-n-butylborane (TBB) initiated resin, 9.0 MPa for the Multi-Bond II resin, and 8.1 MPa for the Metaltite and Bistite II system. It can be concluded that a combination of thiouracil-based primer and TBB initiated resin is effective for bonding Ag-Pd-Cu-Au alloy.

  15. Effects of alloying on crack-tip deformation and shielding in gamma-based titanium aluminides

    SciTech Connect

    Mercer, C.; Soboyejo, W.O.

    1997-03-01

    Alloys based on gamma titanium aluminide (TiAl) are being considered as structural materials in a number of aerospace and automotive applications. The effects of ternary alloying of Ti-48Al (with 1--3 at.% Mn, Cr and V), and micro-alloying with 0.2% W, on crack-tip deformation and shielding mechanisms are discussed in this paper, for failure under cyclic (fatigue) loading. Crack-tip deformation mechanisms are elucidated by crack-tip transmission electron microscopy examination. Twin process zone dimensions and the degree of deformation-induced twinning are also determined via optical interference and transmission electron microscopy techniques, respectively. A micromechanics-based model is proposed for the estimation of twin toughening ratios under monotonic or cyclic loading. The model, which is based on non-linear fracture mechanics concepts, assumes an average smeared plastic stress distribution across the twin process zone. Differences in the resistance to crack growth in the ternary alloys are related to intrinsic microstructural features and crack-tip shielding phenomena.

  16. First-principles investigations of iron-based alloys and their properties

    NASA Astrophysics Data System (ADS)

    Limmer, Krista Renee

    Fundamental understanding of the complex interactions governing structure-property relationships in iron-based alloys is necessary to advance ferrous metallurgy. Two key components of alloy design are carbide formation and stabilization and controlling the active deformation mechanism. Following a first-principles methodology, understanding on the electronic level of these components has been gained for predictive modeling of alloys. Transition metal carbides have long played an important role in alloy design, though the complexity of their interactions with the ferrous matrix is not well understood. Bulk, surface, and interface properties of vanadium carbide, VCx, were calculated to provide insight for the carbide formation and stability. Carbon vacancy defects are shown to stabilize the bulk carbide due to increased V-V bonding in addition to localized increased V-C bond strength. The VCx (100) surface energy is minimized when carbon vacancies are at least two layers from the surface. Further, the Fe/VC interface is stabilized through maintaining stoichiometry at the Fe/VC interface. Intrinsic and unstable stacking fault energy, gammaisf and gamma usf respectively, were explicitly calculated in nonmagnetic fcc Fe-X systems for X = Al, Si, P, S, and the 3d and 4d transition elements. A parabolic relationship is observed in gamma isf across the transition metals with minimums observed for Mn and Tc in the 3d and 4d periods, respectively. Mn is the only alloying addition that was shown to decrease gamma isf in fcc Fe at the given concentration. The effect of alloying on gammausf also has a parabolic relationship, with all additions decreasing gammaisf yielding maximums for Fe and Rh.

  17. Breaking through the strength-ductility trade-off dilemma in an Al-Si-based casting alloy

    NASA Astrophysics Data System (ADS)

    Dang, B.; Zhang, X.; Chen, Y. Z.; Chen, C. X.; Wang, H. T.; Liu, F.

    2016-08-01

    Al-Si-based casting alloys have a great potential in various industrial applications. Common strengthening strategies on these alloys are accompanied inevitably by sacrifice of ductility, known as strength-ductility trade-off dilemma. Here, we report a simple route by combining rapid solidification (RS) with a post-solidification heat treatment (PHT), i.e. a RS + PHT route, to break through this dilemma using a commercial Al-Si-based casting alloy (A356 alloy) as an example. It is shown that yield strength and elongation to failure of the RS + PHT processed alloy are elevated simultaneously by increasing the cooling rate upon RS, which are not influenced by subsequent T6 heat treatment. Breaking through the dilemma is attributed to the hierarchical microstructure formed by the RS + PHT route, i.e. highly dispersed nanoscale Si particles in Al dendrites and nanoscale Al particles decorated in eutectic Si. Simplicity of the RS + PHT route makes it being suitable for industrial scaling production. The strategy of engineering microstructures offers a general pathway in tailoring mechanical properties of other Al-Si-based alloys. Moreover, the remarkably enhanced ductility of A356 alloy not only permits strengthening further the material by work hardening but also enables possibly conventional solid-state forming of the material, thus extending the applications of such an alloy.

  18. Breaking through the strength-ductility trade-off dilemma in an Al-Si-based casting alloy.

    PubMed

    Dang, B; Zhang, X; Chen, Y Z; Chen, C X; Wang, H T; Liu, F

    2016-08-09

    Al-Si-based casting alloys have a great potential in various industrial applications. Common strengthening strategies on these alloys are accompanied inevitably by sacrifice of ductility, known as strength-ductility trade-off dilemma. Here, we report a simple route by combining rapid solidification (RS) with a post-solidification heat treatment (PHT), i.e. a RS + PHT route, to break through this dilemma using a commercial Al-Si-based casting alloy (A356 alloy) as an example. It is shown that yield strength and elongation to failure of the RS + PHT processed alloy are elevated simultaneously by increasing the cooling rate upon RS, which are not influenced by subsequent T6 heat treatment. Breaking through the dilemma is attributed to the hierarchical microstructure formed by the RS + PHT route, i.e. highly dispersed nanoscale Si particles in Al dendrites and nanoscale Al particles decorated in eutectic Si. Simplicity of the RS + PHT route makes it being suitable for industrial scaling production. The strategy of engineering microstructures offers a general pathway in tailoring mechanical properties of other Al-Si-based alloys. Moreover, the remarkably enhanced ductility of A356 alloy not only permits strengthening further the material by work hardening but also enables possibly conventional solid-state forming of the material, thus extending the applications of such an alloy.

  19. Breaking through the strength-ductility trade-off dilemma in an Al-Si-based casting alloy

    PubMed Central

    Dang, B.; Zhang, X.; Chen, Y. Z.; Chen, C. X.; Wang, H. T.; Liu, F.

    2016-01-01

    Al-Si-based casting alloys have a great potential in various industrial applications. Common strengthening strategies on these alloys are accompanied inevitably by sacrifice of ductility, known as strength-ductility trade-off dilemma. Here, we report a simple route by combining rapid solidification (RS) with a post-solidification heat treatment (PHT), i.e. a RS + PHT route, to break through this dilemma using a commercial Al-Si-based casting alloy (A356 alloy) as an example. It is shown that yield strength and elongation to failure of the RS + PHT processed alloy are elevated simultaneously by increasing the cooling rate upon RS, which are not influenced by subsequent T6 heat treatment. Breaking through the dilemma is attributed to the hierarchical microstructure formed by the RS + PHT route, i.e. highly dispersed nanoscale Si particles in Al dendrites and nanoscale Al particles decorated in eutectic Si. Simplicity of the RS + PHT route makes it being suitable for industrial scaling production. The strategy of engineering microstructures offers a general pathway in tailoring mechanical properties of other Al-Si-based alloys. Moreover, the remarkably enhanced ductility of A356 alloy not only permits strengthening further the material by work hardening but also enables possibly conventional solid-state forming of the material, thus extending the applications of such an alloy. PMID:27502444

  20. Thermal cooling effects in the microstructure and properties of cast cobalt-base biomedical alloys

    NASA Astrophysics Data System (ADS)

    Vega Valer, Vladimir

    Joint replacement prosthesis is widely used in the biomedical field to provide a solution for dysfunctional human body joints. The demand for orthopedic knee and hip implants motivate scientists and manufacturers to develop novel materials or to increase the life of service and efficiency of current materials. Cobalt-base alloys have been investigated by various researchers for biomedical implantations. When these alloys contain Chromium, Molybdenum, and Carbon, they exhibit good tribological and mechanical properties, as well as excellent biocompatibility and corrosion resistance. In this study, the microstructure of cast Co-Cr-Mo-C alloy is purposely modified by inducing rapid solidification through fusion welding processes and solution annealing heat treatment (quenched in water at room temperature. In particular the effect of high cooling rates on the athermal phase transformation FCC(gamma)↔HCP(epsilon) on the alloy hardness and corrosion resistance is investigated. The Co-alloy microstructures were characterized using metallography and microscopy techniques. It was found that the as cast sample typically dendritic with dendritic grain sizes of approximately 150 microm and containing Cr-rich coarse carbide precipitates along the interdendritic boundaries. Solution annealing gives rise to a refined microstructure with grain size of 30 microm, common among Co-Cr-Mo alloys after heat treating. Alternatively, an ultrafine grain structure (between 2 and 10 microm) was developed in the fusion zone for specimens melted using Laser and TIG welding methods. When laser surface modification treatments were implemented, the developed solidification microstructure shifted from dendritic to a fine cellular morphology, with possible nanoscale carbide precipitates along the cellular boundaries. In turn, the solidified regions exhibited high hardness values (461.5HV), which exceeds by almost 110 points from the alloy in the as-cast condition. The amount of developed athermal

  1. Deformation behavior of NiAl-based alloys containing iron, cobalt, and hafnium

    NASA Technical Reports Server (NTRS)

    Pank, D. R.; Koss, D. A.; Nathal, M. V.

    1989-01-01

    The effects of alloying additions on the mechanical properties of the B2 intermetallic NiAl have been investigated in both the melt-spun ribbon and consolidated, bulk form. The study is based on a matrix of NiAl-based alloys with up to 20 at. pct Co and Fe additions and with reduced Al levels in the range of 30-40 at. pct. Characterization of the melt-spun ribbon by optical and scanning electron microscopy indicates a range of microstructures, including single-phase beta, gamma-prime necklace phase surrounding either martensitic or beta grains, and a mixture of equiaxed martensitic and gamma-prime grains. Bend ductility is present in melt-spun and annealed ribbons exhibiting the gamma-prime necklace structure and in a single-phase beta material containing 20 at. pct Fe. The analysis of compressive flow behavior on consolidated, bulk specimens indicates that the single-phase beta alloys exhibit a continuous decrease in yield stress with increasing temperature and profuse microcracking at grain boundaries. In contrast, multiphase (gamma-prime + either martensite or beta) alloys tend to display a peak in flow stress between 600 and 800 K, with little or no signs of microcracking. In general, heat treatments which convert the martensitic grains to beta + gamma-prime result in improved strength at temperatures above 600 K and better resistance to crack initiation.

  2. Biocorrosion behavior and cell viability of adhesive polymer coated magnesium based alloys for medical implants

    NASA Astrophysics Data System (ADS)

    Abdal-hay, Abdalla; Dewidar, Montasser; Lim, Jae Kyoo

    2012-11-01

    The present study was ultimately aimed to design novel adhesive biodegradable polymer, poly(vinyl acetate) (PVAc), coatings onto Mg based alloys by the dip-coating technique in order to control the degradation rate and enhance the biocompatibility of magnesium alloys. The influence of various solvents on PVAc surface topography and their protection of Mg alloys were dramatically studied in vitro. Electrochemical polarization, degradation, and PVAc film cytocompatibility were also tested. Our results showed that the solvent had a significant effect on coating quality. PVAc/dichloromethane solution showed a porous structure and solution concentration could control the porous size. The coatings prepared using tetrahydrofuran and dimethylformamide solvents are exceptional in their ability to generate porous morphology even at low polymer concentration. In general, the corrosion performance appears to be different on different PVAc-solvent system. Immersion tests illustrated that the porous morphology on PVAc stabilized corrosion rates. A uniform corrosion attack in artificial simulation body fluid was also exhibited. The cytocompatibility of osteoblast cells (MC3T3) revealed high adherence, proliferation, and survival on the porous structure of PVAc coated Mg alloy, which was not observed for the uncoated samples. This novel PVAc coating is a promising candidate for biodegradable implant materials, which might widen the use of Mg based implants.

  3. Industrial Environmental Testing of Coupons and Prototype Cylinders Coated With Iron-Based Amorphous Alloys

    SciTech Connect

    Rebak, R B; Aprigliano, L F; Day, S D; Lian, T; Farmer, J C

    2007-03-06

    Iron-based amorphous alloys are desirable for many industrial applications due to their dual capacity to resist corrosion and wear. These alloys may also contain a significant amount of boron which makes them candidates for criticality control, for example, in high-level nuclear waste disposition applications. The Fe-based amorphous alloys can be produced in powder form and then deposited using a HVOF thermal spray process on any surface that needs to be protected. For the current testing coupons of 316L stainless steels were coated with the amorphous alloy SAM2X5 and then tested for corrosion resistance in the salt-fog chamber and in other industrial environments. Prototype cylinders were also prepared and environmentally tested. One cylinder was 30-inch diameter, 88-inch long, and 3/8-inch thick. The coating thickness was 0.015 to 0.019-inch thick. The cylinder was in good condition after the test. Along the body of the cylinder only two pinpoint spot sized signs of rust were seen. Test results will be compared with the behavior of witness materials under the same tested conditions.

  4. Shape-Memory Effect and Pseudoelasticity in Fe-Mn-Based Alloys

    NASA Astrophysics Data System (ADS)

    La Roca, P.; Baruj, A.; Sade, M.

    2017-03-01

    Several Fe-based alloys are being considered as potential candidates for applications which require shape-memory behavior or superelastic properties. The possibility of using fabrication methods which are well known in the steel industry is very attractive and encourages a large amount of research in the field. In the present article, Fe-Mn-based alloys are mainly addressed. On the one hand, attention is paid to the shape-memory effect where the alloys contain (a) a maximum amount of Mn up to around 30 wt%, (b) several possible substitutional elements like Si, Cr, Ni, Co, and Nb and (c) some possible interstitial elements like C. On the other hand, superelastic alloys are analyzed, mainly the Fe-Mn-Al-Ni system discovered a few years ago. The most noticeable properties resulting from the martensitic transformations which are responsible for the mentioned properties, i.e., the fcc-hcp in the first case and the bcc-fcc in the latter are discussed. Selected potential applications are also analyzed.

  5. Shape-Memory Effect and Pseudoelasticity in Fe-Mn-Based Alloys

    NASA Astrophysics Data System (ADS)

    La Roca, P.; Baruj, A.; Sade, M.

    2016-12-01

    Several Fe-based alloys are being considered as potential candidates for applications which require shape-memory behavior or superelastic properties. The possibility of using fabrication methods which are well known in the steel industry is very attractive and encourages a large amount of research in the field. In the present article, Fe-Mn-based alloys are mainly addressed. On the one hand, attention is paid to the shape-memory effect where the alloys contain (a) a maximum amount of Mn up to around 30 wt%, (b) several possible substitutional elements like Si, Cr, Ni, Co, and Nb and (c) some possible interstitial elements like C. On the other hand, superelastic alloys are analyzed, mainly the Fe-Mn-Al-Ni system discovered a few years ago. The most noticeable properties resulting from the martensitic transformations which are responsible for the mentioned properties, i.e., the fcc-hcp in the first case and the bcc-fcc in the latter are discussed. Selected potential applications are also analyzed.

  6. The resistance to embrittlement by a hydrogen environment of selected high strength iron-manganese base alloys

    NASA Technical Reports Server (NTRS)

    Benson, R. B., Jr.; Kim, D. K.; Atteridge, D.; Gerberich, W. W.

    1974-01-01

    Fe-16Mn and Fe-25Mn base alloys, which had been cold worked to yield strength levels of 201 and 178 KSI, were resistant to degradation of mechanical properties in a one atmosphere hydrogen environment at ambient temperature under the loading conditions employed in this investigation. Transmission electron microscopy established that bands of epsilon phase martensite and fcc mechanical twins were formed throughout the fcc matrix when these alloys were cold worked. In the cold worked alloys a high density of crystal defects were observed associated with both types of strain induced structures, which should contribute significantly to the strengthening of these alloys. High strength iron base alloys can be produced which appear to have some resistance to degradation of mechanical properties in a hydrogen environment under certain conditions.

  7. Axial and torsional fatigue behavior of a cobalt-base alloy

    NASA Technical Reports Server (NTRS)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1991-01-01

    In order to develop elevated temperature multiaxial fatigue life prediction models for the wrought cobalt-base alloy, Haynes 188, a multiaxial fatigue data base is required. To satisfy this need, an elevated temperature experimental program on Haynes 188 consisting of axial, torsional, inphase and out of phase axial-torsional fatigue experiments was designed. Elevated temperature axial and torsional fatigue experiments were conducted under strain control on thin wall tubular specimens of Haynes 188 in air. Test results are given.

  8. Antimonide-Based Heterostructure p-Channel MOSFETs With Ni-Alloy Source/Drain

    DTIC Science & Technology

    2013-11-01

    IEEE ELECTRON DEVICE LETTERS, VOL. 34, NO. 11, NOVEMBER 2013 1367 Antimonide-Based Heterostructure p-Channel MOSFETs With Ni-Alloy Source/Drain Ze...density of 2×1012cm−2. Index Terms— Antimonide semiconductors, metal source/drain (S/D), Ni-GaSb, p-channel MOSFET . I. INTRODUCTION ANTIMONIDE-based...channel MOSFETs [3], [4], performance of III–V p- MOSFETs traditionally lagged behind. Recently, high-performance antimonide p- MOSFETs have been

  9. A nickel base alloy, NASA WAZ-16, with potential for gas turbine stator vane application

    NASA Technical Reports Server (NTRS)

    Waters, W. J.; Freche, J. C.

    1974-01-01

    A nickel-base superalloy based on the nickel-aluminum-tungsten system designated WAZ-16 was developed for high strength in the 1095 C (2000 F) to 1205 C (2200 F) range. Its tensile strength at the latter temperature is approximately 186 MN/m2 (27,000 psi). The combination of properties of the alloy suggest that it has potential as a stator vane material in advanced gas turbine engines.

  10. A Study of Fatigue Crack Propagation in Powder Metallurgy Hot Isotatically Pressed Nickel-Base Alloy.

    DTIC Science & Technology

    1984-01-31

    GR. Fatigue crack propagation, nickel-based superalloys, powder metallurgy, HIP , grain size influence t3ABSRACT (Continue on everse if neceaaary and...AD-A13L9290 ’A STUDY OF FATIGUE CRACK PROPAGATION IN POWDER METALLURGY HOT SOTATCAL.U) LEHIGHUNIVBETHEHEM PA DEPT 0F METALLURGY AND MATERIALS ENG...ClaaaficatioA Study of Fatigue Crack Propagation in Powder Metallurgy Hot Iso tatically Pressed Nickel-Base Alloy 12. PERSONAL AUTHOR(S) (Unclassified

  11. Helium-3 behavior in some nickel-based amorphous alloys

    SciTech Connect

    Unlu, K.; Vincent, D.H. )

    1992-04-01

    In this paper, helium trapping and release are studied for the nickel-rich amorphous alloys Ni{sub 75.1}Cr{sub 14.0}P{sub 10.1}C{sub 0.08}, Ni{sub 63.5}Zr{sub 36.5}, and Ni{sub 87.7}P{sub 12.3}. Helium-3 is introduced into the samples by implantation at 150-kev energy. The depth distribution of the implanted helium is observed by neutron depth profiling employing he reaction {sup 3}He(n,p){sup 3}H. Two implantation doses are used: 1 {times} 10{sup 16} and 5 {times} 10{sup 16} {sup 3}He/cm{sup 2}. Both implantation doses were chosen to be low enough to avoid blistering or flaking of the surface of the samples. The helium release behavior of the samples is studied by taking depth profiles after each annealing stage. At the same time, electron diffraction is used on parallel samples to observe the microstructure of the samples as a function of annealing. The annealing sequence for each material is broken off when electron diffraction indicated the existence of relatively large crystals in a sample. Only a small fraction of the implanted helium is released in most cases, and a clear correlation between helium release and recrystallization can be found in only one case.

  12. Densification behavior, nanocrystallization, and mechanical properties of spark plasma sintered Fe-based bulk amorphous alloys

    NASA Astrophysics Data System (ADS)

    Singh, Ashish Kumar

    Fe-based amorphous alloys are gaining increasing attention due to their exceptional wear and corrosion resistance for potential structural applications. Two major challenges that are hindering the commercialization of these amorphous alloys are difficulty in processing of bulk shapes (diameter > 10 mm) and lack of ductility. Spark plasma sintering (SPS) is evolving as a promising technique for processing bulk shapes of amorphous and nanocrystalline materials. The objective of this work is to investigate densification behavior, nanocrystallization, and mechanical properties of SPS sintered Fe-based amorphous alloys of composition Fe48Cr15Mo14Y2C15B6. SPS processing was performed in three distinct temperature ranges of amorphous alloys: (a) below glass transition temperature (Tg), (b) between Tg and crystallization temperature (Tx), and (c) above Tx. Punch displacement data obtained during SPS sintering was correlated with the SPS processing parameters such as temperature, pressure, and sintering time. Powder rearrangement, plastic deformation below T g, and viscous flow of the material between Tg and Tx were observed as the main densification stages during SPS sintering. Micro-scale temperature distributions at the point of contact and macro-scale temperature distribution throughout the sample during SPS of amorphous alloys were modeled. The bulk amorphous alloys are expected to undergo structural relaxation and nanocrystallization during SPS sintering. X-ray diffraction (XRD), small angle neutron scattering (SANS), and transmission electron microscopy (TEM) was performed to investigate the evolution of nanocrystallites in SPS sintered Fe-based bulk amorphous alloys. The SANS analysis showed significant scattering for the samples sintered in the supercooled region indicating local structural and compositional changes with the profuse nucleation of nano-clusters (~4 nm). Compression tests and microhardness were performed on the samples sintered at different

  13. Finger vein recognition based on local directional code.

    PubMed

    Meng, Xianjing; Yang, Gongping; Yin, Yilong; Xiao, Rongyang

    2012-11-05

    Finger vein patterns are considered as one of the most promising biometric authentication methods for its security and convenience. Most of the current available finger vein recognition methods utilize features from a segmented blood vessel network. As an improperly segmented network may degrade the recognition accuracy, binary pattern based methods are proposed, such as Local Binary Pattern (LBP), Local Derivative Pattern (LDP) and Local Line Binary Pattern (LLBP). However, the rich directional information hidden in the finger vein pattern has not been fully exploited by the existing local patterns. Inspired by the Webber Local Descriptor (WLD), this paper represents a new direction based local descriptor called Local Directional Code (LDC) and applies it to finger vein recognition. In LDC, the local gradient orientation information is coded as an octonary decimal number. Experimental results show that the proposed method using LDC achieves better performance than methods using LLBP.

  14. Finger Vein Recognition Based on Local Directional Code

    PubMed Central

    Meng, Xianjing; Yang, Gongping; Yin, Yilong; Xiao, Rongyang

    2012-01-01

    Finger vein patterns are considered as one of the most promising biometric authentication methods for its security and convenience. Most of the current available finger vein recognition methods utilize features from a segmented blood vessel network. As an improperly segmented network may degrade the recognition accuracy, binary pattern based methods are proposed, such as Local Binary Pattern (LBP), Local Derivative Pattern (LDP) and Local Line Binary Pattern (LLBP). However, the rich directional information hidden in the finger vein pattern has not been fully exploited by the existing local patterns. Inspired by the Webber Local Descriptor (WLD), this paper represents a new direction based local descriptor called Local Directional Code (LDC) and applies it to finger vein recognition. In LDC, the local gradient orientation information is coded as an octonary decimal number. Experimental results show that the proposed method using LDC achieves better performance than methods using LLBP. PMID:23202194

  15. Thermodynamic Considerations of Contamination by Alloying Elements of Remelted End-of-Life Nickel- and Cobalt-Based Superalloys

    NASA Astrophysics Data System (ADS)

    Lu, Xin; Matsubae, Kazuyo; Nakajima, Kenichi; Nakamura, Shinichiro; Nagasaka, Tetsuya

    2016-06-01

    Cobalt and nickel are high-value commodity metals and are mostly used in the form of highly alloyed materials. The alloying elements used may cause contamination problems during recycling. To ensure maximum resource efficiency, an understanding of the removability of these alloying elements and the controllability of some of the primary alloying elements is essential with respect to the recycling of end-of-life (EoL) nickel- and cobalt-based superalloys by remelting. In this study, the distribution behaviors of approximately 30 elements that are usually present in EoL nickel- and cobalt-based superalloys in the solvent metal (nickel, cobalt, or nickel-cobalt alloy), oxide slag, and gas phases during the remelting were quantitatively evaluated using a thermodynamic approach. The results showed that most of the alloying elements can be removed either in the slag phase or into the gas phase. However, the removal of copper, tin, arsenic, and antimony by remelting is difficult, and they remain as tramp elements during the recycling. On the other hand, the distribution tendencies of iron, molybdenum, and tungsten can be controlled by changing the remelting conditions. To increase the resource efficiency of recycling, preventing contamination by the tramp elements and identifying the alloying compositions of EoL superalloys are significantly essential, which will require the development of efficient prior alloy-sorting systems and advanced separation technologies.

  16. Comparison of Crevice Corrosion of Fe-Based Amorphous Metal and Crystalline Ni-Cr-Mo Alloy

    SciTech Connect

    Shan, X; Ha, H; Payer, J H

    2008-07-24

    The crevice corrosion behaviors of an Fe-based bulk metallic glass alloy (SAM1651) and a Ni-Cr-Mo crystalline alloy (C-22) were studied in 4M NaCl at 100 C with cyclic potentiodynamic polarization and constant potential tests. The corrosion damage morphologies, corrosion products and the compositions of corroded surfaces of these two alloys were studied with optical 3D reconstruction, Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Auger Electron Spectroscopy (AES). It was found that the Fe-based bulk metallic glass (amorphous alloy) SAM1651 had a more positive breakdown potential and repassivation potential than crystalline alloy C-22 in cyclic potentiodynamic polarization tests and required a more positive oxidizing potential to initiate crevice corrosion in constant potential test. Once crevice corrosion initiated, the corrosion propagation of C-22 was more localized near the crevice border compared to SAM1651, and SAM1651 repassivated more readily than C-22. The EDS results indicated that the corrosion products of both alloys contained high amount of O and were enriched in Mo and Cr. The AES results indicated that a Cr-rich oxide passive film was formed on the surfaces of both alloys, and both alloys were corroded congruently.

  17. HIGH-TEMPERATURE OXIDATION PROTECTIVE COATINGS FOR VANADIUM-BASE ALLOYS

    DTIC Science & Technology

    SILICIDES , SILICON COATINGS , TENSILE PROPERTIES, TITANIUM ALLOYS, YTTRIUM COMPOUNDS....CERAMIC COATINGS , *METAL COATINGS , *VANADIUM ALLOYS, ALLOYS, ANTIOXIDANTS, BORON COMPOUNDS, COATINGS , DEFORMATION, ELECTRODEPOSITION, FLAME SPRAYING...HEAT RESISTANT ALLOYS, HIGH TEMPERATURE, INTERMETALLIC COMPOUNDS, MECHANICAL PROPERTIES, NICKEL, NICKEL COMPOUNDS, NIOBIUM ALLOYS, OXIDES, PLATING

  18. Influence of the pulsed plasma treatment on the corrosion resistance of the low-alloy steel plated by Ni-based alloy

    NASA Astrophysics Data System (ADS)

    Dzhumaev, P.; Yakushin, V.; Kalin, B.; Polsky, V.; Yurlova, M.

    2016-04-01

    This paper presents investigation results of the influence of high temperature pulsed plasma flows (HTPPF) treatment on the corrosion resistance of low-alloy steel 0.2C-Cr-Mn- Ni-Mo cladded by the rapidly quenched nickel-based alloy. A technique that allows obtaining a defect-free clad layer with a good adhesion to the substrate was developed. It is shown that the preliminary treatment of steel samples by nitrogen plasma flows significantly increases their corrosion resistance in the conditions of intergranular corrosion test in a water solution of sulfuric acid. A change of the corrosion mechanism of the clad layer from intergranular to uniform corrosion was observed as a result of sub-microcrystalline structure formation and homogeneous distribution of alloying elements in the plasma treated surface layer thus leading to the significant increase of the corrosion resistance.

  19. The Effect of Solution Heat Treatment on an Advanced Nickel-Base Disk Alloy

    NASA Technical Reports Server (NTRS)

    Gayda, J.; Gabb, T. P.; Kantzos, P. T.

    2004-01-01

    Five heat treat options for an advanced nickel-base disk alloy, LSHR, have been investigated. These included two conventional solution heat treat cycles, subsolvus/oil quench and supersolvus/fan cool, which yield fine grain and coarse grain microstructure disks respectively, as well as three advanced dual microstructure heat treat (DMHT) options. The DMHT options produce disks with a fine grain bore and a coarse grain rim. Based on an overall evaluation of the mechanical property data, it was evident that the three DMHT options achieved a desirable balance of properties in comparison to the conventional solution heat treatments for the LSHR alloy. However, one of the DMHT options, SUB/DMHT, produced the best set of properties, largely based on dwell crack growth data. Further evaluation of the SUB/DMHT option in spin pit experiments on a generic disk shape demonstrated the advantages and reliability of a dual grain structure at the component level.

  20. Microstructural Evolution During Friction Stir Welding of Mild Steel and Ni-Based Alloy 625

    NASA Astrophysics Data System (ADS)

    Fernandez, Johnnatan Rodriguez; Ramirez, Antonio J.

    2017-01-01

    Microstructure evolution during friction stir welding (FSW) of mild steel and Ni-based alloy 625 was studied. Regarding the Ni-based alloy, the welding process led to grain refinement caused by discontinuous and continuous dynamic recrystallization, where bulging of the pre-existing grains and subgrain rotation were the primary mechanisms of recrystallization. In the steel, discontinuous dynamic recrystallization was identified as the recovery process experienced by the austenite. Simple shear textures were observed in the regions affected by the deformation of both materials. Although the allotropic transformation obscured the deformation history, the thermo-mechanically affected zone was identified in the steel by simple shear texture components. A new methodology for the study of texture evolution based on rotations of the slip systems using pole figures is presented as an approximation to describe the texture evolution in FSW.

  1. Microstructural Evolution During Friction Stir Welding of Mild Steel and Ni-Based Alloy 625

    NASA Astrophysics Data System (ADS)

    Fernandez, Johnnatan Rodriguez; Ramirez, Antonio J.

    2017-03-01

    Microstructure evolution during friction stir welding (FSW) of mild steel and Ni-based alloy 625 was studied. Regarding the Ni-based alloy, the welding process led to grain refinement caused by discontinuous and continuous dynamic recrystallization, where bulging of the pre-existing grains and subgrain rotation were the primary mechanisms of recrystallization. In the steel, discontinuous dynamic recrystallization was identified as the recovery process experienced by the austenite. Simple shear textures were observed in the regions affected by the deformation of both materials. Although the allotropic transformation obscured the deformation history, the thermo-mechanically affected zone was identified in the steel by simple shear texture components. A new methodology for the study of texture evolution based on rotations of the slip systems using pole figures is presented as an approximation to describe the texture evolution in FSW.

  2. Electron phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    SciTech Connect

    Samolyuk, German D.; Stocks, George Malcolm; Stoller, Roger E.

    2016-04-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.

  3. Microstructural characterization of a new mechanically alloyed Ni-base ODS superalloy powder

    SciTech Connect

    Seyyed Aghamiri, S.M.; Shahverdi, H.R.; Ukai, S.; Oono, N.; Taya, K.; Miura, S.; Hayashi, S.; Okuda, T.

    2015-02-15

    The microstructure of a new Ni-base oxide dispersion strengthened superalloy powder was studied for high temperature gas turbine applications after the mechanical alloying process. In this study, an atomized powder with a composition similar to the CMSX-10 superalloy was mechanically alloyed with yttria and Hf powders. The mechanically alloyed powder included only the supersaturated solid solution γ phase without γ′ and yttria provided by severe plastic deformation, while after the 3-step aging, the γ′ phase was precipitated due to the partitioning of Al and Ta to the γ′ and Co, Cr, Re, W, and Mo to the γ phase. Mechanical alloying modified the morphology of γ′ to the new coherent γ–γ′ nanoscale lamellar structure to minimize the elastic strain energy of the precipitation, which yielded a low lattice misfit of 0.16% at high temperature. The γ′ lamellae aligned preferentially along the elastically soft [100] direction. Also, the precipitated oxide particles were refined in the γ phase by adding Hf from large incoherent YAlO{sub 3} to fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles with the average size of 7 nm and low interparticle spacing of 76 nm. - Highlights: • A new Ni-base ODS superalloy powder was produced by mechanical alloying. • The nanoscale γ–γ′ lamellar structure was precipitated after the aging treatment. • Fine semi-coherent Y{sub 2}Hf{sub 2}O{sub 7} oxide particles were precipitated by addition of Hf.

  4. Failure analysis of AZ31 magnesium alloy sheets based on the extended GTN damage model

    NASA Astrophysics Data System (ADS)

    Wang, Rui-ze; Chen, Zhang-hua; Li, Yu-jie; Dong, Chao-fang

    2013-12-01

    Based on the Gurson-Tvergaard-Needleman (GTN) model and Hill's quadratic anisotropic yield criterion, a combined experimental-numerical study on fracture initiation in the process of thermal stamping of Mg alloy AZ31 sheets was carried out. The aim is to predict the formability of thermal stamping of the Mg alloy sheets at different temperatures. The presented theoretical framework was implemented into a VUMAT subroutine for ABAQUS/EXPLICIT. Internal damage evolution due to void growth and coalescence developed at different temperatures in the Mg alloy sheets was observed by scanning electron microscopy (SEM). Moreover, the thermal effects on the void growth, coalescence, and fracture behavior of the Mg alloy sheets were analyzed by the extended GTN model and forming limit diagrams (FLD). Parameters employed in the GTN model were determined from tensile tests and numerical iterative computation. The distribution of major and minor principal strains in the specimens was determined from the numerical results. Therefore, the corresponding forming limit diagrams at different stress levels and temperatures were drawn. The comparison between the predicted forming limits and the experimental data shows a good agreement.

  5. Urinary levels of nickel and chromium associated with dental restoration by nickel-chromium based alloys.

    PubMed

    Chen, Bo; Xia, Gang; Cao, Xin-Ming; Wang, Jue; Xu, Bi-Yao; Huang, Pu; Chen, Yue; Jiang, Qing-Wu

    2013-03-01

    This paper aims to investigate if the dental restoration of nickel-chromium based alloy (Ni-Cr) leads to the enhanced excretions of Ni and Cr in urine. Seven hundred and ninety-five patients in a dental hospital had single or multiple Ni-Cr alloy restoration recently and 198 controls were recruited to collect information on dental restoration by questionnaire and clinical examination. Urinary concentrations of Ni and Cr from each subject were measure by graphite furnace atomic absorption spectrometry. Compared to the control group, the urinary level of Ni was significantly higher in the patient group of <1 month of the restoration duration, among which higher Ni excretions were found in those with either a higher number of teeth replaced by dental alloys or a higher index of metal crown not covered with the porcelain. Urinary levels of Cr were significantly higher in the three patient groups of <1, 1 to <3 and 3 to <6 months, especially in those with a higher metal crown exposure index. Linear curve estimations showed better relationships between urinary Ni and Cr in patients within 6-month groups. Our data suggested significant increased excretions of urinary Ni and Cr after dental restoration. Potential short- and long-term effects of Ni-Cr alloy restoration need to be investigated.

  6. Ignition characteristics of the nickel-based alloy UNS N07001 in pressurized oxygen

    NASA Technical Reports Server (NTRS)

    Bransford, J. W.; Billiard, P. A.

    1990-01-01

    The development of ignition and combustion in pressurized oxygen atmospheres was studied for the nickel-based alloy UNS N07001. Ignition of the alloy was achieved by heating the top surface of a cylindrical specimen with a continuous-wave CO2 laser. Two heating procedures were used. In the first, laser power was adjusted to maintain an approximately linear increase in surface temperature. In the second, laser power was periodically increased until autoheating (self-heating) was established. It was found that the alloy would autoheat to combustion from temperatures below the solidus temperature. In addition, the alloy had a tendency to develop combustion zones (hot spots) at high oxygen pressures when the incremental (step) heating test mode was used. Unique points on the temperature-time curves that describe certain events are defined and the temperatures at which these events occur are given for the oxygen pressure range of 1.72 to 13.8 MPa (250 to 2000 psia).

  7. Effects in Mg-Zn-based alloys strengthened by quasicrystalline phase

    NASA Astrophysics Data System (ADS)

    Vlček, M.; Čížek, J.; Lukáč, F.; Melikhova, O.; Hruška, P.; Procházka, I.; Vlach, M.; Stulíková, I.; Smola, B.; Jäger, A.

    2016-01-01

    Magnesium Mg-based alloys are promising lightweight structural materials for automotive, aerospace and biomedical applications. Recently Mg-Zn-Y system attracted a great attention due to a stable icosahedral phase (I-phase) with quasicrystalline structure which is formed in these alloys. Positron lifetime spectroscopy and in situ synchrotron X-ray diffraction were used to study thermal stability of I-phase and precipitation effects in Mg-Zn-Y and Mg- Zn-Al alloys. All alloys containing quasicrystalline I-phase exhibit misfit defects characterized by positron lifetime of ∼ 300 ps. These defects are associated with the interfaces between I- phase particles and Mg matrix. The quasicrystalline I-phase particles were found to be stable up to temperatures as high as ∼ 370°C. The W-phase is more stable and melts at ∼ 420°C. Concentration of defects associated with I-phase decreases after annealing at temperatures above ∼ 300°C.

  8. Growth Stresses in Thermally Grown Oxides on Nickel-Based Single-Crystal Alloys

    NASA Astrophysics Data System (ADS)

    Rettberg, Luke H.; Laux, Britta; He, Ming Y.; Hovis, David; Heuer, Arthur H.; Pollock, Tresa M.

    2016-03-01

    Growth stresses that develop in α-Al2O3 scale that form during isothermal oxidation of three Ni-based single crystal alloys have been studied to elucidate their role in coating and substrate degradation at elevated temperatures. Piezospectroscopy measurements at room temperature indicate large room temperature compressive stresses in the oxides formed at 1255 K or 1366 K (982 °C or 1093 °C) on the alloys, ranging from a high of 4.8 GPa for René N4 at 1366 K (1093 °C) to a low of 3.8 GPa for René N5 at 1255 K (982 °C). Finite element modeling of each of these systems to account for differences in coefficients of thermal expansion of the oxide and substrate indicates growth strains in the range from 0.21 to 0.44 pct at the oxidation temperature, which is an order of magnitude higher than the growth strains measured in the oxides on intermetallic coatings that are typically applied to these superalloys. The magnitudes of the growth strains do not scale with the parabolic oxidation rate constants measured for the alloys. Significant spatial inhomogeneities in the growth stresses were observed, due to (i) the presence of dendritic segregation and (ii) large carbides in the material that locally disrupts the structure of the oxide scale. The implications of these observations for failure during cyclic oxidation, fatigue cycling, and alloy design are considered.

  9. Stress corrosion cracking of Ni-base and Ti alloys under controlled potential

    SciTech Connect

    Estill, J C; Gordon, S R; Logeteta, L F; Roy, A K

    1998-10-22

    Susceptibility to stress corrosion cracking (SCC) of alloy C-22 and Ti Gr-12, two candidate alloys for the inner-container of the multi-barrier nuclear waste package, was evaluated by using the slow-strain-rate (SSR) test technique in a deaerated acidic brine (pH {approx} 2.70) at 90 C. The strain rate used was 3.3 x 10{sup {minus}6} sec{sup {minus}1}. Prior to being tested in the acidic brine, specimens of each alloy were pulled inside the test chamber in the dry condition at room temperature (RT). Then specimens were exposed to the test solution while being strained under different controlled electrochemical potentials. The magnitude of the controlled potential was selected based on the corrosion potential measured in the test solution prior to straining of the specimen. Results indicate that, for Ti Gr-12, the times to failure were significantly shorter compared to those for alloy C-22. Furthermore, Ti Gr-12 showed reduced ductility in terms of percent reduction in area and true fracture stress, as the controlled potential became more cathodic. Results also indicate that the time-to-failure and percent elongation reached the minimum values when Ti Gr-12 was tested under impressed potential of {minus}1162 mV. Finally, metallographic examination was performed to evaluate the primary fracture, and the secondary cracking, if any, along the gage section of the broken tensile specimen.

  10. Highly efficient functional GexPb1-xTe based thermoelectric alloys.

    PubMed

    Gelbstein, Yaniv; Davidow, Joseph

    2014-10-07

    Methods for enhancement of the direct thermal to electrical energy conversion efficiency, upon development of advanced thermoelectric materials, are constantly investigated mainly for efficient implementation of thermoelectric devices in automotive vehicles, for converting the waste heat generated in such engines into useful electrical power and thereby reduction of the fuel consumption and CO2 emission levels. It was recently shown that GeTe based compounds and specifically GeTe-PbTe rich alloys are efficient p-type thermoelectric compositions. In the current research, Bi2Te3 doping and PbTe alloying effects in GexPb1-xTe alloys, subjected to phase separation reactions, were investigated for identifying the phase separation potential for enhancement of the thermoelectric properties beyond a pure alloying effect. All of the investigated compositions exhibit maximal dimensionless figure of merit, ZT, values beyond 1, with the extraordinary value of 2.1 found for the 5% Bi2Te3 doped-Ge0.87Pb0.13Te composition, considered as among the highest ever reported.

  11. Interaction of lead with nickel-base Alloys 600 and 690

    SciTech Connect

    Costa, D.; Talah, H.; Marcus, P.; Calvar, M. Le; Gelpi, A.

    1995-12-31

    The results of a combined electrochemical and (X-Ray Photoelectron Spectroscopy (XPS)) study of the effects of lead on the passivation of nickel, chromium and nickel-based alloys with compositions close to Alloy 600 and 690 in acidic solutions at room temperature are reported. Lead was present as soluble PbO in 0.1M HClO{sub 4} and PbSO{sub 4} in 0.05M H{sub 2}SO{sub 4} or as controlled amounts of metallic lead deposited on the surface of the samples. Lead enhances the anodic dissolution of nickel (in perchloric and sulfuric acid solutions) and of Alloy 600 (in perchloric acid solution) whereas it has no effect on Cr and on Alloy 690. Pb{sup 2+} does not interact with an already formed passive film. The XPS study showed that the increased dissolution observed is caused by the formation of a Ni-Pb-anion (ClO{sub 4}{sup {minus}} or SO{sub 4}{sup 2{minus}}) complex on the metallic surface. Such a species is not produced on an oxidized surface.

  12. Neutronics and activation analysis of lithium-based ternary alloys in IFE blankets

    SciTech Connect

    Jolodosky, Alejandra; Kramer, Kevin; Meier, Wayne; DeMuth, James; Reyes, Susana; Fratoni, Massimiliano

    2016-04-09

    Here we report that an attractive feature of using liquid lithium as the breeder and coolant in fusion blankets is that it has very high tritium solubility and results in very low levels of tritium permeation throughout the facility infrastructure. However, lithium metal vigorously reacts with air and water and presents plant safety concerns. The Lawrence Livermore National Laboratory is carrying an effort to develop a lithium-based alloy that maintains the beneficial properties of lithium (e.g. high tritium breeding and solubility) and at the same time reduces overall flammability concerns. This study evaluates the neutronics performance of lithium-based alloys in the blanket of an inertial fusion energy chamber in order to inform such development. 3-D Monte Carlo calculations were performed to evaluate two main neutronics performance parameters for the blanket: tritium breeding ratio (TBR), and the fusion energy multiplication factor (EMF). It was found that elements that exhibit low absorption cross sections and higher q-values such as lead, tin, and strontium, perform well with those that have high neutron multiplication such as lead and bismuth. These elements meet TBR constrains ranging from 1.02 to 1.1. However, most alloys do not reach EMFs greater than 1.15. Additionally, it was found that enriching lithium significantly increases the TBR and decreases the minimum lithium concentration by more than 60%. The amount of enrichment depends on how much total lithium is in the alloy to begin with. Alloys that performed well in the TBR and EMF calculations were considered for activation analysis. Activation simulations were executed with 50 years of irradiation and 300 years of cooling. It was discovered that bismuth is a poor choice due to achieving the highest decay heat, contact dose rates, and accident doses. In addition, it does not meet the waste disposal ratings (WDR). Some of the activation results for alloys with tin, zinc, and gallium were in the higher

  13. Neutronics and activation analysis of lithium-based ternary alloys in IFE blankets

    DOE PAGES

    Jolodosky, Alejandra; Kramer, Kevin; Meier, Wayne; ...

    2016-04-09

    Here we report that an attractive feature of using liquid lithium as the breeder and coolant in fusion blankets is that it has very high tritium solubility and results in very low levels of tritium permeation throughout the facility infrastructure. However, lithium metal vigorously reacts with air and water and presents plant safety concerns. The Lawrence Livermore National Laboratory is carrying an effort to develop a lithium-based alloy that maintains the beneficial properties of lithium (e.g. high tritium breeding and solubility) and at the same time reduces overall flammability concerns. This study evaluates the neutronics performance of lithium-based alloys inmore » the blanket of an inertial fusion energy chamber in order to inform such development. 3-D Monte Carlo calculations were performed to evaluate two main neutronics performance parameters for the blanket: tritium breeding ratio (TBR), and the fusion energy multiplication factor (EMF). It was found that elements that exhibit low absorption cross sections and higher q-values such as lead, tin, and strontium, perform well with those that have high neutron multiplication such as lead and bismuth. These elements meet TBR constrains ranging from 1.02 to 1.1. However, most alloys do not reach EMFs greater than 1.15. Additionally, it was found that enriching lithium significantly increases the TBR and decreases the minimum lithium concentration by more than 60%. The amount of enrichment depends on how much total lithium is in the alloy to begin with. Alloys that performed well in the TBR and EMF calculations were considered for activation analysis. Activation simulations were executed with 50 years of irradiation and 300 years of cooling. It was discovered that bismuth is a poor choice due to achieving the highest decay heat, contact dose rates, and accident doses. In addition, it does not meet the waste disposal ratings (WDR). Some of the activation results for alloys with tin, zinc, and gallium were in

  14. Rare-earth metals (REMs) in nickel aluminide-based alloys: II. Effect of a REM on the phase composition of a multicomponent Ni3Al-based alloy

    NASA Astrophysics Data System (ADS)

    Povarova, K. B.; Drozdov, A. A.; Kazanskaya, N. K.; Morozov, A. E.; Kolobov, Yu. R.; Vershinina, T. N.; Kozlov, E. V.

    2008-10-01

    The hardening mechanisms are studied in the cast high-temperature next-generation materials that are based on the intermetallic compound Ni3Al and are low alloyed with refractory (W, Re, Mo, Cr) and reaction- and surface-active (REM, Ti, etc.) metals. The interaction of the main impurities (C, O, Si, S) with three characteristic representatives of the REM group (namely, Y, La, Ce), which can be used for alloying, is analyzed. The reported data on the behavior of some REMs in the alloys based on nickel monoaluminide NiAl are considered. The effect of the REMs on the phase compositions of real multicomponent semicommercial Ni3Al-based VKNA alloys produced by directional solidification is investigated, and the excess phases precipitating upon alloying are revealed. Alloying with refractory metals and REMs is shown to lead to the formation of nanophases that stabilize the dendritic or single-crystal structure of VKNA-type cast alloys and strengthen the interface boundaries in them.

  15. Corrosion of ferritic-martensitic steels and nickel-based alloys in supercritical water

    NASA Astrophysics Data System (ADS)

    Ren, Xiaowei

    The corrosion behavior of ferritic/martensitic (F/M) steels and Ni-based alloys in supercritical water (SCW) has been studied due to their potential applications in future nuclear reactor systems, fossil fuel power plants and waste treatment processes. 9˜12% chromium ferritic/martensitic steels exhibit good radiation resistance and stress corrosion cracking resistance. Ni-based alloys with an austenitic face-centered cubic (FCC) structure are designed to retain good mechanical strength and corrosion/oxidation resistance at elevated temperatures. Corrosion tests were carried out at three temperatures, 360°C, 500°C and 600°C, with two dissolved oxygen contents, 25 ppb and 2 ppm for up to 3000 hours. Alloys modified by grain refinement and reactive element addition were also investigated to determine their ability to improve the corrosion resistance in SCW. A duplex oxide structure was observed in the F/M steels after exposure to 25 ppb oxygen SCW, including an outer oxide layer with columnar magnetite grains and an inner oxide layer constituted of a mixture of spinel and ferrite phases in an equiaxed grain structure. An additional outermost hematite layer formed in the SCW-exposed samples when the oxygen content was increased to 2 ppm. Weight gain in the F/M steels increased with exposure temperatures and times, and followed parabolic growth kinetics in most of the samples. In Ni-based alloys after exposure to SCW, general corrosion and pitting corrosion were observed, and intergranular corrosion was found when exposed at 600°C due to formation of a local healing layer. The general oxide structure on the Ni-based alloys was characterized as NiO/Spinel/(CrxFe 1-x)2O3/(Fe,Ni). No change in oxidation mechanism was observed in crossing the critical point despite the large change in water properties. Corrosion resistance of the F/M steels was significantly improved by plasma-based yttrium surface treatment because of restrained outward diffusion of iron by the

  16. Influence of creep damage on the low cycle thermal-mechanical fatigue behavior of two tantalum base alloys

    NASA Technical Reports Server (NTRS)

    Sheffler, K. D.; Doble, G. S.

    1972-01-01

    Low cycle fatigue tests have been performed on the tantalum base alloys T-111 and ASTAR 811C with synchronized, independently programmed temperature and strain cycling. The thermal-mechanical cycles applied fell into three basic categories: these were isothermal cycling, in-phase thermal cycling, and out-of-phase thermal cycling. In-phase cycling was defined as tensile deformation associated with high temperature and compressive deformation with low temperature, while out-of-phase thermal cycling was defined as the reverse case. The in-phase thermal cycling had a pronounced detrimental influence on the fatigue life of both alloys, with the life reduction being greater in the solid solution strengthened T-111 alloy than in the carbide strengthened ASTAR 811C alloy. The out-of-phase tests also showed pronounced effects on the fatigue life of both alloys, although not as dramatic.

  17. NASA-UVa light aerospace alloy and structures technology program supplement: Aluminum-based materials for high speed aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr. (Editor)

    1995-01-01

    This report on the NASA-UVa light aerospace alloy and structure technology program supplement: Aluminum-Based Materials for High Speed Aircraft covers the period from July 1, 1992. The objective of the research is to develop aluminum alloys and aluminum matrix composites for the airframe which can efficiently perform in the HSCT environment for periods as long as 60,000 hours (certification for 120,000 hours) and, at the same time, meet the cost and weight requirements for an economically viable aircraft. Current industry baselines focus on flight at Mach 2.4. The research covers four major materials systems: (1) Ingot metallurgy 2XXX, 6XXX, and 8XXX alloys, (2) Powder metallurgy 2XXX alloys, (3) Rapidly solidified, dispersion strengthened Al-Fe-X alloys, and (4) Discontinuously reinforced metal matrix composites. There are ten major tasks in the program which also include evaluation and trade-off studies by Boeing and Douglas aircraft companies.

  18. Thermophysical Properties of Uranium-Based Niobium and Zirconium Alloys from 23 °C to 175 °C

    NASA Astrophysics Data System (ADS)

    Camarano, D. M.; Migliorini, F. L.; Silva, E. H. C.; Grossi, P. A.; Ferraz, W. B.; de Paula, J. B.

    2010-09-01

    The thermal diffusivities of uranium alloys were measured by the laser-flash method between room temperature and 448 K. In recent years, several UZrNb alloys have been studied by many researchers and it was shown that additions of niobium and zirconium improve the properties of uranium-based alloys. The purpose of this article is to summarize the thermophysical properties of two uranium alloys that have been studied by CDTN in a program of development of fuel for low-power reactors. The nominal compositions of the studied alloys are U4Zr6Nb and U3Zr9Nb. The results obtained by the original laser-flash method and by the mathematical model developed by the laboratory were compared to the literature data. The adaptive Monte Carlo method was used to obtain the endpoints of the probabilistically symmetric 95% coverage interval for estimates of the output quantities and its uncertainties.

  19. Clarification of stress corrosion cracking mechanism on nickel base alloys in steam generators for their long lifetime assurance

    SciTech Connect

    Nagano, Hiroo; Kajimura, Haruhiko

    1995-12-31

    Thermally treated (TT) Alloys 600 (16%Cr-8%Fe-bal.Ni) and 690 (30%Cr-10%Fe-bal.Ni) have been successfully used in the steam generators of operating pressurized water reactors (PWRs). This paper deals with intergranular stress corrosion cracking (IGSCC) mechanisms in Ni-base alloys in various corrosive environments such as deaerated water, air-saturated chloride medium, and caustic solutions at high temperatures with focus on Cr content and Cr carbide precipitation at grain boundaries in the alloys. Nickel base alloys of high purity, or with different Cr, C, and B contents with different heat treatments were put to various corrosion tests. SCC resistance of Alloy 600 is affected differently by water chemistry of environments, while Alloy 690 is almost immune to the environments investigated: (1) Cr depletion at grain boundaries is clearly detrimental to IGSCC resistance of Alloy 600 in air-saturated water containing Cl{sup {minus}} ions at 300 C. (2) High purity Alloy 600 has weaker SCC resistance in deaerated water at 360 C than commercially available Alloy 600. Cr depletion along grain boundaries is detrimental to the IGSCC resistance, however its detrimental effect disappears when Cr carbides precipitate at grain boundaries in semi-continuous or continuous way. The NiCr{sub 2}O{sub 4} film formed on the metal surfaces enhances the IGSCC resistance. Similar relationship between Cr depletion and Cr carbide precipitation is also observed in Alloy 600 in deaerated caustic solutions at high temperatures. (3) Concerning intergranular attack (IGA), which occurs in oxidizing caustic solutions at high temperature, existence of semi-continuous or continuous Cr carbides improves the IGA resistance regardless of Cr depletion. A dual layer corrosion protective film composed of an upper layer of NiO and lower layer of Cr{sub 2}O{sub 3} formed on metal surfaces, of which formation is accelerated by selective Cr carbide dissolution, may be responsible for the IGA resistance.

  20. Brushing-Induced Surface Roughness of Two Nickel Based Alloys and a Titanium Based Alloy: A Comparative Study - In Vitro Study

    PubMed Central

    Acharya, B L Guruprasanna; Nadiger, Ramesh; Shetty, Bharathraj; Gururaj, G; Kumar, K Naveen; Darshan, D D

    2014-01-01

    be given to the selection of the toothbrushes and toothpastes with the medium abrasives in patients with these restorations. How to cite the article: Acharya BL, Nadiger R, Shetty B, Gururaj G, Kumar KN, Darshan DD. Brushing induced surface roughness of two nickel based alloys and a titanium based alloy: A comparative study - In vitro study. J Int Oral Health 2014;6(3):36-49. PMID:25083031

  1. A simple spectrophotometric method for determination of zirconium or hafnium in selected molybdenum-base alloys

    NASA Technical Reports Server (NTRS)

    Dupraw, W. A.

    1972-01-01

    A simple analytical procedure is described for accurately and precisely determining the zirconium or hafnium content of molybdenum-base alloys. The procedure is based on the reaction of the reagent Arsenazo III with zirconium or hafnium in strong hydrochloric acid solution. The colored complexes of zirconium or hafnium are formed in the presence of molybdenum. Titanium or rhenium in the alloy have no adverse effect on the zirconium or hafnium complex at the following levels in the selected aliquot: Mo, 10 mg; Re, 10 mg; Ti, 1 mg. The spectrophotometric measurement of the zirconium or hafnium complex is accomplished without prior separation with a relative standard deviation of 1.3 to 2.7 percent.

  2. AB INITIO Modeling of Thermomechanical Properties of Mo-Based Alloys for Fossil Energy Conversion

    SciTech Connect

    Ching, Wai-Yim

    2013-12-31

    In this final scientific/technical report covering the period of 3.5 years started on July 1, 2011, we report the accomplishments on the study of thermo-mechanical properties of Mo-based intermetallic compounds under NETL support. These include computational method development, physical properties investigation of Mo-based compounds and alloys. The main focus is on the mechanical and thermo mechanical properties at high temperature since these are the most crucial properties for their potential applications. In particular, recent development of applying ab initio molecular dynamic (AIMD) simulations to the T1 (Mo{sub 5}Si{sub 3}) and T2 (Mo{sub 5}SiB{sub 2}) phases are highlighted for alloy design in further improving their properties.

  3. Manufacturing Techniques for Titanium Aluminide Based Alloys and Metal Matrix Composites

    DTIC Science & Technology

    2010-01-01

    that dispersion strengthening is the primary strengthening mechanism reported in TiAl-C based composites. Similarly, the addition of nitrogen leads... strengthening for TiAl alloys. As a result, the ductility, strength as well as oxidation resistance of a TiAl + TiB2 composite were found to be...aerospace and automobile applications. High specific strength coupled with good high temperature performance in the areas of creep and oxidation

  4. Effects of Ion Implantation on Cavitation Erosion of a Cobalt Based Metal/Carbide Alloy.

    DTIC Science & Technology

    1987-09-01

    L_____ L -_ 0nion source. The samlies were heat sunk onto100 200 300 400o100 DEPH a water-cooled holder during implantat ion to limnit tihe temerature...by water test times of between 20 and 35 h, are shown jets ( pump circulated test water) through the in Fig. 2. SEM micrographs showing the dam...qualitative measure of the relative amounts of the - hcp and fcc phases in the alloy [4]. Calculations based on the mass adsorbtion coefficient for

  5. Corrosion behavior of iron and nickel base alloys under solid oxide fuel cell exposure conditions

    SciTech Connect

    Ziomek-Moroz, M.; Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.

    2006-03-01

    Topography and phase composition of the scales formed on commercial ferritic stainless steels and experimental low CTE nickel-based alloys were studied in atmospheres simulating solid oxide fuel cell (SOFC) environments. The materials were studied under dual environment conditions with air on one side of the sample and carbon monoxide on the other side at 750°C. Surface characterization techniques, such as scanning electron microscopy and X-ray diffraction analysis were used in this study.

  6. Effect of residual strain in Fe-based amorphous alloys on field induced magnetic anisotropy and domain structure

    NASA Astrophysics Data System (ADS)

    Azuma, Daichi; Hasegawa, Ryusuke; Saito, Shin; Takahashi, Migaku

    2013-05-01

    Field induced magnetic anisotropy in two Fe-based amorphous alloys with different saturation induction levels (1.56 T and 1.64 T) was investigated by varying magnetic field strength and annealing temperature and domain images were taken on these samples. Residual strain was evaluated by measuring coercivities of the materials after stress-relief annealing. These results are discussed, clarifying the difference between the two Fe-based amorphous alloys.

  7. Development of a Mathematical Model of Crevice Corrosion Propagation on Nickel Base Alloys in Natural and Chlorinated Sea Water

    DTIC Science & Technology

    1994-08-30

    then bromamines and chloramines are formed and the processes become even more complicated. [10]. 0 From the point of view of crevice corrosion ... Corrosion Propagation on Nickel Base Alloys in Natural and Chlorinated Sea Water Thi! os 7 -= n %:ý 7e~~r: :-ppcved tor piU&* : e --I . " dcktr!u-,J...Summary Crevice corrosion initiation and propagation of nickel base alloys Inconel 625, Hastelloy C276 and Hastelloy 22 in sea water and chlorinated sea

  8. The impact of carbon on single crystal nickel-base superalloys: Carbide behavior and alloy performance

    NASA Astrophysics Data System (ADS)

    Wasson, Andrew Jay

    Advanced single crystal nickel-base superalloys are prone to the formation of casting grain defects, which hinders their practical implementation in large gas turbine components. Additions of carbon (C) have recently been identified as a means of reducing grain defects, but the full impact of C on single crystal superalloy behavior is not entirely understood. A study was conducted to determine the effects of C and other minor elemental additions on the behavior of CMSX-4, a commercially relevant 2nd generation single crystal superalloy. Baseline CMSX-4 and three alloy modifications (CMSX-4 + 0.05 wt. % C, CMSX-4 + 0.05 wt. % C and 68 ppm boron (B), and CMSX-4 + 0.05 wt. % C and 23 ppm nitrogen (N)) were heat treated before being tested in high temperature creep and high cycle fatigue (HCF). Select samples were subjected to long term thermal exposure (1000 °C/1000 hrs) to assess microstructural stability. The C modifications resulted in significant differences in microstructure and alloy performance as compared to the baseline. These variations were generally attributed to the behavior of carbide phases in the alloy modifications. The C modification and the C+B modification, which both exhibited script carbide networks, were 25% more effective than the C+N modification (small blocky carbides) and 10% more effective than the baseline at preventing grain defects in cast bars. All C-modified alloys exhibited reduced as-cast gamma/gamma' eutectic and increased casting porosity as compared to baseline CMSX-4. The higher levels of porosity (volume fractions 0.002 - 0.005 greater than the baseline) were attributed to carbides blocking molten fluid flow during the final stages of solidification. Although the minor additions resulted in reduced solidus temperature by up to 16 °C, all alloys were successfully heat treated without incipient melting by modifying commercial heat treatment schedules. In the B-containing alloy, heat treatment resulted in the transformation of

  9. Development of wear-resistant coatings for cobalt-base alloys

    SciTech Connect

    Cockeram, B.V.

    1999-03-01

    The costs and hazards resulting from nuclear plant radiation exposure with activated cobalt wear debris could potentially be reduced by covering the cobalt-base materials with a wear resistant coating. However, the hardnesses of many cobalt-base wear alloys are significantly lower than conventional PVD hard coatings, and mechanical support of the hard coating is a concern. Four approaches have been taken to minimize the hardness differences between the substrate and PVD hard coating: (1) use a thin Cr-nitride hard coating with layers that are graded with respect to hardness, (2) use a thicker, multilayered coating (Cr-nitride or Zr-nitride) with graded layers, (3) use nitriding to harden the alloy subsurface followed by application of a multilayered coating of Cr-nitride, and (4) use of nitriding alone. Since little work has been done on application of PVD hard coatings to cobalt-base alloys, some details on process development and characterization of the coatings is presented. Scratch testing was used to evaluate the adhesion of the different coatings. A bench-top rolling contact test was used to evaluate the wear resistance of the coatings. The test results are discussed, and the more desirable coating approaches are identified.

  10. COATED ALLOYS

    DOEpatents

    Harman, C.G.; O'Bannon, L.S.

    1958-07-15

    A coating is described for iron group metals and alloys, that is particularly suitable for use with nickel containing alloys. The coating is glassy in nature and consists of a mixture containing an alkali metal oxide, strontium oxide, and silicon oxide. When the glass coated nickel base metal is"fired'' at less than the melting point of the coating, it appears the nlckel diffuses into the vitreous coating, thus providing a closely adherent and protective cladding.

  11. Cation Ordering in [(Tl,M)O] Layers of ``1201''-Based Cuprates: Similarity to Ordering in fcc-Based Alloys

    NASA Astrophysics Data System (ADS)

    Van Tendeloo, G.; De Meulenaere, P.; Letouzé, F.; Martin, C.; Hervieu, M.; Raveau, B.

    1997-08-01

    "1201" Tl-based substituted cuprates of the type (Tl1-xMx)Sr2CuO5have been synthesized forM=Nb, Ta, or W. These materials do not superconduct due to a statistical distribution of some of theMfor Cu. The remarkable feature of these materials is the ordering observed between Tl andMin the (Tl1-xMx-ε)O plane. The type of ordering depends on the composition and shows remarkable similarities with the ordering in Ni-Mo or other so-called 1 1/2 0 type fcc-based alloys or with the ordering in rocksalt oxides TiOx. The short-range order, forM=W, can be readily interpreted in terms of a mixing of nano-clusters with two different compositions. These observations of two-dimensional ordering confirm recent ideas about ordering in three-dimensional fcc-based alloys.

  12. Novel bioactive Co-based alloy/FA nanocomposite for dental applications

    PubMed Central

    Fathi, Mohammadhossein; Ahmadian, Mehdi; Bahrami, Mojgan

    2012-01-01

    Background: Dental cobalt base alloys are biocompatible dental materials and have been widely used in dentistry. However, metals are bioinert and may not present bioactivity in human body. Bioactivity is the especial ability to interact with human body and make a bonding to soft and hard tissues. The aim of the present research was fabrication and bioactivity evaluation of novel cobalt alloy/Fluorapatite nanocomposite (CoA/FaNC) with different amounts of Fluorapatite (FA) nanopowder. Materials and Methods: Co-Cr-Mo alloy (ASTM F75) powder was prepared and mixed in a planetary ball mill with different amounts of FA nanopowders (10, 15, 20% wt). Prepared composite powders were cold pressed and sintered at 1100°C for 4 h. X-ray diffraction (XRD), scanning electron microscopy and transition electron microscopy techniques were used for phase analysis, crystallite size determination of FA and also for phase analysis and evaluation of particle distribution of composites. Bioactivity behavior of prepared nanocomposites was evaluated in simulated body fluid (SBF) for 1 up to 28 days. Materials and Methods: Co-Cr-Mo alloy (ASTM F75) powder was prepared and mixed in a planetary ball mill with different amounts of FA nanopowders (10, 15, 20% wt). Prepared composite powders were cold pressed and sintered at 1100°C for 4 h. X-ray diffraction (XRD), scanning electron microscopy and transition electron microscopy techniques were used for phase analysis, crystallite size determination of FA and also for phase analysis and evaluation of particle distribution of composites. Bioactivity behavior of prepared nanocomposites was evaluated in simulated body fluid (SBF) for 1 up to 28 days. Results: Results showed that nucleus of apatite were formed on the surface of the prepared CoA/FaNC during 1 up to 28 days immersion in the SBF solution. On the other hand, CoA/FaNC unlike Co-base alloy possessed bone-like apatite-formation ability. Conclusion: It was concluded that bioinert Co

  13. Remanufacture of Zirconium-Based Conversion Coatings on the Surface of Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Liu, Zhe; Jin, Guo; Song, Jiahui; Cui, Xiufang; Cai, Zhaobing

    2017-03-01

    Brush plating provides an effective method for creating a coating on substrates of various shapes. A corroded zirconium-based conversion coating was removed from the surface of a magnesium alloy and then replaced with new coatings prepared via brush plating. The structure and composition of the remanufactured coating were determined via x-ray photoelectron spectroscopy, x-ray diffraction, and Fourier transform infrared spectroscopy. The results revealed that the coatings consist of oxide, fluoride, and tannin-related organics. The composition of the coatings varied with the voltage. Furthermore, as revealed via potentiodynamic polarization spectroscopy, these coatings yielded a significant increase in the corrosion resistance of the magnesium alloy. The friction coefficient remained constant for almost 300s during wear resistance measurements performed under a 1-N load and dry sliding conditions, indicating that the remanufactured coatings provide effective inhibition to corrosion.

  14. Microstructure and properties of Fe-base alloy fabricated using selective laser melting

    NASA Astrophysics Data System (ADS)

    Sun, Manlong; Lu, Li; Fuh, Jerry Y. H.

    2002-02-01

    This paper studies recent advances in rapid tooling (RT) of high performance components via selective laser melting (SLM). The present study of SLM focuses on the development of materials used in injection molding. In the process, the pre-alloyed iron-base alloy powder was used to fabricate parts using a 3KW CO2 laser machine. Iron components with nearly full density have been directly produced under suitable laser parameters. The result of the SLM processed parts showed very fine dendrite microstructure. The surface hardness measured is 35-40 HRC, which is comparable to that of the AISI P20 steel (30-35 HRC). The advantages of this technique include elimination of a secondary infiltration process used by former selective laser sintering technology, reduced pre-processing time, and reduction in post- processing steps. The SLM process has a great potential in the field of RT.

  15. Observation of Pseudopartial Grain Boundary Wetting in the NdFeB-Based Alloy

    NASA Astrophysics Data System (ADS)

    Straumal, B. B.; Mazilkin, A. A.; Protasova, S. G.; Schütz, G.; Straumal, A. B.; Baretzky, B.

    2016-08-01

    The NdFeB-based alloys were invented in 1980s and remain the best-known hard magnetic alloys. In order to reach the optimum magnetic properties, the grains of hard magnetic Nd2Fe14B phase have to be isolated from one another by the (possibly thin) layers of a non-ferromagnetic Nd-rich phase. In this work, we observe that the few-nanometer-thin layers of the Nd-rich phase appear between Nd2Fe14B grains due to the pseudopartial grain boundary (GB) wetting. Namely, some Nd2Fe14B/Nd2Fe14B GBs are not completely wetted by the Nd-rich melt and have the high contact angle with the liquid phase and, nevertheless, contain the 2-4-nm-thin uniform Nd-rich layer.

  16. Identification of epsilon martensite in a Fe-based shape memory alloy by means of EBSD.

    PubMed

    Verbeken, K; Van Caenegem, N; Raabe, D

    2009-01-01

    Ferrous shape memory alloys (SMAs) are often thought to become a new, important group of SMAs. The shape memory effect in these alloys is based on the reversible, stress-induced martensitic transformation of austenite to epsilon martensite. The identification and quantification of epsilon martensite is crucial when evaluating the shape memory behaviour of this material. Previous work displayed that promising results were obtained when studying the evolution of the amount of epsilon martensite after different processing steps with Electron BackScatter Diffraction (EBSD). The present work will discuss in detail, on the one hand, the challenges and opportunities arising during the identification of epsilon martensite by means of EBSD and, on the other hand, the possible interpretations that might be given to these findings. It will be illustrated that although the specific nature of the austenite to epsilon martensite transformation can still cause some points of discussion, EBSD has a high potential for identifying epsilon martensite.

  17. A structural investigation of a plasma sprayed Ni--Cr based alloy coating

    SciTech Connect

    Sampath, S.; Neiser, R.A.; Herman, H. ); Kirkland, J.P.; Elam, W.T. )

    1993-01-01

    A Ni--Cr based hardfacing alloy has been plasma sprayed in ambient and low pressure atmospheres onto mild steel substrates. These coatings exhibit excellent wear and corrosion resistance; however, the significance of microstructure on properties has not been reported. This study relates the structure of the sprayed coatings to the processing conditions. X-ray diffraction results indicate phase separation in air plasma sprayed deposits, while low pressure plasma sprayed deposits exhibit a single supersaturated solid solution. Annealing of the air plasma sprayed coating shows dissolution of the bcc chromium phase, confirming its metastable nature. These results were confirmed using Extended X-ray Absorption Fine Structure (EXAFS) analysis, which further suggests a highly disordered structure, with partial oxidation of selected alloying elements, such as chromium. Transmission electron microscopy indicates a wide variety of microstructures in the air plasma sprayed deposit. In the case of low pressure sprayed deposit, the microstructures are homogeneous and uniform.

  18. Lithium based alloy-thionyl chloride cells for applications at temperatures to 200 C

    NASA Astrophysics Data System (ADS)

    Kane, P.; Marincic, N.; Epstein, J.; Lindsey, A.

    A long-life lithium battery for industrial applications at temperatures up to 200 C was developed by combining Li-based alloy anodes with oxyhalide electrolytes. Cathodes were fabricated by rolling the blend of polycarbonomonofluoride, a conductive carbon additive, and a binder, while anodes were fabricated as those used in oxyhalide cells, incorporating a modified anode current collector designed to prevent the formation of 'lithium islands' at the end of discharge; nonwoven glass fiber separators were pretreated to remove excessive binders and lubricants. Various active electrode surface areas were combined with a corresponding thickness of electrodes and separators, matched in capacity. Tests of the high-rate electrode structure, using Li-Mg alloy anode in conjunction with thionyl chloride electrolyte, have demonstrated that the battery with this anode can be used under abusive conditions such as short circuit and external heating (at 175 C). Raising the operating temperature to 200 C did require some modifications of regular cell hardware.

  19. Development of strength and conductivity in deformation processed copper base alloys

    SciTech Connect

    Insoo, M.

    1992-07-20

    Deformation processed copper based composite alloys have been recently investigated. In these composite alloys, copper, a matrix material, contributes to a high thermal and electrical conductivity, and a second phase material such as Fe, Nb, Cr, Mo, Ta and W acts as a reinforcement of the strength of the composites. Tungsten was chosen as the bcc phase in the first experiment because W has a high melting temperature which is expected to reduce the decrease in high temperature strength resulting from coarsening of fibers. However, brittleness of tungsten may bring crack problems. Because the matrix is ductile but the second phase is hard enough to resist the external forces, cracks may occur at the interfaces between deformed matrix and undeformed second phase. The purpose of the first experiment is to investigate the possibility of deformation of Cu-W compacts.

  20. Comparison of joining processes for Haynes 230 nickel based super alloy

    NASA Astrophysics Data System (ADS)

    Williston, David Hugh

    Haynes 230 is a nickel based, solid-solution strengthened alloy that is used for high-temperature applications in the aero-engine and power generation industries. The alloy composition is balanced to avoid precipitation of undesirable topologically closed-packed (TCP) intermetallic phases, such as Sigma, Mu, or Laves-type, that are detrimental to mechanical and corrosion properties. This material is currently being used for the NASA's J2X upper stage rocket nozzle extension. Current fabrication procedures use fusion welding processes to join blanks that are subsequently formed. Cracks have been noted to occur in the fusion welded region during the forming operations. Use of solid state joining processes, such as friction stir welding are being proposed to eliminate the fusion weld cracks. Of interest is a modified friction stir welding process called thermal stir welding. Three welding process: Gas Metal Arc Welding (GMAW), Electron Beam Welding (EBW), and Thermal Stir Welding (TSWing) are compared in this study.

  1. Rapid solidification processing of iron-base alloys for structural applications

    SciTech Connect

    Flinn, J.E.

    1991-09-01

    The response of iron-base alloys to rapid solidification is reviewed with an emphasis on the effects of processing on the microstructure and mechanical property behavior. The processing topics addressed are powder atomization, powder consolidation, joining, and thermal-mechanical exposure. The value of rapid solidification processing (RSP) lies in the ability to promote compositional homogeneity and retention of fine and stable (to high temperatures) microstructures. Achieving the maximum benefit from RSP requires proper application of the basic principles of composition control and rapid crystallization. This investigation has disclosed two very important facets of the RSP approach that can be applied using current technologies. Dissociated oxygen appears to play a significant role in stabilizing microstructural features. In conjunction with oxygen, vacancies trapped during crystallization provide a very stable matrix dispersion for enhanced strengthening. With a fundamental understanding of the response of iron-base alloys to RSP, alloys can be designed that will have substantially better properties and performance than their conventionally processed counterparts. 77 refs., 94 figs., 14 tabs.

  2. GRCop-84: A High Temperature Copper-based Alloy For High Heat Flux Applications

    NASA Technical Reports Server (NTRS)

    Ellis, David L.

    2005-01-01

    While designed for rocket engine main combustion chamber liners, GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) offers potential for high heat flux applications in industrial applications requiring a temperature capability up to approximately 700 C (1292 F). GRCop-84 is a copper-based alloy with excellent elevated temperature strength, good creep resistance, long LCF lives and enhanced oxidation resistance. It also has a lower thermal expansion than copper and many other low alloy copper-based alloys. GRCop-84 can be manufactured into a variety of shapes such as tubing, bar, plate and sheet using standard production techniques and requires no special production techniques. GRCop-84 forms well, so conventional fabrication methods including stamping and bending can be used. GRCop-84 has demonstrated an ability to be friction stir welded, brazed, inertia welded, diffusion bonded and electron beam welded for joining to itself and other materials. Potential applications include plastic injection molds, resistance welding electrodes and holders, permanent metal casting molds, vacuum plasma spray nozzles and high temperature heat exchanger applications.

  3. Thermodynamic properties and atomic structure of Ca-based liquid alloys

    NASA Astrophysics Data System (ADS)

    Poizeau, Sophie

    To identify the most promising positive electrodes for Ca-based liquid metal batteries, the thermodynamic properties of diverse Ca-based liquid alloys were investigated. The thermodynamic properties of Ca-Sb alloys were determined by emf measurements. It was found that Sb as positive electrode would provide the highest voltage for Ca-based liquid metal batteries (1 V). The price of such a battery would be competitive for the grid-scale energy storage market. The impact of Pb, a natural impurity of Sb, was predicted successfully and confirmed via electrochemical measurements. It was shown that the impact on the open circuit voltage would be minor. Indeed, the interaction between Ca and Sb was demonstrated to be much stronger than between Ca and Pb using thermodynamic modeling, which explains why the partial thermodynamic properties of Ca would not vary much with the addition of Pb to Sb. However, the usage of the positive electrode would be reduced, which would limit the interest of a Pb-Sb positive electrode. Throughout this work, the molecular interaction volume model (MIVM) was used for the first time for alloys with thermodynamic properties showing strong negative deviation from ideality. This model showed that systems such as Ca-Sb have strong short-range order: Ca is most stable when its first nearest neighbors are Sb. This is consistent with what the more traditional thermodynamic model, the regular association model, would predict. The advantages of the MIVM are the absence of assumption regarding the composition of an associate, and the reduced number of fitting parameters (2 instead of 5). Based on the parameters derived from the thermodynamic modeling using the MIVM, a new potential of mixing for liquid alloys was defined to compare the strength of interaction in different Ca-based alloys. Comparing this trend with the strength of interaction in the solid state of these systems (assessed by the energy of formation of the intermetallics), the systems with

  4. High-temperature, low-cycle fatigue of advanced copper-base alloys for rocket nozzles. Part 2: NASA 1.1, Glidcop, and sputtered copper alloys

    NASA Technical Reports Server (NTRS)

    Conway, J. B.; Stentz, R. H.; Berling, J. T.

    1974-01-01

    Short-term tensile and low-cycle fatigue data are reported for five advance copper-base alloys: Sputtered Zr-Cu as received, sputtered Zr-Cu heat-treated, Glidcop AL-10, and NASA alloys 1-1A and 1-1B. Tensile tests were performed in argon at 538 C using an axial strain rate of 0.002/sec. Yield strength and ultimate tensile strength data are reported along with reduction in area values. Axial strain controlled low-cycle fatigue tests were performed in argon at 538C using an axial strain rate of 0.002/sec to define the fatigue life over the range from 100 to 3000 cycles for the five materials studied. It was found that the fatigue characteristics of the NASA 1-1A and NASA 1-1B compositions are identical and represent fatique life values which are much greater than those for the other materials tested. The effect of temperature on NASA 1-1B alloy at a strain rate of 0.002/sec was evaluated along with the effect of strain rates of 0.0004 and 0.01/sec at 538 C. Hold-time data are reported for the NASA 1-1B alloy at 538 C using 5 minute hold periods in tension only and compression only at two different strain range values. Hold periods in tension were much more detrimental than hold periods in compression.

  5. Surface modification of high temperature iron alloys

    DOEpatents

    Park, J.H.

    1995-06-06

    A method and article of manufacture of a coated iron based alloy are disclosed. The method includes providing an iron based alloy substrate, depositing a silicon containing layer on the alloy surface while maintaining the alloy at a temperature of about 700--1200 C to diffuse silicon into the alloy surface and exposing the alloy surface to an ammonia atmosphere to form a silicon/oxygen/nitrogen containing protective layer on the iron based alloy. 13 figs.

  6. Surface modification of high temperature iron alloys

    DOEpatents

    Park, Jong-Hee

    1995-01-01

    A method and article of manufacture of a coated iron based alloy. The method includes providing an iron based alloy substrate, depositing a silicon containing layer on the alloy surface while maintaining the alloy at a temperature of about 700.degree. C.-1200.degree. C. to diffuse silicon into the alloy surface and exposing the alloy surface to an ammonia atmosphere to form a silicon/oxygen/nitrogen containing protective layer on the iron based alloy.

  7. Investigation on corrosion behavior of Ni-based alloys in molten fluoride salt using synchrotron radiation techniques

    NASA Astrophysics Data System (ADS)

    Liu, Min; Zheng, Junyi; Lu, Yanling; Li, Zhijun; Zou, Yang; Yu, Xiaohan; Zhou, Xingtai

    2013-09-01

    Ni-based alloys have been selected as the structural materials in molten-salt reactors due to their high corrosion resistance and excellent mechanical properties. In this paper, the corrosion behavior of some Ni-based superalloys including Inconel 600, Hastelloy X and Hastelloy C-276 were investigated in molten fluoride salts at 750 °C. Morphology and microstructure of corroded samples were analyzed using scanning electron microscope (SEM), synchrotron radiation X-ray microbeam fluorescence (μ-XRF) and synchrotron radiation X-ray diffraction (SR-XRD) techniques. Results from μ-XRF and SR-XRD show that the main depleted alloying element of Ni-based alloys in molten fluoride salt is Cr. In addition, the results indicate that Mo can enhance the corrosion resistance in molten FLiNaK salts. Among the above three Ni-based alloys, Hastelloy C-276 exhibits the best corrosion resistance in molten fluoride salts 750 °C. Higher-content Mo and lower-content Cr in Hastelloy C-276 alloy were responsible for the better anti-corrosive performance, compared to the other two alloys.

  8. Zirconium, calcium, and strontium contents in magnesium based biodegradable alloys modulate the efficiency of implant-induced osseointegration.

    PubMed

    Mushahary, Dolly; Sravanthi, Ragamouni; Li, Yuncang; Kumar, Mahesh J; Harishankar, Nemani; Hodgson, Peter D; Wen, Cuie; Pande, Gopal

    2013-01-01

    Development of new biodegradable implants and devices is necessary to meet the increasing needs of regenerative orthopedic procedures. An important consideration while formulating new implant materials is that they should physicochemically and biologically mimic bone-like properties. In earlier studies, we have developed and characterized magnesium based biodegradable alloys, in particular magnesium-zirconium (Mg-Zr) alloys. Here we have reported the biological properties of four Mg-Zr alloys containing different quantities of strontium or calcium. The alloys were implanted in small cavities made in femur bones of New Zealand White rabbits, and the quantitative and qualitative assessments of newly induced bone tissue were carried out. A total of 30 experimental animals, three for each implant type, were studied, and bone induction was assessed by histological, immunohistochemical and radiological methods; cavities in the femurs with no implants and observed for the same period of time were kept as controls. Our results showed that Mg-Zr alloys containing appropriate quantities of strontium were more efficient in inducing good quality mineralized bone than other alloys. Our results have been discussed in the context of physicochemical and biological properties of the alloys, and they could be very useful in determining the nature of future generations of biodegradable orthopedic implants.

  9. [Cast structures and mechanical properties of Ir added to Ag-based alloys. (Part 1) (author's transl)].

    PubMed

    Honma, H; Iijima, K

    1981-04-01

    The effect of very small quantity of Ir added to pure Agb or Ab-based casting alloys on the mechanical properties were investigated by microstructure observation, tensile test, XMA (electron probe micro analysis) and electrical resistivity measurement. 1) An addition of 0.005% Ir to pure Ag caused grain refinement, increased elongation, yield point, tensile strength. However, the refinement effect did not proportionally increase to the amount of additional Ir. 2) An addition of Ir to Ag alloy containing 7% Cu caused to finely dispersed beta phase in the as cast alloy and degraded the dendrite structure. As a result, homogenization and aging were accelerated. Mechanical properties i. e. elongation, yield point and tensile strength increased in castings and homogeneous state and yield point increased in aging state. The addition of about 0.05% Ir appeared optimum. 3) An addition of Ir to an Ag alloy containing 15% Cu caused grain refinement of the alloy as cast but its effect on the mechanical properties of the alloy was not clarified owing to casting defects. 4) 0.05% Ir added to an Ag alloy containing 20% Pd and 7% Cu did not show an apparent refinement effect. The optimum quantity of Ir is assumed to differ depending on the amount of Pd content.

  10. Research into oil-based high-dispersion graphite lubricants for extrusion of Ni-based alloys

    NASA Astrophysics Data System (ADS)

    Petrov, Alexander N.; Petrov, Mikhail A.; Petrov, Pavel A.

    2016-10-01

    The presented paper deals with oil-based high-dispersion graphite lubricants for hot extrusion Ni-based alloys. This paper emphasize an influence of the lubricant's flash point and oil burning on composition changing of the lubricants. It was found out that oil-based lubricants increase heat shielding properties of the die during extrusion. The temperature of a die surface was estimated on the base of production tests on the mechanical press with nominal force of 1,6MN. The practical recommendations were presented and should help to choose lubricants properly in accordance to the analysis.

  11. Infrared repair brazing of 403 stainless steel with a nickel-based braze alloy

    NASA Astrophysics Data System (ADS)

    Shiue, R. K.; Wu, S. K.; Hung, C. M.

    2002-06-01

    Martensitic stainless steel (403SS) is extensively used for intermediate and low-pressure steam turbine blades in fossil-fuel power plants. The purpose of this investigation is to study the repair of shallow cracks on the surface of 403SS steam turbine blades by infrared repair brazing using rapid thermal cycles. A nickel-based braze alloy (NICROBRAZ LM) is used as filler metal. The braze alloy after brazing is primarily comprised of borides and an FeNi3 matrix with different amounts of alloying elements, especially B and Si. As the brazing temperature increases, more Fe atoms are dissolved into the molten braze. Some boron atoms diffuse into the 403SS substrate primarily via grain boundary diffusion and form B-Cr-Fe intermetallic precipitates along the grain boundaries. The LM filler metal demonstrates better performance than 403SS in both microhardness and wear tests. It is also noted that specimens brazed in a vacuum have less porosity than those brazed in an Ar atmosphere. The shear strength of the joint is around 300 MPa except for specimens brazed in short time periods, e.g., 5 seconds in Ar flow and 30 seconds in vacuum. The fractographs mainly consist of brittle fractures and no ductile dimple fractures observed in the scanning electron microscope (SEM) examination.

  12. Resistance to sulfur poisoning of Ni-based alloy with coinage (IB) metals

    NASA Astrophysics Data System (ADS)

    Xu, Xiaopei; Zhang, Yanxing; Yang, Zongxian

    2015-12-01

    The poisoning effects of S atom on the (1 0 0), (1 1 0) and (1 1 1) metal surfaces of pure Ni and Ni-based alloy with IB (coinage) metals (Cu, Ag, Au) are systematically studied. The effects of IB metal dopants on the S poisoning features are analyzed combining the density functional theory (DFT) results with thermodynamics data using the ab initio atomistic thermodynamic method. It is found that introducing IB doping metals into Ni surface can shift the d-band center downward from the Fermi level and weaken the adsorption of S on the (1 0 0) and (1 1 0) surfaces, and the S tolerance ability increases in the order of Ni, Cu/Ni, Ag/Ni and Au/Ni. Nevertheless, on the (1 1 1) surface, the S tolerance ability increases in the order of Ag/Ni (or Cu/Ni), Ni, and Au/Ni. When we increase the coverage of the IB metal dopants, we found that not only Au, but Cu and Ag can increase its S tolerance. We therefore propose that alloying can increase its S tolerance and alloying with Au would be a better way to increase the resistance to sulfur poisoning of the Ni anode as compared with the pure Ni and the Ag- or, Cu-doped Ni materials.

  13. Impact properties of vanadium-base alloys irradiated at < 430 C

    SciTech Connect

    Chung, H.M.; Smith, D.L.

    1998-03-01

    Recent attention to vanadium-base alloys has focused on the effect of low-temperature (<430 C) neutron irradiation on the mechanical properties, especially the phenomena of loss of work-hardening capability under tensile loading and loss of dynamic toughness manifested by low impact energy and high ductile-brittle-transition temperature (DBTT). This paper summarizes results of an investigation of the low-temperature impact properties of V-5Ti, V-4Cr-4Ti, and V-3Ti-Si that were irradiated in several fission reactor experiments, i.e., FFTF-MOTA, EBR-II X-530, and ATR-A1. Irradiation performance of one production-scale and one laboratory heat of V-4C-4Ti and one laboratory heat of V-3Ti-Si was the focus of the investigation. Even among the same lass of alloy, strong heat-to-heat variation was observed in low-temperature impact properties. A laboratory heat of V-4Cr-4Ti and V-3Ti-1Si exhibited good impact properties whereas a 500-kg heat of V-4Cr-4Ti exhibited unacceptably high DBTT. The strong heat-to-heat variation in impact properties of V-4Cr-4Ti indicates that fabrication procedures and minor impurities play important roles in the low-temperature irradiation performance of the alloys.

  14. Preparation of tantalum-based alloys by a unique CVD process

    NASA Technical Reports Server (NTRS)

    Bryant, W. A.; Meier, G. H.

    1975-01-01

    The paper describes a sequential pulsing technique for deposition of refractory alloys and evaluates the technique for the deposition of the tantalum-base alloys Ta-10W (Ta-10 st% W) and T-111 (Ta-8 wt% W-2 wt% Hf). The deposition cycle for Ta-10W was chosen as alternate injections of TaCl5 plus hydrogen and WCl6 plus hydrogen. The cycle for T-111 was chosen as injections of TaCl5 plus hydrogen interspersed with injections of WCl6 plus hydrogen. A temperature range of 900-1300 C was chosen for both alloys. The ability of the pulse process to blanket a uniformly heated section of substrate with a mixture of gases, whose composition varies not with position on the substrate but instead with time of residence in the reactor, allows metal of uniform thickness to be deposited. It is shown that Ta and W can be deposited at high temperature with the formation of a dense columnar grain structure, so that the feasibility of preparing uniformly thick deposits of these elements by a 'pulsing' modification of CVD is demonstrated. A similar attempt to deposit T-111 was unsuccessful due to the difficulty in reducing HfCl4.

  15. Enhanced ferroelectric polarization and possible morphotrophic phase boundary in PZT-based alloys

    SciTech Connect

    Parker, David S.; Singh, David; McGuire, Michael A.; Herklotz, Andreas; Ward, Thomas Zac

    2016-05-16

    We present a combined theoretical and experimental study of alloys of the high performance piezoelectric PZT (PbZr0.5Ti0.5O3) with BZnT (BiZn0.5Ti0.5O3) and BZnZr (BiZn0.5Zr0.5O3), focusing on atomic displacements, ferroelectric polarization, and elastic stability. From theory we find that the 75-25 PZT-BZnT alloy has substantially larger cation displacements, and hence ferroelectric polarization than the PZT base material, on the tetragonal side of the phase diagram. We also find a possible morphotrophic phase boundary in this system by comparing displacement patterns and optimized c/a ratios. Elastic stability calculations find the structures to be essentially stable. Lastly, experiments indicate the feasibility of sample synthesis within this alloy system, although measurements do not find significant polarization, probably due to a large coercive field.

  16. Control of Interfacial Reactivity Between ZrB2 and Ni-Based Brazing Alloys

    NASA Astrophysics Data System (ADS)

    Valenza, F.; Muolo, M. L.; Passerone, A.; Cacciamani, G.; Artini, C.

    2012-05-01

    Transition metals diborides (Ti,Zr,Hf)B2 play a key role in applications where stability at extremely high temperatures and damage tolerance are required; however, much research has still to be done to optimize the joining of these materials to themselves or to other high-temperature materials. In this study, the reactivity at the solid-liquid interface between ZrB2 ceramics and Ni-based brazing alloys has been addressed; it is shown how the reactivity and the dissolution of the solid phase can be controlled and even suppressed by adjusting the brazing alloy composition on the basis of thermodynamic calculations. Wetting experiments on ZrB2 ceramics by Ni, Ni-B 17 at.%, and Ni-B 50 at.% were performed at 1500 and 1200 °C by the sessile drop technique. The obtained interfaces were characterized by optical microscopy and SEM-EDS, and interpreted by means of the ad hoc-calculated B-Ni-Zr ternary diagram. A correlation among microstructures, substrate dissolution, shape of the drops, spreading kinetics, and the phase diagram was found. The effect on the interfacial reactivity of Si3Ni4 used as a sintering aid and issues related to Si diffusion into the brazing alloy are discussed as well.

  17. Enhanced ferroelectric polarization and possible morphotrophic phase boundary in PZT-based alloys

    DOE PAGES

    Parker, David S.; Singh, David; McGuire, Michael A.; ...

    2016-05-16

    We present a combined theoretical and experimental study of alloys of the high performance piezoelectric PZT (PbZr0.5Ti0.5O3) with BZnT (BiZn0.5Ti0.5O3) and BZnZr (BiZn0.5Zr0.5O3), focusing on atomic displacements, ferroelectric polarization, and elastic stability. From theory we find that the 75-25 PZT-BZnT alloy has substantially larger cation displacements, and hence ferroelectric polarization than the PZT base material, on the tetragonal side of the phase diagram. We also find a possible morphotrophic phase boundary in this system by comparing displacement patterns and optimized c/a ratios. Elastic stability calculations find the structures to be essentially stable. Lastly, experiments indicate the feasibility of sample synthesismore » within this alloy system, although measurements do not find significant polarization, probably due to a large coercive field.« less

  18. Manufacturing of self-passivating tungsten based alloys by different powder metallurgical routes

    NASA Astrophysics Data System (ADS)

    Calvo, A.; Ordás, N.; Iturriza, I.; Pastor, J. Y.; Tejado, E.; Palacios, T.; García-Rosales, C.

    2016-02-01

    Self-passivating tungsten based alloys will provide a major safety advantage compared to pure tungsten when used as first wall armor of future fusion reactors, due to the formation of a protective oxide layer which prevents the formation of volatile and radioactive WO3 in case of a loss of coolant accident with simultaneous air ingress. Bulk WCr10Ti2 alloys were manufactured by two different powder metallurgical routes: (1) mechanical alloying (MA) followed by hot isostatic pressing (HIP) of metallic capsules, and (2) MA, compaction, pressureless sintering in H2 and subsequent HIPing without encapsulation. Both routes resulted in fully dense materials with homogeneous microstructure and grain sizes of 300 nm and 1 μm, respectively. The content of impurities remained unchanged after HIP, but it increased after sintering due to binder residue. It was not possible to produce large samples by route (2) due to difficulties in the uniaxial compaction stage. Flexural strength and fracture toughness measured on samples produced by route (1) revealed a ductile-to-brittle-transition temperature (DBTT) of about 950 °C. The strength increased from room temperature to 800 °C, decreasing significantly in the plastic region. An increase of fracture toughness is observed around the DBTT.

  19. Atomic dynamics in Zr-based glass forming alloys near the liquidus temperature

    NASA Astrophysics Data System (ADS)

    Basuki, Sri Wahyuni; Yang, Fan; Gill, Elisabeth; Rätzke, Klaus; Meyer, Andreas; Faupel, Franz

    2017-01-01

    We report simultaneous radiotracer diffusion experiments of Co-57 and of Zr-95 in binary Z r64N i36 , Z r36N i64 , and ternary Z r60N i25A l15 alloys above but near the liquidus temperature (Tl). In contrast to the multicomponent Z r46.75T i8.25C u7.5N i10B e27.5 (Vit4), where a significant component decoupling at the Tl is observed, the ratio between Zr and Co self-diffusion coefficients is smaller than two in the alloys with fewer components. The difference in the degree of decoupling compared to Vit4 can be explained in terms of different Tl's. Moreover, owing to the high accuracy of the simultaneous tracer diffusion technique, we are able to resolve a small but notable composition dependence of the ratio DCo/DZr , which decreases with increasing Zr content for all glass forming alloys reported here. In contrast to a hard sphere (HS)-like mixture, where decoupling is controlled only by atomic sizes, this indicates a coupling of the Co/Ni and Zr diffusion, due to the strong chemical affinity between the diffusing components. Our results are in very good agreement with recent simulations in Z r64N i36 based on mode coupling theory (MCT).

  20. First-principles studies of hydrogen interaction with ultrathin Mg and Mg-based alloy films

    NASA Astrophysics Data System (ADS)

    Yoon, Mina; Weitering, Hanno H.; Zhang, Zhenyu

    2011-01-01

    The search for technologically and economically viable storage solutions for hydrogen fuel would benefit greatly from research strategies that involve systematic property tuning of potential storage materials via atomic-level modification. Here, we use first-principles density-functional theory to investigate theoretically the structural and electronic properties of ultrathin Mg films and Mg-based alloy films and their interaction with atomic hydrogen. Additional delocalized charges are distributed over the Mg films upon alloying them with 11.1% of Al or Na atoms. These extra charges contribute to enhance the hydrogen binding strength to the films. We calculated the chemical potential of hydrogen in Mg films for different dopant species and film thickness, and we included the vibrational degrees of freedom. By comparing the chemical potential with that of free hydrogen gas at finite temperature (T) and pressure (P), we construct a hydrogenation phase diagram and identify the conditions for hydrogen absorption or desorption. The formation enthalpies of metal hydrides are greatly increased in thin films, and in stark contrast to its bulk phase, the hydride state can only be stabilized at high P and T (where the chemical potential of free H2 is very high). Metal doping increases the thermodynamic stabilities of the hydride films and thus significantly helps to reduce the required pressure condition for hydrogen absorption from H2 gas. In particular, with Na alloying, hydrogen can be absorbed and/or desorbed at experimentally accessible T and P conditions.

  1. Failure Analysis of Warm Stamping of Magnesium Alloy Sheet Based on an Anisotropic Damage Model

    NASA Astrophysics Data System (ADS)

    Zhao, P. J.; Chen, Z. H.; Dong, C. F.

    2014-11-01

    Based on the frame work of continuum damage mechanics, a research work of anisotropic damage evolution in warm stamping process of magnesium alloy sheets has been carried out by means of a combined experimental-numerical method. The aim was to predict formability of warm stamping of AZ31 Mg alloy sheets by taking the thermal and damage effects into account. In the presented work, a temperature-dependent anisotropic yield function suitable for cold rolling sheet metals together with an anisotropic damage model was implemented into the a VUMAT subroutine for ABAQUS/EXPLICIT. The evolution of internal damage in the form of void growth and coalescence in AZ31 Mg alloy sheet was observed by means of scanning electron microscopy (SEM). Moreover, a coupled thermo-mechanical simulation of the stamping process was performed using the implemented code at different temperatures. The parameters employed in the simulation were determined by the standard tensile tests and algebraic manipulation. The overall anisotropic damage process from crack initiation to final propagation in local area of blank was simulated. Numerical results show that the prediction of the site of crack initiation and the orientation of crack propagation are consistent with the data observed in warm stamping experiments.

  2. Nickel-based Gadolinium Alloy for Neutron Adsorption Application in Ram Packages

    SciTech Connect

    Gregg Wachs; James Sterbentz; William Hurt; P. E. McConnell; C. V. Robino; F. Tovesson; T. S. Hill

    2007-10-01

    Neutron transmission experiments were performed on samples of an advanced nickel-chromium-molybdenum-gadolinium (Ni-Cr-Mo-Gd) neutron absorber alloy and chromium-nickel (Cr-Ni) stainless steel, modified by the addition of boron. The primary purpose of the experiments was to demonstrate the thermal neutron absorbing capability of the materials at specific gadolinium and boron dopant levels. The Ni-Cr-Mo-Gd alloy is envisioned to be deployed for criticality control of highly enriched U.S. Department of Energy (DOE)-owned spent nuclear fuel (SNF). For these transmission experiments, test samples were fabricated with 0.0, 1.58 and 2.1 wt% natural gadolinium dispersed in a Ni-Cr-Mo base alloy and 1.16 wt% boron in stainless steel. The transmission experiments were successfully carried out at the Los Alamos Neutron Science Center (LANSCE). Measured data from the neutron transmission experiments were compared to calculated results derived from a simple exponential transmission formula using total neutron cross sections. Excellent agreement between the measured and calculated results demonstrated the expected strong thermal absorption capability of the gadolinium and boron elements and in addition, verified the measured elemental composition of the Ni-Cr-Mo-Gd alloy and borated stainless steel test samples. The good agreement also indirectly confirmed that the size and distribution of the gadolinium in both the hot-top (as-cast) and Ni-Cr-Mo-Gd converted to plate was not a discriminator related to neutron absorption. Moreover, the Evaluated Nuclear Data File (ENDF VII) total neutron cross section data were accurate.

  3. Effect of preconditioning cobalt and nickel based dental alloys with Bacillus sp. extract on their surface physicochemical properties and theoretical prediction of Candida albicans adhesion.

    PubMed

    Balouiri, Mounyr; Bouhdid, Samira; Sadiki, Moulay; Ouedrhiri, Wessal; Barkai, Hassan; El Farricha, Omar; Ibnsouda, Saad Koraichi; Harki, El Houssaine

    2017-02-01

    Biofilm formation on dental biomaterials is implicated in various oral health problems. Thus the challenge is to prevent the formation of this consortium of microorganisms using a safe approach such as antimicrobial and anti-adhesive natural products. Indeed, in the present study, the effects of an antifungal extract of Bacillus sp., isolated from plant rhizosphere, on the surface physicochemical properties of cobalt and nickel based dental alloys were studied using the contact angle measurements. Furthermore, in order to predict the adhesion of Candida albicans to the treated and untreated dental alloys, the total free energy of adhesion was calculated based on the extended Derjaguin-Landau-Verwey-Overbeek approach. Results showed hydrophobic and weak electron-donor and electron-acceptor characteristics of both untreated dental alloys. After treatment with the antifungal extract, the surface free energy of both dental alloys was influenced significantly, mostly for cobalt based alloy. In fact, treated cobalt based alloy became hydrophilic and predominantly electron donating. Those effects were time-dependent. Consequently, the total free energy of adhesion of C. albicans to this alloy became unfavorable after treatment with the investigated microbial extract. A linear relationship between the electron-donor property and the total free energy of adhesion has been found for both dental alloys. Also, a linear relationship has been found between this latter and the hydrophobicity for the cobalt based alloy. However, the exposure of nickel based alloy to the antifungal extract failed to produce the same effect.

  4. Photonic crystal waveguides based on wide-gap semiconductor alloys

    NASA Astrophysics Data System (ADS)

    Martin, Aude; Combrié, Sylvain; De Rossi, Alfredo

    2017-03-01

    This review is devoted to integrated photonic platforms based on large band-gap semiconductors, alternatives to silicon photonics. The large electronic band gap of the material employed is chosen to address the specific needs of nonlinear optics, and, in particular, lower nonlinear losses and the capability of handling larger optical power densities. Moreover, these new platforms offer broader transmission spectra, extending to the visible spectral region, which is also required for other applications, particularly sensing and bio-related photonics. The focus is on nanoscale patterned waveguiding structures, which, owing to the tight confinement of light, have demonstrated a large nonlinear response. The third-order nonlinear response and the related parametric interactions will be considered here, encompassing four-wave mixing, phase-sensitive amplification, wavelength conversion, and also nonlinear pulse propagation and soliton dynamics. The comparison between different materials and waveguide design highlights specific features of photonic crystal waveguides.

  5. Technological features of metal-ceramic prosthesis frameworks manufactured from domestic alloys of precious and base metals.

    PubMed

    Parunov, V A; Yurkovets, P V; Lebedenko, I Yu

    2016-01-01

    The aim of the study was to examine changes in physical and mechanical properties of dental alloys depending of the initial composition at re-casting. Russianc precious alloys: Plagodent (AuPtPd) and Palladent (PdAu) and base alloys: Vitiriy-N (NiCrMo) and Vitiriy-C (CoCrMo) were used as study samples, which were divided in three groups: a primary casting from the granules; 50% of re-casting; 100% of re-casting. We investigated the yield strength in bending, coefficient of thermal expansion and hardness. Changing in the composition of the alloys has led to changes of all physical and mechanical properties.

  6. High gas velocity oxidation and hot corrosion testing of oxide dispersion-strengthened nickel-base alloys

    NASA Technical Reports Server (NTRS)

    Deadmore, D. L.; Lowell, C. E.

    1975-01-01

    Several oxide dispersion strengthened (ODS) nickel-base alloys were tested in high velocity gases for cyclic oxidation resistance at temperatures to 1200 C and times to 500 hours and for hot corrosion resistance at 900 C for 200 hours. Nickel-chromium-aluminum ODS alloys were found to have superior resistance to oxidation and hot corrosion when compared to bare and coated nickel-chromium ODS alloys. The best of the alloys tested had compositions of nickel - 15.5 to 16 weight percent chromium with aluminum weight percents between 4.5 and 5.0. All of the nickel-chromium-aluminum ODS materials experienced small weight losses (less than 16 mg/sq cm).

  7. PLUTONIUM-THORIUM ALLOYS

    DOEpatents

    Schonfeld, F.W.

    1959-09-15

    New plutonium-base binary alloys useful as liquid reactor fuel are described. The alloys consist of 50 to 98 at.% thorium with the remainder plutonium. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are easy fabrication, phase stability, and the accompanying advantuge of providing a means for converting Th/sup 232/ into U/sup 233/.

  8. STRUCTURE AND HIGH-FIELD PERFORMANCE OF JELLY ROLL PROCESSED Nb{sub 3}Sn WIRES USING Sn-Ta AND Sn-Ti BASED ALLOY SHEET

    SciTech Connect

    Tachikawa, K.; Tsuyuki, T.; Hayashi, Y.; Nakata, K.; Takeuchi, T.

    2008-03-03

    Sn-Ta based alloy buttons of different compositions were prepared by the melt diffusion process among constituent metal powders, and then pressed into plates. Meanwhile Sn-Ti based alloy plates were sliced from the melt and cast ingot. Resulting Sn-based alloy plates were rolled into thin sheets. The Sn-based alloy sheet was laminated with a Nb sheet, and wound into a Jelly Roll (JR) composite. The composite was encased in a sheath, and fabricated into a thin wire followed by the heat treatment. The application of hydrostatic extrusion is useful at the initial stage of the fabrication. The JR wires using Sn-Ta and Sn-Ti based alloy sheets show a non-Cu J{sub c} of {approx}250 A/mm{sup 2} and {approx}150 A/mm{sup 2} at 20 T and 22 T, respectively, at 4.2 K. It has been found that the Nb impregnates into the Sn-based alloy layers during the reaction, and Nb{sub 3}Sn layers are synthesized by the mutual diffusion between the Nb sheet and the Sn-based alloy sheet without formation of voids. Sn-Ti based alloy sheets are attractive due to their easiness of mass production. Structure and high-field performance of JR processed Nb{sub 3}Sn wires prepared from Sn-based alloy sheets with different compositions are compared in this article.

  9. A crystallographic model for nickel base single crystal alloys

    NASA Technical Reports Server (NTRS)

    Dame, L. T.; Stouffer, D. C.

    1988-01-01

    The purpose of this research is to develop a tool for the mechanical analysis of nickel-base single-crystal superalloys, specifically Rene N4, used in gas turbine engine components. This objective is achieved by developing a rate-dependent anisotropic constitutive model and implementing it in a nonlinear three-dimensional finite-element code. The constitutive model is developed from metallurgical concepts utilizing a crystallographic approach. An extension of Schmid's law is combined with the Bodner-Partom equations to model the inelastic tension/compression asymmetry and orientation-dependence in octahedral slip. Schmid's law is used to approximate the inelastic response of the material in cube slip. The constitutive equations model the tensile behavior, creep response and strain-rate sensitivity of the single-crystal superalloys. Methods for deriving the material constants from standard tests are also discussed. The model is implemented in a finite-element code, and the computed and experimental results are compared for several orientations and loading conditions.

  10. The effect of interface properties on nickel base alloy composites

    NASA Technical Reports Server (NTRS)

    Groves, M.; Grossman, T.; Senemeier, M.; Wright, K.

    1995-01-01

    This program was performed to assess the extent to which mechanical behavior models can predict the properties of sapphire fiber/nickel aluminide matrix composites and help guide their development by defining improved combinations of matrix and interface coating. The program consisted of four tasks: 1) selection of the matrices and interface coating constituents using a modeling-based approach; 2) fabrication of the selected materials; 3) testing and evaluation of the materials; and 4) evaluation of the behavior models to develop recommendations. Ni-50Al and Ni-20AI-30Fe (a/o) matrices were selected which gave brittle and ductile behavior, respectively, and an interface coating of PVD YSZ was selected which provided strong bonding to the sapphire fiber. Significant fiber damage and strength loss was observed in the composites which made straightforward comparison of properties with models difficult. Nevertheless, the models selected generally provided property predictions which agreed well with results when fiber degradation was incorporated. The presence of a strong interface bond was felt to be detrimental in the NiAI MMC system where low toughness and low strength were observed.

  11. Degradation of the shape memory effect in copper-base alloys

    SciTech Connect

    Stalmans, R.; Van Humbeeck, J.; Delaey, L. . Dept. of Metallurgy and Materials Science)

    1994-12-01

    The reversible transformation of the parent phase (austenite) to the product phase (martensite) is the basis of several shape memory properties in specific Cu-base alloys. In this respect, the two-way memory effect (TWME) refers the reversible, spontaneous shape change from a hot austenitic shape to a cold martensitic shape during cooling and heating without the application of external stresses. It is known that the magnitude of the TWME decrease during thermal or thermomechanical cycling, in particular in Cu-base shape memory alloys. It is however important to remark that this decrease, indicated as degradation of the TWME, can be caused as well by a decrease of the spontaneous martensitic strain, i.e. a degradation of the cold shape, as by an increase of the residual austenitic strain, i.e. a degradation of the hot shape, or by a combination of both. The degradation of the TWME, and of the hot and cold shape is influenced by a number of factors including the alloy composition, the processing, the heat treatment, the training procedure and the parameters of the thermal or thermomechanical cycling. The knowledge of the degradation phenomena is still limited. In a subsequent study of the relationships between training and the two-way memory behavior, the authors have shown that the degradation of the hot shape already starts during training. It was found that the residual austenitic strain [gamma][sub a] increases gradually during training cycling; [gamma][sub a] is also in the case of training composed of a recoverable residual strain [gamma][sub ar] and a non-recoverable residual strain [gamma][sub anr]. The present paper reports the results of the specific experiments which were designed based upon the results described above. The evolutions during thermal cycling of the TWME, of the martensitic strain and austenitic strain, and of the recoverable and non-recoverable austenitic strain are presented and discussed.

  12. Friction and wear with a single-crystal abrasive grit of silicon carbide in contact with iron base binary alloys in oil: Effects of alloying element and its content

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1979-01-01

    Sliding friction experiments were conducted with various iron-base binary alloys (alloying elements were Ti, Cr, Mn, Ni, Rh, and W) in contact with a rider of 0.025-millimeter-radius, single-crystal silicon carbide in mineral oil. Results indicate that atomic size and content of alloying element play a dominant role in controlling the abrasive-wear and -friction properties of iron-base binary alloys. The coefficient of friction and groove height (wear volume) general alloy decrease, and the contact pressure increases in solute content. There appears to be very good correlation of the solute to iron atomic radius ratio with the decreasing rate of coefficient of friction, the decreasing rate of groove height (wear volume), and the increasing rate of contact pressure with increasing solute content C. Those rates increase as the solute to iron atomic radius ratio increases from unity.

  13. A Comparison between Shear Bond Strength of VMK Master Porcelain with Three Base-metal Alloys (Ni-cr-T3, VeraBond, Super Cast) and One Noble Alloy (X-33) in Metal-ceramic Restorations

    PubMed Central

    Ahmadzadeh, A; Neshati, A; Mousavi, N; Epakchi, S; Dabaghi Tabriz, F; Sarbazi, AH

    2013-01-01

    Statement of Problem: The increase in the use of metal-ceramic restorations and a high prevalence of porcelain chipping entails introducing an alloy which is more compatible with porcelain and causes a stronger bond between the two. This study is to compare shear bond strength of three base-metal alloys and one noble alloy with the commonly used VMK Master Porcelain. Materials and Method: Three different groups of base-metal alloys (Ni-cr-T3, Super Cast, and VeraBond) and one group of noble alloy (X-33) were selected. Each group consisted of 15 alloy samples. All groups went through the casting process and change from wax pattern into metal disks. The VMK Master Porcelain was then fired on each group. All the specimens were put in the UTM; a shear force was loaded until a fracture occurred and the fracture force was consequently recorded. The data were analyzed by SPSS Version 16 and One-Way ANOVA was run to compare the shear strength between the groups. Furthermore, the groups were compared two-by-two by adopting Tukey test. Results: The findings of this study revealed shear bond strength of Ni-Cr-T3 alloy was higher than the three other alloys (94 MPa or 330 N). Super Cast alloy had the second greatest shear bond strength (80. 87Mpa or 283.87 N). Both VeraBond (69.66 MPa or 245 N) and x-33 alloys (66.53 MPa or 234 N) took the third place. Conclusion: Ni-Cr-T3 with VMK Master Porcelain has the greatest shear bond strength. Therefore, employment of this low-cost alloy is recommended in metal-ceramic restorations. PMID:24724144

  14. Thermal and mechanical treatments for nickel and some nickel-base alloys: Effects on mechanical properties

    NASA Technical Reports Server (NTRS)

    Hall, A. M.; Beuhring, V. F.

    1972-01-01

    This report deals with heat treating and working nickel and nickel-base alloys, and with the effects of these operations on the mechanical properties of the materials. The subjects covered are annealing, solution treating, stress relieving, stress equalizing, age hardening, hot working, cold working, combinations of working and heat treating (often referred to as thermomechanical treating), and properties of the materials at various temperatures. The equipment and procedures used in working the materials are discussed, along with the common problems that may be encountered and the precautions and corrective measures that are available.

  15. Mechanical properties of molybdenum alloyed liquid phase-sintered tungsten-based composites

    SciTech Connect

    Kemp, P.B.; German, R.M.

    1995-08-01

    Tungsten-based composites are fabricated from mixed elemental powders using liquid phase sintering, usually with a nickel-iron matrix. During sintering, the tungsten undergoes grain growth, leading to microstructure coarsening that lowers strength but increases ductility. Often the desire is to increase strength at the sacrifice of ductility, and historically, this has been performed by postsintering deformation. Swaging a 93W-5Ni-2Fe alloy with 15 to 20 pct area reduction gives a 1000 to 1200 MPa tensile strength, 70 HRA hardness, and 15 to 20 pct fracture elongation.

  16. Metal elution from Ni- and Fe-based alloy reactors under hydrothermal conditions.

    PubMed

    Faisal, Muhammad; Quitain, Armando T; Urano, Shin-Ya; Daimon, Hiroyuki; Fujie, Koichi

    2004-05-20

    Elution of metals from Ni- and Fe-based alloy (i.e. Inconel 625 and SUS 316) under hydrothermal conditions was investigated. Results showed that metals could be eluted even in a short contact time. At subcritical conditions, a significant amount of Cr was extracted from SUS 316, while only traces of Ni, Fe, Mo, and Mn were eluted. In contrast, Ni was removed in significant amounts compared to Cr when Inconel 625 was tested. Several factors including temperature and contact time were found to affect elution behavior. The presence of air in the fluid even promoted elution under subcritical conditions.

  17. Durability of nanostructured coatings based on PTFE nanoparticles deposited on porous aluminum alloy

    NASA Astrophysics Data System (ADS)

    Ghalmi, Zahira; Farzaneh, Masoud

    2014-09-01

    Ice accumulation on outdoor structures is a serious problem in cold climate regions of the world. To address this issue, several surface treatment methods have been developed for structures made of aluminum alloys. In this study, an Al2O3 porous oxide layer was formed by anodization using a phosphoric acid electrolyte. Subsequently, polytetrafluoroethylene (PTFE) was used to coat the porous surface. After PTFE impregnation, a nanostructured surface along with a low surface energy of PTFE resulted in significantly reduced ice adhesion strength. In fact, even after fifteen icing/deicing cycles, the PTFE-based coating remained highly hydrophobic with static contact angles higher than smooth Teflon® surface.

  18. Laser-Aided Direct Writing of Nickel-Based Single-Crystal Super Alloy (N5)

    NASA Astrophysics Data System (ADS)

    Wang, Yichen; Choi, Jeongyoung; Mazumder, Jyoti

    2016-12-01

    This communication reports direct writing of René N5 nickel-based Super alloy. N5 powder was deposited on (100) single-crystal substrate of René N5, for epitaxial growth, using laser and induction heating with a specially designed closed-loop thermal control system. A thin wall (1 mm width) of René N5 single crystal of 22.1 mm (including 3 mm SX substrate) in height was successfully deposited within 100 layers. SEM and EBSD characterized the single-crystal nature of the deposit.

  19. Optical properties of surface layers of Co-based amorphous metallic alloys

    NASA Astrophysics Data System (ADS)

    Poperenko, L. V.; Kravets, V. G.; Lysenko, S. I.; Vinnichenko, K. L.

    2005-04-01

    The modification of roughness and structure of the surface layers of a cobalt-based amorphous metal alloy after thermal treatment at elevated and cryogenic temperatures and under the influence of an external magnetic field is studied by light scattering and atomic force microscopy. The parameters of the surface roughness were calculated from the measured indicatrices of light scattering. It is shown that heating of the metal ribbons to T=350-475 °C partially relieves stresses arising in the course of the ribbon preparation and increases the surface roughness compared to freshly prepared samples.

  20. Ion irradiation induced disappearance of dislocations in a nickel-based alloy

    NASA Astrophysics Data System (ADS)

    Chen, H. C.; Li, D. H.; Lui, R. D.; Huang, H. F.; Li, J. J.; Lei, G. H.; Huang, Q.; Bao, L. M.; Yan, L.; Zhou, X. T.; Zhu, Z. Y.

    2016-06-01

    Under Xe ion irradiation, the microstructural evolution of a nickel based alloy, Hastelloy N (US N10003), was studied. The intrinsic dislocations are decorated with irradiation induced interstitial loops and/or clusters. Moreover, the intrinsic dislocations density reduces as the irradiation damage increases. The disappearance of the intrinsic dislocations is ascribed to the dislocations climb to the free surface by the absorption of interstitials under the ion irradiation. Moreover, the in situ annealing experiment reveals that the small interstitial loops and/or clusters induced by the ion irradiation are stable below 600 °C.

  1. Transient liquid phase bonding of titanium-, iron- and nickel-based alloys

    NASA Astrophysics Data System (ADS)

    Rahman, A. H. M. Esfakur

    The operating temperature of land-based gas turbines and jet engines are ever-increasing to increase the efficiency, decrease the emissions and minimize the cost. Within the engines, complex-shaped parts experience extreme temperature, fatigue and corrosion conditions. Ti-based, Ni-based and Fe-based alloys are commonly used in gas turbines and jet engines depending on the temperatures of different sections. Although those alloys have superior mechanical, high temperature and corrosion properties, severe operating conditions cause fast degradation and failure of the components. Repair of these components could reduce lifecycle costs. Unfortunately, conventional fusion welding is not very attractive, because Ti reacts very easily with oxygen and nitrogen at high temperatures, Ni-based superalloys show heat affected zone (HAZ) cracking, and stainless steels show intergranular corrosion and knife-line attack. On the other hand, transient liquid phase (TLP) bonding method has been considered as preferred joining method for those types of alloys. During the initial phase of the current work commercially pure Ti, Fe and Ni were diffusion bonded using commercially available interlayer materials. Commercially pure Ti (Ti-grade 2) has been diffusion bonded using silver and copper interlayers and without any interlayer. With a silver (Ag) interlayer, different intermetallics (AgTi, AgTi2) appeared in the joint centerline microstructure. While with a Cu interlayer eutectic mixtures and Ti-Cu solid solutions appeared in the joint centerline. The maximum tensile strengths achieved were 160 MPa, 502 MPa, and 382 MPa when Ag, Cu and no interlayers were used, respectively. Commercially pure Fe (cp-Fe) was diffusion bonded using Cu (25 m) and Au-12Ge eutectic interlayer (100 microm). Cu diffused predominantly along austenite grain boundaries in all bonding conditions. Residual interlayers appeared at lower bonding temperature and time, however, voids were observed in the joint

  2. General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated Corrosion Methods

    DTIC Science & Technology

    2009-09-01

    General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated... Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated Corrosion Methods Brian E. Placzankis Weapons and Materials Research Directorate...March 2006–October 2008 4. TITLE AND SUBTITLE General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD

  3. Synthesis of Nanostructured GAMMA-TiAl Based Powders and Bulk Alloys Using High Energy Mechanical Milling and Hip

    NASA Astrophysics Data System (ADS)

    Yu, Hongbao; Zhang, Deliang; Chen, Yuyong; Liu, Zhiguang

    The microstructural evolution and powder particle morphology change in the process used to synthesize bulk nanostructured γ-TiAl intermetallic based binary Ti-47Al (in at%) alloy (TA-1) and complex Ti-45Al-2Cr-2Nb-1B-0.5Ta (in at%) alloy (TA-2) have been studied. This process combines high energy mechanical milling of elemental powder mixtures, thermal treatment and HIP. The bulk alloys consist of predominantly TiAl phase and a small fraction of Ti3Al phase, with the average grain sizes of the TiAl and Ti3Al phases being approximately 45nm and 40nm respectively in the bulk TA-1 alloy and being 37nm and 35nm respectively in the bulk TA-2 alloy. The study also shows that addition of a small fraction of hard powder particles such as Nb, Cr, B and Ta powder particles to the starting powder mixture has a significant effect in maintaining a small average particle size during high energy mechanical milling without using PCA and thus significantly enhances the mechanical alloying effect of the milling process.

  4. Tailoring the physical properties of Ni-based single-phase equiatomic alloys by modifying the chemical complexity.

    PubMed

    Jin, K; Sales, B C; Stocks, G M; Samolyuk, G D; Daene, M; Weber, W J; Zhang, Y; Bei, H

    2016-02-01

    Equiatomic alloys (e.g. high entropy alloys) have recently attracted considerable interest due to their exceptional properties, which might be closely related to their extreme disorder induced by the chemical complexity. In order to understand the effects of chemical complexity on their fundamental physical properties, a family of (eight) Ni-based, face-center-cubic (FCC), equiatomic alloys, extending from elemental Ni to quinary high entropy alloys, has been synthesized, and their electrical, thermal, and magnetic properties are systematically investigated in the range of 4-300 K by combining experiments with ab initio Korring-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) calculations. The scattering of electrons is significantly increased due to the chemical (especially magnetic) disorder. It has weak correlation with the number of elements but strongly depends on the type of elements. Thermal conductivities of the alloys are largely lower than pure metals, primarily because the high electrical resistivity suppresses the electronic thermal conductivity. The temperature dependence of the electrical and thermal transport properties is further discussed, and the magnetization of five alloys containing three or more elements is measured in magnetic fields up to 4 T.

  5. Feedforward-feedback hybrid control for magnetic shape memory alloy actuators based on the Krasnosel'skii-Pokrovskii model.

    PubMed

    Zhou, Miaolei; Zhang, Qi; Wang, Jingyuan

    2014-01-01

    As a new type of smart material, magnetic shape memory alloy has the advantages of a fast response frequency and outstanding strain capability in the field of microdrive and microposition actuators. The hysteresis nonlinearity in magnetic shape memory alloy actuators, however, limits system performance and further application. Here we propose a feedforward-feedback hybrid control method to improve control precision and mitigate the effects of the hysteresis nonlinearity of magnetic shape memory alloy actuators. First, hysteresis nonlinearity compensation for the magnetic shape memory alloy actuator is implemented by establishing a feedforward controller which is an inverse hysteresis model based on Krasnosel'skii-Pokrovskii operator. Secondly, the paper employs the classical Proportion Integration Differentiation feedback control with feedforward control to comprise the hybrid control system, and for further enhancing the adaptive performance of the system and improving the control accuracy, the Radial Basis Function neural network self-tuning Proportion Integration Differentiation feedback control replaces the classical Proportion Integration Differentiation feedback control. Utilizing self-learning ability of the Radial Basis Function neural network obtains Jacobian information of magnetic shape memory alloy actuator for the on-line adjustment of parameters in Proportion Integration Differentiation controller. Finally, simulation results show that the hybrid control method proposed in this paper can greatly improve the control precision of magnetic shape memory alloy actuator and the maximum tracking error is reduced from 1.1% in the open-loop system to 0.43% in the hybrid control system.

  6. Tailoring the physical properties of Ni-based single-phase equiatomic alloys by modifying the chemical complexity

    SciTech Connect

    Jin, Ke; Sales, Brian C.; Stocks, George Malcolm; Samolyuk, German D.; Daene, Markus; Weber, William J.; Zhang, Yanwen; Bei, Hongbin

    2016-02-01

    We discovered that equiatomic alloys (e.g. high entropy alloys) have recently attracted considerable interest due to their exceptional properties, which might be closely related to their extreme disorder induced by the chemical complexity. To understand the effects of chemical complexity on their fundamental physical properties, a family of (eight) Ni-based, face-center-cubic (FCC), equiatomic alloys, extending from elemental Ni to quinary high entropy alloys, has been synthesized, and their electrical, thermal, and magnetic properties are systematically investigated in the range of 4–300 K by combining experiments with ab initio Korring-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) calculations. The scattering of electrons is significantly increased due to the chemical (especially magnetic) disorder. It has weak correlation with the number of elements but strongly depends on the type of elements. Thermal conductivities of the alloys are largely lower than pure metals, primarily because the high electrical resistivity suppresses the electronic thermal conductivity. Moreover, the temperature dependence of the electrical and thermal transport properties is further discussed, and the magnetization of five alloys containing three or more elements is measured in magnetic fields up to 4 T.

  7. A microstructure-based yield stress and work-hardening model for textured 6xxx aluminium alloys

    NASA Astrophysics Data System (ADS)

    Khadyko, M.; Myhr, O. R.; Dumoulin, S.; Hopperstad, O. S.

    2016-04-01

    The plastic properties of an aluminium alloy are defined by its microstructure. The most important factors are the presence of alloying elements in the form of solid solution and precipitates of various sizes, and the crystallographic texture. A nanoscale model that predicts the work-hardening curves of 6xxx aluminium alloys was proposed by Myhr et al. The model predicts the solid solution concentration and the particle size distributions of different types of metastable precipitates from the chemical composition and thermal history of the alloy. The yield stress and the work hardening of the alloy are then determined from dislocation mechanics. The model was largely used for non-textured materials in previous studies. In this work, a crystal plasticity-based approach is proposed for the work hardening part of the nanoscale model, which allows including the influence of the crystallographic texture. The model is evaluated by comparison with experimental data from uniaxial tensile tests on two textured 6xxx alloys in five temper conditions.

  8. Tailoring the physical properties of Ni-based single-phase equiatomic alloys by modifying the chemical complexity

    DOE PAGES

    Jin, Ke; Sales, Brian C.; Stocks, George Malcolm; ...

    2016-02-01

    We discovered that equiatomic alloys (e.g. high entropy alloys) have recently attracted considerable interest due to their exceptional properties, which might be closely related to their extreme disorder induced by the chemical complexity. To understand the effects of chemical complexity on their fundamental physical properties, a family of (eight) Ni-based, face-center-cubic (FCC), equiatomic alloys, extending from elemental Ni to quinary high entropy alloys, has been synthesized, and their electrical, thermal, and magnetic properties are systematically investigated in the range of 4–300 K by combining experiments with ab initio Korring-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) calculations. The scattering of electrons is significantly increased duemore » to the chemical (especially magnetic) disorder. It has weak correlation with the number of elements but strongly depends on the type of elements. Thermal conductivities of the alloys are largely lower than pure metals, primarily because the high electrical resistivity suppresses the electronic thermal conductivity. Moreover, the temperature dependence of the electrical and thermal transport properties is further discussed, and the magnetization of five alloys containing three or more elements is measured in magnetic fields up to 4 T.« less

  9. Static and dynamic cyclic oxidation of 12 nickel-, cobalt-, and iron-base high-temperature alloys

    NASA Technical Reports Server (NTRS)

    Barrett, C. A.; Johnston, J. R.; Sanders, W. A.

    1978-01-01

    Twelve typical high-temperature nickel-, cobalt-, and iron-base alloys were tested by 1 hr cyclic exposures at 1038, 1093, and 1149 C and 0.05 hr exposures at 1093 C. The alloys were tested in both a dynamic burner rig at Mach 0.3 gas flow and in static air furnace for times up to 100 hr. The alloys were evaluated in terms of specific weight loss as a function of time, and X-ray diffraction analysis and metallographic examination of the posttest specimens. A method previously developed was used to estimate specific metal weight loss from the specific weight change of the sample. The alloys were then ranked on this basis. The burner-rig test was more severe than a comparable furnace test and resulted in an increased tendency for oxide spalling due to volatility of Cr in the protective scale and the more drastic cooling due to the air-blast quench of the samples. Increased cycle frequency also increased the tendency to spall for a given test exposure. The behavior of the alloys in both types of tests was related to their composition and their tendency to form scales. The alloys with the best overall behavior formed alpha-Al2O3 aluminate spinels.

  10. Safe and simple detection of sparse hydrogen by Pd-Au alloy/air based 1D photonic crystal sensor

    NASA Astrophysics Data System (ADS)

    Mitra, S.; Biswas, T.; Chattopadhyay, R.; Ghosh, J.; Bysakh, S.; Bhadra, S. K.

    2016-11-01

    A simple integrated hydrogen sensor using Pd-Au alloy/air based one dimensional photonic crystal with an air defect layer is theoretically modeled. Structural parameters of the photonic crystal are delicately scaled to generate photonic band gap frequencies in a visible spectral regime. An optimized defect thickness permits a localized defect mode operating at a frequency within the photonic band gap region. Hydrogen absorption causes modification in the band gap characteristics due to variation of refractive index and lattice parameters of the alloy. As a result, the transmission peak appeared due to the resonant defect state gets shifted. This peak shifting is utilized to detect sparse amount of hydrogen present in the surrounding environment. A theoretical framework is built to calculate the refractive index profile of hydrogen loaded alloy using density functional theory and Bruggeman's effective medium approximation. The calculated refractive index variation of Pd3Au alloy film due to hydrogen loading is verified experimentally by measuring the reflectance characteristics. Lattice expansion properties of the alloy are studied through X-ray diffraction analyses. The proposed structure shows about 3 nm red shift of the transmission peak for a rise of 1% atomic hydrogen concentration in the alloy.

  11. Tailoring the physical properties of Ni-based single-phase equiatomic alloys by modifying the chemical complexity

    NASA Astrophysics Data System (ADS)

    Jin, K.; Sales, B. C.; Stocks, G. M.; Samolyuk, G. D.; Daene, M.; Weber, W. J.; Zhang, Y.; Bei, H.

    2016-02-01

    Equiatomic alloys (e.g. high entropy alloys) have recently attracted considerable interest due to their exceptional properties, which might be closely related to their extreme disorder induced by the chemical complexity. In order to understand the effects of chemical complexity on their fundamental physical properties, a family of (eight) Ni-based, face-center-cubic (FCC), equiatomic alloys, extending from elemental Ni to quinary high entropy alloys, has been synthesized, and their electrical, thermal, and magnetic properties are systematically investigated in the range of 4–300 K by combining experiments with ab initio Korring-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) calculations. The scattering of electrons is significantly increased due to the chemical (especially magnetic) disorder. It has weak correlation with the number of elements but strongly depends on the type of elements. Thermal conductivities of the alloys are largely lower than pure metals, primarily because the high electrical resistivity suppresses the electronic thermal conductivity. The temperature dependence of the electrical and thermal transport properties is further discussed, and the magnetization of five alloys containing three or more elements is measured in magnetic fields up to 4 T.

  12. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    PubMed Central

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-01-01

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications. PMID:26892834

  13. Fe-based bulk amorphous alloys with iron contents as high as 82 at%

    NASA Astrophysics Data System (ADS)

    Li, Jin-Feng; Liu, Xue; Zhao, Shao-Fan; Ding, Hong-Yu; Yao, Ke-Fu

    2015-07-01

    Fe-based bulk amorphous alloys (BAAs) with high Fe contents are advantageous due to their high saturation magnetization and low cost. However, preparing Fe-based BAAs with Fe contents higher than 80 at% is difficult due to their poor glass forming abilities (GFA). In this study, an Fe81P8.5C5.5B2Si3 BAA with a diameter of 1 mm and a saturation magnetization of 1.56 T was successfully prepared using the fluxing and copper mold casting methods. In addition, by introducing a small amount of elemental Mo to the alloy, an Fe82Mo1P6.5C5.5B2Si3 BAA rod with a diameter of 1 mm, a high saturation magnetization of 1.59 T, a high yield stress of 3265 MPa, and a clear plasticity of 1.3% was prepared in the same way. The cost effectiveness and good magnetic properties of these newly-developed Fe-based BAAs with Fe contents as high as 82 at% would be advantageous and promising for industrial applications.

  14. Characterization of fabricated cobalt-based alloy/nano bioactive glass composites.

    PubMed

    Bafandeh, Mohammad Reza; Gharahkhani, Raziyeh; Fathi, Mohammad Hossein

    2016-12-01

    In this work, cobalt-based alloy/nano bioactive glass (NBG) composites with 10, 15 and 20wt% NBG were prepared and their bioactivity after immersion in simulated body fluid (SBF) for 1 to 4weeks was studied. Scanning electron microscopy images of two- step sintered composites revealed relatively dense microstructure. The results showed that density of composite samples decreased with increase in NBG amount. The microstructure analysis as well as energy dispersive X-ray analysis (EDX) revealed that small amount of calcium phosphate phases precipitates on the surface of composite samples after 1week immersion in SBF. After 2weeks immersion, considerable amounts of cauliflower-like shaped precipitations were seen on the surface of the composites. Based on EDX analysis, these precipitations were composed mainly from Ca, P and Si. The observed bands in the Fourier transform infrared spectroscopy of immersed composites samples for 4weeks in SBF, were characteristic bands of hydroxyapatite. Therefore it is possible to form hydroxyapatite layer on the surface of composite samples during immersion in SBF. The results indicated that prepared composites unlike cobalt-based alloy are bioactive, promising their possibility for implant applications.

  15. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths.

    PubMed

    Jiao, Z B; Luan, J H; Miller, M K; Yu, C Y; Liu, C T

    2016-02-19

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications.

  16. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    DOE PAGES

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; ...

    2016-02-19

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for twomore » interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. Lastly, the co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications.« less

  17. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    SciTech Connect

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-02-19

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. Lastly, the co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications.

  18. Corrosion characteristics of nickel alloys. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Zollars, G. F.

    1979-01-01

    This bibliography cites 118 articles from the international literature concerning corrosion characteristics of nickel alloys. Articles dealing with corrosion resistance, corrosion tests, intergranular corrosion, oxidation resistance, and stress corrosion cracking of nickel alloys are included.

  19. Development of improved low-strain creep strength in Cabot alloy R-41 sheet. [nickel base sheet alloy for reentry shielding

    NASA Technical Reports Server (NTRS)

    Rothman, M. F.

    1984-01-01

    The feasibility of improving the low-strain creep properties of a thin gauge nickel base sheet alloy through modified heat treatment or through development of a preferred crystal-lographic texture was investigated. The basic approach taken to improve the creep strength of the material by heat treatment was to increase grain size by raising the solution treatment temperature for the alloy to the range of 1420 K to 1475 K (2100 F to 2200 F). The key technical issue involved was maintenance of adequate tensile ductility following the solutioning of M6C primary carbides during the higher temperature solution treatment. The approach to improve creep properties by developing a sheet texture involved varying both annealing temperatures and the amount of prior cold work. Results identified a heat treatment for alloy R-14 sheet which yields a substantial creep-life advantage at temperatures above 1090 K (1500 F) when compared with material given the standard heat treatment. At the same time, this treatment provides reasonable tensile ductility over the entire temperature range of interest. The mechanical properties of the material given the new heat treatment are compared with those for material given the standard heat treatment. Attempts to improve creep strength by developing a sheet texture were unsuccessful.

  20. The evaluation of iron-base hardfacing alloys on gate valves after cycling under simulated PWR conditions for one year

    SciTech Connect

    Murphy, E.V.; Inglis, I.; Ocken, H.

    1992-12-31

    Gate valves hardfaced with iron-base alloys were exposed for about one year to simulated PWR conditions. The hardfacing alloys tested were EB 5183, EVERIT 50, NOREM 01 and NOREM 04. A gate valve with Satellite 6 was included in the test program as a control standard. During the test period the valves were opened and closed 2000 times. The performance of the valves was assessed by periodic leak tests and visual and profilometric characterisation of sealing surfaces. At the end of the test program, the seats and discs were destructively examined. The various examinations indicated all the iron-base alloys were superior to Satellite 6. Based on the results of hot leakage tests, one valve with EB 5183 and the valve with NOREM 04 were the best performers.

  1. Measuring grain boundary character distributions in Ni-base alloy 725 using high-energy diffraction microscopy

    DOE PAGES

    Bagri, Akbar; Hanson, John P.; Lind, J. P.; ...

    2016-10-25

    We use high-energy X-ray diffraction microscopy (HEDM) to characterize the microstructure of Ni-base alloy 725. HEDM is a non-destructive technique capable of providing three-dimensional reconstructions of grain shapes and orientations in polycrystals. The present analysis yields the grain size distribution in alloy 725 as well as the grain boundary character distribution (GBCD) as a function of lattice misorientation and boundary plane normal orientation. We find that the GBCD of Ni-base alloy 725 is similar to that previously determined in pure Ni and other fcc-base metals. We find an elevated density of Σ9 and Σ3 grain boundaries. We also observe amore » preponderance of grain boundaries along low-index planes, with those along (1 1 1) planes being the most common, even after Σ3 twins have been excluded from the analysis.« less

  2. Measuring grain boundary character distributions in Ni-base alloy 725 using high-energy diffraction microscopy

    SciTech Connect

    Bagri, Akbar; Hanson, John P.; Lind, J. P.; Kenesei, Peter; Suter, Robert; Gradecak, Silvija; Demkowicz, Michael J.

    2016-10-25

    We use high-energy X-ray diffraction microscopy (HEDM) to characterize the microstructure of Ni-base alloy 725. HEDM is a non-destructive technique capable of providing three-dimensional reconstructions of grain shapes and orientations in polycrystals. The present analysis yields the grain size distribution in alloy 725 as well as the grain boundary character distribution (GBCD) as a function of lattice misorientation and boundary plane normal orientation. We find that the GBCD of Ni-base alloy 725 is similar to that previously determined in pure Ni and other fcc-base metals. We find an elevated density of Σ9 and Σ3 grain boundaries. We also observe a preponderance of grain boundaries along low-index planes, with those along (1 1 1) planes being the most common, even after Σ3 twins have been excluded from the analysis.

  3. Measuring Grain Boundary Character Distributions in Ni-Base Alloy 725 Using High-Energy Diffraction Microscopy

    NASA Astrophysics Data System (ADS)

    Bagri, Akbar; Hanson, John P.; Lind, Jonathan; Kenesei, Peter; Suter, Robert M.; Gradečak, Silvija; Demkowicz, Michael J.

    2017-01-01

    We use high-energy X-ray diffraction microscopy (HEDM) to characterize the microstructure of Ni-base alloy 725. HEDM is a non-destructive technique capable of providing three-dimensional reconstructions of grain shapes and orientations in polycrystals. The present analysis yields the grain size distribution in alloy 725 as well as the grain boundary character distribution (GBCD) as a function of lattice misorientation and boundary plane normal orientation. We find that the GBCD of Ni-base alloy 725 is similar to that previously determined in pure Ni and other fcc-base metals. We find an elevated density of Σ9 and Σ3 grain boundaries. We also observe a preponderance of grain boundaries along low-index planes, with those along (1 1 1) planes being the most common, even after Σ3 twins have been excluded from the analysis.

  4. NASA-UVA Light Aerospace Alloy and Structure Technology Program Supplement: Aluminum-Based Materials for High Speed Aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr.

    1997-01-01

    This is the final report of the study "Aluminum-Based Materials for High Speed Aircraft" which had the objectives (1) to identify the most promising aluminum-based materials with respect to major structural use on the HSCT and to further develop those materials and (2) to assess the materials through detailed trade and evaluation studies with respect to their structural efficiency on the HSCT. The research team consisted of ALCOA, Allied-Signal, Boeing, McDonnell Douglas, Reynolds Metals and the University of Virginia. Four classes of aluminum alloys were investigated: (1) I/M 2XXX containing Li and I/M 2XXX without Li, (2) I/M 6XXX, (3) two P/M 2XXX alloys, and (4) two different aluminum-based metal matrix composites (MMC). The I/M alloys were targeted for a Mach 2.0 aircraft and the P/M and MMC alloys were targeted for a Mach 2.4 aircraft. Design studies were conducted using several different concepts including skin/stiffener (baseline), honeycomb sandwich, integrally stiffened and hybrid adaptations (conventionally stiffened thin-sandwich skins). Alloy development included fundamental studies of coarsening behavior, the effect of stress on nucleation and growth of precipitates, and fracture toughness as a function of temperature were an integral part of this program. The details of all phases of the research are described in this final report.

  5. Hydrogen induced cracking tests of high strength steels and nickel-iron base alloys using the bolt-loaded specimen

    SciTech Connect

    Vigilante, G.N.; Underwood, J.H.; Crayon, D.; Tauscher, S.; Sage, T.; Troiano, E.

    1997-12-31

    Hydrogen induced cracking tests were conducted on high strength steels and nickel-iron base alloys using the constant displacement bolt-loaded compact specimen. The bolt-loaded specimen was subjected to both acid and electrochemical cell environments in order to produce hydrogen. The materials tested were A723, Maraging 200, PH 13-8 Mo, Alloy 718, Alloy 706, and A286, and ranged in yield strength from 760--1400 MPa. The effects of chemical composition, refinement, heat treatment, and strength on hydrogen induced crack growth rates and thresholds were examined. In general, all high strength steels tested exhibited similar crack growth rates and thresholds were examined. In general, all high strength steels tested exhibited similar crack growth rates and threshold levels. In comparison, the nickel-iron base alloys tested exhibited up to three orders of magnitude lower crack growth rates than the high strength steels tested. It is widely known that high strength steels and nickel base alloys exhibit different crack growth rates, in part, because of their different crystal cell structure. In the high strength steels tested, refinement and heat treatment had some effect on hydrogen induced cracking, though strength was the predominant factor influencing susceptibility to cracking. When the yield strength of one of the high strength steels tested was increased moderately, from 1130 MPa to 1275 MPa, the incubation times decreased by over two orders of magnitude, the crack growth rates increased by an order of magnitude, and the threshold stress intensity was slightly lower.

  6. Desulfurization of Ni-based super alloys by combined heating and glow discharge

    SciTech Connect

    Outlaw, R.A.; Rezaie-Serej, S.; Allen, W.P.; Latanision, R.M.

    1996-04-15

    The service lifetime of blades and vanes in aircraft gas turbines can be influenced by the degradation of the interface of the Ni-based superalloy and the overlying aluminide coating during cyclic oxidation. Advanced superalloys and coatings rely on formation of a thin and continuous Al{sub 2}O{sub 3} film to protect the base alloy from further oxidative attack at temperatures above 980 C. In order that the Al{sub 2}O{sub 3} scale be protective, it must remain adherent to the underlying alloy under thermal cycling conditions. Recent experimental work indicates that the interfacial binding between Ni and the overlying Al{sub 2}O{sub 3} scale is initially strong, but has also been shown that segregation of indigenous sulfur to the metal/oxide interface induces premature scale spallation, apparently through a reduction in the interfacial adhesive strength with a concomitant reduction in component lifetime. Removal of the sulfur is the best solution to this problem.

  7. Welding and mechanical properties of cast FAPY (Fe-16 at. % Al-based) alloy slabs

    SciTech Connect

    Sikka, V.K.; Goodwin, G.M.; Alexander, D.J.; Howell, C.R.

    1995-05-01

    This report deals with the welding procedure development and weldment properties of an Fe-16 at. % Al alloy known as FAPY. The welding procedure development was carried out on 12-, 25-, and 51-mm (0.5-, 1-, and 2-in.) -thick plates of the alloy in the as-cast condition. The welds were prepared by using the gas tungsten arc process and filler wire of composition matching the base-metal composition. The preheat temperatures varied from room temperature to 350{degrees}C, and the postweld heat treatment (PWHT) was limited only for 1 h at 750{degrees}C. The welds were characterized by microstructural. analysis and microhardness data. The weldment specimens were machined for Charpy-impact, tensile, and creep properties. The tensile and creep properties of the weldment specimens were essentially the same as that of the base metal. The Charpy-impact properties of the weldment specimens improved with the PWHT and were somewhat lower than previously developed data on the wrought material. Additional work is required on welding of thicker sections, development of PWHT temperatures as a function of section thickness, and mechanical properties.

  8. Analysis of wear properties of aluminium based journal bearing alloys with and without lubrication.

    NASA Astrophysics Data System (ADS)

    Mathavan, J. Joy; Patnaik, Amar

    2016-09-01

    Apart from classical bearing materials, Aluminium alloys are used as bearing materials these days because of their superior quality. In this analysis, new Aluminium based bearing materials, with filler metals Si, Ni, and Cr are prepared by metal mould casting in burnout furnace machine, and tribological properties of these alloys with and without lubrication were tested. The experiments for wear with lubrication are conducted on multiple specimen tester and experiments without lubrication is conducted on Pin on disk tribometer. The disc material used was SAE 1050 steel. Wear tests were conducted at a sliding speed of 0.785 m/s and at a normal load of 20 N. Coefficient of friction values, temperature changes and wear of the specimens were plotted on graph according to the above mentioned working conditions. Hardness and weight losses of the specimens were calculated. The obtained results demonstrate how the friction and wear properties of these samples have changed with the % addition of Silicon, Chromium and Nickel to the base metal aluminium.

  9. Laser cladding of nickel-based alloy coatings on copper substrates

    NASA Astrophysics Data System (ADS)

    Balu, Prabu; Rea, Edward; Deng, Justin

    2015-07-01

    The wear resistance of high-value copper components used in the metal casting, automotive, aerospace and electrical equipment industries can be improved by applying nickel (Ni)-based coatings through laser cladding. A high-power diode laser array providing continuous power levels up to 10 kilowatts with beam-shaping optics providing a rectangular focal region of various dimensions was used to deposit Ni-based alloy coatings with controlled thickness ranging from 0.3 mm to 1.6 mm in a single pass on copper (Cu) substrates. Slotted powder feeding plates with various discrete widths delivered uniform streams of powdered metal particles entrained in a carrier gas, matching the selected focal spot dimensions. To enhance laser beam coupling with the substrate and to avoid defects such as cracks, delamination and porosity, Cu substrates were preheated to a temperature of 300°C. The effect of heat input on microstructure of the cladding and extent of the heat-affected zone (HAZ) was evaluated using optical microscopy and scanning electron microscopy. Excessive heat input with longer interaction time increased dilution, porosity and expanded HAZ that significantly reduced the hardness of both the clad and the Cu substrates. Average microhardness of the Ni-C-B-Si-W alloy coating was 572 HV, which was almost 7 times greater than the hardness of the Cu substrate (84 HV).

  10. Optimizing Ni-Ti-based shape memory alloys for ferroic cooling

    NASA Astrophysics Data System (ADS)

    Wieczorek, A.; Frenzel, J.; Schmidt, M.; Maaß, B.; Seelecke, S.; Schütze, A.; Eggeler, G.

    Due to their large latent heats, pseudoelastic Ni-Ti-based shape memory alloys (SMAs) are attractive candidate materials for ferroic cooling, where elementary solid-state processes like martensitic transformations yield the required heat effects. The present work aims for a chemical and microstructural optimization of Ni-Ti for ferroic cooling. A large number of Ni-Ti-based alloy compositions were evaluated in terms of phase transformation temperatures, latent heats, mechanical hysteresis widths and functional stability. The aim was to identify material states with superior properties for ferroic cooling. Different material states were prepared by arc melting, various heat treatments and thermo-mechanical processing. The cooling performance of selected materials was assessed by differential scanning calorimetry, uniaxial tensile loading/unloading, and by using a specially designed ferroic cooling demonstrator setup. A Ni45Ti47.25Cu5V2.75 SMA was identified as a potential candidate material for ferroic cooling. This material combines extremely stable pseudoelasticity at room temperature and a very low hysteresis width. The ferroic cooling efficiency of this material is four times higher than in the case of binary Ni-Ti.

  11. Use of Ni{sub 3}Al-based alloys for walking-beam furnaces

    SciTech Connect

    Sikka, V.K.; Dailey, R.E.

    1996-02-01

    This report summarizes the joint work performed by the Oak Ridge National Laboratory (ORNL) and Rapid Technologies, Inc. (the CRADA partner) to determine the potential of Ni{sub 3}Al-based alloys for use in gas-fired walking-beam furnace components. The report identifies tasks to be performed as part of the CRADA and the organization responsible for each task. The work required under each task was completed and is described. The CRADA accomplished the primary goal of utilizing cast Ni{sub 3}Al-based alloy as rails and other components for walking-beam furnaces manufactured by Rapid Technologies. Rapid Technologies, a small business, is implementing on a commercial basis a highly energy efficient rapid-heating technology for use in the metal manufacturing industry. The rapid heating process allows energy savings of up to 95%. Although goals of all of the tasks of this CRADA were met, there is still a need for a material to work in the rapid heating furnaces at temperatures in the range of 1,350 to 1,400 C. Future effort should be focused in fulfilling this need.

  12. Shape memory alloys for astronomical instrumentation: space and ground-based applications

    NASA Astrophysics Data System (ADS)

    Riva, M.; Rigamonti, D.; Zanetti, F.; Passaretti, F.; Villa, E.; Zerbi, F. M.

    2012-09-01

    This paper wants to illustrate possible applications of Shape Memory Alloy (SMA) as functional devices for space and ground based application in Instrumentations for Astronomy. Thermal activated Shape Memory Alloys are materials able to recover their original shape, after an external deformation, if heated above a characteristic temperature. If the recovery of the shape is completely or partially prevented by the presence of constraints, the material can generate recovery stress. Thanks to this feature, these materials can be positively exploited in Smart Structures if properly embedded into host materials. Some technological processes developed for an ecient use of SMA-based actuators embedded in smart structures tailored to astronomical instrumentation will be presented here. Some possible modeling approaches of the actuators behavior will be addressed taking into account trade- offs between detailed analysis and overall performance prediction as a function of the computational time. The Material characterization procedure adopted for the constitutive laws implementation will be described as well. Deformable composite mirrors,1 opto-mechanical mounting with superelastic kinematic behavior and damping of launch loads onto optical element2 are feasible applications that will be deeply investigated in this paper.

  13. In vivo evaluation of a Ti-based bulk metallic glass alloy bar.

    PubMed

    Kokubun, Ryo; Wang, Wei; Zhu, Shengli; Xie, Guoqiang; Ichinose, Shizuko; Itoh, Soichiro; Takakuda, Kazuo

    2015-01-01

    Ti-based bulk metallic glasses are reported with high strength, low Young modulus and high corrosion resistance, suggesting their potentials in biomedical applications. However a thorough in vivo evaluation of its biocompatibilities has not been conducted yet. In this study, we implanted bars of Ti-based bulk metallic glass in the femoral bone of rats, followed up local tissue reaction as well as its component ions' diffusion in local area and whole body. The Ti-based BMG (Ti40Zr10Cu34Pd14Sn2) alloy exhibited favorable features of both high strength and high elasticity. In vivo implant evaluation showed that it has a good tissue compatibility, equivalent bone integration and bonding ability with Ti sample. No component ion diffusion was detected up to 3 months post implantation. The possibility and efficacy of its use for bone implant is confirmed. Thus further long term implant study is recommended.

  14. Constitutive Description of 7075 Aluminum Alloy During Hot Deformation by Apparent and Physically-Based Approaches

    NASA Astrophysics Data System (ADS)

    Mirzadeh, Hamed

    2015-03-01

    Hot flow stress of 7075 aluminum alloy during compressive hot deformation was correlated to the Zener-Hollomon parameter through constitutive analyses based on the apparent approach and the proposed physically-based approach which accounts for the dependence of the Young's modulus and the self-diffusion coefficient of aluminum on temperature. It was shown that the latter approach not only results in a more reliable constitutive equation, but also significantly simplifies the constitutive analysis, which in turn makes it possible to conduct comparative hot working studies. It was also demonstrated that the theoretical exponent of 5 and the lattice self-diffusion activation energy of aluminum (142 kJ/mol) can be set in the hyperbolic sine law to describe the peak flow stresses and the resulting constitutive equation was found to be consistent with that resulted from the proposed physically-based approach.

  15. Properties of vanadium-base alloys irradiated in the dynamic helium charging experiment

    SciTech Connect

    Chung, H.M.; Loomis, B.A.; Smith, D.L.

    1996-02-01

    One property of vanadium-base alloys that is not well understood in terms of their potential use as fusion reactor structural materials is the effect of simultaneous generation of helium and neutron damage. In the present Dynamic Helium Charging Experiment (DHCE), helium was produced uniformly in the specimen at linear rates of {approx} 0.4 to 4.2 appm helium/dpa by the decay of tritium during irradiation to 18--31 dpa at 425--600 C in Li-filled capsules in a sodium-cooled fast reactor. This paper presents results of postirradiation examination and tests of microstructure and mechanical properties of V-5Ti, V-3Ti-1Si, V-8Cr-6Ti, and V-4Cr-4Ti (the latter alloy has been identified as the most promising candidate vanadium alloy). Effects of helium on tensile strength and ductility were insignificant after irradiation and testing at > 420 C. However, postirradiation ductilities at < 250 C were higher than those of the non-DHCE specimens (< 0.1 appm helium), whereas strengths were lower, indicating that different types of hardening centers are produced during DHCE and non-DHCE irradiation. Ductile-brittle transition behavior of the DHCE specimens was also determined from bend tests and fracture appearance of transmission electron microscopy (TEM) disks and broken tensile specimens. No brittle behavior was observed at temperatures > {minus}150 C in DHCE specimens. Predominantly brittle-cleavage fracture morphologies were observed only at {minus}196 C in some specimens that were irradiated to 31 dpa at 425 C during the DHCE. For the helium generation rates in this experiment ({approx} 0.4--4.2 appm He/dpa), grain-boundary coalescence of helium microcavities was negligible and intergranular fracture was not observed.

  16. Effects of alloying element and temperature on the stacking fault energies of dilute Ni-base superalloys.

    PubMed

    Shang, S L; Zacherl, C L; Fang, H Z; Wang, Y; Du, Y; Liu, Z K

    2012-12-19

    A systematic study of stacking fault energy (γ(SF)) resulting from induced alias shear deformation has been performed by means of first-principles calculations for dilute Ni-base superalloys (Ni(23)X and Ni(71)X) for various alloying elements (X) as a function of temperature. Twenty-six alloying elements are considered, i.e., Al, Co, Cr, Cu, Fe, Hf, Ir, Mn, Mo, Nb, Os, Pd, Pt, Re, Rh, Ru, Sc, Si, Ta, Tc, Ti, V, W, Y, Zn, and Zr. The temperature dependence of γ(SF) is computed using the proposed quasistatic approach based on a predicted γ(SF)-volume-temperature relationship. Besides γ(SF), equilibrium volume and the normalized stacking fault energy (Γ(SF) = γ(SF)/Gb, with G the shear modulus and b the Burgers vector) are also studied as a function of temperature for the 26 alloying elements. The following conclusions are obtained: all alloying elements X studied herein decrease the γ(SF) of fcc Ni, approximately the further the alloying element X is from Ni on the periodic table, the larger the decrease of γ(SF) for the dilute Ni-X alloy, and roughly the γ(SF) of Ni-X decreases with increasing equilibrium volume. In addition, the values of γ(SF) for all Ni-X systems decrease with increasing temperature (except for Ni-Cr at higher Cr content), and the largest decrease is observed for pure Ni. Similar to the case of the shear modulus, the variation of γ(SF) for Ni-X systems due to various alloying elements is traceable from the distribution of (magnetization) charge density: the spherical distribution of charge density around a Ni atom, especially a smaller sphere, results in a lower value of γ(SF) due to the facility of redistribution of charges. Computed stacking fault energies and the related properties are in favorable accord with available experimental and theoretical data.

  17. A first-principles study of the phase stability of fcc-based Ti-Al alloys

    SciTech Connect

    Asta, M. . Dept. of Materials Science and Mineral Engineering); de Fontaine, D. . Dept. of Materials Science and Mineral Engineering Lawrence Berkeley Lab., CA ); van Schilfgaarde, M. ); Sluiter, M. (Lawrence Livermore National Lab., CA (Un

    1992-04-01

    In this paper we present results of a first-principles phase stability study of fcc-based Ti-Al alloys. In particular the full-potential linear muffin tin orbital method has been used to determine heats of format on and other zero-temperature properties of 9 fcc ordered superstructures as well as fcc and hcp Ti, and fcc Al. From these results a set of effective cluster interactions are determined which are used in a cluster variation method calculation of the thermodynamic properties and the composition-temperature phase diagram of fcc-based alloys.

  18. Detection and distribution of lithium in Mg-Li-Al based alloy by ToF-SIMS

    NASA Astrophysics Data System (ADS)

    Kumar, Vinod

    2016-12-01

    Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) is used to investigate the surface as well as bulk microstructural features of novel Mg-Li-Al based alloy namely Mg-9Li-7Al-3Sn-1Zn (LATZ9531). ToF-SIMS study indicates that there are six multi-oxide layers present within the surface film of LATZ9531. Furthermore, The presence of Li containing phase has been qualitatively confirmed based on the high number of Li-ion counts in SIMS, and the same is verified quantitatively by using electron probe microanalysis (EPMA). The novel approach may be useful to determine the chemical composition of the phases in various alloys which has lighter alloying elements such as lithium.

  19. Fe-Cr-Mo based ODS alloys via spark plasma sintering: A combinational characterization study by TEM and APT

    SciTech Connect

    Y. Q. Wu; K. N. Allahar; J. Burns; B. Jacques; I Charit; D. P. Butt; J. I. Cole

    2013-08-01

    Nanoscale oxides play an important role in oxide dispersion strengthened (ODS) alloys for improved high temperature creep resistance and enhanced radiation damage tolerance. In this study, transmission electron microscopy (TEM) and atom probe tomography (APT) were combined to investigate two novel Fe-16Cr-3Mo (wt.%) based ODS alloys. Spark plasma sintering (SPS) was used to consolidate the ODS alloys from powders that were milled with 0.5 wt.% Y2O3 powder only or with Y2O3 powder and 1 wt.% Ti. TEM characterization revealed that both alloys have a bimodal structure of nanometer-size (~ 100 – 500 nm) and micron-size grains with nanostructured oxide precipitates formed along and close to grain boundaries with diameters ranging from five to tens of nanometers. APT provides further quantitative analyses of the oxide precipitates, and also reveals Mo segregation at grain boundaries next to oxide precipitates. The alloys with and without Ti are compared based on their microstructures.

  20. Observations on the oxidation of Mn-modified Ni-base Haynes 230 alloy under SOFC exposure conditions

    SciTech Connect

    Yang, Z Gary; Xia, Gordon; Stevenson, Jeffry W.; Singh, Prabhakar

    2005-07-01

    The commercial Ni-base Haynes 230 alloy (Ni-Cr-Mo-W-Mn) was modified with two increased levels of Mn (1 and 2 wt per cent) and evaluated for its oxidation resistance under simulated SOFC interconnect exposure conditions. Oxidation rate, oxide morphology, oxide conductivity and thermal expansion were measured and compared with commercial Haynes 230. It was observed that additions of higher levels of Mn to the bulk alloy facilitated the formation of a bi-layered oxide scale that was comprised of an outer M3O4 (M=Mn, Cr, Ni) spinel-rich layer at the oxide – gas interface over a Cr2O3-rich sub-layer at the metal – oxide interface. The modified alloys showed higher oxidation rates and the formation of thicker oxide scales compared to the base alloy. The formation of a spinel-rich top layer improved the scale conductivity, especially during the early stages of the oxidation, but the higher scale growth rate resulted in an increase in the area-specific electrical resistance over time. Due to their face-centered cubic crystal structure, both commercial and modified alloys demonstrated a coefficient of thermal expansion that was higher than that of typical anode-supported and electrolyte-supported SOFCs.

  1. Initial assessment of Ni-base alloy performance in 0.1 MPa and supercritical CO2

    DOE PAGES

    Pint, B. A.; Keiser, J. R.

    2015-09-25

    There is considerable interest in increasing the working temperature of both open and closed supercritical CO2 (sCO2) cycles to ≥700 °C. At these temperatures, it is unlikely that any Fe-base alloys have suitable strength and therefore the focus is on Ni-base alloys for this application. To begin addressing the lack of compatibility data under these conditions, initial work exposed a wide range of candidate alloys in 500-h exposures at 20 MPa (200 bar) CO2 at 650 -750 °C in high purity CO2. In general, the reaction products were thin and protective in these exposures. A smaller group of alloy couponsmore » focusing on chromia- and alumina-forming alloys was exposed for 500h in 0.1 MPa (1bar) air, CO2, CO2+O2 and CO2+H2O for comparison. Thus, the thin surface oxides formed were very similar to those formed at high pressure and no clear detrimental effect of CO2 oxidation or O2 or H2O impurities could be observed in these exposures.« less

  2. Films of Soft-Magnetic Fe-Based Nanocrystalline Alloys for High-Density Magnetic Storage Application

    NASA Astrophysics Data System (ADS)

    Shefteľ, E. N.; Bannykh, O. A.

    This paper presents a review of works related to the problem of development of soft-magnetic film Fe-based alloys exhibiting the combination of properties, such as the high saturation inductance, high level of soft-magnetic parameters over a wide range of MHz-frequencies, high wear-resistance and thermal stability, and an ability to be prepared by thin-film technologies. Magnetic cores of high-density recording heads are the principal application of these materials. Physical fundamentals of explanation of ferromagnetic behavior of a material with nano-sized structure, which have been developed for FINEMETs (Fe-Nb-Cu-Si-B) with the mixed amorphous + nanocrystalline structure, are considered. A new class of alloys Fe-Me-X (Me=Metal of III-V groups of the Periodic Table and X=C, N, O, and B) whose properties are higher that those of FINEMETs are discussed. The structure of these alloys consists of two nanocrystalline phases, such as the ferromagnetic α-Fe-based and nonmagnetic MeX phases. This structure provides the dispersion strengthening of the alloys. Metal science approaches to the selection of both chemical compositions and conditions of structure formation for these film alloys have been developed by authors and are discussed in this article.

  3. [Study on grinding of base metal alloys. 4. Constant pressure grinding of a Ni-Cr alloy with vitrified wheels].

    PubMed

    Miyakawa, O; Watanabe, K; Okawa, S; Nakano, S; Shiokawa, N; Kobayashi, M; Tamura, H

    1989-09-01

    The grinding techniques and the constituent element of vitrified wheels suitable for a 13% Cr-Ni dental casting alloy were determined. The lever-type grinding test machine used in the previous study was modified so that a work might be ground under a constant pressure as it moved reciprocally within a short stroke along the tangential direction of a rotating wheel. The grinding performance of two marketed wheels and eleven experimental wheels with different constituent elements was tested. Abrasive grains on the working surface of alumina wheel wore extremely due to abrasive attrition. Carborundum wheels proved to be more suitable for grinding of the comparatively soft Ni-Cr alloy. Not only depressing a wheel against a work but also moving the wheel over it with heavier pressure should be desired for the maximal grinding efficiency. The experimental carborundum wheels exhibited much the same performance as the marketed carborundum wheel under a less grinding pressure that 100 gf. Only the wheel of grain size #150 bonded with 19% binder wore obviously under the pressure of 150 or 200 gf and provided about two times the performance of the marketed wheel.

  4. Characterization of Sputtered Nickel-Titanium (NiTi) Stress and Thermally Actuated Cantilever Bimorphs Based on NiTi Shape Memory Alloy (SMA)

    DTIC Science & Technology

    2015-11-01

    Actuated Cantilever Bimorphs Based on NiTi Shape Memory Alloy (SMA) by Merric D Srour, Cory R Knick, and Christopher J Morris Sensors and...applications7 so a natural focus was to achieve large recovery stresses in films as thin as possible. By varying the sputtering parameters of NiTi...alloys. Sensors and Actuators A. 2002;99:55–58. 2. Ohta A, Bhansali S, Kishimoto I, Umeda A. Novel fabrication techique of TiNi shape memory alloy

  5. Shakedown based model for high-cycle fatigue of shape memory alloys

    NASA Astrophysics Data System (ADS)

    Gu, Xiaojun; Moumni, Ziad; Zaki, Wael; Zhang, Weihong

    2016-11-01

    The paper presents a high-cycle fatigue criterion for shape memory alloys (SMAs) based on shakedown analysis. The analysis accounts for phase transformation as well as reorientation of martensite variants as possible sources of fatigue damage. In the case of high-cycle fatigue, once the structure has reached an asymptotic state, damage is assumed to become confined at the mesoscopic scale, or the scale of the grain, with no discernable inelasticity at the macroscopic scale. Using a multiscale approach, a high-cycle fatigue criterion analogous to the Dang Van model (Dang Van 1973) for elastoplastic metals is derived for SMAs obeying the Zaki-Moumni model for SMAs (Zaki and Moumni 2007a). For these alloys, a safe domain is established in stress deviator space, consisting of a hypercylinder with axis parallel to the direction of martensite orientation at the mesoscopic scale. Safety with regard to high-cycle fatigue, upon elastic shakedown, is conditioned by the persistence of the macroscopic stress path at every material point within the hypercylinder, whose size depends on the volume fraction of martensite. The proposed criterion computes a fatigue factor at each material point, indicating its degree of safeness with respect to high cycle fatigue.

  6. Tensile and creep rupture behavior of P/M processed Nb-base alloy, WC-3009

    SciTech Connect

    Hebsur, M.G.; Titran, R.H.

    1988-09-01

    Due to its high strength at temperatures up to 1600 K, fabrication of niobium base alloy WC-3009 (Nb30Hf9W) by traditional methods is difficult. Powder metallurgy (P/M) processing offers an attractive fabrication alternative for this high strength alloy. Spherical powders of WC-3009 produced by electron beam atomizing (EBA) process were successfully consolidated into a one inch diameter rod by vacuum hot pressing and swaging techniques. Tensile strength of the fully dense P/M material at 300-1590 K were similar to the arc-melted material. Creep rupture tests in vacuum indicated that WC-3009 exhibits a class 1 solid solution (glide controlled) creep behavior in the 1480 to 1590 K temperature range and stress range of 14 to 70 MPa. The creep behavior was correlated with temperature and stress using a power law relationship. The calculated stress exponent n, was about 3.2 and the apparent activation energy, Q, was about 270 kJ/mol. The large creep ductility exhibited by WC-3009 was attributed to its high strain rate sensitivity.

  7. Tensile and creep rupture behavior of P/M processed Nb-base alloy, WC-3009

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.; Titran, Robert H.

    1988-01-01

    Due to its high strength at temperatures up to 1600 K, fabrication of niobium base alloy WC-3009 (Nb30Hf9W) by traditional methods is difficult. Powder metallurgy (P/M) processing offers an attractive fabrication alternative for this high strength alloy. Spherical powders of WC-3009 produced by electron beam atomizing (EBA) process were successfully consolidated into a one inch diameter rod by vacuum hot pressing and swaging techniques. Tensile strength of the fully dense P/M material at 300-1590 K were similar to the arc-melted material. Creep rupture tests in vacuum indicated that WC-3009 exhibits a class 1 solid solution (glide controlled) creep behavior in the 1480 to 1590 K temperature range and stress range of 14 to 70 MPa. The creep behavior was correlated with temperature and stress using a power law relationship. The calculated stress exponent n, was about 3.2 and the apparent activation energy, Q, was about 270 kJ/mol. The large creep ductility exhibited by WC-3009 was attributed to its high strain rate sensitivity.

  8. HfCo7-Based Rare-Earth-Free Permanent-Magnet Alloys

    SciTech Connect

    Das, B; Balamurugan, B; Kumar, P; Skomski, R; Shah, VR; Shield, JE; Kashyap, A; Sellmyer, DJ

    2013-07-01

    This study presents the structural and magnetic properties of melt-spun HfCo7, HfCo7-xFex (0.25 <= x <=), and HfCo7Six (0.2 <= x <= 1.2) alloys. Appreciable permanent-magnet properties with a magnetocrystalline anisotropy of about 9.6-16.5, Mergs/cm(3), a magnetic polarization J(s) approximate to 7.2-10.6 kG, and coercivities H-c = 0.5-3.0 kOe were obtained by varying the composition of these alloys. Structural analysis reveals that the positions of x-ray diffraction peaks of HfCo7 show good agreement with those corresponding to an orthorhombic structure having lattice parameters of about a = 4.719 angstrom, b = 4.278 angstrom, and c = 8.070 angstrom. Based on these results, a model crystal structure for HfCo7 is developed and used to estimate the magnetic properties of HfCo7 using density-functional calculations, which agree with the experimental results.

  9. High temperature deformation behavior of spray-formed and subsequently extruded Al-25Si based alloy

    NASA Astrophysics Data System (ADS)

    Lee, Sin-Woo; Kim, Mok-Soon

    2016-07-01

    The high temperature deformation behavior of spray-formed and subsequently extruded Al-25Si based alloy containing fine Si and ultra-fine intermetallic phases was examined by compressive tests at temperatures between 523 and 743 K and strain rates between 1.0 × 10-3 and 1.0 × 100/s. The true stress-true strain curves obtained from the compressive tests revealed a peak stress at the initial stage of deformation. The peak stress decreased with increasing temperature or decreasing strain rate. A close relationship was observed between the peak stress and the constitutive equation for high temperature deformation. In the deformed specimens, fine equiaxed grains were observed with a mean grain size of 330 590 nm, which was much finer than that measured prior to deformation (1.4 μm). A dislocation structure within the grains was also observed in the deformed specimens, indicating the occurrence of dynamic recrystallization during high temperature deformation of the present alloy. The occurrence of dynamic recrystallization was also supported by the existence of a peak stress in the flow curve.

  10. Synthesis and thermal behavior of tin-based alloy (Sn-Ag-Cu) nanoparticles.

    PubMed

    Roshanghias, Ali; Yakymovych, Andriy; Bernardi, Johannes; Ipser, Herbert

    2015-03-19

    The prominent melting point depression of nanoparticles has been the subject of a considerable amount of research. For their promising applications in electronics, tin-based nano-alloys such as near-eutectic Sn-Ag-Cu (SAC) alloys have been synthesized via various techniques. However, due to issues such as particle aggregation and oxidation or introduced impurities, the application of these nano-size particles has been confined or aborted. For instance, thermal investigations by DTA/DSC in a large number of studies revealed exothermic peaks in the range of 240-500 °C, i.e. above the melting point of SAC nanoparticles, with different and quite controversial explanations for this unclear phenomenon. This represents a considerable drawback for the application of nanoparticles. Correspondingly, in the current study, the thermal stability of SAC nanoparticles has been investigated via electron microscopy, XRD, FTIR, and DSC/TG analysis. It was found that the nanoparticles consist mainly of a metallic β-Sn core and an amorphous tin hydroxide shell structure. The SnO crystalline phase formation from this amorphous shell has been associated with the exothermic peaks on the first heating cycle of the nanoparticles, followed by a disproportionation reaction into metallic Sn and SnO₂.The results also revealed that the surfactant and reducing agent cannot only affect the size and size distribution of the nanoparticles, they might also alter the ratio between the amorphous shell and the crystalline core in the structure of particles.

  11. Effect of alloy additions on wear resistance of nickel based hardfacing

    SciTech Connect

    Su, Y.L.; Chen, K.Y.

    1997-03-01

    The purpose of this research is to study the influence of the microstructure and hardness of the nickel based hardfacing alloy on wear resistance of deposit layers when different alloy elements are added. Different deposit layers were obtained by SMAW in which AWS RNiCr bare electrodes were coated by fluxes, to which different measures of ferro-niobium, ferro-chromium, and carbon had been added. The result of the experiment showed that when subject to abrasive wear, if the abrasive particles were silicon carbide, the increase of the volume fraction of the hard phase had only a slight effect on improving the wear resistance of the deposit layers. On adhesive wear, the niobium added specimens formed some spherical niobium carbide particles in the matrix of the deposit layer which reduced the friction coefficient of the specimens. The addition of carbon and chromium can enhance macrohardness and wear resistance of the welding deposit significantly. This same addition will also aid wear resistance by forming a continuous phase in the microstructure of the deposit metal. While there was no significant difference between the macrohardnesses of the metals, the form of this precipitate in the deposit metals was actually the most important factor in their wear resistance.

  12. Influence of fiber-reinforcement on the microstructure of an Al-Si-based alloy

    SciTech Connect

    Baer, J.; Klubmann, H.-G.; Gudladt, H.-J. . Inst. fuer Werkstoffwissenschaft)

    1993-09-01

    The aim of the present paper is to discuss some aspects, i.e., hardness and tensile strength considering the changes in the microstructure of an Al-Si-based alloy due to fibre-reinforcement. The investigations have been undertaken with an AlSi12CuMgNi alloy and two metal matrix composites reinforced with 20 vol% of either Saffil, a nearly pure alumina fibre with a silica content of about 3-4 %, or Fiberfrax, consisting of 50% SiO[sub 2] and 50% Al[sub 2]O[sub 3], respectively. The tensile tests have been performed on flat specimens that were cut from rectangular plates by spark-erosion. These specimens were heat treated for 100 h at 623 K to a highly overaged conditions (HOA). The aging behavior of the three materials has been investigated for an aging temperature of 473 K by Vickers hardness measurements. These experiments were performed using a Wolpert Dia Testor 2 with a force of 200 N. Tensile experiments were carried out on an Instron-testing machine with a constant strain rate of 3.3[center dot]10[sup [minus]4] s[sup [minus]1]. These investigations have been undertaken at temperature of 295, 473, 623 and 723 K, respectively.

  13. The Influence of Fluid Flow on the Microstructure of Directionally Solidified AlSi-Base Alloys

    NASA Astrophysics Data System (ADS)

    Steinbach, S.; Ratke, L.

    2007-07-01

    To obtain a quantitative understanding of the effect of fluid flow on the microstructure of cast alloys, a technical Al-7 wt pct Si-0.6 wt pct Mg alloy (A357) has been directionally solidified with a medium temperature gradient under well-defined thermal and fluid-flow conditions. The solidification was studied in an aerogel-based furnace, which established flat isotherms and allowed the direct optical observation of the solidification process. A coil system around the sample induces a homogeneous rotating magnetic field (RMF) and, hence, a well-defined flow field close to the growing solid-liquid interface. The application of RMFs during directional solidification results in pronounced segregation effects: a change to pure eutectic solidification at the axis of the sample at high magnetic field strengths is observed. The investigations show that with increasing magnetic induction and, therefore, fluid flow, the primary dendrite spacing decreases, whereas the secondary dendrite arm spacing increases. An apparent flow effect on the eutectic spacing is observed.

  14. The surface and electrochemical analysis of permanganate based conversion coating on alclad and unclad 2024 alloy

    NASA Astrophysics Data System (ADS)

    Yoganandan, G.; Balaraju, J. N.; William Grips, V. K.

    2012-09-01

    In the present investigation permanganate based conversion coating (PCC) was developed on AA 2024 alloy using alkaline bath containing Mn/Mo oxyanions. Conversion coating was formed on alclad (APCC) and unclad (UPCC) aluminium alloys by simple immersion method. Surface morphology of the APCC and UPCC specimens exhibited smooth and mud-crack patterns respectively. Elemental analysis showed the presence of higher amounts of Mn (5-6 wt.%) and Mo (0.3 wt.%) on UPCC. Raman and XPS analysis showed the presence of compounds such as MnOx (Mn3O4 and Mn2O3), MnO2, KMnO4, MoOx, MoO2, MoO3/polymolybdate on both coating surfaces. The corrosion current density (icorr) values obtained for both coated surfaces were less than 1 μA/cm2. However, APCC specimen showed the lowest icorr value of about 0.05 μA/cm2 after 168 h of immersion in 3.5% NaCl. EIS studies revealed the higher charge transfer resistance (Rct) values for APCC specimen after 1 and 168 h immersion compared to UPCC. Coated specimens were also tested by continuous salt spray exposure (ASTM B117) with and without cross-hatch mark ('X') for about 750 h. Coating discoloration along with the presence of few corrosion products had been noticed on UPCC specimen after continuous salt spray exposure.

  15. Piercing mandrel strengthening by surfacing with nickel aluminide-based alloy

    NASA Astrophysics Data System (ADS)

    Zorin, I. V.; Dubtsov, Yu N.; Sokolov, G. N.; Artem'ev, A. A.; Lysak, V. I.; Elsukov, S. N.

    2017-02-01

    Electrode composite wire (CW) was used for argon-arc surfacing of a thermal-resisting nickel aluminide-based alloy (Ni-Al-Cr-W-Mo-Ta system) on the butt-end surface of the non-water-cooled piercing mandrel. It was shown that multipassing surfacing forms a defect-free deposited metal based on the γ’-Ni3Al phase of various structural origins. Using high-temperature sclerometry and thermal fatigue testing methods, the metal deposited with CW containing ultrafine particle of 0.3–0.4 % wt. WC carbide features increased resistance to thermal and force effects at temperatures up to 1200 °C.

  16. Corrosion of Nickel-Based Alloys in Ultra-High Temperature Heat Transfer Fluid

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Reddy, Ramana G.

    2017-03-01

    MgCl2-KCl binary system has been proposed to be used as high temperature reactor coolant. Due to its relatively low melting point, good heat capacity and excellent thermal stability, this system can also be used in high operation temperature concentrating solar power generation system as heat transfer fluid (HTF). The corrosion behaviors of nickel based alloys in MgCl2-KCl molten salt system at 1,000 °C were determined based on long-term isothermal dipping test. After 500 h exposure tests under strictly maintained high purity argon gas atmosphere, the weight loss and corrosion rate analysis were conducted. Among all the tested samples, Ni-201 demonstrated the lowest corrosion rate due to the excellent resistance of Ni to high temperature element dissolution. Detailed surface topography and corrosion mechanisms were also determined by using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS).

  17. Development, processing and fabrication of a nickel based nickel-chromium-iron alloy

    NASA Astrophysics Data System (ADS)

    Akinlade, Dotun Adebayo

    An optimal powder metallurgy (P/M) approach to produce a nickel base Superalloy similar in composition to INCONEL(TM) 600 was carried out utilising a simple uniaxial pressing process. The efficiencies of a lubricant addition, binder, sintering times and temperatures were measured in terms of green and sintered densities as well as microstructural changes that occurred during processing. It was observed that with increasing % polyvinyl alcohol (PVA), an overall decrease in density of compact was obtained and that using 0.75wt % of lubricant (microwax) green densities in excess of 70% can be obtained. The samples were subsequently sintered in air at 1270°C for times ranging from 0.5h to 5h and also in vacuum (6 millitorr) with temperatures ranging from 1260 through to 1400°C. The air sintering was carried out to optimize sintering time, whereas the vacuum sintering was employed to optimize sintering temperature. On sintering for 5h in air, chromium enrichment occurred at the grain boundaries with subsequent depletion of nickel and iron; this was not noted for 2h sintering or for sintering under vacuum. The optimum sintering conditions were determined to be at 1300°C sintering for 2h in vacuum. The samples processed under the optimum conditions were successfully cold rolled to 40% of the original thickness without cracking. An investigation was also undertaken to determine the effect of Al concentration (1-12w/o) on the microstructure of the powder metallurgically (P/M) processed Ni-Cr-Fe ternary alloy, with a view to determine the concentration of aluminium that would yield a homogenously distributed and optimum volume fraction of the intermetallic-gamma'(Ni3Al) phase without the formation of topologically closed packed phases in the ternary alloy. The phases that were likely to form with the variation in concentration of Al were first simulated by JMatPro(TM) thermodynamic software package, and then Ni-Cr-Fe alloys with varying concentration of aluminum were

  18. Mechanisms of radiation-induced segregation in CrFeCoNi-based single-phase concentrated solid solution alloys

    DOE PAGES

    He, Mo-Rigen; Wang, Shuai; Shi, Shi; ...

    2016-12-31

    Single-phase concentrated solid solution alloys have attracted wide interest due to their superior mechanical properties and enhanced radiation tolerance, which make them promising candidates for the structural applications in next-generation nuclear reactors. However, little has been understood about the intrinsic stability of their as-synthesized, high-entropy configurations against radiation damage. In this paper, we report the element segregation in CrFeCoNi, CrFeCoNiMn, and CrFeCoNiPd equiatomic alloys when subjected to 1250 kV electron irradiations at 400 °C up to a damage level of 1 displacement per atom. Cr/Fe/Mn/Pd can deplete and Co/Ni can accumulate at radiation-induced dislocation loops, while the actively segregating elementsmore » are alloy-specific. Moreover, electron-irradiated matrix of CrFeCoNiMn and CrFeCoNiPd shows L10 (NiMn)-type ordering decomposition and <001>-oriented spinodal decomposition between Co/Ni and Pd, respectively. Finally, these findings are rationalized based on the atomic size difference and enthalpy of mixing between the alloying elements, and identify a new important requirement to the design of radiation-tolerant alloys through modification of the composition.« less

  19. Mechanisms of radiation-induced segregation in CrFeCoNi-based single-phase concentrated solid solution alloys

    SciTech Connect

    He, Mo-Rigen; Wang, Shuai; Shi, Shi; Jin, Ke; Bei, Hongbin; Yasuda, Kazuhiro; Matsumura, Syo; Higashida, Kenji; Robertson, Ian M.

    2016-12-31

    Single-phase concentrated solid solution alloys have attracted wide interest due to their superior mechanical properties and enhanced radiation tolerance, which make them promising candidates for the structural applications in next-generation nuclear reactors. However, little has been understood about the intrinsic stability of their as-synthesized, high-entropy configurations against radiation damage. In this paper, we report the element segregation in CrFeCoNi, CrFeCoNiMn, and CrFeCoNiPd equiatomic alloys when subjected to 1250 kV electron irradiations at 400 °C up to a damage level of 1 displacement per atom. Cr/Fe/Mn/Pd can deplete and Co/Ni can accumulate at radiation-induced dislocation loops, while the actively segregating elements are alloy-specific. Moreover, electron-irradiated matrix of CrFeCoNiMn and CrFeCoNiPd shows L10 (NiMn)-type ordering decomposition and <001>-oriented spinodal decomposition between Co/Ni and Pd, respectively. Finally, these findings are rationalized based on the atomic size difference and enthalpy of mixing between the alloying elements, and identify a new important requirement to the design of radiation-tolerant alloys through modification of the composition.

  20. Effects of Changes in Chemistry on Flex Bending Fatigue Behavior of Al-Based Amorphous Alloy Ribbons

    NASA Astrophysics Data System (ADS)

    Huang, Chun-Kuo; Lewandowski, John J.

    2012-08-01

    The effects of changes in composition on the flow behavior and flex bending fatigue behavior of a series of Al-Gd-Ni- X ( X = Fe or Co) amorphous alloy ribbons have been determined at 1 Hz at room temperature. It has been shown that the addition of Fe, Co, and Fe/Co combination into these materials increases the strength, T g, and T x1 in addition to the activation energy for crystallization. The lowest strength ( i.e., 880 MPa) base alloy Al87Gd6Ni7 exhibited the best low-cycle fatigue (LCF) and worst high-cycle fatigue (HCF) behavior, whereas the higher strength alloys (~1100 MPa) Al85Gd6Ni7Fe2 and Al85Gd6Ni7Fe1Co1 exhibited worse LCF and better HCF behavior. The ratio of the stress amplitude at the fatigue limit at 1 × 106 cycles to uniaxial failure strength ranged from 0.25 to 0.37 (240 to 397 MPa), much higher than conventional aluminum alloys. These results are also compared with those obtained on other amorphous alloy ribbons.

  1. In-Situ Fracture Observation and Fracture Toughness Analysis of Zr-Based Amorphous Alloys Containing Ductile Dendrites

    NASA Astrophysics Data System (ADS)

    Jeon, Changwoo; Kim, Choongnyun Paul; Lee, Sunghak

    2012-10-01

    Effects of dendrite size on fracture properties of Zr-based amorphous alloys containing ductile β dendrites were explained by directly observing microfracture processes using an in-situ loading stage installed inside a scanning electron microscope (SEM) chamber. Three amorphous alloy plates having different thicknesses were fabricated by varying cooling rates after vacuum arc melting. The effective size of β dendrites was varied from 14.7 to 30.1 μm in the alloy plates, while their volume fraction was almost constant. According to microfracture observation of the alloy containing fine β dendrites, shear bands initiated at the amorphous matrix were connected with the notch tip as they were deepened through dendrites, which led to abrupt crack propagation. In the alloy containing coarser β dendrites, shear bands were initiated at the amorphous matrix to form a crack near the notch tip region and were expanded over large matrix areas. The crack propagation was frequently blocked by β dendrites, and many shear bands are formed near or in front of the propagating crack, thereby resulting in stable crack growth, which could be confirmed by the fracture resistance curve ( R-curve) behavior. This increase in fracture resistance with increasing crack length could be explained by mechanisms of blocking of crack growth, multiple shear band formation, and crack blunting.

  2. Vacancy trapping by solute atoms during quenching in Cu-based dilute alloys studied by positron annihilation spectroscopy

    NASA Astrophysics Data System (ADS)

    Yabuuchi, A.; Yamamoto, Y.; Ohira, J.; Sugita, K.; Mizuno, M.; Araki, H.; Shirai, Y.

    2009-11-01

    Frozen-in vacancies and the recovery have been investigated in some Cu-based dilute alloys by using positron annihilation lifetime spectroscopy. Cu-0.5at%Sb, Cu-0.5at%Sn and Cu-0.5at%In dilute bulk alloys were quenched to ice water from 1223 K. A pure-Cu specimen was also quenched from the same temperature. As a result, no frozen-in vacancies have been detected in as-quenched pure-Cu specimen. On the other hand, as-quenched Cu-0.5at%Sb alloy contained frozen-in thermal equilibrium vacancies with concentration of 3 × 10-5. Furthermore, these frozen-in vacancies in Cu-0.5at%Sb alloy were stable until 473 K, and began to migrate at 523 K. Finally, the Cu-Sb alloy were recovered to the fully annealed state at 823 K. This thermal stability clearly implies some interaction exists between a vacancy and Sb atom and due to the interaction, thermal equilibrium vacancies are trapped by Sb atoms during quenching.

  3. Formation of equiaxed crystal structures in directionally solidified Al-Si alloys using Nb-based heterogeneous nuclei

    PubMed Central

    Bolzoni, Leandro; Xia, Mingxu; Babu, Nadendla Hari

    2016-01-01

    The design of chemical compositions containing potent nuclei for the enhancement of heterogeneous nucleation in aluminium, especially cast alloys such as Al-Si alloys, is a matter of importance in order to achieve homogeneous properties in castings with complex geometries. We identified that Al3Nb/NbB2 compounds are effective heterogeneous nuclei and are successfully produced in the form of Al-2Nb-xB (x = 0.5, 1 and 2) master alloys. Our study shows that the inoculation of Al-10Si braze alloy with these compounds effectively promotes the heterogeneous nucleation of primary α-Al crystals and reduces the undercooling needed for solidification to take place. Moreover, we present evidences that these Nb-based compounds prevent the growth of columnar crystals and permit to obtain, for the first time, fine and equiaxed crystals in directionally solidified Al-10Si braze alloy. As a consequence of the potent heterogeneous particles, the size of the α-Al crystals was found to be less dependent on the processing conditions, especially the thermal gradient. Finally, we also demonstrate that the enhanced nucleation leads to the refinement of secondary phases such as eutectic silicon and primary silicon particles. PMID:28008967

  4. Formation of equiaxed crystal structures in directionally solidified Al-Si alloys using Nb-based heterogeneous nuclei

    NASA Astrophysics Data System (ADS)

    Bolzoni, Leandro; Xia, Mingxu; Babu, Nadendla Hari

    2016-12-01

    The design of chemical compositions containing potent nuclei for the enhancement of heterogeneous nucleation in aluminium, especially cast alloys such as Al-Si alloys, is a matter of importance in order to achieve homogeneous properties in castings with complex geometries. We identified that Al3Nb/NbB2 compounds are effective heterogeneous nuclei and are successfully produced in the form of Al-2Nb-xB (x = 0.5, 1 and 2) master alloys. Our study shows that the inoculation of Al-10Si braze alloy with these compounds effectively promotes the heterogeneous nucleation of primary α-Al crystals and reduces the undercooling needed for solidification to take place. Moreover, we present evidences that these Nb-based compounds prevent the growth of columnar crystals and permit to obtain, for the first time, fine and equiaxed crystals in directionally solidified Al-10Si braze alloy. As a consequence of the potent heterogeneous particles, the size of the α-Al crystals was found to be less dependent on the processing conditions, especially the thermal gradient. Finally, we also demonstrate that the enhanced nucleation leads to the refinement of secondary phases such as eutectic silicon and primary silicon particles.

  5. NASA-UVa light aerospace alloy and structure technology program supplement: Aluminum-based materials for high speed aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr.

    1993-01-01

    This report on the NASA-UVa Light Aerospace Alloy and Structure Technology Program Supplement: Aluminum-Based Materials for High Speed Aircraft covers the period from January 1, 1992 to June 30, 1992. The objective of the research is to develop aluminum alloys and aluminum matrix composites for the airframe which can efficiently perform in the HSCT environment for periods as long as 60,000 hours (certification for 120,000 hours) and, at the same time, meet the cost and weight requirements for an economically viable aircraft. Current industry baselines focus on flight at Mach 2.4. The research covers four major materials systems: (1) ingot metallurgy 2XXX, 6XXX, and 8XXX alloys, (2) powder metallurgy 2XXX alloys, (3) rapidly solidified, dispersion strengthened Al-Fe-X alloys, and (4) discontinuously reinforced metal matrix composites. There are ten major tasks in the program which also include evaluation and trade-off studies by Boeing and Douglas aircraft companies.

  6. Gamma titanium aluminide alloys

    SciTech Connect

    Yamaguchi, M.; Inui, H.; Kishida, K.; Matsumuro, M.; Shirai, Y.

    1995-08-01

    Extensive progress and improvements have been made in the science and technology of gamma titanium aluminide alloys within the last decade. In particular, the understanding of their microstructural characteristics and property/microstructure relationships has been substantially deepened. Based on these achievements, various engineering two-phase gamma alloys have been developed and their mechanical and chemical properties have been assessed. Aircraft and automotive industries arc pursuing their introduction for various structural components. At the same time, recent basic studies on the mechanical properties of two-phase gamma alloys, in particular with a controlled lamellar structure have provided a considerable amount of fundamental information on the deformation and fracture mechanisms of the two-phase gamma alloys. The results of such basic studies are incorporated in the recent alloy and microstructure design of two-phase gamma alloys. In this paper, such recent advances in the research and development of the two-phase gamma alloys and industrial involvement are summarized.

  7. Low cycle fatigue life of two nickel-base casting alloys in a hydrogen environment. [for high-pressure oxidizer turbopump turbine nozzles

    NASA Technical Reports Server (NTRS)

    Cooper, R. A.

    1976-01-01

    Samples of two nickel-base casting alloys, Mar-M-246 (a Martin Company alloy) and 713LC (a low-carbon modification of the alloy 713C developed by International Nickel Company) were tested as candidate materials for the high-pressure fuel and high-pressure oxidizer turbopump turbine nozzles. The samples were subjected to tensile tests and to low cycle fatigue tests in high-pressure hydrogen to study the influence of the hydrogen environment. The Mar-M-246 material was found to have a three times higher cyclic life in hydrogen than the 713LC alloy, and was selected as the nozzle material.

  8. Effect of hydrogen on the structure of quenched orthorhombic titanium aluminide-based alloy and phase transformations during subsequent heating

    NASA Astrophysics Data System (ADS)

    Khadzhieva, O. G.; Illarionov, A. G.; Popov, A. A.; Grib, S. V.

    2013-06-01

    The effect of hydrogen on structure formation and changes in the volume fractions of phases in an alloy based on orthorhombic titanium aluminide ( O phase) alloy upon its quenching is studied. X-ray diffraction analysis is used to determine the lattice parameters of phases. It has been shown that hydrogen is dissolved mainly in the β0 phase. Differential thermal analysis is used to determine stages and temperature ranges of phase transformations during heating; it was found that introduced hydrogen shifts the β0 → O and reverse O → β0 transformations into the low-temperature range; the enthalpies of transformation are calculated.

  9. Effect of aging on structure and properties of quenched alloy based on orthorhombic titanium aluminide Ti2AlNb

    NASA Astrophysics Data System (ADS)

    Khadzhieva, O. G.; Illarionov, A. G.; Popov, A. A.

    2014-01-01

    Phase and structural transformations that occur upon the aging of a titanium alloy based on the O phase have been investigated. The formation of a special type of arrangement (zigzag or packet ensembles) of the O-phase plates that arise in the course of the β → O transformation has been detected. Using transmission electron microscopy, the multistage character of structural changes during the α2 → O transformation has been studied, and a schematic of the occurrence of the transformation has been proposed. The microdurometric characteristics of the indicated alloy that were obtained after different aging regimes have been estimated.

  10. Void structure and density change of vanadium-base alloys irradiated in the dynamic helium charging experiment

    SciTech Connect

    Chung, H.M.; Nowicki, L.; Gazda, J.

    1995-04-01

    The objective of this work is to determine void structure, distribution, and density changes of several promising vanadium-base alloys irradiated in the Dynamic Helium Charging Experiment (DHCE). Combined effects of dynamically charged helium and neutron damage on density change, void distribution, and microstructural evolution of V-4Cr-4Ti alloy have been determined after irradiation to 18-31 dpa at 425-600{degree}C in the DHCE, and the results compared with those from a non-DHCE in which helium generation was negligible.

  11. CORROSION OF AMORPHOUS AND NANOCRYSTALLINE Fe-BASED ALLOYS IN NaCl AND H2SO4 SOLUTIONS

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Lu, Wei; Wang, Yuxin; Yan, Biao; Pan, Deng

    2013-07-01

    Corrosion resistance of nanocrystalline Fe73.5Si13.5B9Nb3Cu1 alloy was investigated and compared to its amorphous counterpart. Low-temperature crystallization occurred during the annealing of amorphous tapes was used to obtain a nanocrystalline structure. The influence of annealing condition on the structure and corrosion resistance of the alloy in NaCl and H2SO4 solutions was investigated. Based on the testing results, it was found that nanocrystalline tapes have higher corrosion resistance than amorphous counterpart and H2SO4 can promote the occurrence of corrosion compared with NaCl.

  12. Oxide Dispersion Strengthened Fe(sub 3)Al-Based Alloy Tubes: Application Specific Development for the Power Generation Industry

    SciTech Connect

    Kad, B.K.

    1999-07-01

    A detailed and comprehensive research and development methodology is being prescribed to produce Oxide Dispersion Strengthened (ODS)-Fe3Al thin walled tubes, using powder extrusion methodologies, for eventual use at operating temperatures of up to 1100C in the power generation industry. A particular 'in service application' anomaly of Fe3Al-based alloys is that the environmental resistance is maintained up to 1200C, well beyond where such alloys retain sufficient mechanical strength. Grain boundary creep processes at such high temperatures are anticipated to be the dominant failure mechanism.

  13. Processing and operating experience of Ni{sub 3}Al-based intermetallic alloy IC-221M

    SciTech Connect

    Sikka, V.K.; Santella, M.L.; Orth, J.E.

    1997-05-01

    The cast Ni{sub 3}Al-based intermetallic alloy IC-221M is the most advanced in its commercial applications. This paper presents progress made for this alloy in the areas of: (1) composition optimization; (2) melting process development; (3) casting process; (4) mechanical properties; (5) welding process, weld repairs, and thermal aging response; and (6) applications. This paper also reviews the operating experience with several of the components. The projection for future growth in the applications of nickel aluminide is also discussed.

  14. A Study of Magnesium-Base Metallic Systems and Development of Principles for Creation of Corrosion-Resistant Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Mukhina, I. Yu.

    2014-11-01

    The effect of 26 alloying elements on the corrosion resistance of high-purity magnesium in a 0.5-n solution of sodium chloride and in a humid atmosphere (0.005 n) is studied. The Mg - Li, Mg - Ag, Mg - Zn, Mg - Cu, Mg - Gd, Mg - Al, Mg - Zr, Mg - Mn and other binary systems, which present interest as a base for commercial or perspective castable magnesium alloys, are studied. The characteristics of corrosion resistance of the binary alloys are analyzed in accordance with the group and period of the Mendeleev's periodic law. The roles of the electrochemical and volume factors and of the factor of the valence of the dissolved element are determined.

  15. Development and Evaluation of Directionally-Solidified NiAl/(CR,MO)-Based Eutectic Alloys for Airfoil Applications

    NASA Technical Reports Server (NTRS)

    Raj, S. V.; Locci, I. E.; Whittenberger, J. D.

    2001-01-01

    The results of recent efforts to develop directionally-solidified alloys based on the Ni-33Al-31Cr-3Mo eutectic composition are discussed. These developmental efforts included studying the effects of macroalloying and growth rates on microstructure formation as well as the elevated temperature compressive and tensile properties of these alloys. These observations revealed that contrary to conventional opinion, the cellular microstructure was stronger and tougher than the planar eutectic microstructure due to a microstructural refinement of the cell size and interlamellar spacing. The high temperature strengths of these alloys are compared with those of commercial superalloys and advanced NiAl single crystals. The implications of this research on airfoil manufacturing and applications are discussed.

  16. The effect of nanobioceramic reinforcement on mechanical and biological properties of Co-base alloy/hydroxyapatite nanocomposite.

    PubMed

    Bahrami, M; Fathi, M H; Ahmadian, M

    2015-03-01

    The goal of the present research was to fabricate, characterize, and evaluate mechanical and biological properties of Co-base alloy composites with different amounts of hydroxyapatite (HA) nanopowder reinforcement. The powder of Co-Cr-Mo alloy was mixed with different amounts of HA by ball milling and it was then cold pressed and sintered. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used. Microhardness measurement and compressive tests were also carried out. Bioactivity behavior was evaluated in simulated body fluid (SBF). A significant decrease in modulus elasticity and an increase in microhardness of the sintered composites were observed. Apatite formation on the surface of the composites showed that it could successfully convert bioinert Co-Cr-Mo alloy to bioactive type by adding 10, 15, and 20wt.% HA which have lower modulus elasticity and higher microhardness.

  17. Understanding the solidification and microstructure evolution during CSC-MIG welding of Fe–Cr–B-based alloy

    SciTech Connect

    Sorour, A.A. Chromik, R.R. Gauvin, R. Jung, I.-H. Brochu, M.

    2013-12-15

    The present is a study of the solidification and microstructure of Fe–28.2%Cr–3.8%B–1.5%Si–1.5%Mn (wt.%) alloy deposited onto a 1020 plain carbon steel substrate using the controlled short-circuit metal inert gas welding process. The as-solidified alloy was a metal matrix composite with a hypereutectic microstructure. Thermodynamic calculation based on the Scheil–Gulliver model showed that a primary (Cr,Fe){sub 2}B phase formed first during solidification, followed by an eutectic formation of the (Cr,Fe){sub 2}B phase and a body-centered cubic Fe-based solid solution matrix, which contained Cr, Mn and Si. Microstructure analysis confirmed the formation of these phases and showed that the shape of the (Cr,Fe){sub 2}B phase was irregular plate. As the welding heat input increased, the weld dilution increased and thus the volume fraction of the (Cr,Fe){sub 2}B plates decreased while other microstructural characteristics were similar. - Highlights: • We deposit Fe–Cr–B-based alloy onto plain carbon steel using the CSC-MIG process. • We model the solidification behavior using thermodynamic calculation. • As deposited alloy consists of (Cr,Fe){sub 2}B plates embedded in Fe-based matrix. • We study the effect of the welding heat input on the microstructure.

  18. Quantitative Analysis of Phase Composition of Alloy TNM-B1 based on TiAl(γ) Titanium Aluminide

    NASA Astrophysics Data System (ADS)

    Belov, N. A.; Chupakhin, I. S.

    2014-01-01

    The Thermo-Calc software is used to design isothermal and polythermal sections of the Ti - Al - Nb - Mo system as applied to a standard TNM-B1 γ-alloy based on TiAl intermetallic. It is shown that the use of special softwares is an effective tool for substantial lowering of the volume of experimental studies.

  19. Prediction of novel, Earth abundant Cu2O based alloys for PV applications

    NASA Astrophysics Data System (ADS)

    Stevanovic, Vladan; Lany, Stephan

    2014-03-01

    Tuning the opto-electronic properties of semiconductors through alloying is essential for semiconductor industry. Currently, mostly isovalent and isostructural alloys are used (e.g. Si/Ge, GaN/InN or CdTe/ZnTe), but a vast and unexplored space of novel functional materials is conceivable when considering more complex alloys by mixing aliovalent and heterostructural constituents. The real challenge lies in the quantitative property prediction for such complex alloys to guide their experimental exploration. In our work we demonstrate how an Earth abundant p-type oxide Cu2O, can be engineered through alloying into a technologically useful absorber material. We use non-local external potentials (NLEP) fitted to GW calculations for correcting the DFT electronic structure and compute absorption coefficient of different alloy compositions and configurations. Work supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Next Generation Photovoltaics II (SunShot initiative).

  20. Evolution of microstructure and defect structure in manganese-aluminum-based permanent magnet alloys

    NASA Astrophysics Data System (ADS)

    Yanar, Cagatay

    In this study, the transformation behavior of MnAl-based ferromagnetic alloys was investigated. The low-cost and availability of the Mn-Al base metals along with their high mechanical strength, machineability and high magnetic energy product (BH) per unit weight make these materials attractive candidates for permanent magnet applications. These alloys derive their magnetic properties from the metastable L10 tau-phase, which generally appears towards the Mn-rich side of the near equiatomic composition. The magnetic properties of these materials are strongly influenced by the microstructure and characteristic defect structure of the tau-phase. The tau-phase exhibits a unique defect structure, which includes twins, stacking faults, anti-phase domain boundaries and dislocations. Understanding the true nature of defect generation is necessary in order to be able to develop processing techniques to enhance and optimize the properties of these materials. The tau-phase derives from a phase mixture of ε(hcp) and ε '(B19) phases through various heat treatment processes. Controversial mechanisms are reported in the literature regarding the nature of the ε + ε' → tau transformation. Phase transformation mechanisms that are displacive and those involving a massive transformation have been reported. In this study, the true nature of the tau-phase formation was investigated experimentally by utilizing techniques such as transmission electron microscopy (TEM), high-resolution electron microscopy (HREM) and in-situ TEM heating experiments. It was shown that both of the transformation modes, i.e. massive and displacive mechanisms, can operate and result in tau-phase formation. The atomic nature of the displacive transformation was studied in detail to elucidate the viability of transformation of a two-phase mixture into a single phase through a shear transformation. In the absence of stress, the massive mode was shown to dominate microstructural evolution in bulk materials

  1. TEM characterization of Au-based alloys to join YSZ to steel for SOFC applications

    SciTech Connect

    Lin, Kun-Lin; Singh, Mrityunjay; Asthana, Rajiv

    2012-01-15

    The microstructures of two gold-based alloys with compositions (in wt.%) of 96.4Au-3Ni-0.6Ti and 97.5Au-0.75Ni-1.75V following oxidation at 850 Degree-Sign C for 200 min were characterized by analytical transmission electron microscopy with energy dispersive spectroscopy and by scanning electron microscopy. In the oxidized 96.4Au-3Ni-0.6Ti interlayer, a dense scale composed of nickel oxide (NiO) and nickel titanate (NiTiO{sub 3}) formed at the alloy surface. No evidence of titanium oxide was found because there was not enough Ti present to form titanium oxide. In the oxidized 97.5Au-0.75Ni-1.75V interlayer, loose vanadium oxide (V{sub 2}O{sub 5}) and nickel vanadate (Ni{sub 2}V{sub 2}O{sub 7}) formed and were distributed within the oxidized 97.5Au-0.75Ni-1.75V interlayer. Similarly, because of the low Ni content in the alloys, no NiO formed. The oxide products in the 96.4Au-3Ni-0.6Ti and 97.5Au-0.75Ni-1.75V interlayers after oxidation are consistent with the Pilling-Bedworth (PB) ratio considerations. - Highlights: Black-Right-Pointing-Pointer Two commercial Au-based reactive metallic interlayers were oxidized at 850 Degree-Sign C for 200 min. Black-Right-Pointing-Pointer The oxidized products at the surface were characterized by TEM/EDS and SEM. Black-Right-Pointing-Pointer NiO and NiTiO{sub 3} formed at the oxidized 96.4Au-3Ni-0.6Ti interlayer. Black-Right-Pointing-Pointer V{sub 2}O{sub 5} and Ni{sub 2}V{sub 2}O{sub 7} were found in the oxidized 97.5Au-0.75Ni-1.75V interlayer. Black-Right-Pointing-Pointer These oxide products are consistent with the Pilling-Bedworth (PB) ratio considerations.

  2. Fundamental Understanding of the Intrinsic Ductility in Nickel-Base L12 Type Alloys.

    DTIC Science & Technology

    1987-05-12

    strain field around the distortions. The convergent beam electron diffraction technique (CBEB), which is extremely sensitive to localized lattice...COSATI CO0ES I L SUBJE CT TIE RMS (Conue an eo e eee it necessary and identify by blb .un bPe) . ". Eo GROUP SUB. G. Nickel Aluminide , Single...Ni3Al alloys, three series of alloys were formulated and produced as singl’e--crtals. The alloying additions selected include tantalum, tin and titanium

  3. The influence of heat treatments on several types of base-metal removable partial denture alloys.

    PubMed

    Morris, H F; Asgar, K; Rowe, A P; Nasjleti, C E

    1979-04-01

    Four removable partial denture alloys, Vitallium (Co-Cr alloy), Dentillium P.D. (Fe-Cr alloy), Durallium L.G. (Co-Cr-Ni alloy), and Ticonium 100 (Ni-Cr alloy), were evaluated in the as-cast condition and after heat treatment for 15 minutes at 1,300 degrees, 1,600 degrees, 1,900 degrees, and 2,200 degrees F followed by quenching in water. The following properties were determined and compared for each alloy at each heat treatment condition: the yield strengths at 0.01%, 0.1%, and 0.2% offsets, the ultimate tensile strength, the percent elongation, the modulus of elasticity, and the Knoop microhardness. The results were statistically analyzed. Photomicrographs were examined for each alloy and test condition. The following conclusions were made: 1. The "highest values" were exhibited by the as-cast alloy. 2. Heat treatment of the partial denture alloys tested resulted in reductions in strength, while the elongations varied. This study demonstrates that, in practice, one should avoid (a) prolonged "heat-soaking" while soldering and (b) grinding or polishing of the casting until the alloy is "red hot". 3. Durallium L.G. was the least affected by the various heat treatment conditions. 4. Conventional reporting of the yield strength at 0.2% offset, the ultimate tensile strength, and percent elongation are not adequate to completely describe and compare the mechanical behavior of alloys. The reporting of the yield strength at 0.01% offset, in addition to the other reported properties, will provide a more complete description of the behavior of the dental alloys.

  4. Creep Resistant Zinc Alloy

    SciTech Connect

    Frank E. Goodwin

    2002-12-31

    This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

  5. Energy-based fatigue model for shape memory alloys including thermomechanical coupling

    NASA Astrophysics Data System (ADS)

    Zhang, Yahui; Zhu, Jihong; Moumni, Ziad; Van Herpen, Alain; Zhang, Weihong

    2016-03-01

    This paper is aimed at developing a low cycle fatigue criterion for pseudoelastic shape memory alloys to take into account thermomechanical coupling. To this end, fatigue tests are carried out at different loading rates under strain control at room temperature using NiTi wires. Temperature distribution on the specimen is measured using a high speed thermal camera. Specimens are tested to failure and fatigue lifetimes of specimens are measured. Test results show that the fatigue lifetime is greatly influenced by the loading rate: as the strain rate increases, the fatigue lifetime decreases. Furthermore, it is shown that the fatigue cracks initiate when the stored energy inside the material reaches a critical value. An energy-based fatigue criterion is thus proposed as a function of the irreversible hysteresis energy of the stabilized cycle and the loading rate. Fatigue life is calculated using the proposed model. The experimental and computational results compare well.

  6. Evaluation of dispersion strengthened nickel-base alloy heat shields for space shuttle application

    NASA Technical Reports Server (NTRS)

    Johnson, R., Jr.; Killpatrick, D. H.

    1976-01-01

    The results obtained in a program to evaluate dispersion-strengthened nickel-base alloys for use in a metallic radiative thermal protection system operating at surface temperatures to 1477 K for the space shuttle were presented. Vehicle environments having critical effects on the thermal protection system are defined; TD Ni-20Cr characteristics of material used in the current study are compared with previous results; cyclic load, temperature, and pressure effects on sheet material residual strength are investigated; the effects of braze reinforcement in improving the efficiency of spotwelded joints are evaluated; parametric studies of metallic radiative thermal protection systems are reported; and the design, instrumentation, and testing of full scale subsize heat shield panels in two configurations are described. Initial tests of full scale subsize panels included simulated meteoroid impact tests, simulated entry flight aerodynamic heating, programmed differential pressure loads and temperatures simulating mission conditions, and acoustic tests simulating sound levels experienced during boost flight.

  7. Fundamental Understanding of the Intrinsic Ductility in Nickel-Base L1 sub 2 Type Alloys

    DTIC Science & Technology

    1988-06-30

    AD-A197 605 FR-20424 "Gm-Two 88 U ,7 FUNDAMENTAL UNDERSTANDING OF THE INTRINSIC DUCTILITY IN NICKEL-BASE L12 TYPE ALLOYS C Lav D.M. Shah,. Un United...ntrlns’c Ductility In *11 :,’ A:- F1 f4I Report - ..,..4e - ,., C .we f tfort. FRC20424"’ I-.. a.-. 4nl jQ’rfU ePA a v,P 3 F orw tr a: we he rqVi t ;6tamit...ixtcen Copfol of tN 14Aac Pratt W to vAu C . C . Law Program Manager cc: Administrative Contracting IJ,’fcev Air Force Plant Representative OJf9--e UTC

  8. Self-healing coatings based on halloysite clay polymer composites for protection of copper alloys.

    PubMed

    Abdullayev, Elshad; Abbasov, Vagif; Tursunbayeva, Asel; Portnov, Vasiliy; Ibrahimov, Hikmat; Mukhtarova, Gulbaniz; Lvov, Yuri

    2013-05-22

    Halloysite clay nanotubes loaded with corrosion inhibitors benzotriazole (BTA), 2-mercaptobenzimidazole (MBI), and 2-mercaptobenzothiazole (MBT) were used as additives in self-healing composite paint coating of copper. These inhibitors form protective films on the metal surface and mitigate corrosion. Mechanisms involved in the film formation have been studied with optical and electron microscopy, UV-vis spectrometry, and adhesivity tests. Efficiency of the halloysite lumen loading ascended in the order of BTA < MBT < MBI; consequently, MBI and MBT halloysite formulations have shown the best protection. Inhibitors were kept in the tubes buried in polymeric paint layer for a long time and release was enhanced in the coating defects exposed to humid media with 20-50 h, sufficient for formation of protective layer. Anticorrosive performance of the halloysite-based composite acrylic and polyurethane coatings have been demonstrated for 110-copper alloy strips exposed to 0.5 M aqueous NaCl for 6 months.

  9. Density functional theory study of CO-induced segregation in gold-based alloys.

    PubMed

    Sansa, Myriam; Dhouib, Adnene; Guesmi, Hazar

    2014-08-14

    This paper reports a systematic study of the effect of CO gas on the chemical composition at the surface of gold-based alloys. Using DFT periodic calculations in presence of adsorbed CO the segregation behavior of group 9-10-11 transition metals (Ag, Cu, Pt, Pd, Ni, Ir, Rh, Co) substituted in semi-infinite gold surfaces is investigated. Although, CO is found to be more strongly adsorbed on (100) than on the (111) surface, the segregation of M impurities is found to be more pronounced on the (111) surface. The results reveal two competitive effects: the effect of M on CO and the effect of CO on M. Thus, on one hand, if M exists on the (100) gold facet, CO would be strongly adsorbed on it. But if M is initially located in the bulk, it would segregate to the (111) facet instead of the (100) in order to bind to CO.

  10. Calibration and Finite Element Implementation of an Energy-Based Material Model for Shape Memory Alloys

    NASA Astrophysics Data System (ADS)

    Junker, Philipp; Hackl, Klaus

    2016-09-01

    Numerical simulations are a powerful tool to analyze the complex thermo-mechanically coupled material behavior of shape memory alloys during product engineering. The benefit of the simulations strongly depends on the quality of the underlying material model. In this contribution, we discuss a variational approach which is based solely on energetic considerations and demonstrate that unique calibration of such a model is sufficient to predict the material behavior at varying ambient temperature. In the beginning, we recall the necessary equations of the material model and explain the fundamental idea. Afterwards, we focus on the numerical implementation and provide all information that is needed for programing. Then, we show two different ways to calibrate the model and discuss the results. Furthermore, we show how this model is used during real-life industrial product engineering.

  11. Deep ultraviolet distributed Bragg reflectors based on graded composition AlGaN alloys

    SciTech Connect

    Brummer, Gordie; Nothern, Denis; Nikiforov, A. Yu.; Moustakas, T. D.

    2015-06-01

    Distributed Bragg reflectors (DBRs) with peak reflectivity at approximately 280 nm, based on compositionally graded Al{sub x}Ga{sub 1−x}N alloys, were grown on 6H-SiC substrates by plasma-assisted molecular beam epitaxy. DBRs with square, sinusoidal, triangular, and sawtooth composition profiles were designed with the transfer matrix method. The crystal structure of these DBRs was studied with high-resolution x-ray diffraction of the (1{sup ¯}015) reciprocal lattice point. The periodicity of the DBR profiles was confirmed with cross-sectional Z-contrast scanning transmission electron microscopy. The peak reflectance of these DBRs with 15.5 periods varies from 77% to 56% with corresponding full width at half maximum of 17–14 nm. Coupled mode analysis was used to explain the dependence of the reflectivity characteristics on the profile of the graded composition.

  12. Dynamic restoration mechanism of a Fe{sub 3}Al based alloy during elevated temperature deformation

    SciTech Connect

    Chen, M.; Shan, A.; Lin, D.

    1995-08-01

    By TEM and metallographic examination, the authors found that dynamic recovery and following continuous recrystallization, which connects with the elevated temperature ductility, takes place in a Fe{sub 3}Al based alloy during elevated temperature deformation. Dynamic restoration consists of the following process: (1) by climbing or cross-slipping, glide dislocations change into dislocation arrays, (2) the dislocation array attracts lattice dislocations, (3) with increasing dislocation density, a non-equilibrium sub boundary forms, which is easy to migrate, slide or rotate under external force, and (4) when the misorientation angle of the sub boundary increases to a critical value, the sub boundary changes into a grain boundary with continuous misfit. By relaxation, the boundary then changes into a grain boundary consisting of periodical structure units.

  13. The preparation of the Ti-Al alloys based on intermetallic phases

    NASA Astrophysics Data System (ADS)

    Kosova, N.; Sachkov, V.; Kurzina, I.; Pichugina, A.; Vladimirov, A.; Kazantseva, L.; Sachkova, A.

    2016-01-01

    This article deals with a method of obtaining materials in the Ti-Al system. Research was carried out in accordance with the phase diagram of the system state. It was established, that both single-phase and multiphase systems, containing finely dispersed intermetallic compositions of phases Ti3Al, TiAl and TiAl3, are formed. Additionally, it was found that the pure finely dispersed (coherent-scattering region (CSR) up to 100 nm) intermetallic compound TiAl3 is formed at molar ratio of Ti:Al = 1:3. Experimentally proved the possibility of produce the complex composition of alloys and intermetallic compounds and products based on them.

  14. Recent progress in perpendicularly magnetized Mn-based binary alloy films

    NASA Astrophysics Data System (ADS)

    Zhu, Li-Jun; Nie, Shuai-Hua; Zhao, Jian-Hua

    2013-11-01

    In this article, we review the recent progress in growth, structural characterizations, magnetic properties, and related spintronic devices of tetragonal MnxGa and MnxAl thin films with perpendicular magnetic anisotropy. First, we present a brief introduction to the demands for perpendicularly magnetized materials in spintronics, magnetic recording, and permanent magnets applications, and the most promising candidates of tetragonal MnxGa and MnxAl with strong perpendicular magnetic anisotropy. Then, we focus on the recent progress of perpendicularly magnetized MnxGa and MnxAl respectively, including their lattice structures, bulk synthesis, epitaxial growth, structural characterizations, magnetic and other spin-dependent properties, and spintronic devices like magnetic tunneling junctions, spin valves, and spin injectors into semiconductors. Finally, we give a summary and a perspective of these perpendicularly magnetized Mn-based binary alloy films for future applications.

  15. Optimization of In-Situ Shot-Peening-Assisted Cold Spraying Parameters for Full Corrosion Protection of Mg Alloy by Fully Dense Al-Based Alloy Coating

    NASA Astrophysics Data System (ADS)

    Wei, Ying-Kang; Luo, Xiao-Tao; Li, Cheng-Xin; Li, Chang-Jiu

    2017-01-01

    Magnesium-based alloys have excellent physical and mechanical properties for a lot of applications. However, due to high chemical reactivity, magnesium and its alloys are highly susceptible to corrosion. In this study, Al6061 coating was deposited on AZ31B magnesium by cold spray with a commercial Al6061 powder blended with large-sized stainless steel particles (in-situ shot-peening particles) using nitrogen gas. Microstructure and corrosion behavior of the sprayed coating was investigated as a function of shot-peening particle content in the feedstock. It is found that by introducing the in-situ tamping effect using shot-peening (SP) particles, the plastic deformation of deposited particles is significantly enhanced, thereby resulting in a fully dense Al6061 coating. SEM observations reveal that no SP particle is deposited into Al6061 coating at the optimization spraying parameters. Porosity of the coating significantly decreases from 10.7 to 0.4% as the SP particle content increases from 20 to 60 vol.%. The electrochemical corrosion experiments reveal that this novel in-situ SP-assisted cold spraying is effective to deposit fully dense Al6061 coating through which aqueous solution is not permeable and thus can provide exceptional protection of the magnesium-based materials from corrosion.

  16. Durability and degradation of HT9 based alloy waste forms with variable Ni and Cr content

    SciTech Connect

    Olson, L.

    2016-12-31

    Short-term electrochemical and long-term hybrid electrochemical corrosion tests were performed on alloy waste forms in reference aqueous solutions that bound postulated repository conditions. The alloy waste forms investigated represent candidate formulations that can be produced with advanced electrochemical treatment of used nuclear fuel. The studies helped to better understand the alloy waste form durability with differing concentrations of nickel and chromium, species that can be added to alloy waste forms to potentially increase their durability and decrease radionuclide release into the environment.

  17. Fiber laser cladding of nickel-based alloy on cast iron

    NASA Astrophysics Data System (ADS)

    Arias-González, F.; del Val, J.; Comesaña, R.; Penide, J.; Lusquiños, F.; Quintero, F.; Riveiro, A.; Boutinguiza, M.; Pou, J.

    2016-06-01

    Gray cast iron is a ferrous alloy characterized by a carbon-rich phase in form of lamellar graphite in an iron matrix while ductile cast iron presents a carbon-rich phase in form of spheroidal graphite. Graphite presents a higher laser beam absorption than iron matrix and its morphology has also a strong influence on thermal conductivity of the material. The laser cladding process of cast iron is complicated by its heterogeneous microstructure which generates non-homogeneous thermal fields. In this research work, a comparison between different types of cast iron substrates (with different graphite morphology) has been carried out to analyze its impact on the process results. A fiber laser was used to generate a NiCrBSi coating over flat substrates of gray cast iron (EN-GJL-250) and nodular cast iron (EN-GJS-400-15). The relationship between processing parameters (laser irradiance and scanning speed) and geometry of a single laser track was examined. Moreover, microstructure and composition were studied by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD). The hardness and elastic modulus were analyzed by means of micro- and nanoindentation. A hardfacing coating was generated by fiber laser cladding. Suitable processing parameters to generate the Ni-based alloy coating were determined. For the same processing parameters, gray cast iron samples present higher dilution than cast iron samples. The elastic modulus is similar for the coating and the substrate, while the Ni-based coating obtained presents a significantly superior hardness than cast iron.

  18. Performance of chromia- and alumina-forming Fe- and Ni-base alloys exposed to metal dusting environments: The effect of water vapor and temperature

    DOE PAGES

    Rouaix-Vande Put, Aurelie; Unocic, Kinga A.; Brady, Michael P.; ...

    2015-11-18

    Fe- and Ni-base alloys including an alumina-forming austenitic alloy were exposed for 500 h under metal dusting environments with varying temperature, gas composition and total pressure. For one H2–CO–CO2–H2O environment, the increase in temperature from 550 to 750 °C generally decreased metal dusting. When H2O was added to a H2–CO–CO2 environment at 650 °C, the metal dusting attack was reduced. Even after 5000 h at a total pressure of 9.1 atm with 20%H2O, the higher alloyed specimens retained a thin protective oxide. Lastly, for gas mixtures containing little or no H2O, the Fe-base alloys were less resistant to metal dustingmore » than Ni-base alloys.« less

  19. Study of Magnetic Alloys: Critical Phenomena.

    DTIC Science & Technology

    MAGNETIC ALLOYS, TRANSPORT PROPERTIES), ELECTRICAL RESISTANCE, SEEBECK EFFECT , MAGNETIC PROPERTIES, ALUMINUM ALLOYS, COBALT ALLOYS, GADOLINIUM ALLOYS, GOLD ALLOYS, IRON ALLOYS, NICKEL ALLOYS, PALLADIUM ALLOYS, PLATINUM ALLOYS, RHODIUM ALLOYS

  20. Effect of β volume fraction on the dynamic grain growth during superplastic deformation of Ti3Al-based alloys

    NASA Astrophysics Data System (ADS)

    Kim, Ji Sik; Nam, Won Jong; Lee, Chong Soo

    1998-10-01

    The superplastic deformation behavior of Ti3Al based (α 2+β alloy was studied with respect to the volume fraction of α2/β. Three alloys containing 21, 50 and 77% in volume fractions of β exhibited large tensile elongations of over 500% at 970°C with a strain rate of 2.5x10-4 sec-1. The largest elongation was observed in the alloy with 21% of β. As the volume fraction of β phase increased, the flow stress and correspondingly, the strain-rate sensitivity values decreased. Due to the higher diffusivity of Ti in,β phase than in α2 phase, the increase in β volume fraction from 21 % to 77% accelerated the dynamic grain growth, and degraded the superplasticity of the Ti3Al-based alloys. The strain-based grain growth behavior was quantitatively analyzed and incorporated into a constitutive equation. The calculated flow curves are in agreement with the experimental ones in the stable deformation region.