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1

Relationship of microstructure and mechanical properties for V-Cr-Ti alloys.  

National Technical Information Service (NTIS)

Relation of composition, number density, and diameter of precipitates in microstructures of unalloyed V and V-Cr-Ti alloys to the yield strength, hardness, creep stress, and ductile-brittle transition temperature (DBTT) for these materials was determined ...

B. A. Loomis J. Gazda L. J. Nowicki D. L. Smith S. Danyluk

1993-01-01

2

Impurity effects on gas tungsten arc welds in V?Cr?Ti alloys  

NASA Astrophysics Data System (ADS)

Plates 6.4 mm thick of V-Cr-Ti alloys, mostly V-4Cr-4Ti, were welded in a glove box argon atmosphere. A hot titanium getter led to excessive hydrogen concentrations. A cold zirconium-aluminum getter was used to reduce both oxygen and hydrogen. It was observed that a major source of hydrogen was dissociation of water vapor by the electric arc of the welding torch. Careful monitoring of atmospheric impurities and successive pumping and backfilling cycles permitted welds of higher quality than previously achieved. Welds were evaluated primarily by the Charpy impact test. A ductile-to-brittle transition temperature (DBTT) of -28C was achieved in V-4Cr-4Ti. Previous GTA welds in the same material seldom had a DBTT below room temperature. Electron beam welding can achieve a DBTT of below -90C in the V-4Cr-4Ti alloy, indicating a lower limit to the DBTT by impurity control.

Grossbeck, M. L.; King, J. F.; Hoelzer, D. T.

2000-12-01

3

Effects of neutron irradiation and hydrogen on ductile-brittle transition temperatures of V-Cr-Ti alloys  

SciTech Connect

The effects of neutron irradiation and hydrogen on the ductile- brittle transition temperatures (DBTTs) of unalloyed vanadium and V-Cr-Ti alloys were determined from Charpy-impact tests on 1/3 ASTM standard size specimens and from impact tests on 3-mm diameter discs. The tests were conducted on specimens containing <30 appm hydrogen and 600-1200 appm hydrogen and on specimens after neutron irradiation to 28-46 dpa at 420, 520, and 600C. The DBTTs were minimum (< {minus}220{degree}C) for V-(105)Ti alloys under for V-4-Cr-4Ti alloy with <30 appm hydrogen. The effect of 600-1200 appm hydrogen in the specimens was to raise the DBTTs by 100--150{degree}C. The DBTTs were minimum (< {minus}220{degree}C) for V-(1-5)Ti alloys and V-4-Cr-4Ti alloys after neutron irradiation.

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

1993-08-01

4

Fatigue and crack growth behavior of V?Cr?Ti alloys  

NASA Astrophysics Data System (ADS)

The results of in-vacuum low cycle fatigue tests are presented for unirradiated V?5Cr?5Ti tested at 25, 250, and 400C. A pronounced environmental degradation of the fatigue properties is observed in this alloy at 25C. Fatigue life was reduced by as much as 84% when testing was completed in a rough vacuum. Cyclic stress range data and SEM observations suggest that this reduction is due to a combination of increases in rates of crack initiation and subsequent growth. In high vacuum, the fatigue results also show a trend of increasing cyclic life with increasing temperature between 25 and 400C. At 250C, life averages 1.7 times that at 25C, and at 400C, life averages 3.2 times that at 25C. A comparison of low cycle fatigue results for V?5Cr?5Ti was made to 20% cold-worked 316 stainless steel and several vanadium-base alloys. The results suggest that V?5Cr?5Ti has better resistance to fatigue than 316-SS in the temperature range of 25 to 400C. At 400C, the data also show that V?5Cr?5Ti out performs Vanstar alloys 7 and 8 over the entire range of strains investigated. Furthermore, the fatigue properties of the V?5Cr?5Ti alloy compare favorably to V?15Cr?5Ti (at 25C) and Vanstar 9 (at 400C) at strains greater than 1%. At lower strains, the lower fatigue resistance of V?5Cr?5Ti is attributed to the higher strengths of the V?15Cr?5Ti and Vanstar 9 alloys.

Gieseke, B. G.; Stevens, C. O.; Grossbeck, M. L.

1996-10-01

5

CaO insulator coatings and self-healing of defects on V-Cr-Ti alloys in liquid lithium  

Microsoft Academic Search

Electrically insulating and corrosion-resistant coatings are required at the liquid metal\\/structural interface in fusion first-wall\\/blanket applications. The electrical resistance of CaO coatings produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li that contained 0.5--85 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600°C. The solute element, Ca in liquid Li, reacted

J. H. Park; T. F. Kassner

1996-01-01

6

CaO insulator coatings and self-healing of defects on V-Cr-Ti alloys in liquid lithium  

SciTech Connect

Electrically insulating and corrosion-resistant coatings are required at the liquid metal/structural interface in fusion first-wall/blanket applications. The electrical resistance of CaO coatings produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li that contained 0.5--85 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degrees}C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400--420{degrees}C to produce a CaO coating. Resistance of the coating layer measured in-situ in liquid Li was {approx}10{sup 6} {Omega} at 400{degrees}C. Thermal cycling between 300 and 700{degrees}C changed the coating layer resistance. which followed insulator behavior. These results suggest that thin homogeneous coatings can be produced on variously shaped surfaces by controlling the exposure time, temperature, and composition of the liquid metal. The technique can be applied to various shapes(e.g., inside/outside of tubes, complex geometrical shapes) because the coating is formed by liquid-phase reaction. Examination of the specimens after cooling to room temperature revealed no spallation, but homogeneous crazing cracks were present in the CaO coating. Additional tests to investigate the in-situ self-healing behavior of the cracks indicated that rapid healing occurred at {ge}360{degrees}C.

Park, J.H.; Kassner, T.F.

1996-02-01

7

CaO insulator coatings and self-healing of defects on V-Cr-Ti alloys in liquid lithium system  

Microsoft Academic Search

Electrically insulating and corrosion-resistant coatings are required at the liquid metal\\/structural interface in fusion first-wall\\/blanket applications. Electrical resistance of CaO coatings that were produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li containing 0.5-85 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600°C. The solute element, Ca in liquid Li, reacted

J. H. Park; T. F. Kassner

1995-01-01

8

CaO insulator coatings and self-healing of defects on V?Cr?Ti alloys in liquid lithium system  

Microsoft Academic Search

Electrically insulating and corrosion-resistant coatings are required at the liquid metal\\/structural interface in fusion first-wall\\/blanket applications. The electrical resistance of CaO coatings produced on V?5%Cr?5%Ti by exposure of the alloy to liquid Li that contained 0.585 wt% dissolved Ca was measured as a function of time at temperatures between 250 and 600C. The solute element, Ca in liquid Li, reacted

J.-H. Park; T. F. Kassner

1996-01-01

9

CaO insulator coatings and self-healing of defects on V?Cr?Ti alloys in liquid lithium system  

NASA Astrophysics Data System (ADS)

Electrically insulating and corrosion-resistant coatings are required at the liquid metal/structural interface in fusion first-wall/blanket applications. The electrical resistance of CaO coatings produced on V?5%Cr?5%Ti by exposure of the alloy to liquid Li that contained 0.5-85 wt% dissolved Ca was measured as a function of time at temperatures between 250 and 600C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400-420C to produce a CaO coating. Resistance of the coating layer measured in-situ in liquid Li was ? 10 6 ? at 400C. Thermal cycling between 300 and 700C changed the coating layer resistance, which followed insulator behavior. These results suggest that thin homogeneous coatings can be produced on variously shaped surfaces by controlling the exposure time, temperature, and composition of the liquid metal. The technique can be applied to various shapes (e.g., inside/outside of tubes, complex geometrical shapes) because the coating is formed by liquid-phase reaction. Examination of the specimens after cooling to room temperature revealed no spallation, but homogeneous crazing cracks were present in the CaO coating. Additional tests to investigate the in-situ self-healing behavior of the cracks indicated that rapid healing occurred at ? 360C.

Park, J.-H.; Kassner, T. F.

1996-10-01

10

CaO insulator coatings and self-healing of defects on V-Cr-Ti alloys in liquid lithium system  

SciTech Connect

Electrically insulating and corrosion-resistant coatings are required at the liquid metal/structural interface in fusion first-wall/blanket applications. Electrical resistance of CaO coatings that were produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li containing 0.5-85 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degrees}C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400-420{degrees}C to produce a CaO coating. Resistance of the coating layer measured in-situ in liquid Li was {approx}10{sup 6} {Omega} at 400{degrees}C. Thermal cycling between 300 and 700{degrees}C changed the coating layer resistance, which followed insulator behavior. These results suggest that thin homogeneous coatings can be produced on variously shaped surfaces by controlling the exposure time, temperature, and composition of the liquid metal. The technique can be applied to various shapes (e.g., inside/outside of tubes, complex geometrical shapes) because the coating is formed by liquid-phase reaction. Examination of the specimens after cooling to room temperature revealed no spallation, but homogeneous crazing cracks were present in the CaO coating. Additional tests to investigate the in-situ self-healing behavior of the cracks indicated that rapid healing occurred at {>=}360{degrees}C.

Park, J.H.; Kassner, T.F.

1995-09-01

11

Effect of irradiation damage and helium on the swelling and structure of vanadium-base alloys  

Microsoft Academic Search

Swelling behavior and microstructural evolution of V-Ti, V-Cr-Ti, and V-Ti-Si alloys were investigated after irradiation at 420--600C 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.

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

1993-01-01

12

Features of dislocation channeling in neutron-irradiated V(Fe, Cr)Ti alloy  

Microsoft Academic Search

Post-irradiation annealing experiments were used to study the recovery of microstructure and mechanical properties in VCrTi and VFeTi alloys irradiated at 228C to 4dpa. After 500C post irradiation annealing, dislocation channeling occurred at deformed area in tensile specimens and significant loss of ductility resulted. For post irradiation annealing above 600C, recovery of damage structure and tensile properties occurred and irradiation

Ken-Ichi Fukumoto; Masanari Sugiyama; Hideki Matsui

2007-01-01

13

Correlation of microstructure and tensile and swelling behavior of neutron-irradiated vanadium alloys  

SciTech Connect

The microstructures of V-Ti, V-Cr-Ti, and V-Ti-Si alloys were characterized by transmission electron microscopy (TEM) after neutron irradiation in the Fast Flux Test Facility (FFTF) at 420 and 600{degrees}C to influences up to 114 dpa. Two types of irradiation-induced precipitates were identified, i.e., Ti{sub 2}O and Ti{sub 5}(Si,P){sub 3}. Blocky Ti(O,N,C) precipitates, which form by thermal processes during ingot fabrication, also were observed in all unirradiated and irradiated specimens. Irradiation-induced precipitation of spherical (<15 nm in diameter) Ti{sub 5}(Si,P){sub 3} phase was associated with superior resistance to void swelling. In specimens with negligible swelling, Ti{sub 5}(Si,P){sub 3} precipitation was significant. It seems that ductility is significantly reduced when the precipitation of Ti{sub 2}O and Ti{sub 5}(Si,P){sub 3} is pronounced. These observations indicate that initial composition; fabrication processes; actual solute compositions of Ti, O, N, C, P, and Si after fabrication; O, N, and C uptake during service; and irradiation-induced precipitation ae interrelated and are important factors to consider in developing an optimized alloy. 15 refs., 8 figs.

Chung, H.M.; Smith, D.L.

1991-10-01

14

Effects of oxygen, hydrogen and neutron irradiation on the mechanical properties of several vanadium alloys  

NASA Astrophysics Data System (ADS)

Several V-Cr-Ti-Al-Si alloys were studied or reviewed of their mechanical properties after their exposure to oxygen, hydrogen and neutron irradiation environments. The results showed that the oxidation kinetic of V4Cr4Ti alloy exhibited parabolic behavior in a flowing argon gas with low partial pressure oxygen over the temperatures from 450 to 600 C. Most of the alloys showed ductility losses with the increasing oxygen concentration with an exception of V4Ti3Al. Strong sensitivity to hydrogen embrittlement was found for the alloys with the combination of high oxygen concentration and high mechanical strength. It was found that the effect of hydrogen and neutron irradiation on the uniform deformation capability caused by their hardening are equivalent with that of the strain hardening. Fine grain was recommended for the alloys to improve their properties against hydrogen embrittlement and neutron irradiation induced ductility loss.

Chen, Jiming; Qiu, Shaoyu; Yang, Lin; Xu, Zengyu; Deng, Ying; Xu, Ying

2002-04-01

15

Superelastic behavior of a ?-type titanium alloy.  

PubMed

The superelasticity of a ? Ti alloy, Ti-7.5Nb-4Mo-2Sn (in atom percent) was evaluated by using loading and unloading cyclic tensile tests under different thermomechanical conditions, and the effects of the plastic deformation, temperature, strain rate and cyclic loading on the superelasticity of the alloy were studied. It is found that, with the applied strain increasing, the stress inducing the reverse martensitic transformation ???-? and the strain recovery rate ? decreases. The increase of deformation temperature promotes ??-??, ???-? and ??, and the temperature dependency of the stresses obeys the Clausius-Clapeyron relation. ??-??, ???-? and ?? are independent on the strain rate when it is lower than 8.3510(-4)s(-1). However, when the strain rate is higher than 8.3510(-4)s(-1), ??-?? and ?? increase, but ???-? decreased with increasing the strain rate. By cyclic loading and unloading to the maximum strain of 6% at 25C under the strain rate of 1.6710(-4)s(-1), the alloy exhibits a improved superelasticity after seventh cycles due to the training effect. PMID:23455161

Zhang, D C; Mao, Y F; Yan, M; Li, J J; Su, E L; Li, Y L; Tan, S W; Lin, J G

2013-04-01

16

Aluminum Alloying Effects on Lattice Types, Microstructures, and Mechanical Behavior of High-Entropy Alloys Systems  

SciTech Connect

The crystal lattice type is one of the dominant factors for controlling the mechanical behavior of high-entropy alloys (HEAs). For example, the yield strength at room temperature varies from 300 MPa for the face-centered-cubic (fcc) structured alloys, such as the CoCrCuFeNiTi{sub x} system, to about 3,000 MPa for the body-centered-cubic (bcc) structured alloys, such as the AlCoCrFeNiTi{sub x} system. The values of Vickers hardness range from 100 to 900, depending on lattice types and microstructures. As in conventional alloys with one or two principal elements, the addition of minor alloying elements to HEAs can further alter their mechanical properties, such as strength, plasticity, hardness, etc. Excessive alloying may even result in the change of lattice types of HEAs. In this report, we first review alloying effects on lattice types and properties of HEAs in five Al-containing HEA systems: Al{sub x}CoCrCuFeNi, Al{sub x}CoCrFeNi, Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5}, Al{sub x} CoCrFeNiTi, and Al{sub x}CrCuFe- Ni{sub 2}. It is found that Al acts as a strong bcc stabilizer, and its addition enhances the strength of the alloy at the cost of reduced ductility. The origins of such effects are then qualitatively discussed from the viewpoints of lattice-strain energies and electronic bonds. Quantification of the interaction between Al and 3d transition metals in fcc, bcc, and intermetallic compounds is illustrated in the thermodynamic modeling using the CALculation of PHAse Diagram method.

Tang, Zhi; Gao, Michael C.; Diao, Haoyan; Yang, Tengfei; Liu, Junpeng; Zuo, Tingting; Zhang, Yong; Lu, Zhaoping; Cheng, Yongqiang; Zhang, Yanwen; Dahmen, Karin A.; Liaw, Peter K.; Egami, Takeshi

2013-12-01

17

Aluminum Alloying Effects on Lattice Types, Microstructures, and Mechanical Behavior of High-Entropy Alloys Systems  

NASA Astrophysics Data System (ADS)

The crystal lattice type is one of the dominant factors for controlling the mechanical behavior of high-entropy alloys (HEAs). For example, the yield strength at room temperature varies from 300 MPa for the face-centered-cubic (fcc) structured alloys, such as the CoCrCuFeNiTi x system, to about 3,000 MPa for the body-centered-cubic (bcc) structured alloys, such as the AlCoCrFeNiTi x system. The values of Vickers hardness range from 100 to 900, depending on lattice types and microstructures. As in conventional alloys with one or two principal elements, the addition of minor alloying elements to HEAs can further alter their mechanical properties, such as strength, plasticity, hardness, etc. Excessive alloying may even result in the change of lattice types of HEAs. In this report, we first review alloying effects on lattice types and properties of HEAs in five Al-containing HEA systems: Al x CoCrCuFeNi, Al x CoCrFeNi, Al x CrFe1.5MnNi0.5, Al x CoCrFeNiTi, and Al x CrCuFeNi2. It is found that Al acts as a strong bcc stabilizer, and its addition enhances the strength of the alloy at the cost of reduced ductility. The origins of such effects are then qualitatively discussed from the viewpoints of lattice-strain energies and electronic bonds. Quantification of the interaction between Al and 3 d transition metals in fcc, bcc, and intermetallic compounds is illustrated in the thermodynamic modeling using the CALculation of PHAse Diagram method.

Tang, Zhi; Gao, Michael C.; Diao, Haoyan; Yang, Tengfei; Liu, Junpeng; Zuo, Tingting; Zhang, Yong; Lu, Zhaoping; Cheng, Yongqiang; Zhang, Yanwen; Dahmen, Karin A.; Liaw, Peter K.; Egami, Takeshi

2013-12-01

18

Mechanism of Pit Initiation on Aluminum Alloy Type 7075.  

National Technical Information Service (NTIS)

The influence of anions on the initiation of pitting and the kinetics of pit growth on aluminum alloy Type 7075 has been investigated. The order of reaction (i.e., the number of anions per Al surface reaction site) and the energy of activation for pitting...

S. Dallek R. T. Foley

1976-01-01

19

Development and testing ov danadium alloys for fusion applications  

SciTech Connect

V base alloys have advantages for fusion reactor first-wall and blanket structure. To screen candidate alloys and optimize a V-base alloy, physical and mechanical properties of V-Ti, V-Cr-Ti, and V-Ti- Si alloys were studied before and after irradiation in Li environment in fast fission reactors. V-4Cr-4Ti containing 500-1000 wppM Si and <1000 wppM O+N+C was investigated as the most promising alloy, and more testing is being done. Major results of the work are presented in this paper. The reference V-4Cr-4Ti had the most attractive combination of the mechanical and physical properties that are prerequisite for first-wall and blanket structures: good thermal creep, good tensile strength/ductility, high impact energy, excellent resistance to swelling, and very low ductile-brittle transition temperature before and after irradiation. The alloy was highly resistant to irradiation-induced embrittlement in Li at 420-600 C, and the effects of dynamically charged He on swelling and mechanical properties were insignificant. However, several important issues remain unresolved: welding, low-temperature irradiation, He effect at high dose and high He concentration, irradiation creep, and irradiation performance in air or He. Initial results of investigation of some of these issues are also given.

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

1996-10-01

20

Investigation of new type Cu-Hf-Al bulk glassy alloys  

Microsoft Academic Search

In the last years new type Cu-Hf-Al ternary alloys were developed with high glass forming ability and ductility. The addition of Al to Cu-Hf alloys results in improvements in glass formation, thermal stability and mechanical properties of these alloys. We have investigated new Cu-based bulk amorphous alloys in Cu-Hf-Al ternary system. The alloys with Cu49Hf42Al9, Cu46Hf45Al9, Cu50Hf42.5Al7.5 and Cu50Hf45Al5 compositions

E. Nagy; V. Ront; J. Slyom; A. Rosz

2009-01-01

21

Studies on cobalt-free AB 5-type hydrogen storage alloys  

Microsoft Academic Search

Cobalt-free AB5-type hydrogen storage alloys were examined for lowering MH raw materials cost. The hydrogen absorptiondesorption and electrode properties of these alloys were investigated. For comparison, a cobalt-containing AB5-type hydrogen storage alloy was also examined. Electrochemical measurements showed that cobalt-containing La0.6Ce0.4Ni3.77Co0.6Mn0.36Al0.27 alloy had a maximum capacity of 295 mAh\\/g at a rate of 0.2 C. The capacity decay is 26.5%

Wei-Kang Hu

1999-01-01

22

Effect of irradiation damage and helium on the swelling and structure of vanadium-base alloys  

SciTech Connect

Swelling behavior and microstructural evolution of V-Ti, V-Cr-Ti, and V-Ti-Si alloys were investigated after irradiation at 420--600C 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. V-20Ti doped with B exhibited somewhat higher swelling because of He generation. Lithium atoms, generated from transmutation of {sup 10}B, formed {gamma}-LiV{sub 2}O{sub 5} precipitates and did not seem to produce undesirable effects on mechanical properties.

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

1993-12-01

23

Beta type Ti-Mo alloys with changeable Young's modulus for spinal fixation applications.  

PubMed

To develop a novel biomedical titanium alloy with a changeable Young's modulus via deformation-induced ? phase transformation for the spinal rods in spinal fixation devices, a series of metastable ? type binary Ti-(15-18)Mo alloys were prepared. In this study, the microstructures, Young's moduli and tensile properties of the alloys were systemically examined to investigate the effects of deformation-induced ? phase transformation on their mechanical properties. The springback of the optimal alloy was also examined. Ti-(15-18)Mo alloys subjected to solution treatment comprise a ? phase and a small amount of athermal ? phase, and they have low Young's moduli. All the alloys investigated in this study show an increase in the Young's modulus owing to deformation-induced ? phase transformation during cold rolling. The deformation-induced ? phase transformation is accompanied with {332}(?) mechanical twinning. This resulted in the maintenance of acceptable ductility with relatively high strength. Among the examined alloys, the Ti-17Mo alloy shows the lowest Young's modulus and the largest increase in the Young's modulus. This alloy exhibits small springback and could be easily bent to the required shape during operation. Thus, Ti-17Mo alloy is considered to be a potential candidate for the spinal rods in spinal fixation devices. PMID:22326686

Zhao, Xingfeng; Niinomi, Mitsuo; Nakai, Masaaki; Hieda, Junko

2012-05-01

24

Nde Detectability of Fatigue Type Cracks in High Strength Alloys.  

National Technical Information Service (NTIS)

Specimens suitable for investigating the reliability of production nondestructive evaluation (NDE) to detect tightly closed fatigue cracks in high strength alloys representative of those materials used in spacecraft engine/booster construction were produc...

B. K. Christner W. D. Rummel

1983-01-01

25

NDE detectability of fatigue type cracks in high strength alloys  

NASA Technical Reports Server (NTRS)

Specimens suitable for investigating the reliability of production nondestructive evaluation (NDE) to detect tightly closed fatigue cracks in high strength alloys representative of those materials used in spacecraft engine/booster construction were produced. Inconel 718 was selected as representative of nickel base alloys and Haynes 188 was selected as representative of cobalt base alloys used in this application. Cleaning procedures were developed to insure the reusability of the test specimens and a flaw detection reliability assessment of the fluorescent penetrant inspection method was performed using the test specimens produced to characterize their use for future reliability assessments and to provide additional NDE flaw detection reliability data for high strength alloys. The statistical analysis of the fluorescent penetrant inspection data was performed to determine the detection reliabilities for each inspection at a 90% probability/95% confidence level.

Christner, B. K.; Rummel, W. D.

1983-01-01

26

alloys  

NASA Astrophysics Data System (ADS)

Structural, magnetic and magnetostrictive properties of Tb0.4Nd0.6(Fe0.8Co0.2) x (1.50 ? x ? 1.90) alloys have been investigated by means of X-ray diffraction (XRD), a vibrating sample magnetometer and a standard strain technique. XRD analysis shows the presence of single Laves phase with a cubic MgCu2-type structure for the high Nd content alloy around the composition of x = 1.80, which tends to be formed by curing at relatively low annealing temperature. The easy direction of magnetization at room temperature is observed toward <111> axis, accompanied by a rhombohedral distortion with a large spontaneous magnetostriction ?111. An optimized effect on the linear anisotropic magnetostriction, 360 ppm at 3 kOe, was observed for the high Nd content Tb0.4Nd0.6(Fe0.8Co0.2)1.80 alloy, which can be attributed to its single Laves phase, the large ?111 (~1,520 ppm) of the MgCu2-type (Tb,Nd)(Fe,Co)2 phase and the good soft magnetic behaviors.

Pan, Z. B.; Liu, J. J.; Wang, R.; Liu, X. Y.; Wang, J.; Sun, N. K.; Si, P. Z.

2014-06-01

27

Grain size control and superplasticity in 6013-type aluminum alloys  

NASA Astrophysics Data System (ADS)

Aluminum alloys have been the material of choice for aircraft construction since the 1930's. Currently, the automotive industry is also showing an increasing interest in aluminum alloys as structural materials. 6xxx aluminum alloys possess a combination of strength and formability which makes them attractive to both industries. In addition, 6xxx alloys are highly weldable, corrosion resistant, and low in cost as compared with the 2xxx and 7xxx aluminum alloys. Superplastic forming (SPF) is a manufacturing process which exploits the phenomenon of superplasticity in which gas pressure is used to form complex-shaped parts in a single forming operation. This reduces part counts and the need for fasteners and connectors, resulting in reduced product weight. Reduced product/vehicle weight improves fuel economy. Most alloys must be specially processed for superplasticity. Much research effort has been directed at the development of thermomechanical processes for the grain refinement of aluminum alloys by static or dynamic recrystallization. to induce superplasticity. While large numbers of studies have been conducted on 2xxx, 5xxx, 7xxx, and 8xxx aluminum alloys, very few studies have been focused on the grain refinement of 6xxx aluminum alloys for superplasticity. The current research describes a new thermomechanical process for application to 6xxx aluminum alloys for grain refinement and superplasticity. The process is shown to successfully refine and induce superplasticity in an Al-Mg-Si-Cu alloy which falls within the compositional limits of both 6013 and 6111. The grain refinement is by particle-stimulated nucleation of recrystallization. The microstructural evolution during the thermomechanical processing is characterized in terms of precipitate size, shape, distribution and composition; texture; recrystallization; and grain size, shape, and thermal stability. The new process produces a statically-stable, weakly-textured, equiaxed grain structure with an average grain diameter of 10 mum. The refined microstructure exhibits superplasticity above 500C, where the strain rate sensitivity reaches a maximum of 0.5 (at 540C for strain rates between 2 x 10-4 s-1 and 5 x 10-4 s-1). The maximum uniaxial elongation (375%) occurred in the regime of the maximum strain rate sensitivity. The corresponding flow stress was 680 psi (4.7 Mpa). Biaxial cone tests were performed in order to better evaluate the high-temperature forming characteristics of the material. During tests with back pressure, cone height-to-radius ratios near 1.2 were obtained with maximum strain approaching 2.0 for strain rates near 1 x 10-3 s-1 . The effect of superplastic deformation on the microstructure is described in terms of the effect of strain on grain size and porosity for a cone sample. The ultimate goal of the project is to advance the fundamental understanding of the complex interrelationships between processing, microstructure, and superplastic performance.

Troeger, Lillianne Plaster Whitelock

28

Invar-type effect induced by cold-rolling deformation in shape memory alloys  

NASA Astrophysics Data System (ADS)

Since the discovery of Fe-Ni alloys showing low thermal expansion (LTE) in 1896, many Invar alloys have been developed based on magnetovolume effect where negative thermal expansion is induced by magnetic transformation. Herein, we show that the control of stress-induced martensitic transformation due to cold working of the Cu-Zn-Al polycrystalline alloy results in the LTE. This type of LTE material is easily fabricated by conventional cold rolling, and the coefficient of thermal expansion in the range from about 0 to 32 x10-6 K-1 can be obtained by controlling the reduction ratio. The LTE effect due to the present method can also be obtained for other shape memory (SM) alloys such as Ni-Ti, Cu-Mn-Al and Ni-Al base alloys, which have high potential for various practical applications.

Kainuma, R.; Wang, J. J.; Omori, T.; Sutou, Y.; Ishida, K.

2002-06-01

29

P and n-type microcrystalline semiconductor alloy material including band gap widening elements, devices utilizing same  

DOEpatents

An n-type microcrystalline semiconductor alloy material including a band gap widening element; a method of fabricating p-type microcrystalline semiconductor alloy material including a band gap widening element; and electronic and photovoltaic devices incorporating said n-type and p-type materials.

Guha, Subhendu (Troy, MI); Ovshinsky, Stanford R. (Bloomfield Hills, MI)

1988-10-04

30

Electrochemical study of cobalt-free AB 5-type hydrogen storage alloys  

Microsoft Academic Search

Cobalt-free AB5-type hydrogen storage alloys have been examined for the purpose of lowering MH raw material costs. The electrochemical measurements showed that the cobalt-containing LaNi3.55Mn0.4Al0.3Co0.75 alloy had a maximum capacity of 300mAh\\/g at a rate of C\\/6. The capacity decrease was calculated by 5% after 20 cycles at C\\/6 rate with 100% depth of discharge (DOD). The cobalt-free LaNi3.55Mn0.4Al0.3Fe0.75 alloy

C. Khaldi; H. Mathlouthi; J. Lamloumi; A. Percheron-Gugan

2004-01-01

31

Magnetic transformation of Ni 2 AlMn heusler-type shape memory alloys  

Microsoft Academic Search

It has recently been reported that the movement of twin (or variant) boundaries, induced by a magnetic field during the martensitic transformation, affects the magnetic properties and shape change in the ferromagnetic NiGaMn shape memory (SM) alloys. These observations suggest that the NiGaMn SM alloys with an L2 (NiGaMn: Heusler) structure have the potential for use as a new type

F. Gejima; Y. Sutou; R. Kainuma; K. Ishida

1999-01-01

32

Distributed type of actuators by shape memory alloy and its application to underwater mobile robotic mechanism  

Microsoft Academic Search

The basic idea of a new type of actuator based on a shape memory alloy (SMA) and its application to underwater mobile robots are presented. The actuator consists of a multimode SMA, so that any shape can be produced as the synthesized sum of excited modes. Thus, the actuator shows the characteristics of distributed-parameter-type actuators with a specified number of

Toshio Fukuda; Hidemi Hosokai; Isamu Kikuchi

1990-01-01

33

Strain glass transition in a multifunctional ?-type Ti alloy.  

PubMed

Recently, a class of multifunctional Ti alloys called GUM metals attracts tremendous attentions for their superior mechanical behaviors (high strength, high ductility and superelasticity) and novel physical properties (Invar effect, Elinvar effect and low modulus). The Invar and Elinvar effects are known to originate from structural or magnetic transitions, but none of these transitions were found in the GUM metals. This challenges our fundamental understanding of their physical properties. In this study, we show that the typical GUM metal Ti-23Nb-0.7Ta-2Zr-1.2O (at%) alloy undergoes a strain glass transition, where martensitic nano-domains are frozen gradually over a broad temperature range by random point defects. These nano-domains develop strong texture after cold rolling, which causes the lattice elongation in the rolling direction associated with the transition upon cooling and leads to its Invar effect. Moreover, its Elinvar effect and low modulus can also be explained by the nano-domain structure of strain glass. PMID:24500779

Wang, Yu; Gao, Jinghui; Wu, Haijun; Yang, Sen; Ding, Xiangdong; Wang, Dong; Ren, Xiaobing; Wang, Yunzhi; Song, Xiaoping; Gao, Jianrong

2014-01-01

34

Strain glass transition in a multifunctional ?-type Ti alloy  

PubMed Central

Recently, a class of multifunctional Ti alloys called GUM metals attracts tremendous attentions for their superior mechanical behaviors (high strength, high ductility and superelasticity) and novel physical properties (Invar effect, Elinvar effect and low modulus). The Invar and Elinvar effects are known to originate from structural or magnetic transitions, but none of these transitions were found in the GUM metals. This challenges our fundamental understanding of their physical properties. In this study, we show that the typical GUM metal Ti-23Nb-0.7Ta-2Zr-1.2O (at%) alloy undergoes a strain glass transition, where martensitic nano-domains are frozen gradually over a broad temperature range by random point defects. These nano-domains develop strong texture after cold rolling, which causes the lattice elongation in the rolling direction associated with the transition upon cooling and leads to its Invar effect. Moreover, its Elinvar effect and low modulus can also be explained by the nano-domain structure of strain glass.

Wang, Yu; Gao, Jinghui; Wu, Haijun; Yang, Sen; Ding, Xiangdong; Wang, Dong; Ren, Xiaobing; Wang, Yunzhi; Song, Xiaoping; Gao, Jianrong

2014-01-01

35

Spark plasma sintering synthesis of porous nanocrystalline titanium alloys for biomedical applications.  

PubMed

The reason for the extended use of titanium and its alloys as implant biomaterials stems from their lower elastic modulus, their superior biocompatibility and improved corrosion resistance compared to the more conventional stainless steel and cobalt-based alloys [Niinomi, M., Hattori, T., Niwa, S., 2004. Material characteristics and biocompatibility of low rigidity titanium alloys for biomedical applications. In: Jaszemski, M.J., Trantolo, D.J., Lewandrowski, K.U., Hasirci, V., Altobelli, D.E., Wise, D.L. (Eds.), Biomaterials in Orthopedics. Marcel Dekker Inc., New York, pp. 41-62]. Nanostructured titanium-based biomaterials with tailored porosity are important for cell-adhesion, viability, differentiation and growth. Newer technologies like foaming or low-density core processing were recently used for the surface modification of titanium alloy implant bodies to stimulate bone in-growth and improve osseointegration and cell-adhesion, which in turn play a key role in the acceptance of the implants. We here report preliminary results concerning the synthesis of mesoporous titanium alloy bodies by spark plasma sintering. Nanocrystalline cp Ti, Ti-6Al-4V, Ti-Al-V-Cr and Ti-Mn-V-Cr-Al alloy powders were prepared by high-energy wet-milling and sintered to either full-density (cp Ti, Ti-Al-V) or uniform porous (Ti-Al-V-Cr, Ti-Mn-V-Cr-Al) bulk specimens by field-assisted spark plasma sintering (FAST/SPS). Cellular interactions with the porous titanium alloy surfaces were tested with osteoblast-like human MG-63 cells. Cell morphology was investigated by scanning electron microscopy (SEM). The SEM analysis results were correlated with the alloy chemistry and the topographic features of the surface, namely porosity and roughness. PMID:17869173

Nicula, R; Lthen, F; Stir, M; Nebe, B; Burkel, E

2007-11-01

36

Corrosion potential measurements on type 304 SS and alloy 182 in simulated BWR environments  

SciTech Connect

The effects of dissolved oxygen, hydrogen, and hydrogen peroxide on the corrosion (electrochemical) potentials (ECPs) of type 304 SS and alloy 182 in simulated boiling water reactor (BWR) coolant environments under various water chemistry conditions at 288 C are reported. In oxygenated systems, the measured ECP fell within the range +20 to [minus]600 mV (vs SHE) depending on the O[sub 2] concentration. The effect of water flow rate on the ECP was also studied as function of dissolved O[sub 2] concentration. Increasing flow rate at constant oxygen concentration increased the ECPs of type 304 SS and alloy 182. The effect of hydrogen peroxide (H[sub 2]O[sub 2]) on the ECP of type 304 SS and alloy 182 in pure water was also determined. The authors found that the concentration of oxygen and the ECP increased immediately when H[sub 2]O[sub 2] was injected into the cell. The measured corrosion potentials of both alloys were 200 to 400 mV more positive than for dissolved O[sub 2] at similar levels. However, the ECP was lower than that expected theoretically from a mixed potential model (COREPOTENTIAL), which the authors attribute to thermal decomposition of H[sub 2]O[sub 2]. The ECPs of type 304 SS and alloy 182 in water containing various O[sub 2]/H[sub 2]/H[sub 2]O[sub 2] combinations were measured and compared with theoretical data from COREPOTENTIAL. The ECPs were lower than expected due to decomposition of H[sub 2]O[sub 2] in the high-temperature environment. Finally, the difference between the ECP of type 304 SS and alloy 182 was negligible (normally < [plus minus] 20 mV) under all conditions.

Macdonald, D.D. (Pennsylvania State Univ., University Park (United States)); Song, H. (SRI International, Menlo Park, CA (United States)); Makela, K. (VTT, Espoo (Finland)); Yoshida, K. (Ishikawajima-Harima Heavy Industries Co., Ltd., Yokohama (Japan))

1993-01-01

37

Magnetic transformation of Ni{sub 2}AlMn Heusler-type shape memory alloys  

SciTech Connect

It has recently been reported that the movement of twin (or variant) boundaries, induced by a magnetic field during the martensitic transformation, affects the magnetic properties and shape change in the ferromagnetic NiGaMn shape memory (SM) alloys. These observations suggest that the NiGaMn SM alloys with an L2{sub 1} (Ni{sub 2}GaMn: Heusler) structure have the potential for use as a new type of smart materials whose SM properties can be controlled not only by temperature and stress, but also by a magnetic field. Very recently, the present authors have detected that in the alloys with compositions near the stoichiometric Ni{sub 2}AlMn, the ferromagnetic L2{sub 1} phase appears on low-temperature aging and it transforms martensitically from B2 to 2M. This suggests that the NiAlMn Heusler alloys could also exhibit unique magnetic and SM properties similar to those of the NiGaMn alloys. It is the purpose of this article to report the results of investigations on the magnetic properties of the NiAlMn Heusler alloys.

Gejima, F.; Sutou, Y.; Kainuma, R.; Ishida, K.

1999-10-01

38

Alloy development for first wall materials used in water-cooling type fusion reactors  

NASA Astrophysics Data System (ADS)

Austenitic stainless steels with high resistance to IASCC were developed for the first wall used in a water cooling type fusion reactor. New alloys with ultra low carbon content were designed to improve all-round properties relevant to the reliability below 450C, by enhancing the austenite phase stability and purifying the austenite matrix. For this purpose, these were manufactured by means of controlling minor elements, adjusting principal elements and applying SAR thermomechanical treatment. The major characteristics of these alloys were compared with that of Type 316 and JPCA. These alloys showed a good swelling resistance to electron irradiation and high cracking resistance to high heat fluxes of hydrogen beam. The ductility loss and decrease of tensile strength at the objective temperature were also minimized.

Kiuchi, K.; Ishiyama, T.; Hishinuma, A.

1991-03-01

39

Effect of the mode of plastic deformation on the formation of the alloy-type texture  

Microsoft Academic Search

The aim of this work was to explore the role of heterogeneous deformation in the formation of the alloy-type texture. Recent works on the role of the deformation mode in evolution of the deformation texture seem to shed new light on the problem of texture formation. In particular it has been shown, that the texture typical for pure fcc metals

F. Dobrza?ski; W. Bochniak

1995-01-01

40

Three defect types in friction stir welding of aluminum die casting alloy  

Microsoft Academic Search

For different tool plunge downforces, the optimum FSW conditions of aluminum die casting alloy were examined. The higher the tool plunge downforce is, the wider the range of the optimum FSW conditions is. The following three different types of defects are formed, depending on the FSW conditions. (1) A large mass of flash due to the excess heat input; (2)

Y. G. Kim; H. Fujii; T. Tsumura; T. Komazaki; K. Nakata

2006-01-01

41

Alloying effect of Ni and Cr on irradiated microstructural evolution of type 304 stainless steels  

NASA Astrophysics Data System (ADS)

Life extension of the existing nuclear power plants imposes significant challenges to core structural materials that suffer increased fluences. This paper presents the microstructural evolution of a type 304 stainless steel and its variants alloyed with extra Ni and Cr under neutron irradiation at 320 C for up to 10.2 dpa. Similar to the reported data of type 304 variants, a large amount of Frank loops, ultrafine G-phase/M23C6 particles, and limited amount of cavities were observed in the irradiated samples. The irradiation promoted the growth of pre-existing M23C6 at grain boundaries and resulted in some phase transformation to CrC in the alloy with both extra Ni and Cr. A new type of ultrafine precipitates, possibly (Ti,Cr)N, was observed in all the samples, and its amount was increased by the irradiation. Additionally, ?-ferrite was observed in the type 304 steel but not in the Ni or Ni + Cr alloyed variants. The effect of Ni and Cr alloying on the microstructural evolution is discussed.

Tan, L.; Busby, J. T.

2013-11-01

42

Effects of SiC Nanodispersion on the Thermoelectric Properties of p-Type and n-Type Bi2Te3-Based Alloys  

NASA Astrophysics Data System (ADS)

Polycrystalline p-type Bi0.5Sb1.5Te3 and n-type Bi2Te2.7Se0.3 thermoelectric (TE) alloys containing a small amount (vol.% ?5) of SiC nanoparticles were fabricated by mechanical alloying and spark plasma sintering. It was revealed that the effects of SiC addition on TE properties can be different between p-type and n-type Bi2Te3-based alloys. SiC addition slightly increased the power factor of the p-type materials by decreasing both the electrical resistivity ( ?) and Seebeck coefficient ( ?), but decreased the power factor of n-type materials by increasing both ? and ?. Regardless of the conductivity type, the thermal conductivity was reduced by dispersing SiC nanoparticles in the Bi2Te3-based alloy matrix. As a result, a small amount (0.1 vol.%) of SiC addition increased the maximum dimensionless figure of merit ( ZT max) of the p-type Bi0.5Sb1.5Te3 alloys from 0.88 for the SiC-free sample to 0.97 at 323 K, though no improvement in TE performance was obtained in the case of n-type Bi2Te2.7Se0.3 alloys. Importantly, the SiC-dispersed alloys showed better mechanical properties, which can improve material machinability and device reliability.

Liu, Da-Wei; Li, Jing-Feng; Chen, Chen; Zhang, Bo-Ping

2011-05-01

43

Development of improved p-type silicon-germanium alloys  

NASA Technical Reports Server (NTRS)

Annealing experiments in the temperature range 1100-1275 C have been performed on p-type Si(0.8)Ge(0.2) samples with BP, B(6.5)P, and GaSb material additives. Both electrical resistivity and Seebeck coefficient generally decrease for these samples as annealing temperature is increased, with thermoelectric power factor sometimes being improved by annealing.

Mclane, George; Wood, Charles; Vandersande, Jan; Raag, Valvo; Heshmatpour, Ben

1987-01-01

44

Alloys  

NASA Astrophysics Data System (ADS)

The effects of mechanical deformation and subsequent annealing on the thermoelectric properties and microstructure have been investigated for p-type (Bi0.25Sb0.75)2Te3 alloys prepared by melting followed by quenching. The mechanically deformed pellets were prepared by repetition of cold-pressing of quenched samples at room temperature. Cold-pressed pellets were then annealed at 300C in vacuum, and the thermoelectric properties and microstructure were traced through the course of the heat treatment. For the heavily deformed samples, the Seebeck coefficient rapidly increased at the very early stage of annealing and did not change as the annealing time increased, due to recrystallization of a new ?-phase which equilibrated at the annealing temperature of 300C (?300-phase). At the initial stage of annealing (recovery stage), the electrical resistivity sharply increased, probably due to the interaction of antistructural defects with vacancies produced during the cold-pressing treatment. However, for the lightly deformed samples, recrystallization occurred only at some portion of the grain boundaries, and the newly generated ?300-phase slowly replaced the original, as-solidified ?ingot-phase.

Jung, Sung-Jin; Kim, Seong Keun; Park, Hyung-Ho; Hyun, Dow-Bin; Baek, Seung-Hyub; Kim, Jin-Sang

2014-06-01

45

Electrochemical kinetics of the high entropy alloys in aqueous environmentsa comparison with type 304 stainless steel  

Microsoft Academic Search

A high entropy alloy (HEA) is a multi-component alloy containing several major alloying elements, which has a high degree of atomic disorder that leads to various unique magnetic, mechanical, and electrochemical properties. It is known that one HEA, evaluated previously, is more resistant to general corrosion than type 304 stainless steel (304s), both in H2SO4 and in NaCl solutions at

Y. Y. Chen; U. T. Hong; H. C. Shih; J. W. Yeh; T. Duval

2005-01-01

46

Precipitation of an intermetallic phase with Pt2Mo-type structure in alloy 625  

NASA Astrophysics Data System (ADS)

The microstructure of Alloy 625, which has undergone prolonged (70,000 hours) service at temperatures close to but less than 600 C, has been characterized by transmission electron microscopy. The precipitation of an intermetallic phase Ni2(Cr, Mo) with Pt2Mo-type structure has been observed in addition to that of the ?? phase. Six variants of Ni2(Cr, Mo) precipitates have been found to occur in the austenite grains. These particles exhibit a snowflake-like morphology and are uniformly distributed in the matrix. They have been found to dissolve when the alloy is subjected to short heat treatments at 700 C. The occurrence of the Ni2(Cr, Mo) phase has been discussed by taking the alloy chemistry into consideration. Apart from the intermetallic phases, the precipitation of a M6C-type carbide phase within the matrix and the formation of near continuous films, comprising discrete M6C/M23C6 carbide particles, at the austenite grain boundaries have been noticed in the alloy after prolonged service.

Sundararaman, M.; Kumar, Lalit; Prasad, G. Eswara; Mukhopadhyay, P.; Banerjee, S.

1999-01-01

47

Structure and Properties of Type KhN 60 NBTYu (EP 487) Alloy (Stryaktyara i Svoistva Splava Marki KHN60 MVTYU (EP 487).  

National Technical Information Service (NTIS)

The development of a new weldable, heat resistant alloy (Type EP 487) with a nickel-chromium base is discussed. The alloy possess improved mechanical properties in comparison to the currently employed EP 202 alloy. The maximum hardening of the new alloy w...

B. A. Karbonov G. F. Kosheleva L. N. Zemina V. K. Tsvetkova

1970-01-01

48

Caustic stress corrosion cracking studies at 288 C (550 F) using the straining electrode technique--comparison of Alloy 600, Alloy 800, and Type 304 stainless steel  

Microsoft Academic Search

Constant pull rate tests were conducted on tensile specimens of Inconel Alloy 600, Incoloy Alloy 800, and Type 304 stainless steel in deaerated 10% NaOH solution at 288 C (550 F) with a cover gas of 5% H in N. The pull rate used for most experiments was 3.3 x 10⁻⁶ cm\\/s, which corresponds to an initial strain rate of

Cels

1978-01-01

49

Precipitation of an intermetallic phase with Pt 2 Mo-type structure in alloy 625  

Microsoft Academic Search

The microstructure of Alloy 625, which has undergone prolonged (?70,000 hours) service at temperatures close to but less than\\u000a 600 C, has been characterized by transmission electron microscopy. The precipitation of an intermetallic phase Ni2(Cr, Mo) with Pt2Mo-type structure has been observed in addition to that of the ?? phase. Six variants of Ni2(Cr, Mo) precipitates have been found to

M. Sundararaman; Lalit Kumar; G. Eswara Prasad; P. Mukhopadhyay; S. Banerjee

1999-01-01

50

Corrosion Potential Measurements on Type 304 SS and Alloy 182 in Simulated BWR Environments  

Microsoft Academic Search

The effects of dissolved oxygen, hydrogen, and hydrogen peroxide on the corrosion (electrochemical) potentials (ECPs) of type 304 SS and alloy 182 in simulated boiling water reactor (BWR) coolant environments under various water chemistry conditions at 288 C are reported. In oxygenated systems, the measured ECP fell within the range +20 to [minus]600 mV (vs SHE) depending on the O[sub

D. D. Macdonald; K. D. Makela; K. D. Yoshida; H. D. Song

1993-01-01

51

New type of decagonal quasicrystal with superlattice order in AlNiCo alloy  

Microsoft Academic Search

A new type of decagonal phase having superlattice order has been found in an AI70Ni15Co15 alloy by means of the electron diffraction technique. Most of the grains in the Al70Ni15Co15 sample heat treated at 600C for 216h exhibit superlattice order. In contrast, superlattice order has not been seen for the Al65Cu20Co15 decagonal phase. The relation between the structures with and

K. Edagawa; M. Ichihara; K. Suzuki; S. Takeuchi

1992-01-01

52

Creep behavior of the heusler type structure alloy Ni 2 AlTi  

Microsoft Academic Search

A specific method for improving the high temperature creep strength of ?-NiAl by a ternary addition giving rise to an additional\\u000a degree of order is examined. The ternary alloy thus formed has theA\\u000a 2BC or Heusler type structure, and the present study is devoted to the creep behavior of polycrystalline Ni2AlTi of stoichiometric composition. Possible slip modes are predicted on

P. R. Strutt; R. S. Polvani; J. C. Ingram

1976-01-01

53

Weldability in dissimilar welds between Type 310 austenitic stainless steel and Alloy 657  

Microsoft Academic Search

Microstructural evolution and solidification cracking susceptibility of dissimilar metal welds between Type 310 austenitic\\u000a stainless steel and Inconel 657, a nickel-based alloy, were studied using a combination of electron microscopy analysis and\\u000a Varestraint testing techniques. In addition, the effect of filler metal chemistry on the fusion zone composition, microstructure,\\u000a and resultant weldability was investigated. The good cracking resistance of welds

H. Naffakh; M. Shamanian; F. Ashrafizadeh

2008-01-01

54

Site preference of Mg acceptors and improvement of p-type doping efficiency in nitride alloys  

NASA Astrophysics Data System (ADS)

We perform first-principles density functional calculations to investigate the effect of Al and In on the formation energy and acceptor level of Mg in group-III nitride alloys. Our calculations reveal a tendency for the Mg dopants to prefer to occupy the lattice sites surrounded with Al atoms, whereas hole carriers are generated in In- or Ga-rich sites. The separation of the Mg dopants and hole carriers is energetically more favourable than a random distribution of dopants, being attributed to the local bonding effect of weak In and strong Al potentials in alloys. As a consequence, the Mg acceptor level, which represents the activation energy of Mg, tends to decrease with increasing numbers of Al next-nearest neighbours, whereas it increases as the number of In next-nearest neighbours increases. Based on the results, we suggest that the incorporation of higher Al and lower In compositions will improve the p-type doping efficiency in quaternary alloys, in comparison with GaN or AlGaN ternary alloys with similar band gaps.

Park, Ji-Sang; Chang, K. J.

2013-06-01

55

Alloy  

NASA Astrophysics Data System (ADS)

The Mg98.5Gd1Zn0.5 alloy produced by a powder metallurgy route was studied and compared with the same alloy produced by extrusion of ingots. Atomized powders were cold compacted and extruded at 623 K and 673 K (350 C and 400 C). The microstructure of extruded materials was characterized by ?-Mg grains, and Mg3Gd and 14H-LPSO particles located at grain boundaries. Grain size decreased from 6.8 ?m in the extruded ingot, down to 1.6 ?m for powders extruded at 623 K (350 C). Grain refinement resulted in an increase in mechanical properties at room and high temperatures. Moreover, at high temperatures the PM alloy showed superplasticity at high strain rates, with elongations to failure up to 700 pct.

Cabeza, Sandra; Garcs, Gerardo; Prez, Pablo; Adeva, Paloma

2014-07-01

56

Magnetic studies of Fe-doped martensitic Ni2Mn1.44Sn0.56-type Heusler alloy  

Microsoft Academic Search

Localization and magnetism of Fe replacing either Mn or Ni in the Ni2Mn1.44Sn0.56-type Heusler alloy have been systematically investigated using magnetization, scanning electron microscopy and Mssbauer spectroscopy. It has been shown that the addition of Fe either in Mn or in Ni sites reduces the fraction of the Mn-rich NiMnSn-type Heusler alloys that has short-range antiferromagnetic interactions; consequently it reduces

E. C. Passamani; C. Crdova; A. L. Alves; P. S. Moscon; C. Larica; A. Y. Takeuchi; A. Biondo

2009-01-01

57

Thermoelectric properties of the Heusler-type FeVTaAl alloys  

NASA Astrophysics Data System (ADS)

This study focuses on the thermoelectric properties of the Heusler-type Fe2VTaxAl1-x alloys (0?x?0.12). By means of Rietveld analyses on synchrotron X-ray diffraction patterns, it is shown that the Ta atoms enter sites occupied by V atoms in the stoichiometric Fe2VAl alloy, while the ejected V atoms are transferred to the vacant Al sites. This Ta substitution leads to an improvement of the n-type thermoelectric properties owing to two mechanisms. On the one hand, the atoms position in the structure leads to an off-stoichiometric effect such as already observed in V-rich Fe2V1+yAl1-y compounds: the Seebeck coefficient is increased towards negative absolute values and the electrical resistivity is decreased, with a large shift of their peak temperature towards higher temperature. The maximum power factor is 6.5 10-3 W/mK2 for x = 0.05 at 340 K. On the other hand, the heavy element Ta substitution combined with this off-stoichiometric effect leads to a large decrease of the thermal conductivity, owing to an increase of the scattering events. Consequently, the dimensionless figure of merit is seen to reach higher values than for the Fe2V1+yAl1-y alloys, i.e., 0.21-0.22 around 400-500 K for x = 0.05 and 500 K for x = 0.08.

Renard, Krystel; Mori, Arinori; Yamada, Yuichiro; Tanaka, Suguru; Miyazaki, Hidetoshi; Nishino, Yoichi

2014-01-01

58

Osteoblast cell behavior on the new beta-type Ti-25Ta-25Nb alloy.  

PubMed

Among metallic materials used as bone substitutes, ? titanium alloys gain an increasing importance because of their low modulus, high corrosion resistance and good biocompatibility. In this work, an investigation of the in vitro cytocompatibility of a recently new developed ?-type Ti-25Ta-25Nb alloy was carried out by evaluating the behavior of human osteoblasts. The metallic Ti-6Al-4V biomaterial, which is one of representative ?+? type titanium alloys for biomedical applications, and Tissue Culture Polystyrene (TCPS), were also investigated as reference Ti-based material and control substrate, respectively. Both metallic surfaces were analyzed by X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy. The cellular response was quantified by assessments of viability, cell attachment and spreading, cell morphology, production and extracellular organization of fibronectin and cell proliferation. Polished surfaces from both materials having an equiaxed grain microstructure and nanometre scale surface roughness elicited an essentially identical osteoblast response in terms of all analyzed cellular parameters. Thus, on both surfaces the cells displayed high survival rates, good cell adhesion and spreading, a dense and randomly dispersed fibronectin matrix and increasing cell proliferation rates over the incubation time. Furhermore, the enhanced biological performance of Ti-25Ta-25Nb was highly supported by the results obtained in comparison with TCPS. These findings, together with previously shown superelastic behavior, low Young's modulus and high corrosion resistance, recommend Ti-25Ta-25Nb as good candidate for applications in bone implantology. PMID:24364960

Cimpean, Anisoara; Mitran, Valentina; Ciofrangeanu, Cristina M; Galateanu, Bianca; Bertrand, Emmanuel; Gordin, Doina-Margareta; Iordachescu, Dana; Gloriant, Thierry

2012-08-01

59

Lattice dynamics of FePt alloys of AB 3 type ordered structure  

NASA Astrophysics Data System (ADS)

The lattice dynamics of FePt alloys with the Cu 3Au type crystal structure, FeP 3Pt and FePt 3 have been studied by inelastic neutron scatteing. The phonon dispersion curves along the [100], [110] and [111] directions have been observed over the whole Brillouin zone at room temperature. The observed phonon energies of acoustic modes of Fe 3Pt are almost the same as those of FePt 3 except the [110]TA 1 branch, although the average atomic mass is different by a factor of 1.8. The dispersion relations have been analyzed by the Born-von Krmn (BvK) force constant model where the first two neighbor forces were employed. It turns out that the nearest neighbor Fe-Fe force constant (1 xx) is unusually small in the ferromagnetic Fe 3Pt Invar alloy.

Noda, Y.; Endoh, Y.; Katano, S.; Iizumi, M.

1983-05-01

60

Improved Thermoelectric Properties of p-Type Bismuth Antimony-Based Alloys Prepared by Spark Plasma Sintering  

NASA Astrophysics Data System (ADS)

Bi85Sb15- x Pb x ( x = 0, 0.5, 1, 2, 3) alloys have been prepared by the mechanical alloying-spark plasma sintering (MA-SPS) method. X-ray diffraction and scanning electron microscopy were used to characterize the microstructure of the alloys. The effect of Pb content on the thermoelectric properties was investigated in the temperature range 77-300 K. The results showed that the electrical transport properties of the Bi-Sb alloys changed from n-type to p-type with substitution of Sb by Pb. The maximum power factor reached 1.6 10-3 W/mK2 at 190 K, a significant improvement on values reported elsewhere. This study demonstrated that high-performance p-type thermoelectric Bi-Sb materials can be obtained by spark plasma sintering.

Chen, Z.; Han, Y. M.; Zhou, M.; Song, C. M.; Huang, R. J.; Zhou, Y.; Li, L. F.

2014-04-01

61

Development of a beta-type Ti-12Mo-5Ta alloy for biomedical applications: cytocompatibility and metallurgical aspects.  

PubMed

Ti-based biocompatible alloys are especially used for replacing failed hard tissue. Some of the most actively investigated materials for medical implants are the beta-Ti alloys, as they have a low elastic modulus (to inhibit bone resorption). They are alloyed with elements such as Nb, Ta, Zr, Mo, and Fe. We have prepared a new beta-Ti alloy that combines Ti with the non-toxic elements Ta and Mo using a vacuum arc-melting furnace and then annealed at 950 degrees C for one hour. The alloy was finally quenched in water at room temperature. The Ti-12Mo-5Ta alloy was characterised by X-ray diffraction, optical microscopy, SEM and EDS and found to have a body-centred-cubic structure (beta-type). It had a lower Young's modulus (about 74 GPa) than the classical alpha/beta Ti-6Al-4V alloy (120 GPa), while its Vickers hardness remained very high (about 303 HV). This makes it a good compromise for a use as a bone substitute. The cytocompatibility of samples of Ti-12Mo-5Ta and Ti-6Al-4V titanium alloys with various surface roughnesses was assessed in vitro using organotypic cultures of bone tissue and quantitative analyses of cell migration, proliferation and adhesion. Mechanically polished surfaces were prepared to produce unorientated residual polished grooves and cells grew to a particularly high density on the smoother Ti-12Mo-5Ta surface tested. PMID:15477740

Gordin, D M; Gloriant, T; Texier, G; Thibon, I; Ansel, D; Duval, J L; Nagel, M D

2004-08-01

62

Effects of Fe Addition on the Snoek-Type Damping Behavior of Surface-Oxidation-Treated Ti-Mo Alloys  

NASA Astrophysics Data System (ADS)

Effects of Fe addition on the oxygen diffusion and the Snoek-type relaxation damping behavior of the Ti-15 wt pct Mo alloy were investigated in this study. After surface oxidation treatment, the Ti-15 wt pct Mo-1 wt pct Fe alloy exhibits a higher damping capacity compared to the Ti-15 wt pct Mo alloy. The dual-phase zone and the oxygen-enriched ?-phase zone in the surface-oxidation-treated Ti-Mo alloys were determined by electron backscattered diffraction (EBSD) and hardness measurements. Based on the oxygen distributions in both alloys obtained through a diffusion model, the relative damping capacity of different zones contributing to the beam sample damping was estimated to be proportional to the thickness of the oxygen dissolved zones. On the other hand, the substitutional solute of Fe in the Ti-Mo-Fe alloy is considered to affect the oxygen distribution by lengthening the oxygen diffusion zone and increasing the oxygen concentration in this zone. As a result, the addition of Fe in Ti-Mo alloy improves the damping capacity of the surface-oxidation-treated alloys.

Lu, Hui; Li, Chunxia; Yin, Fuxing; Fang, Qianfeng; Umezawa, Osamu

2011-08-01

63

Microstructures of type 316 model alloys neutron-irradiated at 513 K to 1 dpa  

NASA Astrophysics Data System (ADS)

Solution-annealed, high-purity type 316 stainless steel and its heats doped with C, Ti, Si, P and S alone or together were irradiated at 513 K to a dose level of 1 dpa in the Japan Research Reactor No. 3 at Japan Atomic Energy Research Institute. After irradiation, transmission electron microscopy was carried out. In all alloys, Frank loops were mainly developed. Addition of Mo decreased the number density and the average diameter of Frank loops. Addition of C made the density increase and the diameter decrease, while addition of Si made the density and the diameter decrease.

Miwa, Y.; Tsukada, T.; Tsuji, H.; Nakajima, H.

64

Effect of alloying elements and residuals on corrosion resistance of type 444 stainless steel  

SciTech Connect

The principal criteria for the corrosion resistance of intermediate-grade ferritic stainless steels (SS) were examined in a neutral chloride (Cl{sup {minus}}) solution. The effect of increasing quantities of chromium and molybdenum was estimated for several heats in terms of the breakdown potential (E{sub b}). The effect of inclusions (particularly the oxide-sulfide type) in type 444 SS ([UNS S44400] 19% Cr-2% Mo-Nb or 19% Cr-2% Mo alloy), combined with the alloying element trend, permitted derivation of an expression that integrated both phenomena. The expression represents the mutually opposing effects of the chromium/molybdenum passive film reinforcement as represented by the pitting resistance equivalent number (PREN), as well as incorporating the deleterious contribution of the inclusion density ({Psi}/mm{sup 2}). Aluminum reduced the total inclusion content, which was associated with an increase in E{sub b}. Since no aluminum was detected in the passive film of high aluminum steels, it appeared likely that the prime effect of this element on corrosion resistance was via inclusion suppression. Corrosion studies of welded type 444 SS demonstrated that dual stabilization with low individual concentrations of titanium and niobium provided optimum corrosion resistance. This apparent synergism of niobium and titanium was independent of the surface of the welded materials, which were examined in the as-received, pickled, or polished states. The effect of the surface state in all cases was shown to exercise a critical effect on passive behavior.

Dowling, N.J.E.; Kim, Y.H.; Ahn, S.K.; Lee, Y.D. [Pohang Iron and Steel Co., Kyung (Korea, Republic of). Stainless Steel Research Dept.

1999-02-01

65

Magnetic, structural and thermal properties of the Finemet-type powders prepared by mechanical alloying  

NASA Astrophysics Data System (ADS)

The mechanical alloying process has been used to prepare nanocrystalline Fe73.5Si13.5B9Nb3Cu1 powders in a high energy planetary ball-mill Retsch PM400/2. Morphological, microstructural, structural, thermal and magnetic characterizations of the powders milled several times were investigated by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and hysteresis meter. A mixture of Fe(Si)-type nanograins (14 nm), Fe2B boride phase (12 nm), and bcc substitutional Fe(B)-type solid solution is obtained after 150 h of milling. The coercivity and saturation magnetization values are about 62 Oe and 14 emu/g, respectively. Several magnetic transition temperatures are revealed in the DSC scans of the ball-milled powders in the temperature ranges 500-560 C and 599-606 C, related to the Fe(B) and Fe(Si)-type phases, respectively.

Alleg, S.; Kartout, S.; Ibrir, M.; Azzaza, S.; Fenineche, N. E.; Suol, J. J.

2013-04-01

66

High-temperature ductility of nickel alloys type KhN55MBYu with a high iron content  

Microsoft Academic Search

In order to prepare stamped and welded structures which operate in the temperature range from 750 to -253C there is use of high-strength dispersion-hardening nickel alloys KhN55MBYu (P666) and KhN58MBYuD (K61) which exhibit resistance to hot crack formation during welding and cracking of welded joints during defonnation. Alloys of this type have a high level of strength (sf = 1300

N. A. Sorokina; V. I. Gal'tsova

1994-01-01

67

A Cu-based alloyed Ohmic contact system on n-type GaAs  

SciTech Connect

An alloyed Pd/Ge/Cu Ohmic contact to n-type GaAs is reported for the first time. The Pd/Ge/Cu Ohmic contact exhibited a very low specific contact resistance of 5.73x10{sup -7} {omega} cm{sup 2} at a low annealing temperature of 250 deg. C. This result is comparable to the reported Pd/Ge and Au/Ge/Ni Ohmic contact systems to n-type GaAs with doping concentrations about 1x10{sup 18} cm{sup -3}. The Ohmic contact formation mechanisms and microstructure evolution were investigated using secondary ion mass spectrometry, x-ray diffraction, transmission electron microscopy, and energy dispersive spectrometer. The Ohmic contact behavior was related to the formation of Cu{sub 3}Ge and PdGa{sub x}As{sub y} compounds after annealing.

Chen, K.-S.; Chang, Edward Yi; Lin, C.-C.; Lee, C.-S.; Huang, W.-C.; Lee, C.-T. [Department of Materials Science and Engineering, National Chiao-Tung University, Hsinchu 30050, Taiwan (China); Institute of Microelectronics, National Cheng-Kung University, Tainan 70101, Taiwan (China)

2007-12-03

68

Elasto-Plasticity Behavior of Type 5000 and 6000 Aluminum Alloy Sheets and Its Constitutive Modeling  

SciTech Connect

To examine the deformation characteristic of type 5000 and 6000 aluminum alloy sheets, uniaxial tension, biaxial stretching and in-plane cyclic tension-compression experiments were performed, and from these, r-values (r{sub 0}, r{sub 45} and r{sub 90}), yield loci and cyclic stress-strain responses were obtained. For the accurate description of anisotropies of the materials, high-ordered anisotropic yield functions, such as Gotoh's biquadratic yield function and Barlat's Yld2000-2d, are necessary. Furthermore, for the simulation of cyclic behavior, an advanced kinematic hardening model, such as Yoshida-Uemori model (Y-U model), should be employed. The effect of the selection of material models on the accuracy of the springback prediction was discussed by performing hat bending FE simulation using several yield functions and two types of hardening laws (the isotropic hardening model and Y-U model).

Tamura, Shohei; Sumikawa, Satoshi; Hamasaki, Hiroshi; Yoshida, Fusahito [Department of Mechanical System Engineering, Faculty of Engineering, Hiroshima University, 1-4-1, Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8527 (Japan); Uemori, Takeshi [Faculty of Engineering, Kinki University, 1-Umenobe, Takaya, Higashi-Hiroshima, Hiroshima, 739-2116 (Japan)

2010-06-15

69

Thermal Expansion of NANOPERM-type Alloys from In-situ X-ray Diffraction  

SciTech Connect

NANOPERM-type alloys with nominal compositions of (Fe{sub 1-x}Co{sub x}){sub 76}Mo{sub 8}Cu{sub 1}B{sub 15}(x = 0 and 0.5) were prepared by a single-roller melt-spinning technique. Temperature evolution of the as-quenched ribbons during constant-rate heating (10 degree sign C/min) was continuously followed using a high-energy (88 keV) X-ray diffraction (XRD), performed on the ID11 undulator beamline at the ESRF (Grenoble, France). Moessbauer spectroscopy and XRD confirm an amorphous nature of the melt-spun ribbons. Furthermore, Moessbauer spectroscopy reveals a significant change of magnetic state of the as-quenched precursors when substituting Fe by Co (x 0.5). Analyzing a series of XRD patterns in a reciprocal space yields a thermal expansion of the amorphous alloys providing an insight about the thermally activated effects such as relaxation and crystallization.

Bednarcik, J.; Franz, H. [Deutsches Elektronen Synchrotron, Notkestr. 85, D-22603, Hamburg (Germany); Miglierini, M. [Slovak University of Technology, Ilkovicova 3, 81219 Bratislava (Slovakia); Centre for Nanomaterial Reserach, Palacky University, Svobody 26, 771 46 Olomouc (Czech Republic); Curfs, C. [European Synchrotron Radiation Facility ESRF, BP 220, 38043 Grenoble (France)

2010-07-13

70

High Cycle Fatigue of (Fe, Ni, Co)3V type alloys  

Microsoft Academic Search

High cycle fatigue tests in vacuum have been performed on ordered (Fe, Co, Ni)3V alloys between 25 C and 850 C. Heat-to-heat variations in fatigue properties of a Co-16.5 wtpct Fe-25 pct alloy, LRO-1, appeared to be due to differing quantities of grain boundary precipitates. Modification of this alloy with 0.4 pct Ti, to produce an alloy designated LRO-23, reduced

S. Ashok; K. Kain; J. M. Tartaglia; N. S. Stoloff

1983-01-01

71

High Cycle Fatigue of (Fe, Ni, Co) 3 V type alloys  

Microsoft Academic Search

High cycle fatigue tests in vacuum have been performed on ordered (Fe, Co, Ni)3V alloys between 25 C and 850 C. Heat-to-heat variations in fatigue properties of a Co-16.5 wtpct Fe-25 pct alloy, LRO-1,\\u000a appeared to be due to differing quantities of grain boundary precipitates. Modification of this alloy with 0.4 pct Ti, to\\u000a produce an alloy designated LRO-23, reduced

S. Ashok; K. Kain; J. M. Tartaglia; N. S. Stoloff

1983-01-01

72

Some Factors Affecting the Metallurgical Microstructure and Creep Properties of the Titanium 3 al 6 SN 5 Zr 0.5 Si Type of Alloy.  

National Technical Information Service (NTIS)

Optical and electron metallographic techniques have been used to study the microstructure of Titanium 3Al 6Sn 5Zr 0.5 Si type alloy (Hylite 55) and Titanium 3Al 6Sn 5Zr 2 Mo 0.5 Si type alloy (Hylite 60) containing 0.005 wt %, 0.42 wt % and 0.75 wt % Si a...

C. R. Mayo M. A. P. Dewey P. A. Dow W. K. Armitage

1966-01-01

73

ROLL CLADDING URANIUM-ZIRCONIUM AND URANIUM-ZIRCONIUM-NIOBIUM ALLOYS WITH ZIRCALOY2 FOR PLATE-TYPE FUEL ELEMENTS  

Microsoft Academic Search

Clad plate-type fuel elements containing U--5 wt.% Zr--1.5 wt.% Nb alloy ; cores integrally clad on all surfaces with Zircaloy-2 were developed for the ; Experimental Boiling Water Reactor (EBWR). These plates were prepared by roll ; bonding assembled components inside steel jackets at 850 deg C with 50% reduction ; in thickness to effect sound diffusion bonds at all

C. H. Bean; R. E. Macherey; J. R. Lindgren

1958-01-01

74

Dot arrays of L11 type Co-Pt ordered alloy perpendicular films  

NASA Astrophysics Data System (ADS)

Magnetic properties of dot arrays of L11 type Co-Pt ordered alloy perpendicular films were studied. L11-Co-Pt films with a large uniaxial magnetic anisotropy Ku of the order of 107 erg/cm3 were fabricated at a substrate temperature of 360 C using ultrahigh vacuum sputter film deposition. Dot patterns with dot diameters of 70-200 nm were made using high resolution e-beam lithography and reactive ion etching (RIE). The values of Ku were measured by the GST method using the Anomalous Hall Effect; we observed the averaged signals of 6000 dots. The values of Ku for dot arrays of 10-nm-thick L11-Co50Pt50 films deposited on MgO(111) substrates (single crystal films) and glass disks (polycrystalline films) were nearly the same as those of the original films independent of D, indicating no significant etching damage by the RIE process. Magnetic force microscopy images revealed that all dots were single domains in the present D region. The coercivity Hc of the dot arrays was 25.0 kOe [MgO(111) substrate, D=70 nm] and 14.3 kOe (glass disks, D=80 nm). The switching field distribution ?/Hc was relatively small, ?/Hc=0.15, even for dot arrays fabricated on glass disks, indicating the homogeneous formation of a L11 type ordered structure in the Co50Pt50 layers.

Shimatsu, T.; Sato, H.; Mitsuzuka, K.; Kataoka, H.; Aoi, H.; Okamoto, S.; Kitakami, O.

2009-04-01

75

Use of titanium alloy swarf for the production of TK type hard metals  

SciTech Connect

Titanium alloy swarf has considerable potential as a raw material for the production of powders of titanium and its refractory compounds. This paper employs a trial batch (200 kg) of titanium carbide of nonstoichiometric composition made under industrial conditions for the production of TK grade hard metals. The compositions of VT-3-1 titanium alloy swarf and of titanium carbide, complex carbide and T5K10 alloy produced from it are presented. The results of metallographic analyses of the experimental batches of T5K10 alloy specimens are shown.

Kiparison, S.S.; Deulina, I.P.; Levinskii, Yu. V.; Petrov, A.P.

1986-02-01

76

Precipitation of an intermetallic phase with Pt{sub 2}Mo-type structure in alloy 625  

SciTech Connect

The microstructure of Alloy 625, which has undergone prolonged ({approximately}70,000 hours) service at temperatures close to but less than 600 C, has been characterized by transmission electron microscopy. The precipitation of an intermetallic phase Ni{sub 2}(Cr, Mo) with Pt{sub 2}Mo-type structure has been observed in addition to that of the {gamma}{double_prime} phase. Six variants of Ni{sub 2} (Cr, Mo) precipitates have been found to occur in the austenite grains. These particles exhibit a snowflake-like morphology and are uniformly distributed in the matrix. They have been found to dissolve when the alloy is subjected to short heat treatments at 700 C. The occurrence of the Ni{sub 2}(Cr, Mo) phase has been discussed by taking the alloy chemistry into consideration. Apart from the intermetallic phases, the precipitation of a M{sub 6}C-type carbide phase within the matrix and the formation of near continuous films, comprising discrete M{sub 6}C/M{sub 23}C{sub 6} carbide particles, at the austenite grain boundaries have been noticed in the alloy after prolonged service.

Sundararaman, M.; Kumar, L.; Prasad, G.E.; Mukhopadhyay, P.; Banerjee, S. [Bhabha Atomic Research Centre, Mumbai (India). Materials Science Div.

1999-01-01

77

Microstructure and thermal expansion properties of invar-type Cu-Zn-Al shape memory alloys  

NASA Astrophysics Data System (ADS)

The effects of grain size, volume fraction of the ? (fcc) phase in the ? (bcc) matrix, and thermal stability on low thermal expansion (LTE) properties of Cu-Zn-Al shape memory (SM) alloys induced by cold rolling were investigated by dilatometry, optical microscopy, differential scanning calorimetry, and electrical conductivity measurements. The alloys with the larger grains showed a superior two-way memory (TWM) effect, wider LTE temperature intervals with excellent thermal stability under 80C. The ?+? two-phase alloys also exhibited a good combination of cold workability and LTE properties. These results suggest that the Cu-Zn-Al alloys with high electrical conductivity of about 20% International Annealed Copper Standard (%IACS) have high potential as a new class of Invar alloys that can be applied in various fields.

Wang, J. J.; Omori, T.; Sutou, Y.; Kainuma, R.; Ishida, K.

2004-10-01

78

Influence of substrate metal alloy type on the properties of hydroxyapatite coatings deposited using a novel ambient temperature deposition technique.  

PubMed

Hydroxyapatite (HA) coatings are applied widely to enhance the level of osteointegration onto orthopedic implants. Atmospheric plasma spray (APS) is typically used for the deposition of these coatings; however, HA crystalline changes regularly occur during this high-thermal process. This article reports on the evaluation of a novel low-temperature (<47C) HA deposition technique, called CoBlast, for the application of crystalline HA coatings. To-date, reports on the CoBlast technique have been limited to titanium alloy substrates. This study addresses the suitability of the CoBlast technique for the deposition of HA coatings on a number of alternative metal alloys utilized in the fabrication of orthopedic devices. In addition to titanium grade 5, both cobalt chromium and stainless steel 316 were investigated. In this study, HA coatings were deposited using both the CoBlast and the plasma sprayed techniques, and the resultant HA coating and substrate properties were evaluated and compared. The CoBlast-deposited HA coatings were found to present similar surface morphologies, interfacial properties, and composition irrespective of the substrate alloy type. Coating thickness however displayed some variation with the substrate alloy, ranging from 2.0 to 3.0??m. This perhaps is associated with the electronegativity of the metal alloys. The APS-treated samples exhibited evidence of both coating, and significantly, substrate phase alterations for two metal alloys; titanium grade 5 and cobalt chrome. Conversely, the CoBlast-processed samples exhibited no phase changes in the substrates after depositions. The APS alterations were attributed to the brief, but high-intensity temperatures experienced during processing. PMID:23589437

Barry, J N; Cowley, A; McNally, P J; Dowling, D P

2014-03-01

79

Dot arrays of L1{sub 1} type Co-Pt ordered alloy perpendicular films  

SciTech Connect

Magnetic properties of dot arrays of L1{sub 1} type Co-Pt ordered alloy perpendicular films were studied. L1{sub 1}-Co-Pt films with a large uniaxial magnetic anisotropy K{sub u} of the order of 10{sup 7} erg/cm{sup 3} were fabricated at a substrate temperature of 360 deg. C using ultrahigh vacuum sputter film deposition. Dot patterns with dot diameters of 70-200 nm were made using high resolution e-beam lithography and reactive ion etching (RIE). The values of K{sub u} were measured by the GST method using the Anomalous Hall Effect; we observed the averaged signals of 6000 dots. The values of K{sub u} for dot arrays of 10-nm-thick L1{sub 1}-Co{sub 50}Pt{sub 50} films deposited on MgO(111) substrates (single crystal films) and glass disks (polycrystalline films) were nearly the same as those of the original films independent of D, indicating no significant etching damage by the RIE process. Magnetic force microscopy images revealed that all dots were single domains in the present D region. The coercivity H{sub c} of the dot arrays was 25.0 kOe [MgO(111) substrate, D=70 nm] and 14.3 kOe (glass disks, D=80 nm). The switching field distribution {sigma}/H{sub c} was relatively small, {sigma}/H{sub c}=0.15, even for dot arrays fabricated on glass disks, indicating the homogeneous formation of a L1{sub 1} type ordered structure in the Co{sub 50}Pt{sub 50} layers.

Shimatsu, T.; Mitsuzuka, K.; Aoi, H. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Sato, H. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Institute of Multidisciplinary Research for Advanced Material, Tohoku University, Sendai 980-8577 (Japan); Kataoka, H. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Fuji Electric Device Technology, Co., Ltd., Matsumoto 390-0821 (Japan); Okamoto, S.; Kitakami, O. [Institute of Multidisciplinary Research for Advanced Material, Tohoku University, Sendai 980-8577 (Japan)

2009-04-01

80

Low-Cycle Fatigue of Type 347 Stainless Steel and Hastelloy Alloy X in Hydrogen Gas and in Air at Elevated Temperatures.  

National Technical Information Service (NTIS)

An investigation was conducted to assess the low-cycle fatigue resistance of two alloys, Type 347 stainless steel and Hastelloy Alloy X, that were under consideration for use in nuclear-powered rocket vehicles. Constant-amplitude, strain-controlled fatigu...

C. E. Jaske R. C. Rice R. D. Buchheit D. B. Roach T. L. Porfilio

1976-01-01

81

Two different types of age-hardening behaviors in commercial dental gold alloys.  

PubMed

Age-hardening behavior during continuous heating in commercial dental casting gold alloys was investigated by means of electrical resistivity measurements, hardness tests and X-ray diffraction. Two distinguishable behaviors were detected. It is considered that the difference was attributed to the amount of platinum, and the atomic ratio of gold and copper in each alloy. The phase transformations during continuous heating progressed into two steps (stages I and II). Increase of the platinum addition in gold-based alloys retards the rate of the reaction and decreases remarkably the amount of stage I. PMID:17546416

Hisatsune, Kunihiro; Shiraishi, Takanobu; Takuma, Yasuko; Tanaka, Yasuhiro; Luciano, Rhodora H

2007-04-01

82

Method of fabricating n-type and p-type microcrystalline semiconductor alloy material including band gap widening elements  

DOEpatents

A method of fabricating doped microcrystalline semiconductor alloy material which includes a band gap widening element through a glow discharge deposition process by subjecting a precursor mixture which includes a diluent gas to an a.c. glow discharge in the absence of a magnetic field of sufficient strength to induce electron cyclotron resonance.

Guha, Subhendu (Troy, MI) [Troy, MI; Ovshinsky, Stanford R. (Bloomfield Hills, MI) [Bloomfield Hills, MI

1990-02-02

83

Effect of processing parameters on the earing and mechanical properties of strip cast type 3004 Al alloy  

Microsoft Academic Search

Electrical resistivity, superficial hardness, tensile testing, and quantitative metallography techniques were used in this\\u000a study. The strip cast type 3004 aluminum alloy received sixteen different thermomechanical treatments before cups were drawn.\\u000a The top edges of the drawn cups were not flat. Rather, there were high points or ears with valleys between them. The homogenization\\u000a temperature varied from 510 to 621

O. S. Es-Said; A. Zeihen; M. Ruprich; J. Quattrocchi; M. Thomas; K. H. Shin; M. OBrien; D. Johansen; W. H. Tijoe; D. Ruhl

1994-01-01

84

Effect of processing parameters on the earing and mechanical properties of strip cast type 3004 Al alloy  

Microsoft Academic Search

Electrical resistivity, superficial hardness, tensile testing, and quantitative metallography techniques were used in this\\u000a study. The strip cast type 3004 aluminum alloy received sixteen different thermomechanical treatments before cups were drawn.\\u000a The top edges of the drawn cups were not flat. Rather there were high points or ears with valleys between them. The homogenization\\u000a temperature varied form 510 to 621

O. S. Es-Said; A. Zeihen; M. Ruprich; J. Quattrocchi; M. Thomas; K. H. Shin; M. OBrien; D. Johansen; W. H. Tijoe; D. Ruhl

1995-01-01

85

Magnetic properties and temperature stability of a molybdenum-doped finemet-type alloy  

NASA Astrophysics Data System (ADS)

The influence of nanocrystallization conditions on the structure, magnetic properties, and temperature stability of nanocrystalline magnetically soft Fe73.5Cu1Nb1.5Mo1.5Si13.5B9 alloy is studied. It is found that preliminary low-temperature annealing exerts an influence on subsequent nanocrystallization of the alloy. In addition, preannealing followed by nanocrystallization considerably improves the magnetic properties of the alloy. It is shown that the magnetic properties of the material can be controlled by varying the frequency of a magnetic field used for thermal treatment causing nanocrystallization. It is established that the magnetic properties of nanocrystalline Fe73.5Cu1Nb1.5Mo1.5Si13.5B9 alloy offer a high temperature stability.

Filippov, B. N.; Shulika, V. V.; Potapov, A. P.; Vil'danova, N. F.

2014-03-01

86

Microstructure and thermal expansion properties of invar-type Cu-Zn-Al shape memory alloys  

Microsoft Academic Search

The effects of grain size, volume fraction of the ? (fcc) phase in the ? (bcc) matrix, and thermal stability on low thermal\\u000a expansion (LTE) properties of Cu-Zn-Al shape memory (SM) alloys induced by cold rolling were investigated by dilatometry,\\u000a optical microscopy, differential scanning calorimetry, and electrical conductivity measurements. The alloys with the larger\\u000a grains showed a superior two-way memory

J. J. Wang; T. Omori; Y. Sutou; R. Kainuma; K. Ishida

2004-01-01

87

Effect of alloy type and surface conditioning on roughness and bond strength of metal brackets  

Microsoft Academic Search

The effect of 5 different surface conditioning methods on bonding of metal brackets to cast dental alloys was examined. The surface conditioning methods were fine (30-m) or rough (125-m) diamond bur, sandblasting (50-m or 110-m aluminum oxide (Al2O3)), and silica coating (30-m silica). Fifty disc-shaped specimens of 5 different alloys (gold-silver, palladium-silver, nickel-chromium, cobalt- chromium, and titanium) were ground with

Ibrahim Nergiz; Mutlu Ozcan

88

Effect of alloy type and surface conditioning on roughness and bond strength of metal brackets  

Microsoft Academic Search

The effect of 5 different surface conditioning methods on bonding of metal brackets to cast dental alloys was examined. The surface conditioning methods were fine (30-?m) or rough (125-?m) diamond bur, sandblasting (50-?m or 110-?m aluminum oxide [Al2O3]), and silica coating (30-?m silica). Fifty disc-shaped specimens of 5 different alloys (gold-silver, palladium-silver, nickel-chromium, cobalt-chromium, and titanium) were ground with 1200-grit

Ibrahim Nergiz; Petra Schmage; Wolfram Herrmann; Mutlu zcan

2004-01-01

89

Determination of damage functions for the pitting of AISI type 403 blade alloy and ASTM A470/471 disk alloy  

NASA Astrophysics Data System (ADS)

The prediction of pitting accumulation on turbine blades and disks is of particular importance to predict localized corrosion damages in low pressure (LP) steam turbines. Damage Function Analysis (DFA) and Deterministic Extreme Value Statistics (DEVS) have been employed to predict the pitting damage on AISI Type 403 stainless steel (SS) blade alloy and ASTM A470/471 disk steel in simulated LP steam turbine environments within the phase transition zone. The passivity properties of Type 403 SS and A470/471 steel in the passive regions, including defect type, defect concentration in the barrier film, barrier film thickness, and the steady-state current density, agree with the predictions of the Point Defect Model (PDM) for an n-type semiconductor. Optimization of the PDM based impedance model on the experimental electrochemical impedance data has yielded a set of parameter values that can be used to predict the barrier film growth on Type 403 SS in deaerated borate buffer solution ( pH = 8.2) at ambient temperature. Experimental relationships between the breakdown potential and chloride activity, pH, temperature, and potential scan rate have demonstrated the applicability of the PDM for describing passivity breakdown on Type 403 SS and A470/471 steel. The obtained parameter values were used to calculate the breakdown potential, induction time, and their distributions, via the PDM, which represents the first quantitative characterization of the passivity breakdown behavior on Type 403 SS. Pitting damage functions for Type 403 SS have been experimentally determined for the first time. However, low pit density on A470/471 steel led to insufficient pit numbers on the 1.27 cm2 surface for the effective determination of damage functions. DEVS has been demonstrated by predicting the average maximum pit depth for 750 hours from short-term (24 hours and 240 hours) maximum pit depth data on Type 403 SS in deaerated buffer solution with 0.10 M NaCl at an applied potential of 0.090 VSCE and on A470/471 steel in the solution with 0.028 M NaCl at 0.058 VSCE. To the author's knowledge, the work reported in this dissertation represents the first instance in which DEVS has been used to predict the accumulation of pitting damage on LP steam turbine alloys, thereby heralding a new era in the prediction of corrosion damage in these systems.

Zhang, Yancheng

90

Corrosion of Stainless Steel Type 304 Alloyed with Boron or Gadolinium by Plant Process Solutions Containing Hno sub 3 and HF.  

National Technical Information Service (NTIS)

The co-processing of aluminum and zirconium clad fuel elements, for the recovery of exp 235 U, utilizes highly corrosive solutions containing both nitrates and fluorides. These solutions may contact Type 304 stainless steel alloyed with boron or gadoliniu...

H. S. Cole

1976-01-01

91

Formation Mechanism of Spinel-Type Inclusions in High-Alloyed Stainless Steel Melts  

NASA Astrophysics Data System (ADS)

Fundamental thermodynamics of the relationship between high-alloyed stainless steel melts (Fe-20 mass pct Cr-13 mass pct Ni-3 mass pct Si) and the inclusions were investigated. The formation mechanism of the inclusions containing the spinel crystals was developed based on the experimental results and from the compositions of the inclusions in the steel samples taken during plant operations. The molar content of alumina in the inclusions was found to be linearly proportional to the increase of aluminum content, indicating that the inclusions could contain alumina even with less than about 200 ppm aluminum in the steel melt, e.g., steel melts that were mainly deoxidized by silicon. Furthermore, the composition of the inclusions is shown to be a function of the activity of the deoxidizers such as aluminum and silicon in the steel melt. From the analysis of the plant samples, it was found that the contents of MgO and Al2O3 in the calcium silicate type inclusions increased continuously as the steel melt transfers from the argon oxygen decarburization (AOD) converter to the tundish. This composition change in the inclusions originated from the reduction of MgO and Al2O3 in the slags or refractories by silicon in the steel melt. Increases of MgO and Al2O3 contents were prominent in tundish samples, and thus, the spinel phase could be crystallized in the calcium silicate inclusion matrix in the tundish; and finally the spinel crystals grew during cooling of the steel melt through the continuous casting (CC) mold and in the slabs. On the other hand, manganese silicate type inclusions containing chromium oxide were observed after tapping of the molten steel to the ladle. The MnO and Cr2O3 in these inclusions was initially reduced by silicon in the steel melt in the ladle treatment (LT) process, followed by further reduction by aluminum through the LT to the CC mold. The fractions of inclusions containing spinel crystals in cast slabs were negligible at the alumina content of less than about 20 mass pct, while they critically increased at alumina contents greater than about 20 mass pct.

Park, Joo Hyun

2007-08-01

92

Antiferromagnetic half-metals, gapless half-metals, and spin gapless semiconductors: The D0{sub 3}-type Heusler alloys  

SciTech Connect

High-spin-polarization materials are desired for the realization of high-performance spintronic devices. We combine recent experimental and theoretical findings to theoretically design several high-spin-polarization materials in binary D0{sub 3}-type Heusler alloys: gapless (zero-gap) half-metallic ferrimagnets of V{sub 3}Si and V{sub 3}Ge, half-metallic antiferromagnets of Mn{sub 3}Al and Mn{sub 3}Ga, half-metallic ferrimagnets of Mn{sub 3}Si and Mn{sub 3}Ge, and a spin gapless semiconductor of Cr{sub 3}Al. The high spin polarization, zero net magnetic moment, zero energy gap, and slight disorder compared to the ternary and quaternary Heusler alloys make these binary materials promising candidates for spintronic applications. All results are obtained by the electronic structure calculations from first-principles.

Gao, G. Y., E-mail: guoying-gao@mail.hust.edu.cn; Yao, Kai-Lun, E-mail: klyao@mail.hust.edu.cn [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)] [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

2013-12-02

93

Antiferromagnetic half-metals, gapless half-metals, and spin gapless semiconductors: The D03-type Heusler alloys  

NASA Astrophysics Data System (ADS)

High-spin-polarization materials are desired for the realization of high-performance spintronic devices. We combine recent experimental and theoretical findings to theoretically design several high-spin-polarization materials in binary D03-type Heusler alloys: gapless (zero-gap) half-metallic ferrimagnets of V3Si and V3Ge, half-metallic antiferromagnets of Mn3Al and Mn3Ga, half-metallic ferrimagnets of Mn3Si and Mn3Ge, and a spin gapless semiconductor of Cr3Al. The high spin polarization, zero net magnetic moment, zero energy gap, and slight disorder compared to the ternary and quaternary Heusler alloys make these binary materials promising candidates for spintronic applications. All results are obtained by the electronic structure calculations from first-principles.

Gao, G. Y.; Yao, Kai-Lun

2013-12-01

94

Metastable ?-type Ti-30Nb-1Mo-4Sn Alloy with Ultralow Young's Modulus and High Strength  

NASA Astrophysics Data System (ADS)

The effect of thermo-mechanical treatment on the mechanical properties of a novel metastable ?-type Ti-30Nb-1Mo-4Sn (wt pct) alloy has been investigated. The solution-treated alloy consists of ? and ?? phases and exhibits a two-stage yielding with a low yield stress (around 100 MPa). After cold rolling at a reduction of 87.5 pct and subsequent annealing treat at 623 K (350 C) for 30 minutes, a fine microstructure with nano-sized ? precipitates distributed in small ? grains as well as high density of dislocations was obtained to achieve a yield strength of 954 MPa and an ultimate tensile strength of 999 MPa. With low stability of ? phase and small volume fraction of ? precipitates, the annealed specimen exhibits a low Young's modulus of 45 GPa. Such an excellent combination of the low elastic modulus and high strength in mechanical properties indicates a great potential candidate for biomedical applications.

Hu, Liang; Guo, Shun; Meng, Qingkun; Zhao, Xinqing

2014-02-01

95

Age Hardening Kinetics in 7xxx Type (Al-Mg-Zn) Alloys  

SciTech Connect

Age hardening in industrial 7xxx alloys at the temperature 100 deg. and 150 deg. C up to 144 hrs, after solid solution treatments at 450 deg. and 550 deg. C, has been followed by measurements of Vickers hardness, scanning and transmission electron microscopy. The influence of silicon on phase and kinetic of age hardening zones and precipitates has been studied. High iron and silicon content increase the number of primary particle in the alloy. Size distribution of {eta}'-precipitates has been determined.

Vevecka-Priftaj, A. [Department of Physic, Polytechnic University of Tirana, Sheshi 'Nene Tereza', N.4, Tirana (Albania); Lamani, E. [Department of Production and Menagement, Polytechnic University of Tirana (Albania); Fjerdingen, J. [Vitec AS, Akervegen2, 7650 Verdal (Norway); Langsrud, Y. [Hydro Aluminum Structures, Raufoss, P.O.Box 15, N-2831 Raufoss (Norway); Gjoennes, J. [Center for Materials Science, University of Oslo, Gaustadalleen 21, N-0349, Oslo (Norway); Hansen, V. [Faculty of Science and Technology, University of Stavanger, N-403, Stavanger (Norway)

2007-04-23

96

Thermal expansion match between molybdenum (TZM alloy) and oxides of the perovskite and spinel type  

Microsoft Academic Search

Thermal expansion measurements to 1200°C have been made by the Bureau of Mines of a wide selection of complex oxides of both the perovskite and spinel structures. These are compared with the thermal expansion of molybdenum and the molybdenum alloy TZM to find suitable expansion matches for oxide coating development. A dilatometric technique was employed which makes use of a

J. L. Henry; G. G. Thompson

1976-01-01

97

Surface modification of ?-Type titanium alloy by electrochemical potential pulse polarization  

NASA Astrophysics Data System (ADS)

In the present work, we report the formation of a porous oxide/hydroxide surface layer on the Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy achieved by the combination of an alkali immersion and a potential pulse polarisation process. The alkali treatment has been employed for pure titanium to produce amorphous and porous layer prior to hydroxyapatite (HAp) growth. But, in the case of TNTZ, immersion in 5M NaOH at the open circuit potential (OCP) at 60C for 24 hours, did not yield any uniform layer, instead a thick deposited layer with highly cracked one. The cracks were attributed to the growth of a tantalum enriched particulate. In order to avoid the crack formation, the electrochemical behaviour of the alloy and the pure alloying elements (Ti, Nb, Ta and Zr) was investigated to produce a uniform surface with the application of a square wave modulated potential pulse polarization, leading to the formation of a relatively uniform porous layer on the alloy.

Fujimoto, Shinji; Raman, Vedarajan; Tsuchiya, Hiroaki

2009-05-01

98

Mechanical properties of modified low cobalt powder metallurgy Udimet 700 type alloys  

NASA Technical Reports Server (NTRS)

Eight superalloys derived from Udimet 700 were prepared by powder metallurgy, hot isostatically pressed, heat treated and their tensile and creep rupture properties determined. Several of these alloys displayed properties superior to those of Udimet 700 similarly prepared, in one case exceeding the creep rupture life tenfold. Filter clogging by extracted gamma prime, its measurement and significance are discussed in an appendix.

Harf, Fredric H.

1989-01-01

99

The response of cobalt-free Udimet 700 type alloy to modified heat treatments  

Microsoft Academic Search

A superalloy based on Udimet 700, in which all of the cobalt had been replaced by nickel, was prepared from hot isostatically pressed pre-alloyed powders. This material was given various heat treatments consisting of partial solutioning and ageing in a sequence of four different temperatures. Comparisons were made of microstructures and mechanical properties. Best results were obtained by partially solutioning

Fredric H. Harf

1986-01-01

100

Interaction of a near-{alpha} type titanium alloy with NiCrAlY protective coating at high temperatures  

SciTech Connect

MCrAlY coatings possess the properties of not only excellent oxidation and hot corrosion resistance but also sufficient toughness. This is why they have been commercially used on superalloys for several decades. Nevertheless, investigations revealed that there might be violent interactions between this kind of coating and titanium based alloys at high temperatures. This chemical incompatibility may promote the growth of brittle phases along the substrate/coating interface and thus deteriorates the mechanical properties. An effective barrier layer was desired to be sandwiched between the MCrAlY coating and Ti substrate to weaken the interdiffusion and chemical reactions. Ti60 is a near {alpha} type alloy intended to be used at 600 C. The interaction between this alloy and a NiCrAlY coating has never been investigated. Actually, in addition to the service at high temperature, another high temperature process, i.e., the post heat treatment in vacuum, is generally needed for the MCrAlY coating to eliminate possible defects within the received PVD coatings. Hence, the investigation on the interfacial stability of a Ti60/MCrAlY system at high temperatures is of importance in both theoretical and practical meanings. This paper is aimed at observing the interfacial reactions of this system at various temperatures in excess of 600 C. The obtained data may be useful in further work on optimizing the post treatment parameters and developing new coating systems with barrier interlayer.

Liu, H.; Hao, S.; Wang, X.; Feng, Z.

1998-10-13

101

Surface modification of beta-Type titanium alloy by electrochemical potential pulse polarization  

Microsoft Academic Search

In the present work, we report the formation of a porous oxide\\/hydroxide surface layer on the Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy achieved by the combination of an alkali immersion and a potential pulse polarisation process. The alkali treatment has been employed for pure titanium to produce amorphous and porous layer prior to hydroxyapatite (HAp) growth. But, in the case of TNTZ, immersion

Shinji Fujimoto; Vedarajan Raman; Hiroaki Tsuchiya

2009-01-01

102

Surface modification of ?-Type titanium alloy by electrochemical potential pulse polarization  

Microsoft Academic Search

In the present work, we report the formation of a porous oxide\\/hydroxide surface layer on the Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy achieved by the combination of an alkali immersion and a potential pulse polarisation process. The alkali treatment has been employed for pure titanium to produce amorphous and porous layer prior to hydroxyapatite (HAp) growth. But, in the case of TNTZ, immersion

Shinji Fujimoto; Vedarajan Raman; Hiroaki Tsuchiya

2009-01-01

103

Optical switching properties of RCo2-type alloy hydride based solid state device  

Microsoft Academic Search

The optical switching properties of a solid state device based on Ho0.6Mm0.4Co2 (HMC) alloy thin film as a switching active layer, water pretreated Nafion membrane as a solid electrolyte, and a transparent conducting indium tin oxide (ITO) as a counterelectrode are investigated. The device is simple and has a reduced layer sequence of HMC\\/Pd\\/Nafion\\/ITO. The reversible optical switching of this

G. Srinivas; V. Sankaranarayanan; S. Ramaprabhu

2008-01-01

104

Crevice Repassivation Potential of Alloy 22 in High-Nitrate Dust Deliquescence Type Environments  

SciTech Connect

The nitrate ion (NO{sub 3}{sup -}) is an inhibitor for crevice corrosion of Alloy 22 (N06022) in chloride (Cl{sup -}) aqueous solutions. Naturally formed electrolytes may contain both chloride and nitrate ions. The higher the ratio R = [NO{sub 3}{sup -}]/[Cl{sup -}] in the solution the stronger the inhibition of crevice corrosion. Atmospheric desert dust contains both chloride and nitrate salts, generally based on sodium (Na{sup +}) and potassium (K{sup +}). Some of these salts may deliquescence at relatively low humidity at temperatures on the order of 150 C and higher. The resulting deliquescent brines are highly concentrated and especially rich in nitrate. Electrochemical tests have been performed to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 150 C at ambient atmospheres. Naturally formed brines at temperatures higher than 120 C do not induce crevice corrosion in Alloy 22 because they contain high levels of nitrate. The inhibitive effect of nitrate on crevice corrosion is still active for temperatures higher than 100 C.

Lian, T; Gdowski, G E; Hailey, P D; Rebak, R B

2007-02-08

105

Invar and Elinvar type amorphous Fe-Cr-B alloys with high corrosion resistance  

NASA Technical Reports Server (NTRS)

Amorphous (Fe(1-x)Cr(x))85B15 alloys (x = 0 to 0.15) were prepared from the melts by rapid quenching using a single roller techinque, and their Invar and Elinvar characteristics and corrosion resistance were investigated. With an increase in chromium content the Curie temperature and the saturation magnetic moment per iron atom decreased monotonically, while the crystallization temperature incresed gradually. The thermal expansion coefficient alpha around room temperature became slightly larger with increasing chromium content. Nevertheless, these amorphous alloys exhibited excellent Invar characteristics below the Curie temperature. The value of Young's modulus increased remarkably in a relatively low magnetic field and then saturated at a field of about 80 kA/m, showing a large delta E effect. Its value as well as a longitudinal linear magnetostriction became smaller with an increase in chromium content. The temperature coefficient of Young's modulus changed from postive to negative, and the temperature range showing the Elinvar characteristics became narrower with chromium content. The temperature coefficient of delay time determined from the values of alpha and e was very small. The corrosion resistance of these alloys was extremely improved by chromium addition.

Kikuci, M.; Fukamichi, K.; Masumoto, T.

1987-01-01

106

Magnetic studies of Fe-doped martensitic Ni2Mn1.44Sn0.56-type Heusler alloy  

NASA Astrophysics Data System (ADS)

Localization and magnetism of Fe replacing either Mn or Ni in the Ni2Mn1.44Sn0.56-type Heusler alloy have been systematically investigated using magnetization, scanning electron microscopy and Mssbauer spectroscopy. It has been shown that the addition of Fe either in Mn or in Ni sites reduces the fraction of the Mn-rich NiMnSn-type Heusler alloys that has short-range antiferromagnetic interactions; consequently it reduces the martensitic-austenitic transition temperature and increases the thermal hysteresis width due to an increase in atomic disorder caused by Fe replacements. The Fe atoms in Mn sites have two magnetic configurations with magnetic moments of 0.8?B/Fe and 1.4?B/Fe in the martensitic orthorhombic structure, while Fe in Ni sites have magnetic moments smaller than 0.1?B/Fe. These results indicate that the Fe atoms are distinctly substituting either Mn or Ni and the decrease in the martensitic phase transition temperature for increasing Fe content can be mainly attributed to the Fe atoms in the Mn sites in both cases.

Passamani, E. C.; Crdova, C.; Alves, A. L.; Moscon, P. S.; Larica, C.; Takeuchi, A. Y.; Biondo, A.

2009-11-01

107

Thermoelectric properties of fine-grained FeVSb half-Heusler alloys tuned to p-type by substituting vanadium with titanium  

NASA Astrophysics Data System (ADS)

Fine-grained Ti-doped FeVSb half-Heusler alloys were synthesized by combining mechanical alloying and spark plasma sintering and their thermoelectric properties were investigated with an emphasis on the influences of Ti doping and phase purity. It was found that substituting V with Ti can change the electrical transport behavior from n-type to p-type due to one less valence electron of Ti than V, and the sample with nominal composition FeV0.8Ti0.4Sb exhibits the largest Seebeck coefficient and the maximum power factor. By optimizing the sintering temperature and applying annealing treatment, the power factor is significantly improved and the thermal conductivity is reduced simultaneously, resulting in a ZT value of 0.43 at 500 C, which is relatively high as for p-type half-Heusler alloys containing earth-abundant elements.

Zou, Minmin; Li, Jing-Feng; Kita, Takuji

2013-02-01

108

Irradiation Performance of U-Mo Alloy Based Monolithic Plate-Type Fuel Design Selection  

SciTech Connect

A down-selection process has been applied to the U-Mo fuel alloy based monolithic plate fuel design, supported by irradiation testing of small fuel plates containing various design parameters. The irradiation testing provided data on fuel performance issues such as swelling, fuel-cladding interaction (interdiffusion), blister formation at elevated temperatures, and fuel/cladding bond quality and effectiveness. U-10Mo (wt%) was selected as the fuel alloy of choice, accepting a somewhat lower uranium density for the benefits of phase stability. U-7Mo could be used, with a barrier, where the trade-off for uranium density is critical to nuclear performance. A zirconium foil barrier between fuel and cladding was chosen to provide a predictable, well-bonded, fuel-cladding interface, allowing little or no fuel-cladding interaction. The fuel plate testing conducted to inform this selection was based on the use of U-10Mo foils fabricated by hot co-rolling with a Zr foil. The foils were subsequently bonded to Al-6061 cladding by hot isostatic pressing or friction stir bonding.

A. B. Robinson; G. S. Chang; D. D. Keiser, Jr.; D. M. Wachs; D. L. Porter

2009-08-01

109

SEM, EDS, EPMA-WDS and EBSD characterization of carbides in HP type heat resistant alloys  

SciTech Connect

The microstructure of centrifugally cast heat resistant alloys of the HP-series (Fe-35Ni-25Cr-0.4C, wt.%) contains several minor phases, like carbides (M{sub 7}C{sub 3}, M{sub 23}C{sub 6} and MC). Several alloys are characterized by means of scanning electron microscopy in back-scattered electron imaging and energy dispersive spectroscopy, of electron probe micro-analysis by X-ray wavelength dispersive spectroscopy, and of electron back-scattered diffraction. On the one hand, scanning electron microscopy imaging in the back-scattered mode, associated with energy dispersive spectroscopy analysis and electron back-scattered diffraction, can lead to the identification of all phases, but with a lack of accuracy in certain cases. On the other hand, electron probe micro-analysis by X-ray wavelength dispersive spectroscopy alone can always provide a strict identification of all phases, with additional precise information on phase composition, including for light elements, which is important in the case of carbides.

Laigo, J. [Universite de Nantes, Nantes Atlantique Universites, Polytech'Nantes, LGMPA, Rue Christian Pauc, BP 50609, F-44306 Nantes Cedex 3 (France); Air Liquide, Centre de Recherche Claude-Delorme, 1, chemin de la Porte des Loges, 78354 Jouy-en-Josas (France); Christien, F.; Le Gall, R. [Universite de Nantes, Nantes Atlantique Universites, Polytech'Nantes, LGMPA, Rue Christian Pauc, BP 50609, F-44306 Nantes Cedex 3 (France); Tancret, F. [Universite de Nantes, Nantes Atlantique Universites, Polytech'Nantes, LGMPA, Rue Christian Pauc, BP 50609, F-44306 Nantes Cedex 3 (France)], E-mail: franck.tancret@univ-nantes.fr; Furtado, J. [Air Liquide, Centre de Recherche Claude-Delorme, 1, chemin de la Porte des Loges, 78354 Jouy-en-Josas (France)

2008-11-15

110

High-velocity-oxidation performance of metal-chromium-aluminum (MCrAl), cermet, and modified aluminide coatings on IN-100 and type VIA alloys at 1093 C  

NASA Technical Reports Server (NTRS)

Cermet, MCrAl, and modified aluminide types of coatings applied to IN-100 and NASA-TRW-VIA alloy specimens were cyclically oxidation tested in a high velocity (Mach 1) gas flame at 1093 C. Several coating compositions of each type were evaluated for oxidation resistance. The modified aluminide coating, Pt-Al, applied to alloy 6A proved to be the best, providing oxidation protection to approximately 750 hours based on weight change measurements. The second best, a CoCrAlY coating applied to 6A, provided protection to 450 hours. The third best was a cermet + aluminide coating on 6A with a protection time to 385 hours.

Deadmore, D. L.

1974-01-01

111

Investigation of early cell-surface interactions of human mesenchymal stem cells on nanopatterned ?-type titanium-niobium alloy surfaces.  

PubMed

Multi-potent adult mesenchymal stem cells (MSCs) derived from bone marrow have therapeutic potential for bone diseases and regenerative medicine. However, an intrinsic heterogeneity in their phenotype, which in turn results in various differentiation potentials, makes it difficult to predict the response of these cells. The aim of this study is to investigate initial cell-surface interactions of human MSCs on modified titanium alloys. Gold nanoparticles deposited on ?-type Ti-40Nb alloys by block copolymer micelle nanolithography served as nanotopographical cues as well as specific binding sites for the immobilization of thiolated peptides present in several extracellular matrix proteins. MSC heterogeneity persists on polished and nanopatterned Ti-40Nb samples. However, cell heterogeneity and donor variability decreased upon functionalization of the gold nanoparticles with cyclic RGD peptides. In particular, the number of large cells significantly decreased after 24 h owing to the arrangement of cell anchorage sites, rather than peptide specificity. However, the size and number of integrin-mediated adhesion clusters increased in the presence of the integrin-binding peptide (cRGDfK) compared with the control peptide (cRADfK). These results suggest that the use of integrin ligands in defined patterns could improve MSC-material interactions, not only by regulating cell adhesion locally, but also by reducing population heterogeneity. PMID:24501674

Medda, Rebecca; Helth, Arne; Herre, Patrick; Pohl, Darius; Rellinghaus, Bernd; Perschmann, Nadine; Neubauer, Stefanie; Kessler, Horst; Oswald, Steffen; Eckert, Jrgen; Spatz, Joachim P; Gebert, Annett; Cavalcanti-Adam, Elisabetta A

2014-02-01

112

Optical switching properties of RCo2-type alloy hydride based solid state device  

NASA Astrophysics Data System (ADS)

The optical switching properties of a solid state device based on Ho0.6Mm0.4Co2 (HMC) alloy thin film as a switching active layer, water pretreated Nafion membrane as a solid electrolyte, and a transparent conducting indium tin oxide (ITO) as a counterelectrode are investigated. The device is simple and has a reduced layer sequence of HMC/Pd/Nafion/ITO. The reversible optical switching of this device has been studied during electrochemical galvanostatic charging-discharging as well as cyclic voltammetric measurements. Further, the optical switching durability of the device has been tested by repeated electrochemical hydrogenation-dehydrogenation, and the variations in the optical switching properties are discussed. The special characteristic of the device is that it can reversibly switch between a metallic reflecting state and a semiconducting transparent state by a small reversible applied current/voltage indicating the potential substitution for conventional electrochromic devices.

Srinivas, G.; Sankaranarayanan, V.; Ramaprabhu, S.

2008-09-01

113

NDE detectability of fatigue-type cracks in high-strength alloys: NDI reliability assessments  

NASA Technical Reports Server (NTRS)

This program was conducted to generate quantitative flaw detection capability data for the nondestructive evaluation (NDE) techniques typically practiced by aerospace contractors. Inconel 718 and Haynes 188 alloy test specimens containing fatigue flaws with a wide distribution of sizes were used to assess the flaw detection capabilities at a number of contractor and government facilities. During this program 85 inspection sequences were completed presenting a total of 20,994 fatigue cracks to 53 different inspectors. The inspection sequences completed included 78 liquid penetrant, 4 eddy current, and 3 ultrasonic evaluations. The results of the assessment inspections are presented and discussed. In generating the flaw detection capability data base, procedures for data collection, data analysis, and specimen care and maintenance were developed, demonstrated, and validated. The data collection procedures and methods that evolved during this program for the measurement of flaw detection capabilities and the effects of inspection variables on performance are discussed. The Inconel 718 and Haynes 188 test specimens that were used in conducting this program and the NDE assessment procedures that were demonstrated, provide NASA with the capability to accurately assess the flaw detection capabilities of specific inspection procedures being applied or proposed for use on current and future fracture control hardware program.

Christner, Brent K.; Long, Donald L.; Rummel, Ward D.

1988-01-01

114

Thermoelectric generation and related properties of conventional type module based on SiGe alloy  

Microsoft Academic Search

A conventional type thermoelectric module based on Si2Ge has been made for power use. The module consists of 10 pairs of p- and n-type Si2Ge elements in which B and P were doped (~1020 cm-3) respectively. The elements electrically connected in series using Mo electrodes are sandwiched between AIN plates. Each plate is 20 mm44 mm in area, and the

Masakazu KOBAYASHI; Keiko IKOMA; Kenji FURUYA; Kazuhiko SHINOHARA; Hiroshi TAKAO; Makoto MIYOSHI; Yuichiro IMANISHI; Tetsuo WATANABE

1996-01-01

115

Quantification of zinc atoms in a surface alloy on copper in an industrial-type methanol synthesis catalyst.  

PubMed

Methanol has recently attracted renewed interest because of its potential importance as a solar fuel.1 Methanol is also an important bulk chemical that is most efficiently formed over the industrial Cu/ZnO/Al2 O3 catalyst. The identity of the active site and, in particular, the role of ZnO as a promoter for this type of catalyst is still under intense debate.2 Structural changes that are strongly dependent on the pretreatment method have now been observed for an industrial-type methanol synthesis catalyst. A combination of chemisorption, reaction, and spectroscopic techniques provides a consistent picture of surface alloying between copper and zinc. This analysis enables a reinterpretation of the methods that have been used for the determination of the Cu surface area and provides an opportunity to independently quantify the specific Cu and Zn areas. This method may also be applied to other systems where metal-support interactions are important, and this work generally addresses the role of the carrier and the nature of the interactions between carrier and metal in heterogeneous catalysts. PMID:24764288

Kuld, Sebastian; Conradsen, Christian; Moses, Poul Georg; Chorkendorff, Ib; Sehested, Jens

2014-06-01

116

Fabrication of L1{sub 1}-type (Co-Ni)-Pt ordered alloy films by sputter deposition  

SciTech Connect

L1{sub 1}-type (Co-Ni)-Pt ordered alloy perpendicular films were successfully fabricated on MgO(111) single crystal substrates using ultrahigh vacuum sputter film deposition; the addition of Ni to Co-Pt was effective to reduce saturation magnetization, M{sub s}, maintaining a large K{sub u} of the order of 10{sup 7} erg/cm{sup 3}. L1{sub 1}-type ordered structures, with the <111> direction (easy axis of magnetization) perpendicular to the films, were successfully fabricated at a substrate temperature of 360 deg. C in a wide composition range with Co content less than 60 at. %. The order parameter, S, was almost a constant of about 0.5 in the stoichiometric composition of (Co{sub 1-X}Ni{sub X}){sub 50}Pt{sub 50}, independent of Ni content, X. L1{sub 1}-type Co-Ni-Pt perpendicular films having a large K{sub u} of (1-2.5)x10{sup 7} erg/cm{sup 3} and a relatively low M{sub s} of 400-700 emu/cm{sup 3} were successfully fabricated in the composition range of 10-35 at. % Co, 20-55 at. % Ni, and bal. Pt. K{sub u} should increase further with enhanced ordering. Experimental results demonstrated the potential of these Co-Ni-Pt ordered films for use in data storage applications due to very high K{sub u} potential comparable to L1{sub 0}-type Fe{sub 50}Pt{sub 50} films, relatively low M{sub s}, the relatively low fabrication temperature, and good controllability of the grain orientation.

Sato, H. [Institute of Multidisciplinary Research for Advanced Material, Tohoku University, Sendai 980-8577 (Japan); Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Shimatsu, T.; Aoi, H. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Kataoka, H. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Fuji Electric Device Technology, Co., Ltd., Matsumoto 390-0821 (Japan); Okamoto, S.; Kitakami, O. [Institute of Multidisciplinary Research for Advanced Material, Tohoku University, Sendai 980-8577 (Japan)

2009-04-01

117

Low-cycle fatigue of Type 347 stainless steel and Hastelloy alloy X in hydrogen gas and in air at elevated temperatures  

NASA Technical Reports Server (NTRS)

An investigation was conducted to assess the low-cycle fatigue resistance of two alloys, Type 347 stainless steel and Hastelloy Alloy X, that were under consideration for use in nuclear-powered rocket vehicles. Constant-amplitude, strain-controlled fatigue tests were conducted under compressive strain cycling at a constant strain rate of 0.001/sec and at total axial strain ranges of 1.5, 3.0, and 5.0 %, in both laboratory-air and low-pressure hydrogen-gas environments at temperatures from 538 to 871 C. Specimens were obtained from three heats of Type 347 stainless steel bar and two heats of Hastelloy Alloy X. The tensile properties of each heat were determined at 21, 538, 649, and 760 C. The continuous cycling fatigue resistance was determined for each heat at temperatures of 538, 760, and 871 C. The Type 347 stainless steel exhibited equal or superior fatigue resistance to the Hastelloy Alloy X at all conditions of this study.

Jaske, C. E.; Rice, R. C.; Buchheit, R. D.; Roach, D. B.; Porfilio, T. L.

1976-01-01

118

Effects of the materials processing on the hydrogen absorption properties of MmNi 5 type alloys  

Microsoft Academic Search

The effects of heat treating conditions on the hydrogen absorption characteristics of low-cost cobalt-free Mm(AlMnFeNiCu)5+x alloys were investigated. The alloys were prepared by induction melting and water cooling and thermally treated at temperatures between 1153 and 1353 K in vacuo. For the stoichiometric alloy of Mm(AlMnFeNiCu)5, brittleness was increased abruptly by heat treatment at temperatures above 1300 K; however, electrochemical

K Yasuda

1997-01-01

119

Corrosion of a Type 304 stainless steel and a molybdenum-base TZM alloy in refluxing mercury with a small amount of potassium  

NASA Astrophysics Data System (ADS)

Corrosion of a Type 304 stainless steel and a molybdenum-base TZM alloy (Mo-0.5Ti-0.08Zr-0.025C-0.025 oxygen) in refluxing mercury with and without about 0.004 mol fraction of potassium in mercury has been examined using small capsules made of the steel and the alloy at 600 and 700 C to recognize the corrosion mechanisms. The wall of the austenitic 304 stainless steel capsule was severely corroded due to selective dissolution of nickel and chromium, leading to a ferritic layer which is more stable than the austenitic phase. The corrosion products were deposited near the vapor-liquid interface of the mercury. In contrast, the TZM alloy showed no noticeable changes except for carburization of the surface after heating for 2000 h, probably due to the low solubility of molybdenum in mercury.

Suzuki, Tadashi; Mutoh, Isao

1991-09-01

120

Determination of thermal conductivities of Sn-Zn lead-free solder alloys with radial heat flow and Bridgman-type apparatus  

NASA Astrophysics Data System (ADS)

The variations of thermal conductivities of solid phases versus temperature for pure Sn, pure Zn and Sn-9 wt.% Zn, Sn-14 wt.% Zn, Sn-50 wt.% Zn, Sn-80 wt.% Zn binary alloys were measured with a radial heat flow apparatus. The thermal conductivity ratios of liquid phase to solid phase for the pure Sn, pure Zn and eutectic Sn-9 wt.% Zn alloy at their melting temperature are found with a Bridgman-type directional solidification apparatus. Thus, the thermal conductivities of liquid phases for pure Sn, pure Zn and eutectic Sn-9 wt.% Zn binary alloy at their melting temperature were evaluated by using the values of solid phase thermal conductivities and the thermal conductivity ratios of liquid phase to solid phase.

Meydaneri, Fatma; Saati, Buket; Gndz, Mehmet; zdemir, Mehmet

2013-11-01

121

Properties of a new type Al/Pb-0.3%Ag alloy composite anode for zinc electrowinning  

NASA Astrophysics Data System (ADS)

An Al/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corrosion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode (hard anodizing) displays a more compact interfacial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of Al/Pb-0.3%Ag alloy (hard anodizing) and Al/Pb-0.3%Ag alloy (plating tin) at 500 Am-2 were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, Al/Pb-0.3%Ag alloy (hard anodizing), and Al/Pb-0.3%Ag alloy (plating tin) were 13.977, 9.487, and 11.824 gm-2h-1, respectively, in accelerated corrosion test for 8 h at 2000 Am-2. The anodic oxidation layer of Al/Pb-0.3%Ag alloy (hard anodizing) is more compact than Pb-0.3%Ag alloy and Al/Pb-0.3%Ag alloy (plating tin) after the test.

Yang, Hai-tao; Liu, Huan-rong; Zhang, Yong-chun; Chen, Bu-ming; Guo, Zhong-cheng; Xu, Rui-dong

2013-10-01

122

Formation of the properties of antimony matrix alloys for frame-type composite materials  

Microsoft Academic Search

A frame-type composite material (CM) produced upon impregnation represents a system consisting of a rigid porous frame and a matrix material filling its voids. When metals are used as a matrix material, they bring up specific problems related to melting of a metal, such as the thermal effect of the metal on the frame and the chemical interaction of the

V. A. Gulevskii; V. I. Antipov; L. V. Vinogradov; A. G. Kolmakov; E. M. Lazarev; A. M. Samarina; Yu. E. Mukhina

2009-01-01

123

Growth of creep life of type-347H austenitic stainless steel by micro-alloying elements  

Microsoft Academic Search

The creep life of type-347H austenitic stainless steel modified with B, Ce and N was measured, and microstructures were analyzed by optical microscope, X-ray diffraction, scanning electron microscope and transmission electron microscope equipped with energy dispersive spectroscopy. The results indicate that B, Ce and N can improve the creep life significantly at high temperature. The growth of creep life was

Yulai Xu; Heng Nie; Jun Li; Xueshan Xiao; Changchun Zhu; Junliang Zhao

2010-01-01

124

Formation of the properties of antimony matrix alloys for frame-type composite materials  

Microsoft Academic Search

A frame-type composite material (CM) produced upon impregnation represents a system consisting of a rigid porous frame and\\u000a a matrix material filling its voids. When metals are used as a matrix material, they bring up specific problems related to\\u000a melting of a metal, such as the thermal effect of the metal on the frame and the chemical interaction of the

V. A. Gulevskii; V. I. Antipov; L. V. Vinogradov; A. G. Kolmakov; E. M. Lazarev; A. M. Samarina; Yu. E. Mukhina

2009-01-01

125

Furnace brazing type 304 stainless steel to vanadium alloy (V5Cr5Ti)  

Microsoft Academic Search

In this investigation, pure copper was joined to type 304 stainless steel and V5Cr5Ti by brazing in a high vacuum furnace. Microstructural changes in the brazed region and surrounding substrates were examined as a function of holding time at temperatures of 20C, 40C and 60C above the melting point of copper. Reaction layers, which were extremely brittle, formed between the

R. V Steward; M. L Grossbeck; B. A Chin; H. A Aglan; Y Gan

2000-01-01

126

[Ti-Ni shape memory alloy for dental use. Trial production of prefabricated straight-slit type posts by electric discharge machining].  

PubMed

The possibility of dental application of Ti-Ni shape memory alloys was examined. To determine whether this material which is difficult to be machined could be processed by the electric discharge machining method (E.D.M.), the E.D.M. characteristics of this material were investigated. Trial straight-slit type posts were made by this material under an appropriate electric condition. The term of yield strength, retention force after cementing, and pressure of post when into a root canal filled unset cement were investigated. Ti-Ni shape memory alloy could be processed without a loss of shape memory effect by E.D.M. Hardenning layer in the machined surface was observed by both Ram-type and Wire-type E.D.M., but a thinner hardening layer was observed by the latter method. The retention force after cementing of the trial straight-slit type post were the same or stronger than those of posts on the market. Especially, the dependence for the post's length on this strength was not strong in the trial posts. The pressure produced by inserting the trial post into the root canal filled with unset cement was very low compared with those of post on the market. The trial straight-slit type posts made of Ti-Ni shape memory alloy may be useful for dental application. PMID:2700253

Hasegawa, K

1989-05-01

127

Optimization of Cr content of metastable ?-type Ti-Cr alloys with changeable Young's modulus for spinal fixation applications.  

PubMed

Metallic implant rods used in spinal fixtures should have a Young's modulus that is sufficiently low to prevent stress shielding for the patient and sufficiently high to suppress springback for the surgeon. Therefore, we propose a new concept: novel biomedical titanium alloys with a changeable Young's modulus via deformation-induced ? phase transformation. In this study, the Cr content in the range of 10-14 mass% was optimized to produce deformation-induced ? phase transformation, resulting in a large increase in the Young's modulus of binary Ti-Cr alloys. The springback and cytotoxicity of the optimized alloys were also examined. Ti-(10-12)Cr alloys exhibit an increase in Young's modulus owing to deformation-induced ? phase transformation. In this case, such deformation-induced ? phase transformation occurs along with {332}(?) mechanical twinning, resulting in the maintenance of acceptable ductility with relatively high strength. Among the examined alloys, the lowest Young's modulus and largest increase in Young's modulus are obtained from the Ti-12Cr alloy. This alloy exhibits smaller springback than and comparable cytocompatibility to the biomedical Ti alloy Ti-29Nb-13Ta-4.6Zr. PMID:22342893

Zhao, Xingfeng; Niinomi, Mitsuo; Nakai, Masaaki; Hieda, Junko; Ishimoto, Takuya; Nakano, Takayoshi

2012-07-01

128

Reordering kinetics and magnetic properties of mechanically disordered nanocrystalline L1[sub 2]-type Ni[sub 3]Al + Fe alloys  

SciTech Connect

The paramagnetic disordered high temperature states of L1[sub 2] or [gamma][prime]-type Ni[sub 3]Al-Fe alloys become ferromagnetic at low temperatures if retained in metastable disordered ([gamma]) state. Using mechanical attrition (milling) which also transforms the material into nanocrystalline form, various Ni[sub 3]Al-Fe alloys have been prepared in metastable-[gamma] form and their magnetizations M([gamma]) and M([gamma][prime]) and Curie temperatures [Tc] ([gamma]) and [Tc]([gamma][prime]) measured. Fe atoms possess a giant magnetic moment in these alloys and polarize neighboring Ni atoms but this polarization effect is lower in the disordered state due to a lower number of Fe-Ni nearest neighbors resulting in M([gamma])type alloys. Isothermal ordering kinetics of the metastable-[gamma]-state which is also nanocrystalline indicate that the ordering reaction cannot propagate across the disordered nanograin boundaries and each grain must obtain its own [gamma][prime] nucleus. This results in a Johnson-Mehl-Avrami exponent n [approx] 1.

Yavari, A.R. (Domaine Univ., St Martin d'Heres (France). Inst. National Polytechnique de Grenoble)

1993-05-01

129

Deformation-induced changeable Young's modulus with high strength in ?-type Ti-Cr-O alloys for spinal fixture.  

PubMed

In order to meet the requirements of the patients and surgeons simultaneously for spinal fixation applications, a novel biomedical alloy with a changeable Young's modulus, that is, with a low Young's modulus to prevent the stress-shielding effect for patients and a high Young's modulus to suppress springback for surgeons, was developed. In this study, the chromium and oxygen contents in ternary Ti(11, 12 mass%)Cr-(0.2, 0.4, 0.6 mass%)O alloys were optimized in order to achieve a changeable Young's modulus via deformation-induced ?-phase transformation with good mechanical properties. The Young's moduli of all the examined alloys increase after cold rolling, which is attributed to the deformation-induced ?-phase transformation. This transformation is suppressed by oxygen but enhanced with lower chromium content, which is related to the ?(bcc)-lattice stability. Among the examined alloys, the Ti-11Cr-0.2O alloy shows a low Young's modulus of less than 80GPa in the solution-treated (ST) condition and a high Young's modulus of more than 90GPa in the cold rolled (CR) condition. The Ti-11Cr-0.2O alloy also exhibits a high tensile strength, above 1000MPa, with an acceptable elongation of ~12% in the ST condition. Furthermore, the Ti-11Cr-0.2O alloy exhibits minimal springback. This value of springback is the closest to that of Ti64 ELI alloy among the compared alloys. Therefore, the Ti-11Cr-0.2O alloy, which has a good balance between large changeable Young's modulus, high tensile strength, good plasticity, and minimal springback, is considered to be a potential candidate for spinal fixation applications. PMID:24317494

Liu, Huihong; Niinomi, Mitsuo; Nakai, Masaaki; Hieda, Junko; Cho, Ken

2014-02-01

130

Effect of processing parameters on the earing and mechanical properties of strip cast type 3004 Al alloy  

SciTech Connect

Electrical resistivity, superficial hardness, tensile testing, and quantitative metallography techniques were used in this study. The strip cast type 3004 aluminum alloy received sixteen different thermomechanical treatments before cups were drawn. The top edges of the drawn cups were not flat. Rather there were high points or ears with valleys between them. The homogenization temperature varied from 510 to 621 C at 24 h. Some samples received an additional 426 C/24 h homogenization anneal. Most specimens were rolled along the longitudinal direction of the as-cast material, and some were rolled in the transverse direction. Most samples were recrystallized at 454 C for 24 h in addition to the homogenization treatment. Some were recrystallized for 168 h. All samples were subsequently rolled to 0.33 mm for cup drawing and percent earing determination. The percent earing results of some samples were less than 1.5%, but the mechanical strength was also lowered. The high-temperature recrystallization anneal of 454 C was the controlling factor in determining the earing and mechanical strength of the final rolled sheet.

Es-Said, O.S.; Zeihen, A.; Ruprich, M.; Quattrocchi, J.; Thomas, M.; Shin, K.H.; O`Brien, M.; Johansen, D.; Tijoe, W.H.; Ruhl, D. [Loyola Marymount Univ., Los Angeles, CA (United States). Mechanical Engineering Dept.

1995-06-01

131

Effect of processing parameters on the earing and mechanical properties of strip cast type 3004 Al alloy  

NASA Astrophysics Data System (ADS)

Electrical resistivity, superficial hardness, tensile testing, and quantitative metallography techniques were used in this study. The strip cast type 3004 aluminum alloy received sixteen different thermomechanical treatments before cups were drawn. The top edges of the drawn cups were not flat. Rather there were high points or ears with valleys between them. The homogenization temperature varied form 510 to 621 C at 24 h. Some samples received an additional 426 C/24 h homogenization anneal. Most specimens were rolled along the longitudinal direction of the as-cast material, and some were rolled in the transverse direction. Most samples were recrystallized at 454 C for 24 h in addition to the homogenization treatment. Some were recrystallized for 168 h. All samples were subsequently rolled to 0.33 mm for cup drawing and percent earing determination. The percent earing results of some samples were less than 1.5%, but the mechanical strength was also lowered. The high-temperature recrystallization anneal of 454 C was the controlling factor in determining the earing and mechanical strength of the final rolled sheet.

Es-Said, O. S.; Zeihen, A.; Ruprich, M.; Quattrocchi, J.; Thomas, M.; H. Shin, K.; O'Brien, M.; Johansen, D.; Tijoe, W. H.; Ruhl, D.

1995-06-01

132

Effect of processing parameters on the earing and mechanical properties of strip cast type 3004 Al alloy  

NASA Astrophysics Data System (ADS)

Electrical resistivity, superficial hardness, tensile testing, and quantitative metallography techniques were used in this study. The strip cast type 3004 aluminum alloy received sixteen different thermomechanical treatments before cups were drawn. The top edges of the drawn cups were not flat. Rather, there were high points or ears with valleys between them. The homogenization temperature varied from 510 to 621 C at 24 h. Some samples received an additional 426 C/24 h homogenization anneal. Most specimens were rolled along the longitudinal direction of the as-cast material, and some were rolled in the transverse direction. Most samples were recrystallized at 454 C for 24 h in addition to the homogenization treatment. Some were recrystallized for 168 h. All samples were subsequently rolled to 0.33 mm for cup drawing and percent earing determination. The percent earing results of some samples were less than 1.5%, but the mechanical strength was also lowered. The high-temperature recrystallization anneal of 454 C was the controlling factor in determining the earing and mechanical strength of the final rolled sheet.

Es-Said, O. S.; Zeihen, A.; Ruprich, M.; Quattrocchi, J.; Thomas, M.; Shin, K. H.; O'Brien, M.; Johansen, D.; Tijoe, W. H.; Ruhl, D.

1994-02-01

133

Fabrication of a lotus-type porous Al-Si alloy by continuous casting with a thermal decomposition method  

NASA Astrophysics Data System (ADS)

Lotus-type porous A1-14 wt.%Si alloy was fabricated by continuous casting at a transference velocity of 10 mmmidmin-1 in vacuum and by adding Ca(OH)2 pellets to the crucible. The porosity and the pore diameter increased by varying the amount of Ca(OH)2 from 0.2 g to 0.6 g. In the case of 0.6 g Ca(OH)2, the average porosity was about 30 % and the average pore diameter was about 3.8 mm. XRD patterns of the pellets after continuous casting showed the Ca(OH)2 pellet did not decompose completely during continuous casting. The TG-DTA analysis showed that the Ca(OH)2 pellet decomposes more slowly than Ca(OH)2 powder. These results suggest that the Ca(OH)2 pellets gradually decomposed in the crucible during the continuous casting, which is suitable for the supply of hydrogen over extended periods.

Kim, T. B.; Suzuki, S.; Nakajima, H.

2009-05-01

134

Furnace brazing type 304 stainless steel to vanadium alloy (V?5Cr?5Ti)  

NASA Astrophysics Data System (ADS)

In this investigation, pure copper was joined to type 304 stainless steel and V-5Cr-5Ti by brazing in a high vacuum furnace. Microstructural changes in the brazed region and surrounding substrates were examined as a function of holding time at temperatures of 20C, 40C and 60C above the melting point of copper. Reaction layers, which were extremely brittle, formed between the Cu and V-5Cr-5Ti substrates. The formation of intermetallic phases at the filler metal/substrate interfaces was evaluated. Additionally, precipitates (FeCu 2 and FeCu 18) formed in the Cu rich filler region. For temperatures ?60C above the melting point of Cu, extensive transverse cracking was observed. Hardness tests substantiated the hypothesis that the Cu/V-5Cr-5Ti reaction layer was extremely brittle, since micro-cracks propagated from the tips of the diamond-shaped indentations. Results of mechanical properties tests of the brazed material are also presented.

Steward, R. V.; Grossbeck, M. L.; Chin, B. A.; Aglan, H. A.; Gan, Y.

2000-12-01

135

Improvement in Fatigue Strength of Biomedical beta-type Ti-Nb-Ta-Zr Alloy While Maintaining Low Young's Modulus Through Optimizing omega-Phase Precipitation  

Microsoft Academic Search

The improvement in fatigue strength, with maintenance of a low Young's modulus, in a biomedical beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), by thermomechanical treatment was investigated. A short aging time at an omega-phase-forming temperature combined with severe cold rolling was employed. A fine omega phase is observed in TNTZ subjected to this thermomechanical treatment. Because the rolling texture of beta phase

Masaaki Nakai; Mitsuo Niinomi; Takahiro Oneda

2011-01-01

136

Influence of the Front Surface Passivation Quality on Large Area n-Type Silicon Solar Cells with Al-Alloyed Rear Emitter  

Microsoft Academic Search

Efficiencies of large area n-type silicon solar cells with a screen printed rear side aluminum-alloyed emitter are mainly limited by their front surface recombination velocity. The front surface therefore has to be passivated by an effective passivation layer combined with a front surface field (FSF).In this work we investigate the influence of the front surface passivation quality and the base

T. Wiedenmann; G. Schubert; H. Plagwitz; G. Hahn

2011-01-01

137

A novel catalyst with plate-type anodic alumina supports, Ni\\/NiAl 2O 4\\/?-Al 2O 3\\/alloy, for steam reforming of methane  

Microsoft Academic Search

A series of plate-type metal-monolithic anodic alumina supported nickel catalysts were employed to investigate their reactivity in the steam reforming of methane reactions. After H2 reduction, a fresh 4.7wt% Ni\\/?-Al2O3\\/alloy catalyst provided only a short-term activity, and then deactivated quickly. By the temperature programmed reaction technologies, the oxidation of surface sintered metallic Ni particles in the SRM test was suggested

Lu Zhou; Yu Guo; Qi Zhang; Masayuki Yagi; Jun Hatakeyama; Huabo Li; Jian Chen; Makoto Sakurai; Hideo Kameyama

2008-01-01

138

Electrical properties and stability of p-type ZnO film enhanced by alloying with S and heavy doping of Cu  

SciTech Connect

Single wurtzite p-type Zn{sub 1-y}Cu{sub y}O{sub 1-x}S{sub x} alloy films with 0.081{<=}x{<=}0.186 and 0.09{<=}y{<=}0.159 were grown on quartz reproducibly by magnetron sputtering. The alloys show very stable p-type conductivity with a hole concentration of 4.31-5.78x10{sup 19} cm{sup -3}, a resistivity of 0.29-0.34 {Omega} cm and a mobility of 0.32-0.49 cm{sup 2} V{sup -1} s{sup -1}. The p-type conductivity is attributed to substitution of Cu{sup +1} for the Zn site, and the ionization energy of the Cu{sup +1} acceptor is measured to be 53 meV, much less than that of Cu-doped ZnO reported previously. The small ionization energy is due to Cu heavy doping and increase in valence band maximum of ZnO induced by alloying with S.

Pan, H. L.; Yang, T.; Xu, Y. [Department of Physics, State Key Laboratory Superhard Material, Jilin University, Changchun 130023 (China); Yao, B. [Department of Physics, State Key Laboratory Superhard Material, Jilin University, Changchun 130023 (China); Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Zhang, B. Y.; Liu, W. W.; Shen, D. Z. [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)

2010-10-04

139

Magnetic and Magnetovolume Properties of the Cu3Au Type Ordered Fe-Pt Alloys around the ?-? Phase Boundary  

NASA Astrophysics Data System (ADS)

Magnetization, thermal expansion and forced volume magnetostriction have been measured for Fe1-xPtx ordered alloys (x{=}0.23--0.27). In the fcc alloys (x?q}0.25), the atomic moment and the spontaneous volume magnetostriction increase monotonically with decreasing x, implying the Fe-Pt Invar alloys to be homogeneous and strong ferromagnets even around the ?-? phase boundary. On the other hand, the magnetic moment of the ? phase (x{<0.25) is a little larger than that of the ? phase, suggesting a very weak magnetic field dependence of the Ms temperature. The observed large spontaneous volume magnetostriction may play an important role in determining the favorable conditions for the thermoelastic martensite transformation in the Fe-Pt alloys.

Sumiyama, Kenji; Emoto, Yoshiaki; Shiga, Masayuki; Nakamura, Yoji

1981-10-01

140

Effect of Fe substitution for Co on structure, electrical resistivity, and magnetic properties of Heusler type Co2-xFe1+xSi alloys  

NASA Astrophysics Data System (ADS)

The effect of substitution of Fe for Co on structure, electrical resistivity, and magnetic properties of full Heusler type Co2-xFe1+xSi (0 <= x <= 1) alloys was investigated. The order-disorder transitions were studied by X-ray diffraction measurements followed by Rietveld refinement analysis as well as by 57Fe Mssbauer spectroscopy. The results revealed that these alloys consist of mostly L21 ordered phase and some B2 disordered phase up to x < 0.25. However, for x >= 0.25, the alloys consisted of L21 ordered phase and DO3 disordered phase. The electrical resistivity behaviour with temperature showed two distinct regions. In region I, the resistivity exhibited two-magnon scattering mechanism (T9/2 dependence) showing a signature of half-metallic ferromagnetism. However, in region II, the resistivity behaviour was governed by Tn power law and n value was found to vary from 2.98 to 1.38 with increasing Fe content. The room temperature magnetization studies confirmed the enhancement of the magnetic moment with increasing Fe substitution up to x = 0.5 in Co2-xFe1+xSi alloys. However, upon further increasing Fe content, the magnetic moment was found to decrease and this was explained in terms of localization effects originating mainly in the Co anti-site disorder.

Srinivas, K.; Prasanna Kumari, T.; Manivel Raja, M.; Kamat, S. V.

2013-07-01

141

Deep drawability of type 5083 aluminiummagnesium alloy sheet under various conditions of temperature and forming speed  

Microsoft Academic Search

The effects of forming speed and temperature on the deep drawability were investigated for a fine-grain AlMg alloy (5083-O) sheet by performing cylindrical deep drawing tests at various forming speeds (0.2500mmmin?1) at die temperatures of 293453K (the die was heated, whilst the punch was water-cooled during the tests). In order to examine the mechanical properties of this AlMg alloy sheet,

Tetsuo Naka; Fusahito Yoshida

1999-01-01

142

The TiNiSi-to-Ni2In-type magnetostructural transitions in alloys with largely reduced Ge-concentrations  

NASA Astrophysics Data System (ADS)

The MnNiGe-based and MnCoGe-based intermetallic compounds usually exhibit giant magnetocaloric effects at the TiNiSi-to-Ni2In-type magnetostructural transitions. However, the high concentrations of costly Ge element give rise to relatively high raw-material costs for these alloys. In this work, we realized the TiNiSi-to-Ni2In-type magnetostructural transitions in Mn16Fe16Ni34Si34-xGex system which possesses largely reduced Ge-concentrations. Large magnetic entropy changes were observed under relatively low field in a wide temperature range including room temperature.

Zhang, C. L.; Shi, H. F.; Han, Z. D.; Qian, B.; Zhu, C.; Chen, J.; Wang, T. Z.; Wang, D. H.

2014-07-01

143

Identification of dominant recombination mechanisms in narrow-bandgap InAs/InAsSb type-II superlattices and InAsSb alloys  

NASA Astrophysics Data System (ADS)

Minority carrier lifetimes in doped and undoped mid-wave infrared InAs/InAsSb type-II superlattices (T2SLs) and InAsSb alloys were measured from 77-300 K. The lifetimes were analyzed using Shockley-Read-Hall (SRH), radiative, and Auger recombination, allowing the contributions of the various recombination mechanisms to be distinguished and the dominant mechanisms identified. For the T2SLs, SRH recombination is the dominant mechanism. Defect levels with energies of 130 meV and 70 meV are determined for the undoped and doped T2SLs, respectively. The alloy lifetimes are limited by radiative and Auger recombination through the entire temperature range, with SRH not making a significant contribution.

Olson, B. V.; Shaner, E. A.; Kim, J. K.; Klem, J. F.; Hawkins, S. D.; Flatt, M. E.; Boggess, T. F.

2013-07-01

144

A Finemet-type alloy as a low-cost candidate for high-temperature magnetic refrigeration  

NASA Astrophysics Data System (ADS)

The refrigerant capacity (RC) of Fe68.5Mo5Si13.5B9Cu1Nb3 alloy is studied. For the amorphous sample, RC=63 J kg-1 for an optimal reversible cycle with cold and hot ends at 328 K and 520 K, respectively, for a maximum applied field H=15 kOe. Nanocrystallization diminishes both the peak entropy change and RC of the material. Although the measured RC is smaller than for Gd5Ge1.9Si2Fe0.1 (240 J kg-1 for H=50 kOe), the Mo-Finemet alloy is more than 20 times cheaper, the applied field employed is smaller, and the temperature span of the optimal cycle is increased. This makes this alloy a promising material for high-temperature refrigeration.

Franco, V.; Blzquez, J. S.; Conde, C. F.; Conde, A.

2006-01-01

145

Kinetics of B2-and D0(3)-type ordering and formation of domain structures in Fe-Al alloys.  

PubMed

Time-dependent Ginzburg-Landau (TDGL) formulation has been developed for the ordering processes of B2 and D0(3) types in binary alloy systems. In the formulation, three order parameters are defined in order to describe the state of order. Equivalent variants of B2 and D0(3) structures are distinguished using these order parameters. The mean-field free energy is defined in the form of a Landau-type expansion using the order parameters and a composition parameter. Interface energies due to local variations in the degrees of order and concentration are given with a gradient square approximation. Kinetic equations are derived from the Ginzburg-Landau-type potential in order to describe the time-evolutions of the order parameters and the concentration. Numerical simulations of the kinetic equations have been performed for B2-and D0(3)-type ordering as well as concurrent ordering and phase separation to disordered A2+D0(3). The simulated results provide a good reproduction of the formation processes of B2 and D0(3) ordered domains in an Fe(3)Al alloy. PMID:21694386

Oguma, R; Matsumura, S; Eguchi, T

2008-07-01

146

Correlation between Mechanical Behavior and Actuator-type Performance of Ni-Ti-Pd High-temperature Shape Memory Alloys  

NASA Technical Reports Server (NTRS)

High-temperature shape memory alloys in the NiTiPd system are being investigated as lower cost alternatives to NiTiPt alloys for use in compact solid-state actuators for the aerospace, automotive, and power generation industries. A range of ternary NiTiPd alloys containing 15 to 46 at.% Pd has been processed and actuator mimicking tests (thermal cycling under load) were used to measure transformation temperatures, work behavior, and dimensional stability. With increasing Pd content, the work output of the material decreased, while the amount of permanent strain resulting from each load-biased thermal cycle increased. Monotonic isothermal tension testing of the high-temperature austenite and low temperature martensite phases was used to partially explain these behaviors, where a mismatch in yield strength between the austenite and martensite phases was observed at high Pd levels. Moreover, to further understand the source of the permanent strain at lower Pd levels, strain recovery tests were conducted to determine the onset of plastic deformation in the martensite phase. Consequently, the work behavior and dimensional stability during thermal cycling under load of the various NiTiPd alloys is discussed in relation to the deformation behavior of the materials as revealed by the strain recovery and monotonic tension tests.

Bigelow, Glen S.; Padula, Santo A., II; Garg, Anita; Noebe, Ronald D.

2007-01-01

147

Interaction of a near-? type titanium alloy with NiCrAlY protective coating at high temperatures  

Microsoft Academic Search

MCrAlY coatings possess the properties of not only excellent oxidation and hot corrosion resistance but also sufficient toughness. This is why they have been commercially used on superalloys for several decades. Nevertheless, investigations revealed that there might be violent interactions between this kind of coating and titanium based alloys at high temperatures. This chemical incompatibility may promote the growth of

Haiping Liu; Shanshan Hao; Xiaohong Wang; Zixiu Feng

1998-01-01

148

Occluded solution chemistry control and the role of alloy sulfur on the initiation of crevice corrosion in type 304ss  

Microsoft Academic Search

Because sulfide inclusions are recognized as the primary initiation sites for localized corrosion of austenitic stainless steels, the influence of alloy sulfur on the crevice solution chemistry and nature of the surface in the crevice at initiation were investigated. Through the coordinated use of occluded solution analysis, high resolution TEM?EDS, small-spot XPS, and electrochemical measurements, the dominance of the effects

C. S. Brossia; R. G. Kelly

1998-01-01

149

Synthesis of growth-type polycrystalline diamond compact (PDC) using the solvent Fe55Ni29Co16 alloy under HPHT  

NASA Astrophysics Data System (ADS)

A growth-type polycrystalline diamond compact (PDC) was synthesized under high temperature and high pressure (HPHT). The infiltration technique was used with an Fe55Ni29Co16 (KOV) alloy as the sintering solvent. The morphology and weight ratio of the PDC were investigated through scanning electron microscopy (SEM) and electron dispersion spectroscopy (EDS). Note that the KOV alloy evenly infiltrated throughout the polycrystalline diamond (PCD) layer and WC-Co substrate in a short sintering time due to its low viscosity and high soakage capability. A transition layer confirmed the presence of the M x C phase near the interface of the PDC, which can make the diamond layer and WC-Co substrate combine as a complex material. X-ray diffraction (XRD) performed on the PCD layer confirmed the presence of cubic diamond, WC, cubic CoC x , the high temperature cubic phase of ?-Co, the alloy phase of FeNi x , and no graphite phase. Besides, a surface residual stress of the PCD layer, measured with reasonable accuracy using micro-Raman spectroscopy, is found to be a homogeneous compressive stress with an average value of 0.16 GPa, much lower than that of the powders-mixing method.

Jia, HongSheng; Jia, XiaoPeng; Ma, HongAn; Li, HaiBo

2012-08-01

150

Effect of texture of polishing particle on the surface roughness of a cobalt-chromium alloy using a centrifugal shooting type polishing machine.  

PubMed

In a previous report, we investigated the influence of the shooting angle of polishing particle on the surface roughness of a cobalt-chromium (Co-Cr) alloy using a centrifugal shooting type polishing machine. In the present work, we examined the effects of the texture of polishing particle and polishing time on the surface roughness of Co-Cr alloy cast specimens. Nine different textures of polishing particle were investigated with respect to core material and particle abrasiveness: three different elastic body cores (core A, hard chloroprene rubber; core B, soft chloroprene rubber; core C, natural rubber) and three different green carborundum powders as abrasives (#800, #3000, and #6000). Polishing was performed under a fixed shooting angle of 30 degrees for six different polishing times (1, 2, 3, 5, 7, and 10 minutes). Surface roughness (Ra, Sm) and cutting depth on the polished surface were measured after each polishing stage. Surface roughness was significantly improved within three minutes, particularly using a polishing particle with rough carborundum powder (#800 or #3000) and a heavy core (core A or core B). Cutting depth increased in proportion to polishing time and roughness of carborundum powder, and was least with core C. These results suggested that a polishing particle composed of core B and #3000 carborundum paste was superior for the intermediate polishing of a Co-Cr alloy, and that polishing time should be limited to within three minutes. PMID:16445008

Ono, Takahiro; Ishikawa, Kaori; Yamaba, Osamu; Nokubi, Takashi

2005-12-01

151

Effects of micro- and nano-scale wave-like structures on fatigue strength of a beta-type titanium alloy developed as a biomaterial.  

PubMed

Some newly developed ?-type titanium alloys for biomedical applications exhibit distinctive heterogeneous structures. The formation mechanisms for these structures have not been completely revealed; however, understanding these mechanisms could lead to improving their properties. In this study, the heterogeneous structures of a Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), which is a candidate for next-generation metallic biomaterials, were analyzed. Furthermore, the effects of such heterogeneous structures on the mechanical strength of this alloy, including fatigue strength, were revealed by comparing its strength to that of homogenous TNTZ. The heterogeneous structures were characterized micro-, submicro- and nano-scale wave-like structures. The formation mechanisms of these wave-like structures are found to be different from each other even though their morphologies are similar. It is revealed that the micro-, submicro- and nano-scale wave-like structures are caused by elemental segregation, crystal distortion related to kink band and phase separation into ? and ?', respectively. However, these structures have no significant effect on both tensile properties and fatigue strength comparison with homogeneous structure in this study. PMID:24184863

Narita, Kengo; Niinomi, Mitsuo; Nakai, Masaaki

2014-01-01

152

Structural and dielectric spectroscopy studies of the M-type barium strontium hexaferrite alloys (Ba x Sr 1? x Fe 12 O 19 )  

Microsoft Academic Search

The M-type barium hexaferrite Ba\\u000a x\\u000a Sr1?x\\u000a Fe12O19 (where 0x<1) alloys were prepared by a new ceramic procedure. The samples were studied using X-ray diffraction and Rietveld analysis,\\u000a scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, infrared and Mssbauer spectroscopy. The X-ray analysis\\u000a indicates that the all the samples present a hexagonal structure. The IR spectra showed three main absorption

F. M. M. Pereira; C. A. R. Junior; M. R. P. Santos; R. S. T. M. Sohn; F. N. A. Freire; J. M. Sasaki; J. A. C. de Paiva; A. S. B. Sombra

2008-01-01

153

Compositional short-range ordering in metallic alloys: Band-filling, charge-transfer, and size effects from a first-principles all-electron Landau-type theory  

Microsoft Academic Search

Using a mean-field statistical description, we derive a general formalism to investigate atomic short-range order in alloys based on a density-functional description of the finite-temperature, grand potential of the random alloy. This first-principles,'' Landau-type approach attempts to treat several contributions (electronic structure, Fermi surface, electrostatics, magnetism, etc.) to the electronic energy on an equal footing. An important ingredient for the

J. B. Staunton; D. D. Johnson; F. J. Pinski

1994-01-01

154

Compositional short-range ordering in metallic alloys: Band-filling, charge-transfer, and size effects from a first-principles all-electron Landau-type theory  

Microsoft Academic Search

Using a mean-field statistical description, we derive a general formalism to investigate atomic short-range order in alloys based on a density-functional description of the finite-temperature, grand potential of the random alloy. This ``first-principles,'' Landau-type approach attempts to treat several contributions (electronic structure, Fermi surface, electrostatics, magnetism, etc.) to the electronic energy on an equal footing. An important ingredient for the

J. B. Staunton; D. D. Johnson; F. J. Pinski

1994-01-01

155

The effects of temperature and forming speed on the forming limit diagram for type 5083 aluminummagnesium alloy sheet  

Microsoft Academic Search

The effects of forming speed and temperature on the forming limit diagram (FLD) were investigated experimentally for a fine-grain AlMg alloy (5083-O) sheet by performing stretch-forming tests at various forming speeds (0.2200mmmin?1) at several temperatures from 293 to 573K. The forming limit strain increased drastically with decreasing speed for any strain paths at a high temperature ranging from 423 to

Tetsuo Naka; Gaku Torikai; Ryutaro Hino; Fusahito Yoshida

2001-01-01

156

Properties of the quaternary half-metal-type Heusler alloy Co2Mn1-xFexSi  

NASA Astrophysics Data System (ADS)

This paper reports on the bulk properties of the quaternary Heusler alloy Co2Mn1-xFexSi with the Fe concentration x=0,1/2,1 . All samples, which were prepared by arc melting, exhibit L21 long-range order over the complete range of Fe concentration. The structural and magnetic properties of the Co2Mn1-xFexSi Heusler alloys were investigated by means of x-ray diffraction, high- and low-temperature magnetometry, Mssbauer spectroscopy, and differential scanning calorimetry. The electronic structure was explored by means of high-energy photoemission spectroscopy at about 8keV photon energy. This ensures true bulk sensitivity of the measurements. The magnetization of the Fe-doped Heusler alloys is in agreement with the values of the magnetic moments expected for a Slater-Pauling-like behavior of half-metallic ferromagnets. The experimental findings are discussed on the basis of self-consistent calculations of the electronic and magnetic structure. To achieve good agreement with experiment, the calculations indicate that on-site electron-electron correlation must be taken into account, even at low Fe concentration. The present investigation focuses on searching for the quaternary compound where the half-metallic behavior is stable against outside influences. Overall, the results suggest that the best candidate may be found at an iron concentration of about 50%.

Balke, Benjamin; Fecher, Gerhard H.; Kandpal, Hem C.; Felser, Claudia; Kobayashi, Keisuke; Ikenaga, Eiji; Kim, Jung-Jin; Ueda, Shigenori

2006-09-01

157

Tantalum and tantalum alloy tubing  

SciTech Connect

The specification includes ordering information, manufacture, chemical requirements, tension testing, flare test, ultrasonic test, hydrostatic test, pneumatic proof test, dimensions and tolerances, finish, packaging, marking, inspection, and certification. The specification covers tantalum and tantalum alloy tubing of the following types: Alloy 400 (unalloyed tantalum) and Alloy 401 (tantalum-10% tungsten). (JMT)

Not Available

1981-01-01

158

Electrochemical Behavior of Gold Alloys.  

National Technical Information Service (NTIS)

Reactions resulting from polarization of five dental golds were studied. Test materials included an ADA certified type III alloy (oro B-2) three 'economy' alloys (midas, Neycast and Minigold) and a high-fusing alloy (Olympia). The solvent was dilute lacta...

E. F. Huget S. G. Vermilyea F. A. Modawar L. B. Simon

1979-01-01

159

Thermoelectric Properties and n- to p-Type Conversion of Co-Doped ZrNiSn-Based Half-Heusler Alloys  

NASA Astrophysics Data System (ADS)

Half-Heulser thermoelectric materials ZrNi1- y Co y Sn ( y = 0, 0.02, 0.04, 0.08, 0.12) were prepared by a time-efficient levitation melting and spark plasma sintering procedure. X-ray diffraction analysis and electron probe microanalysis showed that single-phase half-Heusler compounds without compositional segregation have been obtained. The effects of Co doping on the electrical conductivity, Seebeck coefficient, and thermal conductivity of ZrNiSn-based half-Heusler alloys have been investigated from 300 K to 900 K. The Seebeck coefficient displayed a change from negative to positive values above nominal Co doping content of y = 0.02, indicating a transition in the conduction behavior from n-type to p-type. The maximum dimensionless figure of merit ZT of undoped ZrNiSn sample reached 0.5 at 870 K.

Xie, Han-Hui; Yu, Cui; He, Bin; Zhu, Tie-Jun; Zhao, Xin-Bing

2012-06-01

160

In vivo corrosion, tumor outcome, and microarray gene expression for two types of muscle-implanted tungsten alloys.  

PubMed

Tungsten alloys are composed of tungsten microparticles embedded in a solid matrix of transition metals such as nickel, cobalt, or iron. To understand the toxicology of these alloys, male F344 rats were intramuscularly implanted with pellets of tungsten/nickel/cobalt, tungsten/nickel/iron, or pure tungsten, with tantalum pellets as a negative control. Between 6 and 12 months, aggressive rhabdomyosarcomas formed around tungsten/nickel/cobalt pellets, while those of tungsten/nickel/iron or pure tungsten did not cause cancers. Electron microscopy showed a progressive corrosion of the matrix phase of tungsten/nickel/cobalt pellets over 6 months, accompanied by high urinary concentrations of nickel and cobalt. In contrast, non-carcinogenic tungsten/nickel/iron pellets were minimally corroded and urinary metals were low; these pellets having developed a surface oxide layer in vivo that may have restricted the mobilization of carcinogenic nickel. Microarray analysis of tumors revealed large changes in gene expression compared with normal muscle, with biological processes involving the cell cycle significantly up-regulated and those involved with muscle development and differentiation significantly down-regulated. Top KEGG pathways disrupted were adherens junction, p53 signaling, and the cell cycle. Chromosomal enrichment analysis of genes showed a highly significant impact at cytoband 7q22 (chromosome 7) which included mouse double minute (MDM2) and cyclin-dependant kinase (CDK4) as well as other genes associated with human sarcomas. In conclusion, the tumorigenic potential of implanted tungsten alloys is related to mobilization of carcinogenic metals nickel and cobalt from corroding pellets, while gene expression changes in the consequent tumors are similar to radiation induced animal sarcomas as well as sporadic human sarcomas. PMID:22982072

Schuster, B E; Roszell, L E; Murr, L E; Ramirez, D A; Demaree, J D; Klotz, B R; Rosencrance, A B; Dennis, W E; Bao, W; Perkins, E J; Dillman, J F; Bannon, D I

2012-11-15

161

Microstructures and electrochemical properties of Co-free AB 5-type hydrogen storage alloys through substitution of Ni by Fe  

Microsoft Academic Search

The structure and electrochemical properties of a cobalt-free hydrogen storage electrode alloy LaNi4.05?xAl0.45Mn0.5Fex (0?x?0.5) have been investigated with different additions of Fe in replacement of Ni. With the increase of Fe content the maximum discharge capacity gradually decreases from 334.8mAhg?1 to 292.8mAhg?1, however the cycle stability is improved correspondingly. The capacity decay can remain 28.6% (x=0.5) after 300 charge\\/discharge cycles.

Xuedong Wei; Sheshe Liu; Hui Dong; Peng Zhang; Yongning Liu; Jiewu Zhu; Guang Yu

2007-01-01

162

Magnetic properties and origin of the half-metallicity of Ti2MnZ (Z=Al, Ga, In, Si, Ge, Sn) Heusler alloys with the Hg2CuTi-type structure  

NASA Astrophysics Data System (ADS)

Using the first-principles calculations within density functional theory, we investigate the magnetic properties and electronic structures of the Ti2MnZ (Z=Al, Ga, In, Si, Ge, Sn) alloys with the Hg2CuTi-type structure. The Ti2MnZ (Z=Al, Ga, In, Si, Ge, Sn) are found to be half-metallic ferrimagnets. The total magnetic moments (t) of the Ti2MnZ alloys are calculated to be 0 for Z=Al, Ga, In and 1 for Z=Si, Ge, Sn, linearly scaled with the total number of valence electrons (Zt) by t=Zt-18. The origin of the band gap for these half-metallic alloys is well understood. We expect our results to trigger further experimental interest in these alloys.

Fang, Qing-Long; Zhang, Jian-Min; Xu, Ke-Wei

2014-01-01

163

Increase in the density of states in n-type extruded (Bi(1-x)Sbx)2(Te(1-y)Sey)3 thermoelectric alloys  

NASA Astrophysics Data System (ADS)

The concentration and doping of n-type doped (Bi(1-x)Sbx)2(Te(1-y)Sey)3 thermoelectric alloys produced by powder metallurgy followed by hot extrusion are varied in order to optimize their performance for the generation of electricity. The material is polycrystalline and strongly textured, with an undetermined volumetric fraction of nanoscale subgrains, and its thermoelectric properties are optimal along the extrusion direction. Within the composition range 0 <= x, y <= 0.1 the quaternary (Bi0.97Sb0.03)2(Te0.93Se0.07)3 shows the highest temperature-averaged dimensionless figure of merit langZTrang for applications where TC = 295 K and TH = 420 K. This average langZTrang is further optimized for values of carrier concentrations close to n = 3.4 1019 cm-3. The introduction of substitution elements constituting these quaternary alloys leads to an increase in the electronic equivalent density of states compared with Bi2Te3. This increase has a direct impact on the Seebeck coefficient, the electronic contribution to the thermal conductivity and the carrier mobility.

Andr, C.; Vasilevskiy, D.; Turenne, S.; Masut, R. A.

2011-06-01

164

Extrusion die geometry effects on the energy absorbing properties and deformation response of 6063-type Al-Mg-Si aluminum alloy  

NASA Astrophysics Data System (ADS)

The response of 6063-type Al-Mg-Si alloy to deformation via extrusion was studied using tool steel dies with 15, 30, 45, 60 and 75 entry angles. Compressive loads were subjected to each sample using the AVERY DENISON machine, adapted to supply a compressive load on the punch. The ability of the extrudate to absorb energy before fracture was calculated by integrating numerically the polynomial relationship between the compressive stress and sample strains. Strain rate was calculated for each specimen and the deformation zone length was mathematically derived from the die geometry to decipher its influence on both lateral and axial deformations. Results showed that extruding with a 15 die was the fastest as a result of the low flow stress encountered. Outstanding compressive strength, plastic deformation, strain rate and energy absorbing capacity were observed for the alloy extruded with a 75 die angle. Increase in die angles led to a decrease in deformation zone length and samples deformed more in the axial direction than in the lateral except for the 45o die which showed the opposite; the sample also showed the least ductility.

Gbenebor, O. P.; Fayomi, O. S. I.; Popoola, A. P. I.; Inegbenebor, A. O.; Oyawale, F.

165

Platinum-group minerals from placers related to the Nizhni Tagil (Middle Urals, Russia) Uralian-Alaskan-type ultramafic complex: ore-mineralogy and study of silicate inclusions in (Pt, Fe) alloys  

NASA Astrophysics Data System (ADS)

The study of platinum-group minerals (PGM) concentrates from the Nizhni Tagil placers related to the Soloviev Mountain (Gora Solovieva) Uralian-Alaskan-type intrusion revealed a predominance of (Pt, Fe) alloys over Ir-, and Os-bearing alloys. (Pt, Fe) alloys (isoferroplatinum-type) are interstitial with respect to chromite and show important variations in their chemical compositions, which are, however, falling within the experimentally determined stability field of isoferroplatinum. Tetraferroplatinum, enriched in Cu and Ni and tulameenite represent low-temperature mineral phases replacing (Pt, Fe) alloys. Alloys belonging to the Os-Ir-Ru ternary system have compositions corresponding to native osmium, iridium and ruthenium, respectively, and to rutheniridosmine. Osmium exsolutions appear in Ir-, and (Pt, Fe) alloys, and iridium exsolutions in (Pt, Fe) alloys. Laurite is a high-temperature phase included in native iridium and (Pt, Fe) alloys. Low-temperature PGM association comprises Ir-bearing sulpharsenides, including a phase (Ir, Os, Fe, Pt, Ru, Ni)3(As, Sb)0.85S, and a palladium antimonide Pd20Sb7. These two phases were previously unknown in nature. Furthermore, native palladium occurs in the studied concentrates. This low-temperature paragenesis indicates an interaction of Pt-, Os-, Ir- and Ru-bearing alloys with late fluids enriched in volatiles, As and Sb. The chromite composition is characterized by the predominance of Cr3+ ? Fe3+ substitution like in other Uralian-Alaskan-type intrusions; that indicates a fO2 variation during the chromite precipitation. Monomineralic inclusions of euhedral clinopyroxene and chromite crystals in (Pt, Fe) alloys were observed. Furthermore, (Pt, Fe) alloys contain polyphase silicate inclusions, which occupy the alloy negative crystals. Two types of silicate inclusions were recognized: (1) Low-pressure inclusions composed of amphibole, biotite, Jd-poor clinopyroxene, magnetite, apatite and glass; (2) High-pressure inclusions include: omphacitic clinopyroxene (up to 56 mol.% Jd), tremolite, muscovite, apatite, titanite and glass. In this case, the clinopyroxene is strongly zoned, revealing a pressure drop from about 25 to 5 kbar. The chemical composition of glass is corundum-normative and its H2O content varies from about 12 to 15 wt.%. The composition of magmatic melts, from which the silicate inclusions have originated was estimated using EPMA and image analysis interpreted by stereology. Their compositions are close to those obtained experimentally by hydrous partial melting of upper mantle rocks. The interpretation of analytical data shows that magmatic melts entrapped by (Pt, Fe) alloys crystallized from about 1100 to 700 C. The (Pt, Fe) alloys formed after the crystallization of chromite, clinopyroxene and albite. Consequently, the precipitation temperature of (Pt, Fe) alloys is estimated at about 900 C. The significant pressure drop implies a decrease of volatile concentrations in the magmatic melt and the possible formation of a fluid phase, which might have generated, the precipitation of chromite and PGM.

Johan, Z.

2006-05-01

166

High temperature low-cycle fatigue of friction welded joints - type 304-304 stainless steel and alloy 718-718 nickel base superalloy  

SciTech Connect

This paper assesses the high-temperature low-cycle fatigue of the Type 304 stainless steel and Alloy 718 superalloy friction-welded joints. Strain controlled low-cycle fatigue tests for 304-304 and 718-718 friction-welded specimens were carried out at 923 K in air to obtain the fatigue strength of the joints. These materials were selected as the cyclic hardening and softening materials, respectively. The 304-304 welded specimens showed inferior fatigue strength in comparison with the base metal while the 718-718 specimens exhibited fatigue strength equivalent to that of the base metal. The difference in the fatigue strength between the two materials is discussed from the viewpoint of the cyclic deformation behavior and strain reduction at weld interface.

Wakai, T. (Power Reactor and Nuclear Fuel Development Corp., Ibaraki (Japan). Oarai Engineering Center); Sakane, M.; Ohnami, M. (Ritsumeikan Univ., Kyoto (Japan). Dept. of Mechanical Engineering); Okita, K. (Hyogo Prefectural Inst. of Industrial Research, Miki (Japan). Technical Center for Machinery and Metals); Fukuchi, Y. (Hyogo Prefectural Inst. of Industrial Research, Kobe (Japan))

1993-01-01

167

Strong valence-band offset bowing of ZnO1-xSx enhances p-type nitrogen doping of ZnO-like alloys.  

PubMed

Photoelectron spectroscopy, optical characterization, and density functional calculations of ZnO1-xSx reveal that the valence-band (VB) offset E(v)(x) increases strongly for small S content, whereas the conduction-band edge E(c)(x) increases only weakly. This is explained as the formation of local ZnS-like bonds in the ZnO host, which mainly affects the VB edge and thereby narrows the energy gap: E(g)(x=0.28) approximately E(g)(ZnO)-0.6 eV. The low-energy absorption tail is a direct Gamma(v)-->Gamma(c) transition from ZnS-like VB. The VB bowing can be utilized to enhance p-type N(O) doping with lower formation energy DeltaH(f) and shallower acceptor state in the ZnO-like alloys. PMID:17155274

Persson, Clas; Platzer-Bjrkman, Charlotte; Malmstrm, Jonas; Trndahl, Tobias; Edoff, Marika

2006-10-01

168

Disorder-activated Raman spectra of cubic rocksalt-type Li(1-x)/2Ga(1-x)/2MxO (M = Mg, Zn) alloys  

NASA Astrophysics Data System (ADS)

Disorder-activated phonon behaviors of the cubic rocksalt-type semiconductor alloy Li(1-x)/2Ga(1-x)/2MxO (M = Mg, Zn) prepared by high-pressure and high-temperature method has been studied by Raman scattering analysis. The LO Raman phonon in Li(1-x)/2Ga(1-x)/2MxO was found to exhibit a distinct two-mode behavior. The compositional dependence of Raman frequency, peak-width, and intensity has been discussed. A model associated with a composite mode of the Brillouin zone center and edge phonons combined with phonon dispersion curves determined by first-principle calculations were employed to explain the asymmetric broadening of the LO phonon mode. The broadening and asymmetric Raman line-shape in Li(1-x)/2Ga(1-x)/2MxO can be interpreted as a composite mode of the softening Brillouin zone center mode and the Brillouin zone edge mode.

Lei, Li; Ohfuji, Hiroaki; Irifune, Tetsuo; Qin, Jiaqian; Zhang, Xinyu; Shinmei, Toru

2012-08-01

169

Microstructure and martensitic transformation in the Fe-Mn-Al-Ni shape memory alloy with B2-type coherent fine particles  

NASA Astrophysics Data System (ADS)

Microstructure and martensitic transformation yielding a magnetic change were investigated for Fe43.5Mn34Al15Ni7.5 alloy with B2-type fine precipitates. Thermoelastic martensitic transformation from the ferromagnetic parent phase to the weak magnetic martensite with a nano-twinned fcc structure was confirmed. High-angle annular dark-field scanning transmission electron microscopic observation revealed that a ? particle of about 10 nm maintains coherency with the matrix martensite phase, even though distorted due to the martensitic transformation. The martensitic transformation temperatures decreased about 75 K by application of a magnetic field of 70 kOe and magnetic field-induced reverse martensitic transformation was confirmed.

Omori, T.; Nagasako, M.; Okano, M.; Endo, K.; Kainuma, R.

2012-12-01

170

Wetting Characteristics of Novel-type 63Sn29.2Pb6Zn1Ag0.38Cu0.42Bi Solder Alloy  

Microsoft Academic Search

6061 aluminum alloy has many advantages, and soldering is the most attractive joining method for 6061 aluminum alloy. In order\\u000a to expand application of 6061 aluminum alloy, a novel 63Sn-29.2Pb-6Zn-1Ag-0.38Cu-0.42Bi solder alloy was prepared. The melting\\u000a characteristic and microstructure of the solder were analyzed by differential scanning calorimetry and scanning electron microscope.\\u000a Its spreading on the 6061 aluminum alloy was

Ding Min; Zhang Pei-Lei; Zhang Zhen-Yu; Yao Shun

2010-01-01

171

Improving the structure, magnetic properties and thermal stability of rapidly quenched TbCu7-type SmCo6.4Si0.3Zr0.3 alloy by carbon addition  

NASA Astrophysics Data System (ADS)

The effects of carbon addition on the structure and magnetic properties of rapidly quenched TbCu7-type SmCo6.4Si0.3Zr0.3 alloy have been investigated. The alloys with a small amount of C addition (x?0.2) showed single Sm(Co,M)7 phase, while ZrC phase appeared in the alloys with x=0.3 and 0.4. With the increase of C content, the grain size decreased from approximately 850 nm for x=0.1 to approximately 300 nm for x=0.4. The coercivity Hc and maximum magnetic energy product (BH)max increased with the C content from x=0 to 0.2 and then decreased with excessive C addition. The optimal magnetic properties of Hc=1577 kA/m, Jr=0.53 T and (BH)max=52.1 kJ/m3 were achieved for SmCo6.4Si0.3Zr0.3C0.2 alloy with a grain size of 600-700 nm, which is close to the single domain size of TbCu7-type Sm(Co,Zr)7 alloy. Furthermore, C addition also improved the thermal stability by reducing the absolute values of temperature coefficients of remanence and coercivity.

Feng, D. Y.; Liu, Z. W.; Zheng, Z. G.; Zeng, D. C.; Zhang, G. Q.

2014-08-01

172

Alloy materials  

DOEpatents

An alloy that contains at least two metals and can be used as a substrate for a superconductor is disclosed. The alloy can contain an oxide former. The alloy can have a biaxial or cube texture. The substrate can be used in a multilayer superconductor, which can further include one or more buffer layers disposed between the substrate and the superconductor material. The alloys can be made a by process that involves first rolling the alloy then annealing the alloy. A relatively large volume percentage of the alloy can be formed of grains having a biaxial or cube texture.

Hans Thieme, Cornelis Leo (Westborough, MA); Thompson, Elliott D. (Coventry, RI); Fritzemeier, Leslie G. (Acton, MA); Cameron, Robert D. (Franklin, MA); Siegal, Edward J. (Malden, MA)

2002-01-01

173

Effect of applied potential on changes in solution chemistry inside crevices on type 304L stainless steel and alloy 825  

SciTech Connect

Changes in pH, chloride (Cl) concentration, and potential inside a rectangular crevice of metal against polymethyl methacrylate (PMMA) were monitored using microelectrodes as a function of time and externally applied potential. The environment inside the crevice was altered within the experimental time frame only when the external potential was maintained above a certain value. When the external potential exceeded that value, there was an incubation period followed by a rapid increase in current density. This event was succeeded by a decrease in pH and potential inside the crevice. The current density also decreased rapidly upon reversal of the external potential, while a significant reversal of pH occurred over a much longer time. The kinetics of these changes in environment were functions of crevice tightness. A decrease in crevice gap resulted in a greater decrease in pH. Changes in Cl concentration were much more modest, perhaps because of formation of Cl complexes that could not be detected by the silver-silver chloride microelectrode. Chromium depletion on the surface of alloy 825 (UNS N08825) in the crevice resulted in a more rapid decrease in pH even when the surface was rougher. These observations were explained in terms of crevice corrosion nucleation in narrow gaps between peaks of surface asperities, which then propagated laterally to adjoining wider gaps between the peaks and valleys of the asperities.

Sridhar, N.; Dunn, D.S. (Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses)

1994-11-01

174

Characterization of brazing alloys with stainless steels  

Microsoft Academic Search

To simulate braze joints, qualitative x-ray mapping of the elemental ; interactions between brazing alloys and two common types of stainless steels was ; performed via the electron microprobe. In general both steels, Types 304L and 21-; 6-9, react with a particular brazing alloy in a similar manner, the exceptions ; being the gold--copper brazing alloys which show deeper penetration

D. H. Riefenberg; J. H. Doyle; R. F. Hillyer; W. S. Bennett

1975-01-01

175

Osmium isotope systematics of Os-rich alloys and Ru-Os sulfides from oceanic mantle: evidence from Proterozoic and Paleozoic ophiolite-type complexes  

NASA Astrophysics Data System (ADS)

This study presents a substantial data set of Os-isotope compositions of Os-rich alloys and Ru-Os sulfides from deep portions of ophiolite sections from oceanic mantle. These are represented by samples from different in age ophiolite-type massifs (i.e., Neoproterozoic Kunar in Northern Taimyr, Russia, and Hochgrossen in Eastern Alps, Austria, Paleozoic Verkh-Neivinsk in Middle Urals, Russia, and Shetland in northern Scotland). The investigation employed a number of analytical techniques, including electron microprobe analysis, ID ICP-MS after high pressure acid digestion, and laser ablation attached to multiple collector-inductively coupled plasma mass-spectrometry (LA MC-ICP-MS). Two distinct platinum-group mineral (PGM) assemblages have been recognized at the Shetland and Verkh-Neivinsk localities: a 'primary' euhedral PGM assemblage, which occur as inclusions in chromite, and a modified 'secondary' subeuhedral to anhedral PGM assemblage observed in cracks filled by chlorite or serpentine, interstitially to chromite grains [1]. A 'primary' PGM assemblage at Shetland is represented by solitary grains of laurite or iridian osmium and composite grains of laurite + osmian iridium iridian osmium that display well defined phase boundaries between two or three distinct PGMs. A 'primary' PGM assemblage at Verkh-Neivinsk is represented by Ru-Os-Ir alloy grains that frequently mantled by 'secondary' Ru-Os sulfide and/or Ru-Os sulfarsenide overgrowths. The osmium isotope results identify (1) a restricted range of 'unradiogenic' 187Os/188Os values for coexisting laurite and Os-rich alloy pairs that form 'primary' PGM assemblages at Hochgrossen and Shetland (0.11860-0.11866 and 0.12473-0.12488, respectively); (2) similar 'unradiogenic' 187Os/188Os values for both 'primary' and 'secondary' PGM assemblages at Shetland (with mean 187Os/188Os 0.12419 and 0.12464, respectively) and Verkh-Neivinsk (with distinct mean 187Os/188Os values), and (3) a wide scatter of subchondritic 187Os/188Os values for 'primary' PGM assemblages at Kunar (i.e., 187Os/188Os 0.11848-0.11239), Verkh-Neivinsk (0.11619-0.12565), and Hochgrossen (0.11860-0.12450). The whole-rock Os-isotope budget of chromitite at Shetland (0.12400.0006) is largely controlled by laurite-dominant assemblages. In this case, the 'secondary' PGM assemblage inherited the 'unradiogenic' Os-isotope signature of the 'primary' PGMs. No evidence for other source contributions during later thermal events has been observed here. However, the wide range of subchondritic 187Os/188Os values has been found in the 'primary' PGM assemblages (e.g., laurite and Os-rich alloys) from the ophiolite-type complexes worldwide [2 and references cited therein]. This wide range would be consistent with a model, in which a prolonged history of melting events of parent ultramafic source rocks took place in the mantle. This variability is in agreement with the conclusion that the Os-isotope system of PGMs records multiple events during the chemical differentiation history of the mantle [3] and could have been controlled by deep-geodynamic processes [4]. On the other hand, the observed Os-isotope heterogeneity may be also attributed to the presence of subcontinental lithospheric mantle (SCLM), characterized by highly unradiogenic 187Os/188Os values (i.e.,

Badanina, Inna Yu.; Malitch, Kreshimir N.; Belousova, Elena A.; Lord, Richard A.; Meisel, Thomas C.; Murzin, Valery V.; Pearson, Norman J.

2014-05-01

176

Thermoelectric properties of the 0.05 wt.% SbI 3 -Doped n-Type Bi 2 (Te 0. 95 Se 0. 05 ) 3 alloy fabricated by the hot pressing method  

Microsoft Academic Search

Thermoelectric properties of the 0.05 wt.% SbI3-doped n-type Bi2(Teo.95Seo.o5)3 alloy, fabricated by hot pressing at temperatures ranging from 350C to 550C, were characterized. The electron concentration\\u000a of the alloy decreased as the hot pressing temperature increased due to the annealing-out of the excess Te vacancies. When\\u000a hot pressed at 350C, a figure-of-merit of 0.75x10-3\\/K was obtained due to the low

Sun Kyung Lee; Tae Sung Oh; Dow Bin Hyun; Chang Won Hwang

2000-01-01

177

Effects of Stoichiometry on Transformation Temperatures and Actuator-Type Performance of NiTiPd and NiTiPdX High-Temperature Shape Memory Alloys  

NASA Technical Reports Server (NTRS)

High-temperature shape memory NiTiPd and NiTiPdX (X=Au, Pt, Hf) alloys were produced with titanium equivalent (Ti+Hf) compositions of 50.5, 50.0, 49.5, and 49.0 at.%. Thermo-mechanical testing in compression was used to evaluate the transformation temperatures, transformation strain, work output, and permanent deformation behavior of each alloy to study the effects of quaternary alloying and stoichiometry on high-temperature shape memory alloy behavior. Microstructural evaluation showed the presence of second phases for all alloy compositions. No load transformation temperatures in the stoichiometric alloys were relatively unchanged by Au and Pt substitutions, while the substitution of Hf for Ti causes a drop in transformation temperatures. The NiTiPd, NiTiPdAu and NiTiPdHf alloys exhibited transformation temperatures that were highest in the Ti-rich compositions, slightly lower at stoichiometry, and significantly reduced when the Ti equivalent composition was less than 50 at.%. For the NiTiPdPt alloy, transformation temperatures were highest for the Ti-rich compositions, lowest at stoichiometry, and slightly higher in the Ni-rich composition. When thermally cycled under constant stresses of up to 300 MPa, all of the alloys had transformation strains, and therefore work outputs, which increased with increasing stress. In each series of alloys, the transformation strain and thus work output was highest for stoichiometric or Ti-rich compositions while permanent strain associated with the constant-load thermal cycling was lowest for alloys with Ni-equivalent-rich compositions. Based on these results, basic rules for optimizing the composition of NiTiPd alloys for actuator performance will be discussed.

Bigelow, Glen S.; Gaydosh, Darrell; Garg, Anita; Padula, Santo A., II; Noebe, Ronald D.

2007-01-01

178

Effects of alloy composition and processing on the microstructure of D-9 type stainless steel. Final report  

Microsoft Academic Search

The effects of composition modifications of Type 316 stainless steel on the constitution and microstructural stability during extended exposure to elevated temperature has been studied. Conventional TEM, (CTEM), Analytical TEM (STEM) and ultra-high resolution TEM have been used. It has been found that several relatively coarse, heterogeneously distributed constituents including Laves and G phases, TiN and MC can form in

M. Hwang; D. E. Laughlin; J. C. Williams

1983-01-01

179

The effect of current mode and discharge type on the corrosion resistance of plasma electrolytic oxidation (PEO) coated magnesium alloy AJ62  

Microsoft Academic Search

Magnesium alloys are increasingly being used as lightweight materials in the automotive, defense, electronics, biomaterial and aerospace industries. However, their inherently poor corrosion and wear resistance have, so far, limited their application. Plasma electrolytic oxidation (PEO) in an environmentally friendly aluminates electrolyte has been used to produce oxide coatings with thicknesses of ~80?m on an AJ62 magnesium alloy. Optical emission

R. O. Hussein; P. Zhang; X. Nie; Y. Xia; D. O. Northwood

180

Structural, magnetic and electronic state characterization of L1 0-type ordered FeNi alloy extracted from a natural meteorite.  

PubMed

To understand the hard magnetism of L10-type ordered FeNi alloy, we extracted the L10-FeNi phase from a natural meteorite, and evaluated its fundamental solid-state properties: sample composition, magnetic hysteresis, crystal structure and electronic structure. We executed multidirectional analyses using scanning electron microscopy with an electron probe micro-analyzer (SEM-EPMA), a superconducting quantum interference device (SQUID), x-ray diffraction (XRD) and magnetic circular dichroism (MCD). As a result, we found that the composition was Fe: 50.47 1.98 at.%, Ni: 49.60 1.49 at.%, and an obvious superlattice peak is confirmed. The estimated degree of order was 0.608, with lattice constants a = b = 3.582 and c = 3.607 . The obtained coercivity was more than 500 Oe. MCD analysis using the K absorption edge suggests that the magnetic anisotropy could originate from the orbital magnetic moment of 3d electrons in Fe; this result is consistent with that in a previous report obtained with synthetic L10-FeNi. PMID:24469025

Kotsugi, M; Maruyama, H; Ishimatsu, N; Kawamura, N; Suzuki, M; Mizumaki, M; Osaka, K; Matsumoto, T; Ohkochi, T; Ohtsuki, T

2014-02-12

181

Structural, magnetic and electronic state characterization of L1 0-type ordered FeNi alloy extracted from a natural meteorite  

NASA Astrophysics Data System (ADS)

To understand the hard magnetism of L10-type ordered FeNi alloy, we extracted the L10-FeNi phase from a natural meteorite, and evaluated its fundamental solid-state properties: sample composition, magnetic hysteresis, crystal structure and electronic structure. We executed multidirectional analyses using scanning electron microscopy with an electron probe micro-analyzer (SEM-EPMA), a superconducting quantum interference device (SQUID), x-ray diffraction (XRD) and magnetic circular dichroism (MCD). As a result, we found that the composition was Fe: 50.47 1.98 at.%, Ni: 49.60 1.49 at.%, and an obvious superlattice peak is confirmed. The estimated degree of order was 0.608, with lattice constants a = b = 3.582 and c = 3.607 . The obtained coercivity was more than 500 Oe. MCD analysis using the K absorption edge suggests that the magnetic anisotropy could originate from the orbital magnetic moment of 3d electrons in Fe; this result is consistent with that in a previous report obtained with synthetic L10-FeNi.

Kotsugi, M.; Maruyama, H.; Ishimatsu, N.; Kawamura, N.; Suzuki, M.; Mizumaki, M.; Osaka, K.; Matsumoto, T.; Ohkochi, T.; Ohtsuki, T.; Kojima, T.; Mizuguchi, M.; Takanashi, K.; Watanabe, Y.

2014-02-01

182

Improvement in Fatigue Strength of Biomedical ?-type Ti-Nb-Ta-Zr Alloy While Maintaining Low Young's Modulus Through Optimizing ?-Phase Precipitation  

NASA Astrophysics Data System (ADS)

The improvement in fatigue strength, with maintenance of a low Young's modulus, in a biomedical ?-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), by thermomechanical treatment was investigated. A short aging time at an ?-phase-forming temperature combined with severe cold rolling was employed. A fine ? phase is observed in TNTZ subjected to this thermomechanical treatment. Because the rolling texture of ? phase is formed by cold rolling, such as the ? phase may be preferentially oriented to a direction that is effective for inhibiting the increase in Young's modulus. The samples aged at 573 K (300 C) for 3.6 ks and 10.8 ks after cold rolling exhibit a good balance between a high tensile strength and low Young's modulus. In the case of the sample aged for 3.6 ks, the tensile strength is improved, although the fatigue strength is not improved significantly. Both the tensile strength and the fatigue strength of the sample aged for 10.8 ks are improved. This fatigue strength is the highest among the TNTZ samples used in the current and in previous studies with Young's moduli less than 80 GPa.

Nakai, Masaaki; Niinomi, Mitsuo; Oneda, Takahiro

2012-01-01

183

Enhanced thermoelectric performance in p-type BiSbTe bulk alloy with nanoinclusion of ZnAlO  

SciTech Connect

p-type BiSbTe/x wt % ZnAlO (x=0, 0.25, 0.5, 0.75, and 1.0) composites were prepared by zone melting method. A peak thermoelectric figure of merit (ZT) of 1.33 at 370 K was achieved for the sample with x=0.75, about 34% higher than that of BiSbTe at the same temperature, making these composites more attractive for commercial applications. This enhancement of ZT can be mainly ascribed to a remarkable increase of the electrical conductivity and a simultaneous decrease of the lattice thermal conductivity by the introduction of ZnAlO nanopowder.

Zhang Ting; Zhang Qiushi; Jiang Jun; Xiong Zhen; Chen Jianmin; Zhang Yulong; Li Wei; Xu Gaojie [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

2011-01-10

184

Enhanced thermoelectric performance in p-type BiSbTe bulk alloy with nanoinclusion of ZnAlO  

NASA Astrophysics Data System (ADS)

p-type BiSbTe/x wt % ZnAlO (x=0, 0.25, 0.5, 0.75, and 1.0) composites were prepared by zone melting method. A peak thermoelectric figure of merit (ZT) of 1.33 at 370 K was achieved for the sample with x=0.75, about 34% higher than that of BiSbTe at the same temperature, making these composites more attractive for commercial applications. This enhancement of ZT can be mainly ascribed to a remarkable increase of the electrical conductivity and a simultaneous decrease of the lattice thermal conductivity by the introduction of ZnAlO nanopowder.

Zhang, Ting; Zhang, Qiushi; Jiang, Jun; Xiong, Zhen; Chen, Jianmin; Zhang, Yulong; Li, Wei; Xu, Gaojie

2011-01-01

185

The response of shape memory alloy composites  

Microsoft Academic Search

A microstructural model that couples the local and global effects is employed to analyse the behavior of composite materials with shape memory alloy fibers. Both metallic matrices and resin matrix composites with embedded shape memory alloy fibers are considered. Since shape memory alloys form fibers with large diameter, this model is particularly suitable for the analysis of this type of

Jacob Aboudi

1997-01-01

186

Iridium alloy  

US Patent & Trademark Office Database

An iridium alloy consists essentially of iridium and at least one of W and Zr, and optionally Rh. When present, W comprises between 0.01 and 5 wt % of the alloy; when present in combination with W, Zr comprises between 0.01 and 0.5 wt % of the alloy; when present alone or in combination with Rh only, Zr comprises between 0.01 and 0.09 wt % of the alloy; and when present, Rh comprises between 0.1 and 5 wt % of the alloy. The alloys may be modified by the addition of platinum and other platinum group metals and base metals. The alloys demonstrate enhanced physical and chemical properties and are suitable for use as electrode materials in spark plugs and other high temperature applications.

2009-01-27

187

Method for providing ferritic-iron-based alloys  

US Patent & Trademark Office Database

A strengthened creep resistant ferritic iron alloy is provided by alloying the iron with two or more alloying metals of the type that form an intermediate Laves phase in the alloy having the composition Fe.sub.2 X, where X is the alloying metal. One of the alloying metals comprises one to five weight percent of tantalum and/or columbium while the other metal comprises one to eight weight percent of molybdenum and/or tungsten. The total of the Laves phase forming alloying metals is no more than ten weight percent in excess of that necessary to react with interstitial elements that may be added to the alloy.

1978-05-02

188

Effect of chromium content on stress corrosion cracking susceptibility of shielded metal arc weld metals for 600 type alloy in high-temperature pressurised pure water  

Microsoft Academic Search

The stress corrosion cracking (SCC) susceptibility of SMAW metals for Inconel alloy 600 to which Cr was added to 14.821.4 mass% has been investigated on the basis of a creviced bent beam test in pressurized hot water (corresponding to the service condition of boiling water reactor nuclear power plant), since the TIG weld metal of alloy 82 involving 1822 mass%

Satoru Nishikawa; Yukihiko Horii; Kenji Ikeuchi

2012-01-01

189

The influence of boron content on the structural and electrochemical properties of the La15Fe77B8-type hydrogen storage alloy  

NASA Astrophysics Data System (ADS)

La15Fe10-xNi70Mn5Bx (x=0, 1, 1.5, 2, 3) hydrogen storage alloys are prepared using a vacuum induction-quenching furnace. A structure analysis shows that the boron-free alloy is composed of a La0.99Mn0.32Ni4.71 phase and an (Fe, Ni) phase and that the alloys containing boron consist of the La0.99Mn0.32Ni4.71, (Fe, Ni) and La3Ni13B2 phases. As the x increase, the parameter a of the La0.99Mn0.32Ni4.71 and La3Ni13B2 phases increases, while the c decreases. The relative abundance of the La3Ni13B2 phase and the gather degree of the (Fe, Ni) phase increase with increasing x. Electrochemical testing shows that the boron content has an unapparent effect on the alloy electrodes' activation property. The maximum discharge capacity of the alloy electrodes is stable (approximately 310mAhg-1) when x increases from 0 to 2. The cycling capacity retention rate at the 50th cycle monotonically increases from 56.6% (x=0) to 76.7% (x=3). The high-rate dischargeability of the alloy electrodes first increases with increasing x from 0 to 1.5 and then decreases until x increases to 3. The HRD is controlled by the hydrogen diffusion rate in the bulk of the alloy (x=0-1.5) and the charge-transfer reaction of hydrogen on the alloy electrode surface (x=1.5-3).

Wang, Li; Yan, Huizhong; Xiong, Wei; Li, Baoquan; Li, Jin; Kong, Fanqing

190

Dot arrays of L1{sub 0}-type FePt ordered alloy perpendicular films fabricated using low-temperature sputter film deposition  

SciTech Connect

Using ultrahigh vacuum sputter film deposition, we fabricated L1{sub 0}-type Fe{sub 50}Pt{sub 50} ordered alloy perpendicular films on MgO(001) single-crystal substrates and 2.5 in. glass disks at low substrate temperatures of 200-350 deg. C. Then we examined the magnetic properties of the dot arrays made from these films. The uniaxial magnetic anisotropy K{sub u} for L1{sub 0}-type FePt films (10 nm in thickness) deposited with a Pd underlayer on MgO(001) substrates reached about 2 x 10{sup 7} erg/cm{sup 3} at the substrate temperature T{sub s} of 200 deg. C, and 3 x 10{sup 7} erg/cm{sup 3} at T{sub s} = 250 deg. C. The order parameter S was about 0.46 at T{sub s} = 300 deg. C. Moreover, K{sub u} for L1{sub 0}-FePt films fabricated on glass disks using MgO/Cr underlayers shows 3.4 x 10{sup 7} erg/cm{sup 3} at T{sub s} = 300 deg. C, which was almost equal to that for FePt single-crystal films deposited on Pd/MgO(001). The switching field distribution {sigma}/H{sub c} for dot arrays made from L1{sub 0}-FePt film [5 nm in thickness, on Pd/MgO(001) at T{sub s} = 250 deg. C] was small; {sigma}/H{sub c}= 0.11 for a dot diameter of 15 nm. This value was smaller than that of hcp-Co{sub 75}Pt{sub 25} dot arrays ({sigma}/H{sub c} = 0.18). The difference was mainly attributable to the degree of the easy axis distribution. This result demonstrates the homogeneous formation of a L1{sub 0}-type ordered structure in the FePt layers.

Shimatsu, T.; Aoi, H. [Research Institute of Electrical Communication, Tohoku University, Sendai, 980-8577 (Japan); Inaba, Y.; Kataoka, H. [Research Institute of Electrical Communication, Tohoku University, Sendai, 980-8577 (Japan); Fuji Electric Holdings, Co., Ltd., Matsumoto, 390-0821 (Japan); Sayama, J. [Central Research Laboratory, Hitachi, Ltd., Kanagawa, 256-8510 (Japan); Okamoto, S.; Kitakami, O. [Institute of Multidisciplinary Research for Advanced Material, Tohoku University, Sendai, 980-8577 (Japan)

2011-04-01

191

Heusler alloys  

Microsoft Academic Search

In 1903 F. Heusler reported that it was possible to make ferromagnetic alloys from non-ferromagnetic constituents copper-manganese bronze and group B elements such as aluminium and tin. Further investigations showed that the magnetic properties of these alloys are related to their chemical, L21, structure, and to the ordering of the manganese atoms on an f.c.c. sublattice.Heusler alloys are properly described

Peter J. Webster

1969-01-01

192

Crystal structure and electrochemical properties of rare earth non-stoichiometric AB5-type alloy as negative electrode material in Ni-MH battery  

NASA Astrophysics Data System (ADS)

The La 0.85Mg xNi 4.5Co 0.35Al 0.15 (0.05? x?0.35) system compounds have been prepared by arc melting method under Ar atmosphere. X-ray diffraction (XRD) analysis reveals that the as-prepared alloys have different lattice parameters and cell volumes. The electrochemical properties of these alloys have been studied through the charge-discharge recycle testing at different temperatures and discharge currents. It is found that the La 0.85Mg 0.25Ni 4.5Co 0.35Al 0.15 alloy electrode is capable of performing high-rate discharge. Moreover, it has very excellent electrochemical properties as negative electrode materials in Ni-MH battery at low temperature, even at -40C.

Zhang, Xinbo; Chai, Yujun; Yin, Wenya; Zhao, Minshou

2004-07-01

193

Stress corrosion of high strength aluminum alloys.  

NASA Technical Reports Server (NTRS)

An investigation has been carried out to examine the relationship of the observed chemical and mechanical properties of Al-Cu and Al-Zn-Mg alloys to the stress corrosion mechanisms which dominate in each case. Two high purity alloys and analogous commercial alloys were selected. Fundamental differences between the behavior of Al-Cu and of Al-Zn-Mg alloys were observed. These differences in the corrosion behavior of the two types of alloys are augmented by substantial differences in their mechanical behavior. The relative cleavage energy of the grain boundaries is of particular importance.

Cocks, F. H.; Brummer, S. B.

1972-01-01

194

Crystallization and Irradiation Effects in an Amorphous Alloy of the Type Fe sub 40 Ni sub 38 Mo sub 4 B sub 18.  

National Technical Information Service (NTIS)

The structure of an amorphous alloy of the composition Fe sub 40 Ni sub 38 Mo sub 4 B sub 18 either in the untreated fabricated state, or after various thermal treatments, or after irradiation with heavy ions was studied. The amorphous state is not modifi...

N. Azam L. Le Naour C. Rivera P. Grosjean P. Sacovy

1979-01-01

195

Optimum composition of a Bi{sub 2}Te{sub 3-x}Se{sub x} alloy for the n-type leg of a thermoelectric generator  

SciTech Connect

The reliability of determination of model parameters for the Bi{sub 2}Te{sub 3-x}Se{sub x} alloys is improved by extending the concentration and temperature ranges in experimental studies and, correspondingly, in calculations of kinetic coefficients based on the two-band model of the electronic spectrum. The obtained results served as a motivation for a study of the thermoelectric figure of merit for the above-mentioned alloys with x = 0.3, 0.45, and 0.6 and with the electron concentration varied in the range (1-50) x 10{sup 18} cm{sup -3} at temperatures 300-550 K. Comparison of the results showed that the highest efficiency is exhibited by the Bi{sub 2}Te{sub 2.7}Se{sub 0.3} alloy with the absolute value of the thermoelectric power of about 165 {mu}VK{sup -1} at 300 K, and the dimensionless efficiency is equal to 1.2 at 410 K. An appreciable decrease in thermal conductivity in alloys with x = 0.6 at 410 K is related to a larger band gap and could beneficially affect the figure of merit. However, the magnitude of this effect is found to be too small to compensate a decrease in electrical conductivity due to a large fraction of heavy electrons in the concentration and to a high content of selenium.

Prokofieva, L. V., E-mail: lprokofieva496@gmail.com; Pshenay-Severin, D. A.; Konstantinov, P. P.; Shabaldin, A. A. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2009-08-15

196

Growing Rate and the Type of Corrosion Products of Aluminium Alloy AA 5052 in Deionized Water at Temperature Up to 300 exp 0 C.  

National Technical Information Service (NTIS)

The process of corrosion concerning the aluminum alloy AA5052 in deionized water at temperatures of 40 exp 0 C, 80 exp 0 C, 90 exp 0 C, 140 exp 0 C, 200 exp 0 C and 280 exp 0 C is studied. The following methods are used: periodic weighting of the test sam...

E. G. Ferreira

1980-01-01

197

Effect of Mg and Sr additions on the formation of intermetallics in Al-6 wt pct Si-3.5 wt pct Cu-(0.45) to (0.8) wt pct Fe 319-type alloys  

SciTech Connect

Al-Si alloys are materials that have been developed over the years to meet the increasing demands of the automotive industry for smaller, lighter-weight, high-performance components. An important alloy in this respect is the 319 alloy, wherein silicon and copper are the main alloying elements, and magnesium is often added in automotive versions of the alloy for strengthening purposes. the mechanical properties are also ameliorated by modifying the eutectic silicon structure (strontium being commonly employed) and by reducing the harmful effect of the {beta}-Al{sub 5}FeSi iron intermetallic present in the cast structure. Magnesium is also found to refine the silicon structure. The present study was undertaken to investigate the individual and combined roles of Mg and Sr on the morphologies of Si, Mg{sub 2}Si, and the iron and copper intermetallics likely to form during the solidification of 319-type alloys at very slow (close to equilibrium) cooling rates. The results show that magnesium leads to the precipitation of Al{sub 8}Mg{sub 3}FeSi{sub 6}, Mg{sub 2}Si, and Al{sub 5}Mg{sub 8}Cu{sub 2}Si{sub 6} intermetallics. With a strontium addition, dissolution of a large proportion of the needle-like {beta}-Al{sub 5}FeSi intermetallic in the aluminum matrix takes place; no transformation of this phase into any other intermetallics (including the Al{sub 15}(Fe,Mn){sub 3}Si{sub 2} phase) is observed. When both Mg and Sr are added, the diminution of the {beta}-Al{sub 5}FeSi phase is enhanced, through both its dissolution in the aluminum matrix as well as its transformation into Al{sub 8}Mg{sub 3}FeSi{sub 6}. The reactions and phases obtained have been analyzed using thermal analysis, optical microscopy, image analysis, and electron microprobe analysis (EMPA) coupled with energy-dispersive X-ray (EDX) analysis.

Samuel, F.H.; Ouellet, P.; Samuel, A.M. [Univ. of Quebec, Chicoutimi, Quebec (Canada); Doty, H.W. [General Motors Corp., Milford, NH (United States)

1998-12-01

198

Shielding and Density of States in Alloys.  

National Technical Information Service (NTIS)

A relationship between the shielding of the ion-core potentials and the electron density of states rho(E,c) in disordered alloys of concentration c is shown. When one type of atom in a binary disordered alloy is replaced by another type of atom, there wil...

E. A. Stern

1971-01-01

199

Solid State Synthesis of Fe-B-Si Alloys.  

National Technical Information Service (NTIS)

Fe-B and Fe-B-Si elemental and intermetallic powders were synthesized by the mechanical alloying method. Vibratory and planetary type of ball mills were used. The alloying time and the alloying type in the results were investigated. The microstructure and...

P. Ruuskanen O. Heczko

1992-01-01

200

Solid State Synthesis of Fe-B-Si Alloys.  

National Technical Information Service (NTIS)

Fe-B and Fe-B-Si elemental and intermetallic powders were synthesized by mechanical alloying method. Vibratory and planetary type of ball mills were used in the tests. The alloying time and the alloying type in the results were investigated. The microstru...

P. Ruuskanen O. Heczko

1992-01-01

201

Aluminum alloy  

NASA Technical Reports Server (NTRS)

This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

Blackburn, Linda B. (inventor); Starke, Edgar A., Jr. (inventor)

1989-01-01

202

Influence of heat treatment on micro- structure of slurry aluminide coatings type TiAlSi obtained on TiAlCrNb alloy  

Microsoft Academic Search

Purpose: Influence of heat treatment on microstructural changes in slurry TiAlSi coating deposited with 12.5% Si concentration on Ti48Al2Cr2Nb intermetallic alloy and investigation of the influence of Si addition on the structure of obtained coatings is a purpose of this paper. Design\\/methodology\\/approach: The research allowed identifying microstructural changes that took place during annealing at 950C of the TiAlSi coating for

G. Moskal; B. Witala; A. Rozmys?owska

203

Some features of the conduction band structure, transport and optical properties of n-type Mg2Si-Mg2Sn alloys  

Microsoft Academic Search

Mg2SixSn1-x alloys are the perspective material for thermoelectric generators at moderate temperature. However the absence of reliable data on their band structure parameters does not permit to estimate a possible limit thermoelectric efficiency of these materials. According to the phase diagram there are two wide regions of solid solutions in pseudo-binary system Mg2SixSnl-x near the Mg2Si and Mg2Sn compounds. They

V. K. Zaitsev; M. I. Fedorov; A. T. Burkov; E. A. Gurieva; I. S. Eremin; P. P. Konstantinov; S. V. Ordin; S. Sano; M. V. Vedernikov

2002-01-01

204

Properties of the quaternary half-metal-type Heusler alloy Co{sub 2}Mn{sub 1-x}Fe{sub x}Si  

SciTech Connect

This paper reports on the bulk properties of the quaternary Heusler alloy Co{sub 2}Mn{sub 1-x}Fe{sub x}Si with the Fe concentration x=0,1/2,1. All samples, which were prepared by arc melting, exhibit L2{sub 1} long-range order over the complete range of Fe concentration. The structural and magnetic properties of the Co{sub 2}Mn{sub 1-x}Fe{sub x}Si Heusler alloys were investigated by means of x-ray diffraction, high- and low-temperature magnetometry, Moessbauer spectroscopy, and differential scanning calorimetry. The electronic structure was explored by means of high-energy photoemission spectroscopy at about 8 keV photon energy. This ensures true bulk sensitivity of the measurements. The magnetization of the Fe-doped Heusler alloys is in agreement with the values of the magnetic moments expected for a Slater-Pauling-like behavior of half-metallic ferromagnets. The experimental findings are discussed on the basis of self-consistent calculations of the electronic and magnetic structure. To achieve good agreement with experiment, the calculations indicate that on-site electron-electron correlation must be taken into account, even at low Fe concentration. The present investigation focuses on searching for the quaternary compound where the half-metallic behavior is stable against outside influences. Overall, the results suggest that the best candidate may be found at an iron concentration of about 50%.

Balke, Benjamin; Fecher, Gerhard H.; Kandpal, Hem C.; Felser, Claudia; Kobayashi, Keisuke; Ikenaga, Eiji; Kim, Jung-Jin; Ueda, Shigenori [Institut fuer Anorganische und Analytische Chemie, Johannes Gutenberg Universitaet, D-55099 Mainz (Germany); Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), Kouto 1-1-1, Mikaduki-cho, Sayou-gun, Hyogo, 679-5198 (Japan)

2006-09-01

205

Method of producing superplastic alloys and superplastic alloys produced by the method  

NASA Technical Reports Server (NTRS)

A method for producing new superplastic alloys by inducing in an alloy the formation of precipitates having a sufficient size and homogeneous distribution that a sufficiently refined grain structure to produce superplasticity is obtained after subsequent PSN processing. An age-hardenable alloy having at least one dispersoid phase is selected for processing. The alloy is solution heat-treated and cooled to form a supersaturated solid solution. The alloy is plastically deformed sufficiently to form a high-energy defect structure useful for the subsequent heterogeneous nucleation of precipitates. The alloy is then aged, preferably by a multi-stage low and high temperature process, and precipitates are formed at the defect sites. The alloy then is subjected to a PSN process comprising plastically deforming the alloy to provide sufficient strain energy in the alloy to ensure recrystallization, and statically recrystallizing the alloy. A grain structure exhibiting new, fine, equiaxed and uniform grains is produced in the alloy. An exemplary 6xxx alloy of the type capable of being produced by the present invention, and which is useful for aerospace, automotive and other applications, is disclosed and claimed. The process is also suitable for processing any age-hardenable aluminum or other alloy.

Troeger, Lillianne P. (Inventor); Starke, Jr., Edgar A. (Inventor); Crooks, Roy (Inventor)

2002-01-01

206

Effect of a microstructure and surface hydrogen alloying of a VT6 alloy on diffusion welding  

NASA Astrophysics Data System (ADS)

The effect of a structural type (lamellar, fine, gradient) and additional surface alloying with hydrogen on the diffusion bonding of titanium alloy VT6 samples is studied. It is shown that the surface alloying of VT6 alloy parts with hydrogen allows one to decrease the diffusion welding temperature by 50-100C, to obtain high-quality pore-free bonding, and to remove the "structural" boundary between materials to be welded that usually forms during welding of titanium alloys with a lamellar structure.

Senkevich, K. S.; Skvortsova, S. V.; Kudelina, I. M.; Knyazev, M. I.; Zasypkin, V. V.

2014-01-01

207

Disagglomeration in thixoformed wrought aluminium alloy 2014  

Microsoft Academic Search

Thixoforming is a type of semi-solid metal processing, which involves the processing of alloys in the semi-solid state. Disagglomeration of solid globules during thixoforming of wrought aluminium alloy 2014 was investigated by electron back-scatter diffraction. The recrystallisation and partial melting route was used to produce the thixotropic feedstock for thixoforming. The starting material was commercially extruded wrought aluminium alloy 2014

D. Liu; H. V. Atkinson; R. L. Higginson

2005-01-01

208

Effects of Li concentration and a Mg addition on serrated flow in Al-Li alloys  

Microsoft Academic Search

Serrated flow phenomena have been reported in a variety of precipitation-strengthened aluminum alloys. In the particular case of precipitation-strengthened Al-Li alloys, serrated flow effects of similar character have been reported in binary Al-Li alloys and in commercial-type Al-Li alloys containing multiple alloying elements. Observations of serrated flow in binary Al-Li alloys indicate that the presence of Li alone is sufficient

S. J. Zambo; J. A. Wert

1993-01-01

209

Bond Strength of Gold Alloys Laser Welded to Cobalt-Chromium Alloy  

PubMed Central

The objective of this study was to investigate the joint properties between cast gold alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of gold alloys (Type IV, Type II and low-gold) and a Co-Cr alloy. Each gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneously-welded groups showed inferior fracture load compared to corresponding control groups, except for Co-Cr. In the specimens welded heterogeneously to Co-Cr, Type IV was the greatest, followed by low-gold and Type II. There was no statistical difference (P<0.05) in fracture load between Type II control and that welded to Co-Cr. Higher elongations were obtained for Type II in all conditions, whereas the lowest elongation occurred for low-gold welded to Co-Cr. This study indicated that, of the three gold alloys tested, the Type IV gold alloy was the most suitable alloy for laser-welding to Co-Cr.

Watanabe, Ikuya; Wallace, Cameron

2008-01-01

210

VAl Alloy  

NASA Astrophysics Data System (ADS)

Power generation performance of a thermoelectric module consisting of the Heusler Fe2VAl alloy was evaluated. For construction of the module, W-doped Fe2VAl alloys were prepared using powder metallurgy process. Power generation tests of the module consisting of 18 pairs of p- n junctions were conducted on a heat source of 373-673 K in vacuum. The reduction of thermal conductivity and improvement of thermoelectric figure of merit by W-doping enhanced the conversion efficiency and the output power. High output power density of 0.7 W/cm2 was obtained by virtue of the high thermoelectric power factor of the Heusler alloy. The module exhibited good durability, and the relatively high output power was maintained after temperature cycling test in air.

Mikami, M.; Mizoshiri, M.; Ozaki, K.; Takazawa, H.; Yamamoto, A.; Terazawa, Y.; Takeuchi, T.

2014-06-01

211

Thermoelectric performance of nanostructured p-type Zr0.5Hf0.5Co0.4Rh0.6Sb1-xSnx half-Heusler alloys  

NASA Astrophysics Data System (ADS)

Several compositions of the p-type half-Heusler alloys Zr0.5Hf0.5Co0.4Rh0.6Sb1-xSnx (0?x?0.4) were synthesized by mechanically alloying high purity elemental powders using hardened steel jars and balls on a high energy shaker mill. Powder X-ray diffraction (XRD) investigations of several aliquots taken after regularly spaced milling time suggested that single phase products with half-Heusler (HH) structure can be obtained after 10 h. However, XRD and transmission electron microscopy (TEM) studies of several specimens obtained from compacted polycrystalline powders of Zr0.5Hf0.5Co0.4Rh0.6Sb1-xSnx alloys using a uniaxial hot press (HP) revealed the presence of CoSb inclusions with various sizes embedded inside the HH matrix. Hall effect, electrical conductivity, and thermopower data collected between 300 K and 775 K on several compositions suggested that electronic transport in the synthesized Zr0.5Hf0.5Co0.4Rh0.6Sb1-xSnx/CoSb composites strongly depends on the average size and/or mole fraction of the embedded CoSb inclusions rather than the fraction (x) of Sn substituting for Sb. Among the samples investigated, the nanocomposite with x=0.2, which contains nanometer-scale CoSb inclusions, showed the largest power factor (800 ?W/K2 m at 775 K) and the lowest lattice thermal conductivity (2.2 W/m K at 775 K) leading to a six-fold enhancement in the figure of merit when compared to the Zr0.5Hf0.5Co0.4Rh0.6Sb0.99Sn0.01 bulk matrix.

Maji, Pramathesh; Makongo, Julien P. A.; Zhou, Xiaoyuan; Chi, Hang; Uher, Ctirad; Poudeu, Pierre F. P.

2013-06-01

212

Comparison of Three Primary Surface Recuperator Alloys  

SciTech Connect

Extensive work performed by Capstone Turbine Corporation, Oak Ridge National Laboratory, and various others has shown that the traditional primary surface recuperator alloy, type 347 stainless steel, is unsuitable for applications above 650 C ({approx}1200 F). Numerous studies have shown that the presence of water vapor greatly accelerates the oxidation rate of type 347 stainless steel at temperatures above 650 C ({approx}1200 F). Water vapor is present as a product of combustion in the microturbine exhaust, making it necessary to find replacement alloys for type 347 stainless steel that will meet the long life requirements of microturbine primary surface recuperators. It has been well established over the past few years that alloys with higher chromium and nickel contents than type 347 stainless steel have much greater oxidation resistance in the microturbine environment. One such alloy that has replaced type 347 stainless steel in primary surface recuperators is Haynes Alloy HR-120 (Haynes and HR-120 are trademarks of Haynes International, Inc.), a solid-solution-strengthened alloy with nominally 33 wt % Fe, 37 wt % Ni and 25 wt % Cr. Unfortunately, while HR-120 is significantly more oxidation resistant in the microturbine environment, it is also a much more expensive alloy. In the interest of cost reduction, other candidate primary surface recuperator alloys are being investigated as possible alternatives to type 347 stainless steel. An initial rainbow recuperator test has been performed at Capstone to compare the oxidation resistance of type 347 stainless steel, HR-120, and the Allegheny Ludlum austenitic alloy AL 20-25+Nb (AL 20-25+Nb is a trademark of ATI Properties, Inc. and is licensed to Allegheny Ludlum Corporation). Evaluation of surface oxide scale formation and associated alloy depletion and other compositional changes has been carried out at Oak Ridge National Laboratory. The results of this initial rainbow test will be presented and discussed in this paper.

Matthews, Wendy [Capstone Turbines; More, Karren Leslie [ORNL; Walker, Larry R [ORNL

2010-01-01

213

Fabrication of Lotus-Type Porous Al-Si Alloys Using Thermal Decomposition Method Combined with Mold Casting and Continuous Casting Techniques  

NASA Astrophysics Data System (ADS)

Porous Al-Si alloys with directional pores were fabricated using thermal decomposition methods combined with mold casting and continuous casting techniques. The melt of Al-14 mass pct Si alloy was unidirectionally solidified in argon atmospheres by the mold casting or continuous casting technique. Ca(OH)2 compound was added into the melt as a source of hydrogen which forms pores during the solidification. In order to clarify the pore formation behavior, the effects of transfer velocity, ambient argon pressure, the amount, and the morphology of Ca(OH)2 compounds on the porosity were investigated. It was found that the porosity decreases with the increasing transfer velocity (solidification velocity). The pores are formed under the argon pressure of 1 kPa, while not being formed under the pressure higher than 20 kPa. The porosity increases with the increasing amount of Ca(OH)2 when the compacted Ca(OH)2 pellets are used, while pores are not formed when Ca(OH)2 powders are used because of the rapid decomposition of Ca(OH)2.

Kim, Tae Bum; Jung, Taek Kyun; Kim, Yong Hwan; Kim, Taek Soo; Hyun, Soong Keun

2013-05-01

214

Imparting passivity to vapor deposited magnesium alloys  

NASA Astrophysics Data System (ADS)

Magnesium has the lowest density of all structural metals. Utilization of low density materials is advantageous from a design standpoint, because lower weight translates into improved performance of engineered products (i.e., notebook computers are more portable, vehicles achieve better gas mileage, and aircraft can carry more payload). Despite their low density and high strength to weight ratio, however, the widespread implementation of magnesium alloys is currently hindered by their relatively poor corrosion resistance. The objective of this research dissertation is to develop a scientific basis for the creation of a corrosion resistant magnesium alloy. The corrosion resistance of magnesium alloys is affected by several interrelated factors. Among these are alloying, microstructure, impurities, galvanic corrosion effects, and service conditions, among others. Alloying and modification of the microstructure are primary approaches to controlling corrosion. Furthermore, nonequilibrium alloying of magnesium via physical vapor deposition allows for the formation of single-phase magnesium alloys with supersaturated concentrations of passivity-enhancing elements. The microstructure and surface morphology is also modifiable during physical vapor deposition through the variation of evaporation power, pressure, temperature, ion bombardment, and the source-to-substrate distance. Aluminum, titanium, yttrium, and zirconium were initially chosen as candidates likely to impart passivity on vapor deposited magnesium alloys. Prior to this research, alloys of this type have never before been produced, much less studied. All of these metals were observed to afford some degree of corrosion resistance to magnesium. Due to the especially promising results from nonequilibrium alloying of magnesium with yttrium and titanium, the ternary magnesium-yttrium-titanium system was investigated in depth. While all of the alloys are lustrous, surface morphology is observed under the scanning electron microscope. The corrosion rate of the nonequilibrium sputtered alloys, as determined by polarization resistance, is significantly reduced compared to the most corrosion resistant commercial magnesium alloys. The open circuit potentials of the sputter deposited alloys are significantly more noble compared to commercial, equilibrium phase magnesium alloys. Galvanic corrosion susceptibility has also been considerably reduced. Nonequilibrium magnesium-yttrium-titanium alloys have been shown to achieve passivity autonomously by alteration of the composition chemistry of the surface oxide/hydroxide layer. Self-healing properties are also evident, as corrosion propagation can be arrested after initial pitting of the material. A clear relationship exists between the corrosion resistance of sputter vapor deposited magnesium alloys and the amount of ion bombardment incurred by the alloy during deposition. Argon pressure, the distance between the source and the substrate, and alloy morphology play important roles in determining the ability of the alloy to develop a passive film. Thermal effects, both during and after alloy deposition, alter the stress state of the alloys, precipitation of second phases, and the mechanical stability of the passive film. An optimal thermal treatment has been developed in order to maximize the corrosion resistance of the magnesium-yttrium-titanium alloys. The significance of the results includes the acquisition of electrochemical data for these novel materials, as well as expanding the utilization of magnesium alloys by the improvement in their corrosion resistance. The magnesium alloys developed in this work are more corrosion resistant than any commercial magnesium alloy. Structural components comprised of these alloys would therefore exhibit unprecedented corrosion performance. Coatings of these alloys on magnesium components would provide a corrosion resistant yet galvanically-compatible coating. The broad impact of these contributions is that these new low-density, corrosion resistant magnesium alloys can be used to produce engine

Wolfe, Ryan C.

215

Orthodontic silver brazing alloys.  

PubMed

Orthodontic silver brazing alloys suffer from the presence of cadmium, excessive flow temperatures, and crevice corrosion on stainless steel. Seven alloys were examined. Two alloys contained cadmium. The lowest flow temperature observed was 629 degrees C for a cadmium alloy and 651 degrees C for two cadmium free alloys. Three alloys had corrosion resistance superior to the other solders. Addition of low melting temperature elements gallium and indium reduced flow temperature in some cases but produced brittleness in the brazing alloy. PMID:2576971

Brockhurst, P J; Pham, H L

1989-10-01

216

Improved mechanical properties of bulk glassy alloys containing spherical pores  

Microsoft Academic Search

For future extension of application fields for bulk glassy alloys, it is important to develop a new type of glassy alloys which exhibit simultaneously high strength, low Young's modulus, large elastic elongation, high ductility, high corrosion resistance, low density, high specific surface area, etc. Considering that bulk glassy alloys in non-ferrous metal base systems possess unique characteristics of high strength,

Akihisa Inoue; Takeshi Wada; Dmitri V. Louzguine-Luzgin

2007-01-01

217

Zincnickel alloy electrodeposits for water electrolysis  

Microsoft Academic Search

Electrodeposited zincnickel alloys of various compositions were prepared. A suitable electrolyte and conditions to produce alloys of various compositions were identified. Alloys produced on electroformed nickel foils were etched in caustic to leach out zinc and to produce the Raney type, porous electro catalytic surface for hydrogen evolution. The electrodes were examined by polarization measurements, to evaluate their Tafel parameters,

G. Sheela; Malathy Pushpavanam; S. Pushpavanam

2002-01-01

218

New alloys to conserve critical elements  

NASA Technical Reports Server (NTRS)

Based on availability of domestic reserves, chromium is one of the most critical elements within the U.S. metal industry. New alloys having reduced chromium contents which offer potential as substitutes for higher chromium containing alloys currently in use are being investigated. This paper focuses primarily on modified Type 304 stainless steels having one-third less chromium, but maintaining comparable oxidation and corrosion properties to that of type 304 stainless steel, the largest single use of chromium. Substitutes for chromium in these modified Type 304 stainless steel alloys include silicon and aluminum plus molybdenum.

Stephens, J. R.

1978-01-01

219

Influence of the Additives and The pH On the Cobalt-Molybdenum (Co-Mo) Alloy Electrodeposited On n-TypeSilicon  

NASA Astrophysics Data System (ADS)

In this work, thin films of metal alloys (Co-Mo) have been electrodeposited onto silicon (Si) surface. The effects of two different additives (H3BO3 and Na2CO3) and the pH of the solution on the electrochemically deposited films (morphology, stochiometry) have been investigated. The properties of the deposits were characterized by using X-Rays Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). The results show that the morphology and the film composition depend on both the pH of the solution and the additives. The presence of boric acid favors the Mo deposition. Crack-free homogeneous deposits with a low percentage of molybdenum can be easily obtained from high pH bath. The deposits were shown to exhibits a good crystalline structure.

Fekih, Z.; Ghellai, N.; Fortas, G.; Chiboub, N.; Sam, S.; Chabanne-sari, N. E.; Gabouze, N.

220

Castability, opaque masking, and porcelain bonding of 17 porcelain-fused-to-metal alloys.  

PubMed

Seventeen porcelain-fused-to-metal alloys, which represented a cross section of the various alloy types available, were evaluated for castability, opaque masking, and porcelain bond strength. The base metal alloys generally cast more completely than the noble alloys, with the presence of beryllium as an important factor for greater castability among the base metal alloys. Statistically significant differences were observed in the ability of an opaque porcelain to mask the different alloy substrates but no systematic effect of alloy type was observed. Porcelain bond testing revealed that nickel-chromium-beryllium alloys produced significantly better porcelain-metal bonds than nickel-chromium alloys without beryllium. In addition, it was found that palladium-copper alloys produced significantly better bonds with porcelain than palladium-cobalt alloys. PMID:8642521

O'Connor, R P; Mackert, J R; Myers, M L; Parry, E E

1996-04-01

221

High-resolution electron microscopy analysis of structural defects in a (2/1, 5/3)-type approximant of a decagonal quasicrystal of an Al-Pd-Mn alloy  

SciTech Connect

Structural defects were analyzed by means of high-resolution electron microscopy (HREM) in a crystalline (2/1, 5/3)-type Fibonacci approximant of an Al-Pd-Mn alloy system. A kind of stacking fault is observed with a projected displacement vector R parallel to the [{minus}3 0 29] direction; its amplitude {vert_bar}R{vert_bar} = 2a sin 18 deg = 1.19 nm, and its habit plane lies in the (1 0 1) plane. Two kinds of domain boundaries have been found and the domains are related by a 180 deg rotation around the c-axis plus a displacement along the [3 0 {minus}29] or the [{minus}3 0 {minus}29] direction in a plane perpendicular to the b-axis. The domain boundary planes are the {l_brace}1 0 1{r_brace} planes.

Yu, D.P.; Ren, G.; Zhang, Z. [Chinese Academy of Sciences, Beijing (China). Beijing Lab. of Electron Microscopy

1996-10-01

222

Environmental Cracking of Corrosion Resistant Alloys in the Chemical Process Industry - A Review  

SciTech Connect

A large variety of corrosion resistant alloys are used regularly in the chemical process industry (CPI). The most common family of alloys include the iron (Fe)-based stainless steels, nickel (Ni) alloys and titanium (Ti) alloys. There also other corrosion resistant alloys but their family of alloys is not as large as for the three groups mentioned above. All ranges of corrosive environments can be found in the CPI, from caustic solutions to hot acidic environments, from highly reducing to highly oxidizing. Stainless steels are ubiquitous since numerous types of stainless steels exist, each type tailored for specific applications. In general, stainless steels suffer stress corrosion cracking (SCC) in hot chloride environments while high Ni alloys are practically immune to this type of attack. High nickel alloys are also resistant to caustic cracking. Ti alloys find application in highly oxidizing solutions. Solutions containing fluoride ions, especially acid, seem to be aggressive to almost all corrosion resistant alloys.

Rebak, R B

2006-12-04

223

Serrated flow in gold-indium alloys  

Microsoft Academic Search

The characteristics of serrated flow in gold-indium solid solution alloys are studied over a range of strain rates and temperatures. Two types of serrations are distinguished, the general Type A locking serrations which are similar to those observed by Russell (1963) and the Type C unlocking serrations. The Type C serrations are restricted to a narrow temperature range at the

A. J. R. Soler-gomez; W. J. Mcg. Tegart

1969-01-01

224

Study on Improvement of Casting Conditions for Some Aluminum Bronze Alloys  

Microsoft Academic Search

Two types of aluminium bronze alloys have been studied to determine the proper methods of melting and casting in two different conditions; with treating materials as (Albral 2, Logas 50 and deoxidizing tube E3) and without and determine the effects of these conditions on mechanical properties of alloys. These alloys are :- a) Aluminium bronze alloys (AB1). b) Nickel-aluminium bronze

Sami A. Ajeel; Ahmed N. Ibrahiem; Abdul Salam; A. Fadhil

225

Relations between the modulus of elasticity of binary alloys and their structure  

NASA Technical Reports Server (NTRS)

A comprehensive survey of the elastic modulus of binary alloys as a function of the concentration is presented. Alloys that form continuous solid solutions, limited solid solutions, eutectic alloys, and alloys with intermetallic phases are investigated. Systems having the most important structures have been examined to obtain criteria for the relation between lattice structure, type of binding, and elastic behavior.

Koster, Werner; Rauscher, Walter

1951-01-01

226

Alloy softening in binary molybdenum alloys  

NASA Technical Reports Server (NTRS)

An investigation was conducted to determine the effects of alloy additions of Hf, Ta, W, Re, Os, Ir, and Pt on the hardness of Mo. Special emphasis was placed on alloy softening in these binary Mo alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to Mo, while those elements having an equal number or fewer s+d electrons than Mo failed to produce alloy softening. Alloy softening and hardening can be correlated with the difference in number of s+d electrons of the solute element and Mo.

Stephens, J. R.; Witzke, W. R.

1972-01-01

227

Fermi Level in Disordered Alloys.  

National Technical Information Service (NTIS)

The Fermi level or electrochemical potential mu is considered as a function of concentration in disordered alloys. In the case that the perturbation introduced by substituting one type of atom by another is localized around the site of substitution, mu is...

E. A. Stern

1971-01-01

228

Some correlations for duffusion in amorphous alloys  

SciTech Connect

Diffusion of several impurity atoms (Cu, Al, Au, and Sb) has been studied in Zr/sub 61/Ni/sub 39/ and Fe/sub 82/B/sub 18/ amorphous alloys. A definite correlation between the diffusion coefficient (D) and the atomic size of the diffusant is seen for the metal-metal (M-M) alloy, while it is not clear for the metal-metalloid (M-Me) alloy. Based on the present data, as well as other published data in binary amorphous alloys, empirical correlations have been found between (i) the activation energy (/ital Q/) and the energy required to form a hole of the size of the diffusing atom in the host alloy, and (ii) the pre-exponential factor (/ital D//sub 0/) and /ital Q/. While the former correlation is seen only for binary M-M type of amorphous alloys, the latter correlation is more general and holds for all types of amorphous alloys. Based on the correlation between /ital D//sub 0/ and /ital Q/, it is proposed that there are two distinct mechanisms of diffusion in amorphous alloys.

Sharma, S. K.; Banerjee, S.; Kuldeep; Jain, A. K.

1989-05-01

229

Superplastic behavior in a commercial 5083 aluminum alloy  

Microsoft Academic Search

When considering the forming and post-forming properties required of a superplastic material, attractive candidates are commercial Al-Mg-Mn weldable alloys such as AA5083. There have been several investigations of hot deformation of 5083-type alloys in the literature. Only two studies evaluated commercial-purity 5083 and they achieved tensile elongations of 150% and 200%. Alloy modification has produced improved behavior in three 5083-type

J. S. Vetrano; C. A. Lavender; M. T. Smith; S. M. Bruemmer; C. H. Hamilton

1994-01-01

230

Enhancement of p-type conduction in Ag-doped ZnO thin films via Mg alloying: The role of oxygen vacancy  

NASA Astrophysics Data System (ADS)

ZnO, ZnMgO, Ag-doped ZnO (ZnO:Ag), and Ag-doped ZnMgO (ZnMgO:Ag) thin films have been prepared by pulsed laser deposition. All the films have a preferred orientation with the c-axis perpendicular to the substrates. Hall-effect measurements indicate that the ZnO:Ag film exhibits p-type conduction, but obviously worse than that of the ZnMgO:Ag film. A comparative study of p-type ZnO:Ag and ZnMgO:Ag films using photoluminescence and x-ray photoelectron spectroscopy measurements shows that the enhanced p-type conduction in ZnMgO:Ag film is closely related to the increase of the activation energy of the intrinsic donors and the suppression of charge-compensating oxygen-related defects after Mg incorporation.

Cao, Ling; Zhu, Liping; Ye, Zhizhen

2013-05-01

231

Cutting efficiency of air-turbine burs on cast titanium and dental casting alloys  

Microsoft Academic Search

Objective: The purpose of this study was to investigate the cutting efficiency of air-turbine burs on cast free-machining titanium alloy (DT2F) and to compare the results with those for cast commercially pure (CP) Ti, Ti6Al4V alloy, and dental casting alloys.Methods: The cast metal (DT2F, CP Ti, Ti6Al4V, Type IV gold alloy and CoCr alloy) specimens were cut with air-turbine burs

I Watanabe; C Ohkubo; J. P Ford; M Atsuta; T Okabe

2000-01-01

232

On the Formation of non-metallic inclusions in fe-50 pct Ni type alloys by deoxidation with Mn, Si, and Al  

NASA Astrophysics Data System (ADS)

This investigation deals with deoxidation experiments in 30 g lab melts of Fe-50 pct Ni alloys. After deoxidation with different amounts of Mn, Si and Al and their combinations the samples were quenched into water at different times. Metallographic studies comprising light microscopy, scanning electron microscopy, electron microprobe and image analysis were performed. Classical nucleation theory was used for computation of the different supersaturation with oxygen or the deoxidant necessary for homogeneous nucleation. The different deoxidation reactions and the transformation of inclusions due to diffusion of oxygen, or the deoxidant, from or into the inclusions was treated for the different cases of deoxidation. Most deoxidation reactions take place within some seconds. The experimental results were to be used to estimate the pertinent interfacial tensions between the oxides and the melt and the values obtained for the different oxides seemed to be reasonable. The diffusional computations were successfully used for predicting the different transformations taking place. For example, in deoxidation with 0.03 pct Si the oxygen solubility is controlled by the equilibrium with liquid FeO ? SiO2. The time taken to reach equilibrium is determined by the number of inclusions and the particle size. In deoxidation with 0.1 pct Si or more, the equilibrium is controlled by SiO2 inclusions and the time taken to reach equilibrium, less than 1 s, is much shorter compared to the samples with 0.03 pct Si. The deoxidation reactions with aluminum were treated in the same way, and it was shown that the number of particles determined the time elapsing before equilibrium with respect to the formation of FeOAl2O3 or A12O3. It was further shown that transformation of primary liquid FeOAl2O3 with high contents of FeO into solid FeOAl2O3 was expected to occur within one second. However, the experiments showed that it took somewhat longer, due to formation of solid FeOAl2O3 around the liquid FeOAl2O3 inclusions, thereby preventing the diffusion of aluminum into the particles.

Fredriksson, Hasse; Hammar, rjan

1980-09-01

233

Advanced battery grid alloys  

Microsoft Academic Search

The alloys used in lead-acid batteries have changed markedly during the past five years. The problems in casting lead-calcium alloys have been overcome by the addition of aluminum to the alloys. The aluminum protects the alloys and prevents loss of calcium, yielding greatly improved grain structures and corrosion resistance. Concern about reduced water loss has led to a dramatic reduction

Prengaman

1984-01-01

234

Alloy optimization for PWR steam generator heat-transfer tubing  

Microsoft Academic Search

Several materials have been used for heat-transfer tubing in light water reactor steam generators, including Type 316 stainless\\u000a steel (a few early units in the late 1960s), Alloy 600MA (mill annealed), Alloy 600TT (thermally treated), Alloy 800Mod, and\\u000a the current preference, Alloy 690TT. The susceptibility of Alloy 600MA (Ni-16Cr-9Fe) to stress-corrosion cracking led to extensive\\u000a corrosion studies to select and

D. L. Harrod; R. E. Gold; R. J. Jacko

2001-01-01

235

Wetting of molybdenum by commercial brazing filler alloys  

SciTech Connect

Wettability tests have been conducted for each candidate filler alloy at several temperatures. A wetting index, which is a function of contact angle and braze alloy contact area, was determined for each filler alloy at each brazing temperature. The nature and extent of interaction between the brazing alloys and the molybdenum was also investigated. The microstructures of the braze alloys and the base metal were examined with optical metallography, scanning-electron microscopy, and electron microprobe techniques. Results of the present study are compared with results of a previous wettability study on type 304 stainless steel.

McDonald, M.M.; Keller, D.L.; Johns, W.L.

1986-01-01

236

Dresden 1 Radiation Level Reduction Program. Intergranular corrosion tests of sensitized Type304 stainless steel in Dow NS1, and stress corrosion cracking tests of Type304 stainless steel and carbon and low alloy steels in Dow copper rinse solution  

Microsoft Academic Search

Corrosion tests were performed to evaluate the extent of intergranular attack on sensitized Type-304 stainless steel by a proprietary Dow Chemical solvent, NS-1, which is to be used in the chemical cleaning of the Dresden 1 primary system. In addition, tests were performed to evaluate stress corrosion cracking of sensitized Type-304 stainless steel and post-weld heat-treated ASTM A336-F1, A302-B, and

1978-01-01

237

The Strain Rate Dependence of Three High Strength Naval Alloys.  

National Technical Information Service (NTIS)

The properties of three alloys were studied: a Type HY-80 steel, a Type HY-130 steel, and a titanium alloy: Ti-6211. (6Al 1Nb 0.8Mo 1Ta). These materials were subjected to a wide range of uniaxial tensile rates of straining at room temperature: static tes...

A. F. Conn S. L. Rudy S. C. Howard

1974-01-01

238

Effect of temperature on the susceptibility of VT6ch alloy to hydrogen embrittlement  

Microsoft Academic Search

Alloys of the VT6 type are used for parts operating in the temperature range from 450 -500C to cryogenic temperatures. At room temperature and below, alloys of this type can develop hydrogen embrittlement. This paper is devoted to the effect of hydrogen on the mechanical properties of the alloy for temperatures ranging from room to that of liquid helium.

B. A. Kolachev; N. N. Kondrashova; V. N. Skol'tsov; P. D. Drozdov

1996-01-01

239

Elaboration et Caracterisation de Nouveaux Alliages a Memoire de Forme Basse Temperature Type Cu-al-Be (Development and Characterization of Low Temperature Cu-Al-Be Shape Memory Alloys).  

National Technical Information Service (NTIS)

The dynamic characteristics of a Cu-Al-Be shape memory alloy are described. Addition of low percentages of berryllium to the alloy produces a significant drop in the temperature at which martensic transformation occurs. The percentages of the metals givin...

S. Belkahla

1990-01-01

240

Conduction mechanisms in p-type Pb{sub 1-x}Eu{sub x}Te alloys in the insulator regime  

SciTech Connect

Electrical resistivity measurements were performed on p-type Pb{sub 1-x}Eu{sub x}Te films with Eu content x = 4%, 5%, 6%, 8%, and 9%. The well-known metal-insulator transition that occurs around 5% at room temperature due to the introduction of Eu is observed, and we used the differential activation energy method to study the conduction mechanisms present in these samples. In the insulator regime (x > 6%), we found that band conduction is the dominating conduction mechanism for high temperatures with carriers excitation between the valence band and the 4f levels originated from the Eu atoms. We also verified that mix conduction dominates the low temperatures region. Samples with x = 4% and 5% present a temperature dependent metal insulator transition and we found that this dependence can be related to the relation between the thermal energy k{sub B}T and the activation energy {Delta}{epsilon}{sub a}. The physical description obtained through the activation energy analysis gives a new insight about the conduction mechanisms in insulating p-type Pb{sub 1-x}Eu{sub x}Te films and also shed some light over the influence of the 4f levels on the transport process in the insulator region.

Peres, M. L.; Rubinger, R. M.; Ribeiro, L. H.; Rubinger, C. P. L. [Departamento de Fisica e Quimica, Instituto de Ciencias Exatas, Universidade Federal de Itajuba, Itajuba, PB 50, MG CEP 37500-903 (Brazil); Ribeiro, G. M. [Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, Belo Horizonte, PB 702, MG CEP 30123-970 (Brazil); Chitta, V. A. [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, PB 66318, SP CEP 05315-970 (Brazil); Rappl, P. H. O.; Abramof, E. [Laboratorio Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos, PB 515, SP CEP 12201-970 (Brazil)

2012-06-15

241

Strain engineering of nanoscale Si P-type metal-oxide-semiconductor field-effect transistor devices with SiGe alloy integrated with contact-etch-stop layer stressors.  

PubMed

Strained-silicon (Si) has been incorporated into a leading nanoscale logic technology. By means of silicon-germanium (SiGe) alloy stressor embedded in source and drain (S/D) region, the performance of P-type metal-oxide-semiconductor field-effect transistors (PMOSFETs) is effectively enhanced. However, when a compressive contact-etch-stop layer (CESL) is combined, the stress interaction and relative impacts of SiGe stressor integrated with CESL on mobility enhancement has been little reported. Therefore, the research performs a three dimensional (3D) stress simulation evaluation based on finite element method (FEM) for PMOSFETs with S/D SiGe stressor and compressive CESL. The proposed simulation methodology is validated as compared with other technological literatures. In additions, the gate width dependency is systematically discussed to explore the stress effects on devices. The analysis results indicate that a -2.6 GPa CESL would continue boosting the stress magnitude on Si channel region except for a gate width smaller than 50 nm. The results are useful for nanoscale transistor while selecting a proper CESL in the manufacturing processes of advanced logic technologies. PMID:22966579

Lee, Chang-Chun

2012-07-01

242

High figure-of-merit n-type SiGe/GaP alloys. [used in thermoelectric devices for space applications  

NASA Technical Reports Server (NTRS)

Improvements to the figure-of-merit of n-type SiGe have been achieved via a systematic anneal study aimed at determining the optimal P:Ga ratio. Figures-of-merit of 0.85 to 0.90 x 10-3K-1 have been routinely and reproducibly achieved starting with an initial P:Ga ratio of 3:1. These samples have carrier concentrations in excess of 4.0 x 1020/cu cm, the highest reported for SiGe. This value has been shown to be too high, resulting in unfavorably low Seebeck coefficients. The optimal carrier concentration has been shown to be 1.5-3.0 x 1020/cu cm. Thus, further improvements will be achieved by reductions in the P and Ga concentrations.

Scoville, A. N.; Bajgar, Clara; Vandersande, Jan; Fleurial, Jean-Pierre

1991-01-01

243

Resistance Butt Welding of Zirconium Alloy Material  

Microsoft Academic Search

Zirconium alloy is the main structural material used in the nuclear fuel production. This material has distinct advantages like less thermal neutron absorption cross-section and better chemical and mechanical properties for the reactor-working conditions. This material is widely used in boiling water and heavy water type reactors. Natural Uranium Dioxide (UO2) pellets are loaded into thin wall zirconium alloy tubes

D. S. Setty; Reddy P. Ravinder; A. L. N. Murthy

2008-01-01

244

The morphology of martensite in iron alloys  

Microsoft Academic Search

Light and electron microscopy have been used to determine the main structural differences between the two major types of martensite\\u000a in ferrous alloys. In the martensite that forms in dilute alloys of iron, the basic transformation unit takes the shape of\\u000a a lath, and hence the term lath martensite is appropriate for identifying this morphology. Each lath is the result

G. Krauss; A. R. Marder

1971-01-01

245

Development of a carburizing stainless steel alloy  

Microsoft Academic Search

A new carburizing stainless steel alloy that resists corrosion, heat, and fatigue has been developed for bearing and gear applications. Pyrowear 675 Stainless alloy is vacuum induction melted and vacuum arc remelted (VIM\\/VAR) for aircraft-quality cleanliness. Test results show that it has corrosion resistance similar to that of AISI Type 440-C stainless, and its rolling fatigue resistance is superior to

Wert

1994-01-01

246

Corrosion Testing of Ni Alloy HVOF Coatings in High Temperature Environments for Biomass Applications  

NASA Astrophysics Data System (ADS)

This paper reports the corrosion behavior of Ni alloy coatings deposited by high velocity oxyfuel spraying, and representative boiler substrate alloys in simulated high temperature biomass combustion conditions. Four commercially available oxidation resistant Ni alloy coating materials were selected: NiCrBSiFe, alloy 718, alloy 625, and alloy C-276. These were sprayed onto P91 substrates using a JP5000 spray system. The corrosion performance of the coatings varied when tested at ~525, 625, and 725 C in K2SO4-KCl mixture and gaseous HCl-H2O-O2 containing environments. Alloy 625, NiCrBSiFe, and alloy 718 coatings performed better than alloy C-276 coating at 725 C, which had very little corrosion resistance resulting in degradation similar to uncoated P91. Alloy 625 coatings provided good protection from corrosion at 725 C, with the performance being comparable to wrought alloy 625, with significantly less attack of the substrate than uncoated P91. Alloy 625 performs best of these coating materials, with an overall ranking at 725 C as follows: alloy 625 > NiCrBSiFe > alloy 718 ? alloy C-276. Although alloy C-276 coatings performed poorly in the corrosion test environment at 725 C, at lower temperatures (i.e., below the eutectic temperature of the salt mixture) it outperformed the other coating types studied.

Paul, S.; Harvey, M. D. F.

2013-03-01

247

Characterization of Brazing Alloys with Stainless Steels.  

National Technical Information Service (NTIS)

To simulate braze joints, qualitative x-ray mapping of the elemental interactions between brazing alloys and two common types of stainless steels was performed via the electron microprobe. In general both steels, Types 304L and 21-6-9, react with a partic...

D. H. Riefenberg J. H. Doyle R. F. Hillyer W. S. Bennett

1975-01-01

248

Extrusion of Almgsi Alloys.  

National Technical Information Service (NTIS)

Contents: Influence of the composition and structure on the behavior of aluminum-magnesium-silicon alloys on surface treatment, resistance to corrosion of aluminum-magnesium-silicon alloys; influence of the composition on the mechanical properties of alum...

G. E. Gardam

1966-01-01

249

The effect of alloy composition on the localized corrosion behavior of nickel-chromium-molybdenum alloys  

NASA Astrophysics Data System (ADS)

Ni-Cr-Mo alloys are one of the most versatile Ni-based alloys because they resist corrosion in a variety of environments. This versatility is due to the combination of Cr and Mo additions to the alloy. These alloying elements complement each other in producing a highly corrosion resistant alloy. The concentration of the elements in the alloy establishes the corrosion behavior of these alloys. In this study, Ni-Cr-Mo alloys with varying composition were studied using electrochemical methods. The dependency of pitting corrosion on the alloy chemistry was captured in empirical models that roughly rank the pitting susceptibility of the Ni-Cr-Mo alloys studied. The same type of model was also constructed for capturing the effect of alloy composition on the repassivation potential. It was found that these models were specific in terms of alloying element effects on the type of environments exposed to the alloys particularly, pH and temperature. The addition of chromium was shown to contribute to the higher pitting potential on the Ni-Cr-Mo alloys in neural chloride environment while molybdenum was dominant in acidified chloride solutions. In regards to the repassivation potential, both chromium and molybdenum affect the repassivation potential more or less evenly in neutral pH solutions. Under low pH high temperature conditions, molybdenum content has a greater effect on the repassivation potential value than chromium. Stabilization of localized corrosion is increasingly difficult as alloying element content increases. However, metastable pitting occurs in most alloys and the metastable pitting behavior of several Ni-Cr-Mo alloys was studied through potentiostatic analysis. Higher chromium and molybdenum contents decreased the metastable pitting incidence; although, the effect of Mo content was observed to be more dominant. Molybdenum additions were found to suppress the growth of the metastable pits. The growth rate of the fastest growing pits was also reduced by increasing the Mo content. Chromium affects the metastable pits during the repassivation process where higher Cr content produces faster repassivation rates. The last part of the study addressed the role of alloying additions on the repassivation behavior of Ni-Cr-Mo alloys. Alloys with similar Mo content but higher Cr or higher Ni contents exhibited higher repassivation potentials. Higher Mo-containing alloys were shown to be very corrosion resistant since they did not experience any localized corrosion after rigorous polarization tests given that enough Cr was present. The repassivation potential was determined by the surface overpotential and thermodynamic contribution. XPS analysis found evidence of Cr(III) oxide as the main passivating agent. Molybdenum species primarily Mo(VI) and Cr(III) hydroxide were detected on the crevice attack area and on layer of films that formed from transpassive dissolution of higher Cr or higher Mo-containing alloys.

Wong, Fariaty

250

High thermoelectric properties of p-type pseudobinary (Cu4Te3)x-(Bi0.5Sb1.5Te3)1-x alloys prepared by spark plasma sintering  

NASA Astrophysics Data System (ADS)

Cu4Te3 substituted (Cu4Te3)x-(Bi0.5Sb1.5Te3)1-x (x=0-0.2) alloys were prepared using spark plasma sintering technique and their thermoelectric properties were evaluated. Measurements show that the alloy with x=0.025 reveals very high electrical conductivity and low lattice thermal conductivity, the Seebeck coefficient that increases linearly with temperature is dependent on Cu4Te3 concentration. The maximum ZT value of 1.26 for the alloy with x=0.025 is achieved at 474 K, whereas that of the state-of-the-art thermoelectric material Bi0.5Sb1.5Te3 is only 0.58 at 318 K, thus indicating that the currently prepared pseudobinary alloy is very encouraging.

Cui, Jiaolin; Xiu, Weijie; Xue, Haifeng

2007-06-01

251

Nanobelts in multicomponent aluminum alloys  

NASA Astrophysics Data System (ADS)

High density of nanobeltlike precipitates has been observed in an Al-Si-Mg-Hf-Y alloy after heat treatments. Quantitative analysis in scanning transmission electron micrscopy (TEM) shows that the precipitates contain Hf, Si, and some Al. The precipitates have an orthorhombic structure which has been revealed by high-resolution TEM and electron diffraction. The precipitates have been identified to be of the Si2Hf-type phase.

Jia, Z. H.; Arnberg, L.

2008-09-01

252

Microstructural studies on rapidly solidified alloy 600  

SciTech Connect

Rapid solidification processing (RSP) is known to generate unusual microstructures which may be associated with several superior properties as compared with the conventionally processed materials. Due to its many desirable effects on microstructure, RSP is being increasingly used in the processing of many types of alloys, including the nickel based superalloys. It has been observed that in the precipitation hardenable nickel base superalloys, like Alloy 625, the excess vacancy concentration in the RSP microstructure not only accelerates the kinetics of formation of the desirable strengthening precipitate phase during aging but also brings about a relatively rapid coarsening of these particles and promotes the precipitation of the comparatively undesirable equilibrium phases. In some alloys it has been observed that the precipitation reaction in the RSP microstructure differs from that in the conventionally processed microstructure and leads to the formation of a different structure and or morphology of the precipitate phase. It is interesting to compare the microstructure of the conventionally processed and the RSP microstructure in solid solution strengthened alloys such as Alloy 600. In the present work, the RSP microstructure of the commercial, nickel base wrought superalloy, Alloy 600 has been compared with the microstructure of the conventionally processed and solution treated alloy.

Dey, G.K. [Univ. of Cincinnati, OH (United States). Dept. of Materials Science and Engineering] [Univ. of Cincinnati, OH (United States). Dept. of Materials Science and Engineering; Srivastava, D.; Sundararaman, M. [Bhabha Atomic Research Center, Bombay (India). Metallurgy Div.] [Bhabha Atomic Research Center, Bombay (India). Metallurgy Div.

1996-02-15

253

Microstructure and mechanical property of the fusion boundary region in an Alloy 182-low alloy steel dissimilar weld joint  

Microsoft Academic Search

Characterizations of the microstructure and mechanical property of the fusion boundary region of an Alloy 182-A533B low alloy\\u000a steel (LAS) dissimilar weld joint were conducted. The existence of type-II boundary that parallels to the fusion boundary\\u000a in the dilution zone (DZ) of Alloy 182 within a distance of about 50 ?m was observed. The chemical composition transition\\u000a was found in

J. Hou; Q. J. Peng; Y. Takeda; J. Kuniya; T. Shoji; J. Q. Wang; E.-H. Han; W. Ke

2010-01-01

254

Evaluation of alternative alloys for PWR steam generator tubing. Final report  

SciTech Connect

This final report summarizes the results of a project to evaluate alternative alloys for use as PWR steam generator tubing. A literature survey identified alloys 690 and 800 in the mill annealed condition and alloys 600 and 690 after annealing at 705/sup 0/C (1300/sup 0/F) for 15 hours as candidate alloys. Mill annealed alloy 600 was included as a control. C-ring tests were carried out in four secondary and one primary water environment. In the mill annealed condition, alloy 800 was more resistant to stress corrosion cracking than alloys 600 and 690. A low temperature anneal at 705/sup 0/C (1300/sup 0/F) improved the stress corrosion resistance of all the alloys. The greatest improvement was noted in alloy 690 where no failures were observed in any of the specimens even after annealing for only 4 hours. A test technique was developed to examine the stress corrosion behavior of a material by slowly internally pressurizing a section of tubing while the exterior was exposed to a simulated steam generator environment. Cracking of all alloys tested could be initiated in less than 20 days. The results indicate that alloy 600 and alloy 690 given a low temperature anneal at 705/sup 0/C (1300/sup 0/F) for 15 hours are more resistant to stress corrosion cracking than either mill annealed alloy 600 or mill annealed alloy 800. The degree of susceptibility of an alloy in this type of test may be dependent on pressurization rate.

Nelson, J.L.; Floreen, S.

1984-10-01

255

Development of a carburizing stainless steel alloy  

SciTech Connect

A new carburizing stainless steel alloy that resists corrosion, heat, and fatigue has been developed for bearing and gear applications. Pyrowear 675 Stainless alloy is vacuum induction melted and vacuum arc remelted (VIM/VAR) for aircraft-quality cleanliness. Test results show that it has corrosion resistance similar to that of AISI Type 440-C stainless, and its rolling fatigue resistance is superior to that of AISI M50 (UNS K88165). In contrast to alloy gear steels and Type 440C, Pyrowear 675 maintains case hardness of HRC 60 at operating temperatures up to 200 C (400 F). Impact and fracture toughness are superior to that of other stainless bearing steels, which typically are relatively brittle and can break under severe service. Toughness is also comparable or superior to conventional noncorrosion-resistant carburizing bearing steels, such as SAE Types 8620 and 9310.

Wert, D.E. (Carpenter Technology Corp., Reading, PA (United States))

1994-06-01

256

Hydrogen permeation characteristics of Incoloy 907 alloy  

SciTech Connect

The problem of brittle fracture induced by hydrogen ingress from environment must be considered for some high-strength alloys, particularly for the superalloys strengthened by [gamma][prime] precipitation, used in fields such as aerospace and nuclear power. Therefore, a number of studies on hydrogen performance of superalloys have been recently carried out. The understanding of hydrogen transport characteristics in these alloys is important to clarify the hydrogen embrittlement mechanism. Although hydrogen permeabilities and diffusivities of some superalloys have been reported, the study of the hydrogen permeation and diffusion in Incoloy 907 alloy, a type of Fe-Ni-Co based superalloy, is still absent to date. In the present work, a gaseous permeation technique was employed to measure hydrogen permeability and diffusivity in this alloy, in order to understand the relationship between hydrogen permeation and microstructure.

Xu, J.; Sun, X.K.; Liu, Q.Q.; Zhao, X.; Fan, C.G. (Inst. of Metal Research, Shenyang (China))

1993-05-15

257

Environmental embrittlement in ordered intermetallic alloys  

SciTech Connect

Ordered intermetallics based on aluminides and silicides possess many promising properties for elevated-temperature applications; however, poor fracture resistance and limited fabricability restrict their use as engineering material. Recent studies have shown that environmental embrittlement is a major cause of low ductility and brittle fracture in many ordered intermetallic alloys. There are two types of environmental embrittlement observed in intermetallic alloys. One is hydrogen-induced embrittlement occurring at ambient temperatures in air. The other is oxygen-induced embrittlement in oxidizing atmospheres at elevated temperatures. In most cases, the embrittlements are due to a dynamic effect involving generation and penetration of embrittling agents (i.e., hydrogen or oxygen ) during testing. Diffusion of embrittling agents plays a dominant role in fracture of these intermetallic alloys. This chapter summarizes recent progress in understanding and reducing environmental embrittlement in these alloys.

Liu, C.T. [Oak Ridge National Lab., TN (United States); Stoloff, N.S. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Materials Engineering

1992-12-31

258

Production and welding technology of some high-temperature nickel alloys in relation to their properties  

SciTech Connect

The most effective matching of alloys to the needs of advanced high-temperature gas-cooled reactors requires not only a knowledge of material properties, but also some understanding of the inherent general characteristics of this type of alloy. Some of the characteristic features of high-temperature nickel-based alloys are explored and general guidelines offered for their most effective use. Examples are drawn from three commercial materials: Inconel alloy 617, Incoloy alloy 800H, and Nimonic alloy 86. Such items as hot and cold working, heat treating, welding, and mechanical properties are considered.

Bassford, T.H.; Hosier, J.C.

1984-07-01

259

High strength alloys  

DOEpatents

High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

2010-08-31

260

High temperature mechanical properties of a zirconium-modified, precipitation- strengthened nickel, 30 percent copper alloy  

NASA Technical Reports Server (NTRS)

A precipitation-strengthened Monel-type alloy has been developed through minor alloying additions of zirconium to a base Ni-30Cu alloy. The results of this exploratory study indicate that thermomechanical processing of a solution-treated Ni-30Cu-0.2Zr alloy produced a dispersion of precipitates. The precipitates have been tentatively identified as a Ni5Zr compound. A comparison of the mechanical properties, as determined by testing in air, of the zirconium-modified alloy to those of a Ni-30Cu alloy reveals that the precipitation-strengthened alloy has improved tensile properties to 1200 K and improved stress-rupture properties to 1100 K. The oxidation characteristics of the modified alloy appeared to be equivalent to those of the base Ni-30Cu alloy.

Whittenberger, J. D.

1974-01-01

261

Development of new metallic alloys for biomedical applications.  

PubMed

New low modulus ?-type titanium alloys for biomedical applications are still currently being developed. Strong and enduring ?-type titanium alloy with a low Young's modulus are being investigated. A low modulus has been proved to be effective in inhibiting bone atrophy, leading to good bone remodeling in a bone fracture model in the rabbit tibia. Very recently ?-type titanium alloys with a self-tunable modulus have been proposed for the construction of removable implants. Nickel-free low modulus ?-type titanium alloys showing shape memory and super elastic behavior are also currently being developed. Nickel-free stainless steel and cobalt-chromium alloys for biomedical applications are receiving attention as well. Newly developed zirconium-based alloys for biomedical applications are proving very interesting. Magnesium-based or iron-based biodegradable biomaterials are under development. Further, tantalum, and niobium and its alloys are being investigated for biomedical applications. The development of new metallic alloys for biomedical applications is described in this paper. PMID:22765961

Niinomi, Mitsuo; Nakai, Masaaki; Hieda, Junko

2012-11-01

262

Grain boundary segregation in the Ni-base alloy 182  

Microsoft Academic Search

Grain boundary segregation is often considered to play a role in the various types of intergranular failures observed in austenitic alloys. However, there has been little direct study of this segregation because it is usually very difficult to obtain intergranular fracture in these alloys in the high vacuum required for surface analysis. This paper reports an Auger electron spectroscopy study

C. L. Briant

1988-01-01

263

Low melting carat gold brazing alloys for jewellery manufacture  

Microsoft Academic Search

The Au-Ag-Ge-Si system has been investigated as a source of cadmium-free low melting carat gold hard solders but alloys of\\u000a this type have been found to have restricted applicability. In particular, when applied to copper-containing alloys, brittle\\u000a copper germanides and silicides are formed.

G. Zwingmann

1978-01-01

264

Thermal analysis during solidification of cast AlSi alloys  

Microsoft Academic Search

Solidification of a series of aluminium alloys was studied by means of thermal analysis; the study was centred on the effect that silicon and iron exert on the temperatures for the onset of different microstructural characteristics. The alloys were prepared in a gas fired furnace and were poured into graphite moulds instrumented with a type K thermocouple. The cooling curve

A. A. Canales; J. Talamantes-Silva; D. Gloria; S. Valtierra; R. Cols

2010-01-01

265

Braze alloy holds bonding strength over wide temperature range  

NASA Technical Reports Server (NTRS)

Copper-based quaternary alloys of the solid solution type is used for vacuum furnace brazing of large stainless steel components at a maximum temperature of 1975 deg F. The alloy has high bonding strength and good ductility over a temperature range extending from the cryogenic region to approximately 800 deg F.

1966-01-01

266

Creep Resistant Zinc Alloy  

SciTech Connect

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.

Frank E. Goodwin

2002-12-31

267

Advanced battery grid alloys  

SciTech Connect

The alloys used in lead-acid batteries have changed markedly during the past five years. The problems in casting lead-calcium alloys have been overcome by the addition of aluminum to the alloys. The aluminum protects the alloys and prevents loss of calcium, yielding greatly improved grain structures and corrosion resistance. Concern about reduced water loss has led to a dramatic reduction in the antimony content of battery grid alloys to levels of less than 2% Sb. New, very low antimony alloys which can be handled or conventional or continuous casting equipment have increased conductivity, reduced corrosion rates, reduced self-discharge and reduced gassing rates compared to conventional 3-5% alloys, but retain the ability to recover from deep discharge.

Prengaman, R.D.

1984-10-01

268

Braze alloy spreading on steel  

NASA Technical Reports Server (NTRS)

Scanning electron microscopy (SEM) and Auger electron microscopy (AEM) were employed to observe elemental surface decomposition resulting from the brazing of a copper-treated steel. Two types of steel were used for the study, stainless steel (treated with a eutectic silver-copper alloy), and low-carbon steel (treated with pure copper). Attention is given to oxygen partial pressure during the processes; a low enough pressure (8 x 10 to the -5th torr) was found to totally inhibit the spreading of the filler material at a fixed heating cycle. With both types of steel, copper treatment enhanced even spreading at a decreased temperature.

Siewert, T. A.; Heine, R. W.; Lagally, M. G.

1978-01-01

269

Spin Hall and spin Nernst effect in dilute ternary alloys  

NASA Astrophysics Data System (ADS)

We report on ab initio studies of the spin Hall and spin Nernst effect in dilute ternary alloys. Our calculations are performed for a Cu host with different types of substitutional impurities. The obtained numerical results are well approximated by Matthiessen's rule relying on the constituent binary alloys. We show that the spin Nernst effect can be significantly more efficient in a ternary alloy with respect to the related binary alloys. Together with the application of Matthiessen's rule this opens an easy way to design materials for spintronics applications.

Tauber, Katarina; Fedorov, Dmitry V.; Gradhand, Martin; Mertig, Ingrid

2013-04-01

270

Effects of Co and W alloying elements on the electrodeposition aspects and properties of nanocrystalline Ni alloy coatings  

Microsoft Academic Search

Depending on deposition current density and alloying elements, various types of surface structure (surface morphology and grain orientation) were observed for Ni and Ni alloy nanocrystalline coatings. It was found that the variation of surface morphology with current density is in a good agreement with the variation of grain orientation. An increase in the current density produced larger grains and

M. A. Farzaneh; M. R. Zamanzad-Ghavidel; K. Raeissi; M. A. Golozar; A. Saatchi; S. Kabi

2011-01-01

271

Creep crack growth behavior of several structural alloys  

NASA Astrophysics Data System (ADS)

Creep crack growth behavior of several high temperature alloys, Inconel 600, Inconel 625, Inconel X-750, Hastelloy X, Nimonic PE-16, Incoloy 800, and Haynes 25 (HS-25) was examined at 540, 650, 760, and 870 C. Crack growth rates were analyzed in terms of both linear elastic stress intensity factor and J*-integral parameter. Among the alloys Inconel 600 and Hastelloy X did not show any observable crack growth. Instead, they deformed at a rapid rate resulting in severe blunting of the crack tip. The other alloys, Inconel 625, Inconel X-750, Incoloy 800, HS-25, and PE-16 showed crack growth at one or two temperatures and deformed continuously at other temperatures. Crack growth rates of the above alloys in terms ofJ* parameter were compared with the growth rates of other alloys published in the literature. Alloys such as Inconel X-750, Alloy 718, and IN-100 show very high growth rates as a result of their sensitivity to an air environment. Based on detailed fracture surface analysis, it is proposed that creep crack growth occurs by the nucleation and growth of wedge-type cracks at triple point junctions due to grain boundary sliding or by the formation and growth of cavities at the boundaries. Crack growth in the above alloys occurs only in some critical range of strain rates or temperatures. Since the service conditions for these alloys usually fall within this critical range, knowledge and understanding of creep crack growth behavior of the structural alloys are important.

Sadananda, K.; Shahinian, P.

1983-07-01

272

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

NASA Technical Reports Server (NTRS)

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.

Holanda, R.

1984-01-01

273

Superplastic behavior in a commercial 5083 aluminum alloy  

SciTech Connect

When considering the forming and post-forming properties required of a superplastic material, attractive candidates are commercial Al-Mg-Mn weldable alloys such as AA5083. There have been several investigations of hot deformation of 5083-type alloys in the literature. Only two studies evaluated commercial-purity 5083 and they achieved tensile elongations of 150% and 200%. Alloy modification has produced improved behavior in three 5083-type alloys developed specifically for SPF. Two were deemed high-purity 5083 (low Fe and Si) and achieved elongations of 450% and 630%. Engineering strains up to 700% were measured by Watanabe et al. in a 5083-based alloy with the addition of 0.6% Cu as a grain refiner. These results suggest that alloy modifications such as reduced Fe and Si contents or Cu additions may be required to improve superplastic response. Unfortunately, specific SPF-grade 5083 alloys are substantially more expensive than the commercial grade, and the addition of Cu decreases the corrosion resistance of the base material. The purpose of this work is to examine the effect of prior degrees of cold work on the SPF behavior of a standard-grade 5083 alloy. Superplastic behavior of this material at 510[degree]C is assessed and compared to published results for the SPF-grade alloys.

Vetrano, J.S.; Lavender, C.A.; Smith, M.T.; Bruemmer, S.M. (Pacific Northwest Lab., Richland, WA (United States)); Hamilton, C.H. (Washington State Univ., Pullman, WA (United States). Dept. of Mechanical and Materials Engineering)

1994-03-01

274

Oxidation and sulfidation resistant alloys with silicon additions  

SciTech Connect

The Albany Research Center (ARC) has considerable experience in developing lean chromium, austenitic stainless steels with improved high temperature oxidation resistance. Using basic alloy design principles, a baseline composition of Fe-16Cr-16Ni-2Mn-1Mo alloys with Si and Al addition at a maximum of 5 weight percent was selected for potential application at temperatures above 700C for supercritical and ultra-supercritical power plant application. The alloys were fully austenitic. Cyclic oxidation tests in air for 1000 hours were carried out on alloys with Si only or combined Si and Al additions in the temperature range 700C to 800C. Oxidation resistances of alloys with Si only additions were outstanding, particularly at 800C (i.e., these alloys possessed weight gains 4 times less than a standard type-304 alloy). In addition, Si alloys pre-oxidized at 800C, showed a zero weight gain in subsequent testing for 1000 hours at 700C. Similar improvements were observed for Si only alloy after H2S exposure at 700C compared with type 304 stainless steel. SEM and ESCA analysis of the oxide films and base material at the oxide/base metal interface were conducted to study potential rate controlling mechanisms at ARC. Depth profile analysis and element concentration profiles (argon ion etching/x-ray photoelectron spectroscopy) were conducted on oxidized specimens and base material at the National Energy Technology Laboratory.

Dunning, John S.; Alman, David E.; Poston, J.A., Jr. (NETL); Siriwardane, R. (NETL)

2003-01-01

275

Lithium insertion\\/extraction mechanism in alloy anodes for lithium-ion batteries  

Microsoft Academic Search

The electrochemical performance of alloy anodes has been reviewed in a previous paper [1]. In this work, the fundamental understanding of lithium-insertion\\/extraction mechanism in alloy anodes is discussed. The article summarizes the different types of lithium-reaction processes observed in Si, Sn, Sb, Al, Mg and their alloys, with particular emphasis on the characteristics unique to alloy anodes, including the sloping

Wei-Jun Zhang

2011-01-01

276

Investigation on Tool Wear Rate for Modified and Unmodified Aluminium-Silicon Casting Alloy  

Microsoft Academic Search

This study demonstrates and explains the effect of strontium modification on machinability of aluminium-silicon eutectic (LM-6 type) alloy. This alloy is known to have many favourable features including weight to strength ratio, high corrosion resistance and excellent castability. However, normal unmodified LM-6 alloy has poor machinability, which reduces its applications range. In this work, various samples of LM-6 alloy were

M. M. Haque; A. A. Khan; Ahmad F. Ismail

2009-01-01

277

On the precipitation of magnesium silicide in irradiated aluminiummagnesium alloys  

Microsoft Academic Search

Thermal neutron irradiation of aluminium or its alloys causes the production of silicon by transmutation. In aluminiummagnesium alloys, the transmutation-produced silicon reacts with magnesium and forms small precipitates. The precipitation in irradiated AlMg alloys is similar to the early stage of aging in thermally treated AlMgSi alloys. This study evidences the simultaneous generation of two crystallographically different precipitate types. On

M. Verwerft

2000-01-01

278

Photoelectron spectroscopic study on the electronic structures of the dental gold alloys and their interaction with L-cysteine  

NASA Astrophysics Data System (ADS)

The valence electronic structures of the dental gold alloys, type 1, type 3, and K14, and their interaction with L-cysteine have been studied by ultraviolet photoelectron spectroscopy with synchrotron radiation. It was found that the electronic structures of the type-1 and type-3 dental alloys are similar to that of polycrystalline Au, while that of the K14 dental alloy is much affected by Cu. The peak shift and the change in shape due to alloying are observed in all the dental alloys. It is suggested that the new peak observed around 2 eV for the L-cysteine thin films on all the dental alloys may be due to the bonding of S 3sp orbitals with the dental alloy surfaces, and the Cu-S bond, as well as the Au-S and Au-O bonds, may cause the change in the electronic structure of the L-cysteine on the alloys.

Ogawa, Koji; Tsujibayashi, Toru; Takahashi, Kazutoshi; Azuma, Junpei; Ichimiya, Masayoshi; Fujimoto, Hitoshi; Sumimoto, Michinori; Kamada, Masao

2011-11-01

279

Corrosion Embrittlement of Duralumin II Accelerated Corrosion Tests and the Behavior of High-Strength Aluminum Alloys of Different Compositions  

NASA Technical Reports Server (NTRS)

The permanence, with respect to corrosion, of light aluminum alloy sheets of the duralumin type, that is, heat-treatable alloys containing Cu, Mg, Mn, and Si is discussed. Alloys of this type are subject to surface corrosion and corrosion of the interior by intercrystalline paths. Results are given of accelerated corrosion tests, tensile tests, the effect on corrosion of various alloying elements and heat treatments, electrical resistance measurements, and X-ray examinations.

Rawdon, Henry S

1928-01-01

280

Precipitation-hardening alloys  

SciTech Connect

Designers of stainless steel and nickel alloy products are routinely faced with making tradeoffs between the properties needed for manufacturing and those required for its end use. When such compromises begin to adversely impact cost or performance, precipitation hardening (PH) alloys may offer a solution. Despite their more complex metallurgy, PH alloys are not necessarily more costly than many nonage-hardenable alloys. In fact, performance may be substantially higher than such alloys, without a cost penalty. Although corrosion resistance is decreased (or possibly increased) during the aging cycle, it is only by a slight amount. This article takes a closer look at PH stainless steel and nickel alloys, and provides several examples of applications.

Brucker, R. [Ulbrich Stainless Steels and Special Metals, North Haven, CT (United States)

1995-12-01

281

Application of Rapidly Solidified Alloys.  

National Technical Information Service (NTIS)

This program is being conducted for the purpose of applying the principle of rapid solidification of aluminum and iron alloy powders and subsequent development of stronger alloy compositions for fan blade application (Al alloys) and higher speed bearing m...

A. R. Cox T. D. Tillman J. W. Simon

1979-01-01

282

Uranium-titanium-niobium alloy  

Microsoft Academic Search

This patent describes a uranium alloy having small additions of Ti and Nb. It shows improved strength and ductility in cross-section of greater than one inch over prior uranium alloy having only Ti as an alloy element.

Ludtka

1990-01-01

283

Uranium-titanium-niobium alloy  

SciTech Connect

This patent describes a uranium alloy having small additions of Ti and Nb. It shows improved strength and ductility in cross-section of greater than one inch over prior uranium alloy having only Ti as an alloy element.

Ludtka, G.M.

1990-11-06

284

Low activation ferritic alloys  

DOEpatents

Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

1985-02-07

285

Electrical discharge surface alloying  

Microsoft Academic Search

This paper details the electrical discharge surface alloying\\/modification of ?-TiAl (Ti46.5Al4(Cr, Nb, Ta, B)) and ?\\/? Ti alloy (Ti6Al4V) sheet (1mm thick) during wire cutting using deionised water dielectric with nickel and copper wires. In addition, topography, microstructure and wear test data are given for a 2% Cr steel mill roll material textured\\/alloyed using partially sintered powder metallurgy (PM) hardmetal

H. G Lee; J Simao; D. K Aspinwall; R. C Dewes; W Voice

2004-01-01

286

Aluminum alloy development  

SciTech Connect

Development of an aluminum alloy which has higher strength than previous alloys while still showing acceptable levels of corrosion resistance and fracture is presented. Two different approaches to this goal are described; a final thermomechanical treatment method employed deformation and aging, while the second method depended solely on thermal practices to enhance the strength/corrosion resistance combination. Attention is given to a 7055 alloy that offers significant weight savings potential for applications requiring high compression strength combined with good corrosion resistance. It is indicated that structures including keel beams, horizontal tails, upper wings, cargo rails, and seat tracks on commercial transports are all candidate applications for this alloy.

Not Available

1991-09-01

287

Machinability of Titanium Alloys  

NASA Astrophysics Data System (ADS)

Titanium and its alloys find wide application in many industries because of their excellent and unique combination of high strength-to-weight ratio and high resistance to corrosion. The machinability of titanium and its alloys is impaired by its high chemical reactivity, low modulus of elasticity and low thermal conductivity. A number of literatures on machining of titanium alloys with conventional tools and advanced cutting tool materials is reviewed. The results obtained from the study on high speed machining of Ti-6Al-4V alloys with cubic boron nitride (CBN), binderless cubic boron nitride (BCBN) and polycrystalline diamond (PCD) are also summarized.

Rahman, Mustafizur; Wong, Yoke San; Zareena, A. Rahmath

288

Corrosion behaviour of nitrided low alloy steel in chloride solution  

Microsoft Academic Search

Purpose The corrosion behaviour of low alloy steel type AISI 4130 (before and after nitriding) and austenitic stainless steel type AISI 304L were studied in tap water +3.5 per cent NaCl. A liquid nitriding process had been applied on the low alloy steel. Design\\/methodology\\/approach The tests that were carried out in this study were anodic polarization, rotating bending

Fuad M. Khoshnaw; Abdulrazzaq I. Kheder; Fidaa S. M. Ali

2007-01-01

289

Thermoelectric properties of Ag-doped n-type (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2-} {sub x} Ag {sub x} Se{sub 3}){sub 0.1} (x=0-0.4) alloys prepared by spark plasma sintering  

SciTech Connect

Ag-doped n-type (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2-} {sub x} Ag {sub x} Se{sub 3}){sub 0.1} (x=0-0.4) alloys were prepared by spark plasma sintering and their physical properties evaluated. When at low Ag content (x=0.05), the temperature dependence of the lattice thermal conductivity follows the trend of (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2}Se{sub 3}){sub 0.1}; while at higher Ag content, a relatively rapid reduction above 400 K can be observed due possibly to the enhancement of scattering of phonons by the increased defects. The Seebeck coefficient increases with Ag content, with some loss of electrical conductivity, but the maximum dimensionless figure of merit ZT can be obtained to be 0.86 for the alloy with x=0.4 at 505 K, about 0.2 higher than that of the alloy (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2}Se{sub 3}){sub 0.1} without Ag-doping. - Graphical abstract: The temperature dependence of dimensionless thermoelectric figure of merit ZT for different (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2-} {sub x} Ag {sub x} Se{sub 3}){sub 0.1} (x=0-0.4) alloys prepared by spark plasma sintering.

Cui, J.L. [School of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016 (China)], E-mail: cuijl@nbip.net; Xiu, W.J. [School of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016 (China); School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221008 (China); Mao, L.D. [School of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016 (China); College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014 (China); Ying, P.Z. [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221008 (China); Jiang, L. [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221008 (China); Qian, X. [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014 (China)

2007-03-15

290

Thermoelectric properties of Cu-doped n-type (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2-x}Cu{sub x}Se{sub 3}){sub 0.1}(x=0-0.2) alloys  

SciTech Connect

n-Type (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2-x}Cu{sub x}Se{sub 3}){sub 0.1} (x=0-0.2) alloys with Cu substitution for Bi were prepared by spark plasma-sintering technique and their structural and thermoelectric properties were evaluated. Rietveld analysis reveals that approximate 9.0% of Bi atomic sites are occupied by Cu atoms and less than 4.0 wt% second phase Cu{sub 2.86}Te{sub 2} precipitated in the Cu-doped parent alloys. Measurements show that an introduction of a small amount of Cu (x{<=}0.1) can reduce the lattice thermal conductivity ({kappa}{sub L}), and improve the electrical conductivity and Seebeck coefficient. An optimal dimensionless figure of merit (ZT) value of 0.98 is obtained for x=0.1 at 417 K, which is obviously higher than those of Cu-free Bi{sub 2}Se{sub 0.3}Te{sub 2.7} (ZT=0.66) and Ag-doped alloys (ZT=0.86) prepared by the same technologies. - Graphical abstract: After Cu-doping with x=0.1, the highest ZT value of 0.98 is obtained at 417 K, which is about 0.32 and 0.12 higher than those of Cu-free Bi{sub 2}Se{sub 0.3}Te{sub 2.7} and the Ag-doped alloys (Bi{sub 2}Te{sub 3}){sub 0.9}-(Bi{sub 2-x}Ag{sub x}Se{sub 3}){sub 0.1} (x=0.4), respectively.

Cui, J.L. [School of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016 (China)], E-mail: cuijl@nbip.net; Mao, L.D. [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014 (China); School of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016 (China); Yang, W.; Xu, X.B. [School of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016 (China); Chen, D.Y.; Xiu, W.J. [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221008 (China); School of Mechanical Engineering, Ningbo University of Technology, Ningbo 315016 (China)

2007-12-15

291

Evaluation of Aluminum Alloy 7001-T75.  

National Technical Information Service (NTIS)

The purpose of the project was development of design criteria for a material with the strength of 7075-T6 and virtual immunity to stress and exfoliation type corrosion. This evaluation covers the following: Sheet - Aluminum Alloy 7001-T75; Plate - Aluminu...

1966-01-01

292

Corrosion of alloys in the scrubber effluent of a municipal incinerator  

SciTech Connect

Stressed specimens of nickel-base alloys, titanium alloys, and stainless steels were exposed to the scrubber effluent of a municipal incinerator where a Type 316 stainless steel absorber vessel wall had failed. A four month test program was conducted to evaluate the corrosion resistance of the alloys under the operating conditions of ph 4 to 5 and 2300 ppm chloride. Ti-6Al-4V alloy had the best overall corrosion resistance. Of the nickel-base alloys, C, C-276 and 625 performed best. Among the stainless steels, alloy 20 was the most resistant. Laboratory exposures of the alloys to the same hot scrubber solution at a pH of 2 confirmed the results of the field tests, although some of the alloys deteriorated more rapidly in the higher acidity conditions.

Krause, H.H.

1988-01-01

293

Aluminum battery alloys  

SciTech Connect

Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

Thompson, D.S.; Scott, D.H.

1985-11-19

294

Ductile transplutonium metal alloys  

DOEpatents

Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

Conner, William V. (Boulder, CO)

1983-01-01

295

Ductile transplutonium metal alloys  

DOEpatents

Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as souces of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

Conner, W.V.

1981-10-09

296

Aluminum battery alloys  

DOEpatents

Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

Thompson, David S. (Richmond, VA); Scott, Darwin H. (Mechanicsville, VA)

1985-01-01

297

Shape Memory Alloys  

Microsoft Academic Search

This special issue on shape memory alloys (SMA) is an encore to a special issue on the same topic edited by us six years ago (Smart Mater. Struct.9 (5) October 2000). A total of 19 papers is offered in this issue, organized into the three broad categories of modeling, characterization and applications. In addition to thermally activated shape memory alloys,

Abhijit Bhattacharyya; Dimitris C Lagoudas

2007-01-01

298

Neutron Absorbing Alloys  

DOEpatents

The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

Mizia, Ronald E. (Idaho Falls, ID); Shaber, Eric L. (Idaho Falls, ID); DuPont, John N. (Whitehall, PA); Robino, Charles V. (Albuquerque, NM); Williams, David B. (Bethlehem, PA)

2004-05-04

299

Formable Sheet Titanium Alloys.  

National Technical Information Service (NTIS)

The objectives of this program were to evaluate three promising experimental alloys by optimizing mill processing using formability, formageability, and uniformity and consistency of properties as the criteria. The three alloys (1) Ti-8V-7Cr-3Al-4Sn-1Zr, ...

G. Lenning

1976-01-01

300

Advanced Cast Aluminum Alloys.  

National Technical Information Service (NTIS)

A recent advancement in cast aluminum alloys has demonstrated that complex shapes can be cast from a microalloyed Al-Cu alloy in dry sand molds with chills and that these castings can be heat treated to produce mechanical and physical properties nearly co...

A. P. Druschitz J. Griffin

2009-01-01

301

Cesium iodide alloys  

DOEpatents

A transparent, strong CsI alloy is described having additions of monovalent iodides. Although the preferred iodide is AgI, RbI and CuI additions also contribute to an improved polycrystalline CsI alloy with outstanding multispectral infrared transmittance properties. 6 figs.

Kim, H.E.; Moorhead, A.J.

1992-12-15

302

Radiation effects on corrosion of zirconium alloys  

SciTech Connect

From the wide use of zirconium alloys as components in nuclear reactors, has come clear evidence that reactor radiation is a major corrosion parameter. The evidence emerges from comparisons of zirconium alloy corrosion behavior in different reactor types, for example, BWRs versus PWRs and in corresponding reactor loop chemistries; also, oxidation rates differ with location along components such as fuel rods and reactor pressure tubes. In most respects, oxidation effects on power reactor components are paralleled by oxidation behavior on specimens exposed to radiation in reactor loops.

Johnson, A.B. Jr.

1989-06-01

303

Using High Pressure Coolant in the Drilling and Turning of Low Machinability Alloys  

Microsoft Academic Search

The paper examines the results of machining tests carried out on two alloys commonly used in the aircraft industry, specifically,\\u000a alphabeta type titanium alloy Ti6A14V and nickel-based superalloy of type 718. In view of their excellent mechanical properties\\u000a and their resistance to a wide range of temperatures, these alloys are widely used in the manufacture of turbo-engine parts.\\u000a They are

L. N. Lpez de Lacalle; J. Prez-Bilbatua; J. A. Snchez; J. I. Llorente; A. Gutirrez; J. Albniga

2000-01-01

304

Alloys in energy development  

SciTech Connect

The development of new and advanced energy systems often requires the tailoring of new alloys or alloy combinations to meet the novel and often stringent requirements of those systems. Longer life at higher temperatures and stresses in aggressive environments is the most common goal. Alloy theory helps in achieving this goal by suggesting uses of multiphase systems and intermediate phases, where solid solutions were traditionally used. However, the use of materials under non-equilibrium conditions is now quite common - as with rapidly solidified metals - and the application of alloy theory must be modified accordingly. Under certain conditions, as in a reactor core, the rate of approach to equilibrium will be modified; sometimes a quasi-equilibrium is established. Thus an alloy may exhibit enhanced general diffusion at the same time as precipitate particles are being dispersed and solute atoms are being carried to vacancy sinks. We are approaching an understanding of these processes and can begin to model these complex systems.

Frost, B.R.T.

1984-02-01

305

Effects of Loading Type And Cavity Position On The Pattern Height In Micro-manufacturing of Al5083 Superplastic Alloy And Zr62Cu17Ni13Al8 Metallic Glass  

Microsoft Academic Search

Vibrational micro-forming of pyramidal shape patterns was conducted for an Al superplastic alloy, Al 5083 and a Zr-based bulk metallic glass, Zr62Cu17Ni13Al8. A vibrational micro-forming system was specially designed for generating vibrational load by combining a PZT actuator with a signal generator. Si micro dies with wet-etched pyramidal patterns were used as master dies for vibrational micro-forming. The micro-formed pattern

Young-Sang Na; Seon-Cheon Son; Kyu-Yeol Park; Jong-Hoon Lee

2009-01-01

306

Fusion boundary microstructure evolution in aluminum alloys  

NASA Astrophysics Data System (ADS)

A melting technique was developed to simulate the fusion boundary of aluminum alloys using the GleebleRTM thermal simulator. Using a steel sleeve to contain the aluminum, samples were heated to incremental temperatures above the solidus temperature of a number of alloys. In alloy 2195, a 4wt%Cu-1wt%Li alloy, an equiaxed non-dendritic zone (EQZ) could be formed by heating in the temperature range from approximately 630 to 640C. At temperatures above 640C, solidification occurred by the normal epitaxial nucleation and growth mechanism. Fusion boundary behavior was also studied in alloys 5454-H34, 6061-T6, and 2219-T8. Additionally, experimental alloy compositions were produced by making bead on plate welds using an alloy 5454-H32 base metal and 5025 or 5087 filler metals. These filler metals contain zirconium and scandium additions, respectively, and were expected to influence nucleation and growth behavior. Both as-welded and welded/heat treated (540C and 300C) substrates were tested by melting simulation, resulting in dendritic and EQZ structures depending on composition and substrate condition. Orientation imaging microscopy (OIM(TM)) was employed to study the crystallographic character of the microstructures produced and to verify the mechanism responsible for EQZ formation. OIM(TM) proved that grains within the EQZ have random orientation. In all other cases, where the simulated microstructures were dendritic in nature, it was shown that epitaxy was the dominant mode of nucleation. The lack of any preferred crystallographic orientation relationship in the EQZ supports a theory proposed by Lippold et al that the EQZ is the result of heterogeneous nucleation within the weld unmixed zone. EDS analysis of the 2195 on STEM revealed particles with ternary composition consisted of Zr, Cu and Al and a tetragonal type crystallographic lattice. Microdiffraction line scans on EQZ grains in the alloy 2195 showed very good agreement between the measured Cu composition within the interior of the non-dendritic grains and the corresponding value the Scheil equation predicts for the first solid to form upon solidification for a binary Al-Cu alloy with identical Cu composition. In the context of the alloys, compositions and substrate conditions examined a mechanistic model for EQZ zone formation is proposed, helpful in adjusting base metal compositions and/or substrate conditions to control fusion boundary microstructure.

Kostrivas, Anastasios Dimitrios

2000-10-01

307

Phase Relation and Kinetics of the Transformations in Au-Cu-Zn Ternary Alloys  

Microsoft Academic Search

The phase relation in the beta phase AuxCu55-xZn45 ternary alloys was studied. There appear two types of ordered phases, i.e., the Heusler-type and the CsCl-type superlattices, and a martensite structure at low temperatures. The critical temperature (Tc) of CsCl-type superlattice becomes higher than that (455C) of the Cu-Zn binary alloy with the increase in Au content. Tc of the Heusler-type

Yuichiro Murakami; Hajime Asano; Norihiko Nakanishi; Sukeji Kachi

1967-01-01

308

Micro stepping of Shape Memory Alloy based Poly Phase motor  

Microsoft Academic Search

In literature we find broadly two types of shape memory alloy based motors namely limited rotation motor and unlimited rotation motor. The unlimited rotation type SMA based motor reported in literature uses SMA springs for actuation. An attempt has been made in this paper to develop an unlimited rotation type balanced poly phase motor based on SMA wire in series

S. V. Sharma; M. M. Nayak; N. S. Dinesh; L. Umanand

2008-01-01

309

Microstructural development in irradiated vanadium alloys  

SciTech Connect

Three simple vanadium alloys, V-5Al, V-1Ni, and V-2Ti-1Ni have been examined to determine the effects of fast neutron irradiation on microstructural evolution. Specimens were irradiated in EBR II at temperatures in the range 425 to 600{degrees}C to doses of 15 and 31 dpa. Each alloy responded very differently to irradiation. All V-5Al specimens were generally void-free and contained high densities of coherent precipitates, and moderate densities of network dislocations. Swelling was much higher in V-1Ni. Voids were uniformly distributed, but with widely varying shape and size. Precipitation of two types also developed. The response in V-2Ti-1Ni was intermediate to that of the other two alloys. Irradiation produced extensive precipitation of thin rods and a moderate density of large voids often associated with much larger precipitate particles. The dislocation structure strongly interacted with the rod precipitate particles.

Gelles, D.S. [Pacific Northwest Lab., Richland, WA (United States); Stubbins, J.F. [Illinois Univ., Urbana, IL (United States)

1993-09-01

310

Amorphous powders of Al-Hf prepared by mechanical alloying  

SciTech Connect

We synthesized amorphous Al/sub 50/Hf/sub 50/ alloy powder by mechanically alloying an equimolar mixture of crystalline powders of Al and Hf using hexane as a dispersant. We characterized the powder as a function of mechanical-alloying time by scanning electron microscopy, x-ray diffraction, and differential scanning calorimetry. Amorphous Al/sub 50/Hf/sub 50/ powder heated at 10 K s/sup /minus/1/ crystallizes polymorphously at 1003 K into orthorhombic AlHf (CrB-type structure). During mechanical alloying, some hexane decomposes and hydrogen and carbon are incorporated into the amorphous alloy powder. The hydrogen can be removed by annealing the powder by hot pressing at a temperature approximately 30 K below the crystallization temperature. The amorphous compacts have a diamond pyramidal hardness of 1025 DPH. 24 refs., 7 figs., 1 tab.

Schwarz, R.B.; Hannigan, J.W.; Sheinberg, H.; Tiainen, T.

1988-01-01

311

DSC sample preparation for Al-based alloys  

SciTech Connect

Differential Scanning Calorimetry (DSC) is a useful technique for the study of phase transformations and has been widely applied to study precipitation in aluminium alloys. In the present work the effect of sample preparation during DSC heating of a monolithic 8090 (Al-Cu-Mg-Li-Zr) alloy and an 8090 MMC is investigated. The 8090 alloy system seems especially suited for such a study since the main precipitation reactions which occur in this alloy (GPB-zone, {delta}{prime}(Al{sub 3}Li) and S{prime}(Al{sub 2}CuMg) formation) cover a wide range of different types of precipitation reactions. DSC experiments were performed with a Shimadzu DSC-50 employing a nitrogen gas flow using a heating rate of 10 C/min. DSC curves were corrected for the baseline of the DSC and for heat capacity of the alloys following a procedure outlined elsewhere. Hence, the presented DSC curves represent heat flows due to reactions only.

Starink, M.J.; Hobson, A.J.; Gregson, P.J. [Univ. of Southampton (United Kingdom). Dept. of Engineering Materials] [Univ. of Southampton (United Kingdom). Dept. of Engineering Materials

1996-06-01

312

Irradiation-induced softening of Ni[sub 3]P and (Ni, Fe, Cr)[sub 3]P alloys  

Microsoft Academic Search

Production of amorphous alloys by solid state reactions (SSR) has attracted much interest during the last few years. One of the methods to induce such a reaction is the irradiation of suitable crystalline alloys by fast particles. Examination of this kind of SSR in M[sub 3]P type of brazing alloys (M: Metal) is attractive because of the following reason: In

G. Schumacher; W. Miekeley; R. P. Wahi

1993-01-01

313

Magnesium silicide intermetallic alloys  

SciTech Connect

Methods of induction melting an ultra-low-density magnesium silicide (Mg[sub 2]Si) intermetallic and its alloys and the resulting microstructure and microhardness were studied. The highest quality ingots of Mg[sub 2]Si alloys were obtained by triple melting in a graphite crucible coated with boron nitride to eliminate reactivity, under overpressure of high-purity argon (1.3 [times] 10[sup 5] Pa), at a temperature close to but not exceeding 1,105 C [+-] 5 C to avoid excessive evaporation of Mg. After establishing the proper induction-melting conditions, the Mg-Si binary alloys and several Mg[sub 2]Si alloys macroalloyed with 1 at. pct of Al, Ni, Co, Cu, Ag, Zn, Mn, Cr, and Fe were induction melted and, after solidification, investigated by optical microscopy and quantitative X-ray energy dispersive spectroscopy (EDS). Both the Mg-rich and Si-rich eutectic in the binary alloys exhibited a small but systematic increase in the Si content as the overall composition of the binary alloy moved closer toward the Mg[sub 2]Si line compound. The Vickers microhardness (VHN) of the as-solidified Mg-rich and Si-rich eutectics in the Mg-Si binary alloys decreased with increasing Mg (decreasing Si) content in the eutectic. This behavior persisted even after annealing for 75 hours at 0.89 pct of the respective eutectic temperature. The Mg-rich eutectic in the Mg[sub 2]Si + Al, Ni, Co, Cu, Ag, and Zn alloys contained sections exhibiting a different optical contrast and chemical composition than the rest of the eutectic. Some particles dispersed in the Mg[sub 2]Si matrix were found in the Mg[sub 2]Si + Cr, Mn, and Fe alloys. The EDS results are presented and discussed and compared with the VHN data.

Li, G.H.; Gill, H.S.; Varin, R.A. (Univ. of Waterloo, ON (Canada). Dept. of Mechanical Engineering)

1993-11-01

314

Magnesium silicide intermetallic alloys  

NASA Astrophysics Data System (ADS)

Methods of induction melting an ultra-low-density magnesium silicide (Mg2Si) intermetallic and its alloys and the resulting microstructure and microhardness were studied. The highest quality ingots of Mg2Si alloys were obtained by triple melting in a graphite crucible coated with boron nitride to eliminate reactivity, under overpressure of high-purity argon (1.3 X 105 Pa), at a temperature close to but not exceeding 1105 C 5 C to avoid excessive evaporation of Mg. After establishing the proper induction-melting conditions, the Mg-Si binary alloys and several Mg2Si alloys macroalloyed with 1 at. pct of Al, Ni, Co, Cu, Ag, Zn, Mn, Cr, and Fe were induction melted and, after solidification, investigated by optical microscopy and quantitative X-ray energy dispersive spectroscopy (EDS). Both the Mg-rich and Si-rich eutectic in the binary alloys exhibited a small but systematic increase in the Si content as the overall composition of the binary alloy moved closer toward the Mg2Si line compound. The Vickers microhardness (VHN) of the as-solidified Mg-rich and Si-rich eutectics in the Mg-Si binary alloys decreased with increasing Mg (decreasing Si) content in the eutectic. This behavior persisted even after annealing for 75 hours at 0.89 pct of the respective eutectic temperature. The Mg-rich eutectic in the Mg2Si + Al, Ni, Co, Cu, Ag, and Zn alloys contained sections exhibiting a different optical contrast and chemical composition than the rest of the eutectic. Some particles dispersed in the Mg2Si matrix were found in the Mg2Si + Cr, Mn, and Fe alloys. The EDS results are presented and discussed and compared with the VHN data.

Li, Gh.; Gill, H. S.; Varin, R. A.

1993-11-01

315

Alloy development of FeAl aluminide alloys for structural use in corrosive environments  

SciTech Connect

Objectives include adequate ductilities ([ge]10%) at ambient temperature, high-temperature strength better than stainless steels (types 304 and 316), and fabricability and weldability by conventional techniques (gas tungsten arc). The alloys should be capable of being corrosion resistant in molten nitrate salts with rates lower than other iron-base structural alloys and coating materials (such as Fe-Cr-Al alloys). Such corrosion rates should be less than 0.3 mm per year. The FeAl aluminide containing 35.8 at. % Al was selected as base composition. Preliminary studies indicate that additions of B and Zr, increase the room-temperature ductility of FeAl. Further alloying with 0.2% Mo, and/or 5% Cr, improves the creep. Our preliminary alloying effort has led to identification of the following aluminide composition with promising properties: Fe - (35 [plus minus] 2)Al - (0.3 [plus minus] 0.2)Mo - (0.2 [plus minus] 0.15)Zr - (0.3 [plus minus] 0.2)B- up to 5Cr, at. %. However, this composition is likely to be modified in future work to improve the weldability of the alloy. The FeAl alloy FA-362 (Fe-35.8% Al-0.2% Mo-0.05% Zr-0.24% B) produced by hot extrusion at 900C showed a tensile ductility of more than 10% at room temperature and a creep rupture life longer than unalloyed FeAl by more than an order of magnitude at 593C at 138 MPa. Melting and processing of scaled-up heats of selected FeAl alloys are described. Forging, extruding, and hot-rolling processes for the scale-up heats are also described.

Liu, C.T.; Sikka, V.K.; McKamey, C.G.

1993-02-01

316

Alloy development of FeAl aluminide alloys for structural use in corrosive environments  

SciTech Connect

Objectives include adequate ductilities ({ge}10%) at ambient temperature, high-temperature strength better than stainless steels (types 304 and 316), and fabricability and weldability by conventional techniques (gas tungsten arc). The alloys should be capable of being corrosion resistant in molten nitrate salts with rates lower than other iron-base structural alloys and coating materials (such as Fe-Cr-Al alloys). Such corrosion rates should be less than 0.3 mm per year. The FeAl aluminide containing 35.8 at. % Al was selected as base composition. Preliminary studies indicate that additions of B and Zr, increase the room-temperature ductility of FeAl. Further alloying with 0.2% Mo, and/or 5% Cr, improves the creep. Our preliminary alloying effort has led to identification of the following aluminide composition with promising properties: Fe - (35 {plus_minus} 2)Al - (0.3 {plus_minus} 0.2)Mo - (0.2 {plus_minus} 0.15)Zr - (0.3 {plus_minus} 0.2)B- up to 5Cr, at. %. However, this composition is likely to be modified in future work to improve the weldability of the alloy. The FeAl alloy FA-362 (Fe-35.8% Al-0.2% Mo-0.05% Zr-0.24% B) produced by hot extrusion at 900C showed a tensile ductility of more than 10% at room temperature and a creep rupture life longer than unalloyed FeAl by more than an order of magnitude at 593C at 138 MPa. Melting and processing of scaled-up heats of selected FeAl alloys are described. Forging, extruding, and hot-rolling processes for the scale-up heats are also described.

Liu, C.T.; Sikka, V.K.; McKamey, C.G.

1993-02-01

317

Low Sb alloys  

SciTech Connect

A major change in the battery industry is a reduction in the amount of lead in the battery and an increase in the performance of the battery. This reduction in lead comes from the grids. The grids are thinner and lighter, but present several problems. As battery grids become thinner, the resistance to the passage of current increases. The lowest resistance alloys are lead-calcium and low antimony alloys. Fluidity is a problem. The alloys used in the continuous grid casting processes must be very fluid in order to be processed into thin grids. Other problems are also discussed including freezing range, gassing, grain structure, and rate of strengthening.

Prengaman, R.D.

1983-10-01

318

Advanced powder metallurgy aluminum alloys via rapid solidification technology, phase 2  

NASA Technical Reports Server (NTRS)

Marko's rapid solidification technology was applied to processing high strength aluminum alloys. Four classes of alloys, namely, Al-Li based (class 1), 2124 type (class 2), high temperature Al-Fe-Mo (class 3), and PM X7091 type (class 4) alloy, were produced as melt-spun ribbons. The ribbons were pulverized, cold compacted, hot-degassed, and consolidated through single or double stage extrusion. The mechanical properties of all four classes of alloys were measured at room and elevated temperatures and their microstructures were investigated optically and through electron microscopy. The microstructure of class 1 Al-Li-Mg alloy was predominantly unrecrystallized due to Zr addition. Yield strengths to the order of 50 Ksi were obtained, but tensile elongation in most cases remained below 2 percent. The class 2 alloys were modified composition of 2124 aluminum alloy, through addition of 0.6 weight percent Zr and 1 weight percent Ni. Nickel addition gave rise to a fine dispersion of intermetallic particles resisting coarsening during elevated temperature exposure. The class 2 alloy showed good combination of tensile strength and ductility and retained high strength after 1000 hour exposure at 177 C. The class 3 Al-Fe-Mo alloy showed high strength and good ductility both at room and high temperatures. The yield and tensile strength of class 4 alloy exceeded those of the commercial 7075 aluminum alloy.

Ray, Ranjan; Jha, Sunil C.

1987-01-01

319

Wear behavior of TiNi shape memory alloys  

SciTech Connect

TiNi alloy is a well-known shape memory alloy, which has demonstrated its great potential for a large variety of applications; this alloy is being actively applied to the development of new energy conversion systems, to the design for new robots and smart material systems, and to the development of medical implants and instruments. In addition to its shape memory effect, it has been observed that TiNi alloy also exhibits great resistance to wear. It is expected that the TiNi alloy, with its shape memory effect, vibration-damping feature, and high corrosion resistance, may become a new type of tribo-material and find new engineering applications. The high wear resistance of TiNi alloy may be attributed to its pseudoelastic behavior. This paper presents experimental results on wear behavior of TiNi alloy and its variation with microstructure. The pseudoelasticity of TiNi alloy was also studied, and its possible effect on wear resistance has been discussed in this paper.

Li, D.Y. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering] [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering

1996-01-15

320

Mechanical and corrosion resistance of a new nanostructured Ti-Zr-Ta-Nb alloy.  

PubMed

In this work, a multi-elementary Ti-10Zr-5Nb-5Ta alloy, with non-toxic alloying elements, was used to develop an accumulative roll bonding, ARB-type procedure in order to improve its structural and mechanical properties. The alloy was obtained by cold crucible semi-levitation melting technique and then was ARB deformed following a special route. After three ARB cycles, the total deformation degree per layer is about 86%; the calculated medium layer thickness is about 13 ?m. The ARB processed alloy has a low Young's modulus of 46 GPa, a value very close to the value of the natural cortical bone (about 20 GPa). Data concerning ultimate tensile strength obtained for ARB processed alloy is rather high, suitable to be used as a material for bone substitute. Hardness of the ARB processed alloy is higher than that of the as-cast alloy, ensuring a better behaviour as a implant material. The tensile curve for the as-cast alloy shows an elastoplastic behaviour with a quite linear elastic behaviour and the tensile curve for the ARB processed alloy is quite similar with a strain-hardening elastoplastic body. Corrosion behaviour of the studied alloy revealed the improvement of the main electrochemical parameters, as a result of the positive influence of ARB processing. Lower corrosion and ion release rates for the ARB processed alloy than for the as-cast alloy, due to the favourable effect of ARB thermo-mechanical processing were obtained. PMID:21783152

Raducanu, D; Vasilescu, E; Cojocaru, V D; Cinca, I; Drob, P; Vasilescu, C; Drob, S I

2011-10-01

321

Grain boundary segregation in the Ni-base alloy 182  

NASA Astrophysics Data System (ADS)

Grain boundary segregation is often considered to play a role in the various types of intergranular failures observed in austenitic alloys. However, there has been little direct study of this segregation because it is usually very difficult to obtain intergranular fracture in these alloys in the high vacuum required for surface analysis. This paper reports an Auger electron spectroscopy study of grain boundary segregation in the nickel-base Alloy 182. This alloy was used because it would easily fracture along its grain boundaries in high vacuum and because it has a very complex microstructure, as do many nickel-base alloys used in engineering applications. Furthermore, the alloy is widely used as a weld filler metal to join nickel-base alloys to one another or to stainless steels. Phosphorus was found to be the only impurity element that segregated to the grain boundaries. There was considerable variability in segregation from grain boundary to grain boundary and also on a single grain facet. It is suggested that these variations arise primarily from variations in grain boundary structure, in the density and types of precipitates in a grain boundary, and in the consequent variety of precipitate matrix interfaces present at the grain boundary. It is also suggested that quantitative Auger analysis on such a material would be very difficult.

Briant, C. L.

1988-01-01

322

Lightweight Disk Alloy Development.  

National Technical Information Service (NTIS)

A 3-year program was conducted with the intention of developing NiAl-base alloys with mechanical and physical properties suitable for use as a lightweight turbine disk material. The program emphasized overcoming the room temperature brittleness problem an...

C. C. Law D. M. Pease M. J. Blackburn P. C. Clapp S. M. Russell

1991-01-01

323

Electroplating on titanium alloy  

NASA Technical Reports Server (NTRS)

Activation process forms adherent electrodeposits of copper, nickel, and chromium on titanium alloy. Good adhesion of electroplated deposits is obtained by using acetic-hydrofluoric acid anodic activation process.

Lowery, J. R.

1971-01-01

324

Brazing dissimilar aluminum alloys  

NASA Technical Reports Server (NTRS)

Dip-brazing process joins aluminum castings to aluminum sheet made from different aluminum alloy. Process includes careful cleaning, surface preparation, and temperature control. It causes minimum distortion of parts.

Dalalian, H.

1979-01-01

325

On the role of matrix creep in the high temperature deformation of short fiber reinforced aluminum alloys  

Microsoft Academic Search

The present study investigates creep of short fiber reinforced metal matrix composites (MMCs) which were produced by squeeze casting. Two types of aluminum alloys were used as matrix materials with class I (alloy type) and class II (metal type) creep behavior. The creep behavior of the resulting MMCs is similar both in terms of the shape of the individual creep

G. Kaustrter; B. Skrotzki; G. Eggeler

2001-01-01

326

Radiation-induced segregation in candidate fusion-reactor alloys  

SciTech Connect

The effect of radiation on surface segregation of minor and impurity elements has been studied in four candidate fusion reactor alloys. Radiation induced surface segregation of phosphorus was found in both 316 type stainless steel and in Nimonic PE-16. Segregation and depletion of the other alloying elements in 316 stainless steel agreed with that reported by other investigators. Segregation of nitrogen in ferritic HT-9 was enhanced by radiation but no phosphorus segregation was detected. No significant radiation enhanced or induced segregation was observed in a Ti-6Al-4V alloy. The results indicate that radiaton enhanced grain boundary segregation could contribute to the embrittlement of 316 SS and PE-16.

Brimhall, J.L.; Baer, D.R.; Jones, R.H.

1981-07-01

327

Metallographic evaluation of the reactions between boronated graphite and Fe-Ni-Cr alloys  

SciTech Connect

The compatibility of boronated graphite with alloy 800H and type 316 stainless steel was evaluated metallographically after exposures at 700 and 810/sup 0/C for up to 10,000 h. At 700/sup 0/C, the principal reaction with both alloys was limited oxidation. At 810/sup 0/C, three types of reactions were observed: localized reactions at sites where the B/sub 4/C particles were in contact with the alloys' surfaces, intergranular penetration (much more prevalent for alloy 800H), and carburization.

Tortorelli, P.F.; Mayotte, J.R.; Henson, T.J.; DeVan, J.H.

1984-01-01

328

Corrosion behavior of alloys  

NASA Astrophysics Data System (ADS)

Studies of molten nitrates at temperatures in the 450 - 550 C range were made to obtain information which will ultimately permit an understanding of the corrosion behavior of structural alloys, such as Incoloy 800, that will be employed in thermal loops in solar power systems. Initial activity will involve studies of species expected to exist in these melts from corrosion of structural alloys, i.e., iron, nickel and chromium.

Osteryoung, R. A.; Fernandez, H.

1981-03-01

329

Magnesium silicide intermetallic alloys  

Microsoft Academic Search

Methods of induction melting an ultra-low-density magnesium silicide (Mg2Si) intermetallic and its alloys and the resulting microstructure and microhardness were studied. The highest quality ingots of Mg2Si alloys were obtained by triple melting in a graphite crucible coated with boron nitride to eliminate reactivity, under overpressure of high-purity argon (1.3 X 105 Pa), at a temperature close to but not

Gh. Li; H. S. Gill; R. A. Varin

1993-01-01

330

Magnesium silicide intermetallic alloys  

Microsoft Academic Search

Methods of induction melting an ultra-low-density magnesium silicide (Mg2Si) intermetallic and its alloys and the resulting microstructure and microhardness were studied. The highest quality ingots\\u000a of Mg2Si alloys were obtained by triple melting in a graphite crucible coated with boron nitride to eliminate reactivity, under\\u000a overpressure of high-purity argon (1.3 X 105 Pa), at a temperature close to but not

G. H. Li; H. S. Gill; R. A. Varin

1993-01-01

331

nanostructured alloys. Metal matrix composites. Quasicrystal. Dental Implant. Laser Processing. Mg alloy. PLD. TCLP. nanostructured alloys. Metal matrix composites. Quasicrystal. Dental Implant. Laser Processing. Mg alloy. PLD. TCLP.  

EPA Pesticide Factsheets

Did you mean: nanostructured alloys. Metal matrix composites. Quasicrystal. Dental Implant. Laser Processing. Mg alloy. PLD. TCLP. nanostructured alloys. Metal matrix composites. Quasicrystal. Dental Implant. Laser Processing. Mg alloy. PLD. TCLP. ?

332

nanostructured alloys. Metal matrix composites. Quasicrystal. Dental Implant. Laser Processing. Mg alloy. PLD. TCLP. nanostructured alloys. Metal matrix composites. Quasicrystal. Dental Implant. Laser Processing. Mg alloy. PLD. TCLP.  

EPA Pesticide Factsheets

Did you mean nanostructured alloys. Metal matrix composites. Quasicrystal. Dental Implant. Laser Processing. Mg alloy. PLD. TCLP. nanostructured alloys. Metal matrix composites. Quasicrystal. Dental Implant. Laser Processing. Mg alloy. PLD. TCLP. ?

333

Disk Alloy Development  

NASA Technical Reports Server (NTRS)

The advanced powder metallurgy disk alloy ME3 was designed using statistical screening and optimization of composition and processing variables in the NASA HSR/EPM disk program to have extended durability at 1150 to 1250 "Fin large disks. Scaled-up disks of this alloy were produced at the conclusion of this program to demonstrate these properties in realistic disk shapes. The objective of the UEET disk program was to assess the mechanical properties of these ME3 disks as functions of temperature, in order to estimate the maximum temperature capabilities of this advanced alloy. Scaled-up disks processed in the HSR/EPM Compressor / Turbine Disk program were sectioned, machined into specimens, and tested in tensile, creep, fatigue, and fatigue crack growth tests by NASA Glenn Research Center, in cooperation with General Electric Engine Company and Pratt & Whitney Aircraft Engines. Additional sub-scale disks and blanks were processed and tested to explore the effects of several processing variations on mechanical properties. Scaled-up disks of an advanced regional disk alloy, Alloy 10, were used to evaluate dual microstructure heat treatments. This allowed demonstration of an improved balance of properties in disks with higher strength and fatigue resistance in the bores and higher creep and dwell fatigue crack growth resistance in the rims. Results indicate the baseline ME3 alloy and process has 1300 to 1350 O F temperature capabilities, dependent on detailed disk and engine design property requirements. Chemistry and process enhancements show promise for further increasing temperature capabilities.

Gabb, Tim; Gayda, John; Telesman, Jack

2001-01-01

334

Ultrahigh temperature intermetallic alloys  

SciTech Connect

A new family of Cr-Cr{sub 2}Ta intermetallic alloys based on Cr-(6--10)Ta (at.%) is under development for structural use in oxidizing environments in the 1,000-1,300 C (1,832--2,372 F) temperature range. Development objectives relate to high temperature strength and oxidation resistance and room temperature fracture toughness. The 1,200 C (2,192 F) strength goals have been met: yield and fracture strengths of 275 MPa (40 ksi) and 345 MPa (50 ksi), respectively, were achieved. Progress in attaining reasonable fracture toughness of Cr-Cr{sub 2}Ta alloys has been made; current alloys exhibit room-temperature values of about 10--12 MPa{radical}m (1.1 MPa{radical}m = 1 ksi{radical}in.). Oxidation rates of these alloys at 950 C (1,742 F) in air are in the range of those reported for chromia-forming alloys. At 1,100 C (2,012 F) in air, chromia volatility was significant but, nevertheless, no scale spallation and positive weight gains of 1--5 mg/cm{sup 2} have been observed during 120-h, 6-cycle oxidation screening tests. These mechanical and oxidative properties represent substantial improvement over Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr alloys previously developed.

Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.

1998-11-01

335

Hardening process in ternary lead-antimony-tin alloys for battery grids  

NASA Astrophysics Data System (ADS)

It is known that lead-antimony alloys are very well hardened by continuous precipitation, whereas lead-tin alloys present a discontinuous precipitation with a weak hardening effect. In these binary alloys, there is precipitation of either antimony or tin. In ternary alloys, the compound SbSn can also precipitate. This study is focused on the type of precipitation, the nature and the morphology of the precipitated phases, and the intensity of hardening in ternary Pb?Sb?Sn alloys in relation to the composition of the alloys and the ternary diagram. To simulate the different processes of grid production, four states are studied, namely, as-cast product, rehomogenized, cold worked, cold worked and rehomogenized. The alloys contain up to 2.5 wt.% Sb and 2.5 wt.% Sn.

Hilger, J. P.

336

Low Nickel Content FCC Alloys: Recent Evolution and Applications  

Microsoft Academic Search

Invar-type austenitic Fe-Ni alloys have been studied for a long time due to their noticeable physical anomalies and their varied martensite behavior below 28%Ni content. Yet these two aspects are not directly connected and offer the place for a field of low Curie point alloys, between 28 and 36%Ni. Their magnetic behavior has been first interpreted as a mixture of

Thierry Waeckerl

2010-01-01

337

Grain boundary segregation in the Ni-base alloy 182  

Microsoft Academic Search

Grain boundary segregation is often considered to play a role in the various types of intergranular failures observed in austenitic\\u000a alloys. However, there has been little direct study of this segregation because it is usually very difficult to obtain intergranular\\u000a fracture in these alloys in the high vacuum required for surface analysis. This paper reports an Auger electron spectroscopy\\u000a study

C. L. Briant

1988-01-01

338

Strategies for Self-Repairing Shape Memory Alloy Actuators  

Microsoft Academic Search

Shape memory alloys (SMAs) are thermally activated smart materials. Due to their ability to change into a previously imprinted\\u000a actual shape by the means of thermal activation, they are suitable as actuators for microsystems and, within certain limitations,\\u000a macroscopic systems. A commonly used shape memory actuator type is an alloy of nickel and titanium (NiTi), which starts to\\u000a transform its

Sven Langbein; Alexander Jaroslaw Czechowicz; Horst Meier

2011-01-01

339

Mechanisms for the hot corrosion of nickel-base alloys  

Microsoft Academic Search

The Na2SO4-induced accelerated oxidation of nickel-base alloys containing elements such as Cr, Al, Mo, W, and V has been studied in\\u000a 1.0 atm O2 in the temperature range of 650? to 1000?C. It has been found that the hot corrosion behavior of these alloys can usually\\u000a be characterized according to one of two types of attack: 1) Na2SO4-induced accelerated oxidation;

J. A. Goebel; F. S. Pettit; G. W. Goward

1973-01-01

340

Preparation and properties of mechanically alloyed rare earth permanent magnets  

Microsoft Academic Search

Mechanical alloying is applied to prepare Nd-Fe-B and ThMn12-type permanent magnets. Starting from element powders, the hard-magnetic phases are formed by milling in a planetary ball mill and a successive solid-state reaction at relatively low temperatures. For Nd-Fe-B, the magnetically isotropic particles are microcrystalline, show a high coercivity (up to 20 kOe for ternary alloys and above for Dy-substituted samples)

L. Schultz; K. Schnitzke; J. Wecker

1989-01-01

341

Ultraprecision microelectroforming of metals and metal alloys  

NASA Astrophysics Data System (ADS)

In recent years, microsystem technology and its growing importance for actuators, sensors, optics and microfluidics, only to name a few, have gained a lot of attention. Specific applications demand fabrication techniques allowing a fast and reliable replication of microstructure products in a variety of materials. An important technique for replication processes of microstructures in many applications of microsystem technology are microelectroforming processes, generating a variety of metals and metal alloys with tailored characteristics. Here, new results in the development of alloys for specific applications as well as their applications are reported: (1) Newly developed alloys: Nickel-iron alloys enable the production of soft magnetic microstructures e.g. for specific applications in microactuators. Nickel-cobalt and Nickel-tungsten alloys have been employed for the manufacture of microstructured tools with excellent mechanical properties regarding wear and mechanical durability. These tools have been applied to hot-embossing and injection molding processes successfully. (2) Microelectroforming within the frame of the LIGA technique allows the manufacturing of extremely precise electrodes with various cross-sections and heights for (mu) - electro discharge machining. The combination of these techniques enables the production of microstructures from non- electrodepositable materials, like stainless steel e.g. for large scale replication processes. (3) The precision of microelectroforming enables the replication of structured surfaces on a nanoscale for molecular microelectronics or special applications. The new types of alloys reported here significantly enlarge the applicability of microelectroforming processes for tool fabrication or direct use. Moreover combining this process with other microstructuring processes like injection molding or (mu) -EDM techniques generates a powerful tool for microsystem technology.

Loewe, Holger; Ehrfeld, Wolfgang; Diebel, Joerg

1997-09-01

342

Effects of Rh on the thermoelectric performance of the p-type Zr{sub 0.5}Hf{sub 0.5}Co{sub 1-x}Rh{sub x}Sb{sub 0.99}Sn{sub 0.01} half-Heusler alloys  

SciTech Connect

We show that Rh substitution at the Co site in Zr{sub 0.5}Hf{sub 0.5}Co{sub 1-x}Rh{sub x}Sb{sub 0.99}Sn{sub 0.01} (0<=x<=1) half-Heusler alloys strongly reduces the thermal conductivity with a simultaneous, significant improvement of the power factor of the materials. Thermoelectric properties of hot-pressed pellets of several compositions with various Rh concentrations were investigated in the temperature range from 300 to 775 K. The Rh 'free' composition shows n-type conduction, while Rh substitution at the Co site drives the system to p-type semiconducting behavior. The lattice thermal conductivity of Zr{sub 0.5}Hf{sub 0.5}Co{sub 1-x}Rh{sub x}Sb{sub 0.99}Sn{sub 0.01} alloys rapidly decreased with increasing Rh concentration and lattice thermal conductivity as low as 3.7 W/m*K was obtained at 300 K for Zr{sub 0.5}Hf{sub 0.5}RhSb{sub 0.99}Sn{sub 0.01}. The drastic reduction of the lattice thermal conductivity is attributed to mass fluctuation induced by the Rh substitution at the Co site, as well as enhanced phonon scattering at grain boundaries due to the small grain size of the synthesized materials. - Graphical abstract: Significant reduction of the lattice thermal conductivity with increasing Rh concentration in the p-type Zr{sub 0.5}Hf{sub 0.5}Co{sub 1-x}Rh{sub x}Sb{sub 0.99}Sn{sub 0.01} half-Heusler materials prepared by solid state reaction at 1173 K.

Maji, Pramathesh [Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Department of Chemistry, University of New Orleans, New Orleans, LA 70148 (United States); Takas, Nathan J.; Misra, Dinesh K. [Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Gabrisch, Heike [Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Department of Chemistry, University of New Orleans, New Orleans, LA 70148 (United States); Stokes, Kevin [Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Department of Physics, University of New Orleans, New Orleans, LA 70148 (United States); Poudeu, Pierre F.P., E-mail: ppoudeup@uno.ed [Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Department of Chemistry, University of New Orleans, New Orleans, LA 70148 (United States)

2010-05-15

343

Magnetic properties of SmFe(Ti)C(N)\\/?-Fe alloys prepared by mechanical alloying  

Microsoft Academic Search

Magnetic properties of SmFe(Ti)C(N)\\/?-Fe nanocomposite alloys prepared by mechanical alloying (MA) have been studied. The hysteresis loops of MA Sm12Fe74Ti7C7N?, Sm10Fe76Ti7C7N? and Sm19.0Fe66.7C14.3 (i.e. Sm20Fe70C15) made by different processes (annealing, nitriding and re-milling) were measured at the applied magnetic fields with different dH\\/dt at 400, 350 and 295 K. The main phase with hard magnetic properties is of TbCu7-type. These

Dian-yu Geng; Zhi-dong Zhang; Wei Liu; Xin-guo Zhao; Ming-hui Yu; Wei-jun Ren; Qun-feng Xiao; R Grssinger; R Hauser

2003-01-01

344

Magnetic properties of SmFe(Ti)-C(N)\\/alpha-Fe alloys prepared by mechanical alloying  

Microsoft Academic Search

Magnetic properties of Sm-Fe(Ti)-C(N)\\/alpha-Fe nanocomposite alloys prepared by mechanical alloying (MA) have been studied. The hysteresis loops of MA Sm12Fe74Ti7C7Ndelta, Sm10Fe76Ti7C7Ndelta and Sm19.0Fe66.7C14.3 (i.e. Sm20Fe70C15) made by different processes (annealing, nitriding and re-milling) were measured at the applied magnetic fields with different dH\\/dt at 400, 350 and 295 K. The main phase with hard magnetic properties is of TbCu7-type. These

Dian-yu Geng; Zhi-dong Zhang; Wei Liu; Xin-guo Zhao; Ming-hui Yu; Wei-jun Ren; Qun-feng Xiao; R. Grssinger; R. Hauser

2003-01-01

345

Effect of the Alloy Composition on the Grain Refinement Of Aluminum Alloys  

SciTech Connect

Careful experiments were carried out to evaluate the effect of solute element on grain refinement in aluminum based eutectic alloys. Grain size of the as-cast structure was measured. The measured grain size was plotted against the undercooling parameter, P, the growth restriction factor, Q, and the solidification interval, T, of the alloys. The results indicated that grain size decreases with increasing T monotonically over the whole range of the hypoeutectic compositions whereas the relationships between the grain size and P or Q are V type curves.

Xu, Hanbing [ORNL; Xu, Ling D [ORNL; Zhang, Shengjun [ORNL; Han, Qingyou [ORNL

2006-01-01

346

Mechanical behavior and properties of mechanically alloyed aluminum alloys  

Microsoft Academic Search

The fracture and deformation behaviors of several product forms produced from mechanically alloyed (MA) aluminum alloys 9052 and 905XL were studied. The main operative strengthening mechanism is strengthening due to the submicron grain size. Ductility and toughness were found to be controlled by the morphology of the prior particle boundaries. We propose that the work-hardening behavior of these MA alloys

H. R. Last; R. K. Garrett

1996-01-01

347

Effects of Loading Type And Cavity Position On The Pattern Height In Micro-manufacturing of Al5083 Superplastic Alloy And Zr62Cu17Ni13Al8 Metallic Glass  

NASA Astrophysics Data System (ADS)

Vibrational micro-forming of pyramidal shape patterns was conducted for an Al superplastic alloy, Al 5083 and a Zr-based bulk metallic glass, Zr62Cu17Ni13Al8. A vibrational micro-forming system was specially designed for generating vibrational load by combining a PZT actuator with a signal generator. Si micro dies with wet-etched pyramidal patterns were used as master dies for vibrational micro-forming. The micro-formed pattern height was increasing with increasing the frequency of the vibrational load. In particular, the vibrationally-microformed pattern height is similar or even higher than the statically-microformed pattern height when the load frequency exceeded about 125 kHz. It was also observed that the crystal grains affect the surface quality of the microformed pattern and the distribution of the pattern height in the die cavity array.

Na, Young-Sang; Son, Seon-Cheon; Park, Kyu-Yeol; Lee, Jong-Hoon

2009-11-01

348

Mechanical alloying and high pressure processing of a TiAl-V intermetallic alloy.  

PubMed

An alloy with a chemical composition of Ti-45Al-5V (at.%) was synthesized by mechanical alloying in a Szegvari-type attritor from elemental powders of high purity. Before compaction, the powders were characterized by X-ray diffraction and scanning as well as transmission electron microscopy. The compaction of powders was carried out by hot isostatic pressing and hot isostatic extrusion. The resulting material was subjected to microstructural and mechanical characterization. The microstructure investigated by transmission and scanning electron microscopy supplemented by X-ray diffraction revealed that the bulk material was composed of a mixture of TiAl- and Ti(3)Al-based phases, however, the typical lamellar microstructure for such alloys was not observed. The materials exhibited exceptionally high yield strength together with satisfactory ductility and fracture toughness. The high strength was unequivocally due to grain refinement and the presence of oxide dispersoid. PMID:20500422

Dymek, S; Wrbel, M; Witczak, Z; Blicharski, M

2010-03-01

349

Nickel-Titanium Alloys: Corrosion "Proof" Alloys for Space Bearing, Components and Mechanism Applications  

NASA Technical Reports Server (NTRS)

An intermetallic nickel-titanium alloy, 60NiTi (60 wt% Ni, 40 wt% Ti), is shown to be a promising candidate tribological material for space mechanisms. 60NiTi offers a broad combination of physical properties that make it unique among bearing materials. 60NiTi is hard, electrically conductive, highly corrosion resistant, readily machined prior to final heat treatment, and is non-magnetic. Despite its high Ti content, 60NiTi is non-galling even under dry sliding. No other bearing alloy, metallic or ceramic, encompasses all of these attributes. Since 60NiTi contains such a high proportion of Ti and possesses many metallic properties, it was expected to exhibit poor tribological performance typical of Ti alloys, namely galling type behavior and rapid lubricant degradation. In this poster-paper, the oil-lubricated behavior of 60NiTi is presented.

DellaCorte, Christopher

2010-01-01

350

Nickel-Titanium Alloys: Corrosion "Proof" Alloys for Space Bearing, Components and Mechanism Applications  

NASA Technical Reports Server (NTRS)

An intermetallic nickel-titanium alloy, 60NiTi (60wt%Ni, 40wt%Ti), is shown to be a promising candidate tribological material for space mechanisms. 60NiTi offers a broad combination of physical properties that make it unique among bearing materials. 60NiTi is hard, electrically conductive, highly corrosion resistant, readily machined prior to final heat treatment, and is non-magnetic. Despite its high titanium content, 60NiTi is non-galling even under dry sliding. No other bearing alloy, metallic or ceramic, encompasses all of these attributes. Since 60NiTi contains such a high proportion of titanium and possesses many metallic properties, it was expected to exhibit poor tribological performance typical of titanium alloys, namely galling type behavior and rapid lubricant degradation. In this poster-paper, the oil-lubricated behavior of 60NiTi is studied.

DellaCorte, Christopher

2010-01-01

351

Structural and Mssbauer spectroscopic study of Fe-Ni alloy nanoparticles  

NASA Astrophysics Data System (ADS)

Nano-crystalline Fe-Ni alloys have been synthesized in ethylene glycol medium. Based on XRD studies it is confirmed that, in these alloys Fe atoms are incorporated at Ni site to form Ni-Fe solid solutions. Mssbauer studies have established that for alloy particles having smaller size there is significant concentration of two different types of paramagnetic Fe species and their relative concentration decreased with increase in particle size.

Kumar, Asheesh; Meena, S. S.; Banerjee, S.; Sudarsan, V.

2014-04-01

352

Corrosion resistance and microstructure of electrodeposited nickelcobalt alloy coatings  

Microsoft Academic Search

NiCo alloys with varying cobalt content were electrodeposited employing sulphamate electrolyte. The changes in microstructure and corrosion behavior of electrodeposited nickel with respect to cobalt addition were studied. Scanning electron microscope, optical microscope and energy dispersive X-ray analysis were used to characterize the alloy coatings. The alloy co-deposition was observed to be anomalous type. The cross-section microhardness measurement indicated that

Meenu Srivastava; V. Ezhil Selvi; V. K. William Grips; K. S. Rajam

2006-01-01

353

Microstructures and mechanical properties of Fe 3Al-based FeAlC alloys  

Microsoft Academic Search

In this paper results on the microstructures and mechanical properties of Fe3Al-based FeAlC alloys with strengthening precipitates of the perovskite-type ?-phase Fe3AlCx are presented. The alloys are prepared by vacuum induction melting and cast into Cu-moulds. The composition of the Fe3Al matrix of the investigated FeAlC alloys varies between 23 and 29at.% Al. The ternary C-additions range from 1 to

A. Schneider; L. Falat; G. Sauthoff; G. Frommeyer

2005-01-01

354

Solidification behaviour, microstructure and mechanical properties of high Fe-containing AlSiV alloys  

Microsoft Academic Search

The paper deals with effect of Fe on the solidification behaviour and mechanical properties of unmodified and modified AlVSi alloys. Effect of thermo-mechanical processing on the mechanical properties of these alloys was also reported. The solidification proceeds through several invariant reactions, the first one corresponds to formation of Al3(Fe,V,Si)-type phase. Modification with NiMg master alloy changes the morphology, size and

K. L. Sahoo; B. N. Pathak

2009-01-01

355

Electrostatic Deflection Binary Alloy Evaporator.  

National Technical Information Service (NTIS)

A new technique for producing thin film binary alloys is discussed which used periodic deflection of an electron beam between two sources in a vacuum evaporator. This technique makes it possible to produce high quality binary alloys of predetermined ratio...

E. A. Stern J. L. Erskine J. M. Tracy

1970-01-01

356

Solidification of an alloy 625 weld overlay  

Microsoft Academic Search

The solidification behavior (microsegregation, secondary phase formation, and solidification temperature range) of an Alloy\\u000a 625 weld overlay deposited on 2.25Cr - 1Mo steel by gas metal arc welding was investigated by light and electron optical microscopy,\\u000a electron microprobe, and differential thermal analysis techniques. The overlay deposit was found to terminate solidification\\u000a at ? 1216 C by a?\\/Laves eutectic-type reaction. The

J. N. DuPont

1996-01-01

357

Joints in fiber-reinforced aluminum alloys  

NASA Technical Reports Server (NTRS)

Problems of joining involving structural components made of aluminum alloys with boron-fiber reinforcements are discussed, giving attention to a diffusion-welding process. The tension characteristics and weight factors in the case of various types of welded joints are considered. Diffusion-welding equipment used in the experimental investigation is described. The strength characteristics obtained in various cases of weld and component design are examined, taking into account static and dynamic stresses.

Gerber, K.; Vanrensen, E.

1988-01-01

358

Superconducting silver brazing alloy (silver solder).  

PubMed

A superconducting transition has been observed in a type BAg-3 silver brazing alloy (silver solder) with T(c)=96.(6) mK and H(c)=4.7 Oe. The associated diamagnetism indicates that approximately 1/3 of the sample volume displays the Meissner effect. This property dictates caution in its use at very low temperatures, particularly near sensitive magnetic devices such as ac and SQUID magnetometers. PMID:18698980

Thompson, J R; Thomson, J O

1978-10-01

359

Finding the Alloy Genome  

NASA Astrophysics Data System (ADS)

First-principles codes can nowadays provide hundreds of high-fidelity enthalpies on thousands of alloy systems with a modest investment of a few tens of millions of CPU hours. But a mere database of enthalpies provides only the starting point for uncovering the ``alloy genome.'' What one needs to fundamentally change alloy discovery and design are complete searches over candidate structures (not just hundreds of known experimental phases) and models that can be used to simulate both kinetics and thermodynamics. Despite more than a decade of effort by many groups, developing robust models for these simulations is still a human-time-intensive endeavor. Compressive sensing solves this problem in dramatic fashion by automatically extracting the ``sparse model'' of an alloy in only minutes. This new paradigm to model building has enabled a new framework that will uncover, automatically and in a general way across the periodic table, the important components of such models and reveal the underlying ``genome'' of alloy physics.

Hart, Gus L. W.; Nelson, Lance J.; Zhou, Fei; Ozolins, Vidvuds

2012-10-01

360

Aluminum-lithium alloys II  

SciTech Connect

The topics covered in this volume include: methods of alloy preparation (including ingot casting, rapid solidification, and mechanical alloying); processing and alloying effects on microstructure and properties; superplastic deformation; and physical metallurgy fundamentals. Other topics discussed include: weldability; sodium and hydrogen effects on fracture; corrosion behavior (including general corrosion, stress corrosion, and high-temperature oxidation); and monotonic and cyclic properties at ambient and elevated temperatures. Attention is also given to the use of Al-Li alloys in aircraft structures.

Starke, E.A. Jr.; Sanders, T.H. Jr.

1984-01-01

361

A study of surface tension driven segregation in monotectic alloy systems  

NASA Technical Reports Server (NTRS)

The compatibilities of various monotectic alloy systems with several different crucible materials were evaluated. The study was carried out using small candidate alloy samples of compositions that produced fifty volume percent of each liquid phase at the monotectic temperature. Compatibility was based on the evaluation of the wetting tendency of the two immiscible phases with the crucible material in a one-g solidified sample. Three types of wetting phenomena were observed during the evaluation. Type 1 indicates an alloy-crucible combination where the L2 phase preferentially wets the crucible material. Since L2 is usually the minority phase in desirable alloys, this material combination would be difficult to process and is therefore considered incompatible. Type 2 behavior indicates an alloy-crucible combination where the L1 phase preferentially wets the crucible material. This type of combination is considered compatible since surface tension effects should aid in processing the alloy to a useful form. Type 3 indicates any combination that leads to major reactions between the alloy and crucible material, gas entrapment, or separation of the metal from the crucible wall. Additional compatibility evaluations would have to be carried out on combinations of this category. The five alloy systems studied included aluminum-bismuth, copper-lead, aluminum-indium, aluminum-lead and cadmium-gallium. The systems were combined with crucibles of alumina, boron nitride, mullite, quartz, silicon carbide and zirconia.

Andrews, J. Barry; Andrews, Rosalia N.; Gowens, Terrell F.

1988-01-01

362

Segregation phenomena at growing alumina/alloy interfaces  

SciTech Connect

The chemistry and structure at the scale/alloy interface are important factors governing scale adhesion. The chemical changes can occur from segregation of impurities in the alloy, such as sulphur and carbon, or alloying elements such as chromium, aluminium and reactive elements. This paper reviews studies of the changes of interfacial composition with oxidation time for Al{sub 2}O{sub 3} formed on several model alumina-forming alloys, and tries to relate that to the interfacial strength. Results show that sulphur segregation to oxide/metal interfaces can indeed occur, but the type and amount of segregants at the interface depend on the alloy composition and the interface structure. Co-segregation of impurities with alloying elements can also occur, resulting in multi-layer segregants at the interface. Sulphur-containing interfaces are indeed weaker, but the major role of sulphur is to enhance interfacial void formation. Reactive elements in the alloy not only gather sulfur but also exert an additional positive effect on scale adhesion.

Hou, Peggy Y.

2005-03-30

363

Utilization of Copper Alloys for Marine Applications  

NASA Astrophysics Data System (ADS)

Utilization of copper alloy components in systems deployed in marine environment presents potential improvements by reducing maintenance costs, prolonging service life, and increasing reliability. However, integration of these materials faces technological challenges, which are discussed and addressed in this work, including characterization of material performance in seawater environment, hydrodynamics of copper alloy components, and design procedures for systems with copper alloys. To characterize the hydrodynamic behavior of copper alloy nets, mesh geometry of the major types of copper nets currently used in the marine aquaculture are analyzed and formulae for the solidity and strand length are proposed. Experimental studies of drag forces on copper alloy net panels are described. Based on these studies, empirical values for normal drag coefficients are proposed for various types of copper netting. These findings are compared to the previously published data on polymer nets. It is shown that copper nets exhibit significantly lower resistance to normal currents, which corresponds to lower values of normal drag coefficient. The seawater performance (corrosion and biofouling) of copper alloys is studied through the field trials of tensioned and untensioned specimens in a one-year deployment in the North Atlantic Ocean. The corrosion behavior is characterized by weight loss, optical microscopy, and SEM/EDX analyses. The biofouling performance is quantified in terms of the biomass accumulation. To estimate the effects of stray electrical currents on the seawater corrosion measurements, a low cost three-axis stray electric current monitoring device is designed and tested both in the lab and in the 30-day field deployment. The system consists of a remotely operated PC with a set of pseudo-electrodes and a digital compass. The collected data is processed to determine magnitudes of AC and DC components of electric field and dominant AC frequencies. Mechanical behavior of copper alloys is investigated through a series of uniaxial tension tests on virgin and weathered (after one-year deployment in the ocean) specimens. The changes in mechanical properties are quantified in terms of differences in Young's modulus, Poisson's ratio, ultimate strength, and ultimate strain. The obtained stress-strain data is used for numerical modeling of the mechanical behavior of chain-link nets. The simulations are compared with the experimental data on stiffness and strength of the nets. The available information on seawater performance of copper alloys (corrosion, biofouling, mechanics) and copper alloy nets (hydrodynamics) is used to develop engineering procedures for marine aquaculture fish cage systems with copper alloy netting. The design, analysis, and fabrication procedures are illustrated on a commercial size gravity-type offshore fish cage deployed in the Pacific Ocean near Isla Italia (Patagonia, Chile). The funding for this work was provided by the International Copper Association. This work was also supported through two UNH Fellowships: CEPS UNH Graduate Fellowship to Outstanding PhD Program Applicants and Dissertation Year Fellowship.

Drach, Andrew

364

Solidification of an alloy 625 weld overlay  

NASA Astrophysics Data System (ADS)

The solidification behavior (microsegregation, secondary phase formation, and solidification temperature range) of an Alloy 625 weld overlay deposited on 2.25Cr - 1Mo steel by gas metal arc welding was investigated by light and electron optical microscopy, electron microprobe, and differential thermal analysis techniques. The overlay deposit was found to terminate solidification at ? 1216 C by a ?/Laves eutectic-type reaction. The Laves phase was highly enriched in Nb, Mo, and Si. The solidification reaction and microsegregation potential of major alloying elements in the overlay deposit are compared to other Nb-bearing Ni base alloys and found to be very similar to those for Alloy 718. Solidification cracks observed in the overlay were attributed to the wide solidification temperature range (?170 C) and formation of interdendritic ( ?+Laves) constituent. Reasonable agreement is obtained between the calculated and measured volume percent ( ?+Laves) constituent with the Scheil equation by treating the overlay system as a simple ?-Nb binary and using an experimentally determined k Nb value from electron microprobe data.

Dupont, J. N.

1996-11-01

365

Reduction in Defect Content in ODS Alloys  

SciTech Connect

The work detailed within this report is a continuation of earlier work that was carried out under contract number IDX-SY382V. The earlier work comprised a literature review of the sources and types of defects found principally in Fe-based ODS alloys together with a series of experiments designed to identify defects in ODS Fe{sub 3}Al material and recommend methods of defect reduction. Defects found in the Mechanically Alloyed (MA) ODS Fe{sub 3}Al included regions of incomplete MA, porosity, intrusions and fine-grained stringers. Some defects tended to be found in association with one another e.g. intrusions and fine-grained stringers. Preliminary powder separation experiments were also performed. The scope and objectives of the present work were laid out in the technical proposal ``Reduction in Defect Content in ODS Alloys--II'' which formed the basis of amendment 3 of the current contract. The current studies were devised in the context of the preceding work with a view to extending and concluding certain experiments while exploring new avenues of investigation of defect control and reduction where appropriate. All work proposed was within the context of achieving an ODS Fe{sub 3}Al alloy of improved overall quality and potential creep performance (particularly) in the consolidated, release condition. The interim outturn of the experimental work performed is also reported.

Ritherdon, J.; Jones, A.R.

2000-02-01

366

Solidification of an alloy 625 weld overlay  

SciTech Connect

The solidification behavior (microsegregation, secondary phase formation, and solidification temperature range) of an Alloy 625 weld overlay deposited on 2.25Cr-1Mo steel by gas metal arc welding was investigated by light and electron optical microscopy, electron microprobe, and differential thermal analysis techniques. The overlay deposit was found to terminate solidification at {approx}1,216 C by a {gamma}/Laves eutectic-type reaction. The Laves phase was highly enriched in Nb, Mo, and Si. The solidification reaction and microsegregation potential of major alloying elements in the overlay deposit are compared to other Nb-bearing Ni base alloys and found to be very similar to those for Alloy 718. Solidification cracks observed in the overlay were attributed to the wide solidification temperature range ({approx}170 C) and formation of interdendritic ({gamma} + Laves) constituent. Reasonable agreement is obtained between the calculated and measured volume percent ({gamma} + Laves) constituent with the Scheil equation by treating the overlay system as a simple {gamma}-Nb binary and using an experimentally determined k{sub Nb} value from electron microprobe data.

DuPont, J.N. [Lehigh Univ., Bethlehem, PA (United States). Energy Research Center

1996-11-01

367

Laser boriding of titanium alloys  

Microsoft Academic Search

The low wear resistance of titanium and its alloys limits their use in machine building. Methods for the surface hardening of titanium and its alloys, which tend to enhance their antifriction properties. are of significant interest in this respect. Laser alloying is one of the most promising methods of improving the strength of the surface. In this study. we investigated

V. S. Postnikov; M. N. Tagirov

1994-01-01

368

Modeling dissolution in aluminum alloys  

Microsoft Academic Search

Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working,

Tracie Lee Durbin

2005-01-01

369

De-alloyed platinum nanoparticles  

DOEpatents

A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

Strasser, Peter (Houston, TX); Koh, Shirlaine (Houston, TX); Mani, Prasanna (Houston, TX); Ratndeep, Srivastava (Houston, TX)

2011-08-09

370

Method of preparing alloy compositions  

Microsoft Academic Search

This patent describes a method of improving the oxidation resistance of an existing crystalline nickel-based alloy composition. It comprises the steps of: providing an existing crystalline nickel-based alloy comprising: nickel; chromium; and at least one additional alloy element selected from the group consisting of nickel, chromium, molybdenum, manganese, silicon, carbon, vanadium, cobalt, copper, nitrogen, titanium, zirconium, aluminum, and mixtures thereof,

Corwin

1990-01-01

371

ELECTROLESS-PLATED BRAZING ALLOYS  

Microsoft Academic Search

The electroless-plating process deposits an Ni-P brazing alloy that ; exhibits excellent wetability and flowability in conjunction with each high-; temperature alloys as austenitic stainless steels or Inconel when heated above ; the eutectic temperature in a dry hydrogen atmosphere. Complex tubeto-fin heat ; exchanger assemblies can be fabricated by preplating with electroless Ni-P alloy ; and then brazing at

P. Patriarca; G. M. Slaughter; W. D. Manly

1957-01-01

372

The bone tissue compatibility of a new Ti-Nb-Sn alloy with a low Young's modulus.  

PubMed

A Ti-Nb-Sn alloy was developed as a new ?-type titanium alloy which had a low Young's modulus and high strength. The Young's modulus of the Ti-Nb-Sn alloy was reduced to about 45 GPa by cold rolling, much closer to human cortical bone (10-30 GPa) than that of Ti-6Al-4V alloy (110 GPa) and other ?-type titanium alloys developed for biomedical applications. The tensile strength of the Ti-Nb-Sn alloy was increased to a level greater than that of Ti-6Al-4V alloy by heat treatment after severe cold rolling. In this study the cytotoxicity of Ti-25Nb-11Sn alloy was evaluated in direct contact cell culture tests using metal disks and the bone tissue compatibility - examined using metal rods inserted into the medullary canal of rabbit femurs. The remarkable findings were that: (1) there were no significant differences in the relative growth ratio and relative absorbance ratio between cells grown with the Ti-Nb-Sn alloy, Ti-6Al-4V alloy and CP-Ti in direct contact cell culture tests; (2) there were no significant differences in the load at failure between the Ti-Nb-Sn alloy and Ti-6Al-4V alloy in pull-out metal rods tests; (3) there were no significant differences in new bone formation around metal rods between the Ti-Nb-Sn alloy and Ti-6Al-4V alloy in histological evaluations. The new Ti-Nb-Sn alloy with an elasticity closer to that of human bone is thus considered to be bioinert while also having a high degree of bone compatibility similar to that of Ti-6Al-4V alloy. PMID:21316491

Miura, Keiki; Yamada, Norikazu; Hanada, Shuji; Jung, Taek-Kyun; Itoi, Eiji

2011-05-01

373

Formation of amorphous Fe-B alloys by mechanical alloying  

SciTech Connect

Using a novel ball mill with controlled ball movement we have produced for the first time amorphous Fe{sub 50}B{sub 50} and Fe{sub 40}B{sub 60} alloys and nanocrystalline Fe{sub 80}B{sub 20} and Fe{sub 66}B{sub 34} alloys by mechanical alloying. The structural evolution of elemental powder mixtures is studied following milling and subsequent thermal treatment. Upon heating both amorphous and nanostructural mechanically alloyed Fe-B alloys transform into a mixture of equilibrium phases.

Calka, A.; Radlinski, A.P. (Department of Electronic Materials Engineering, Research School of Physical Sciences, Australian National University, Canberra, Australia (AU))

1991-01-14

374

Magnesium and magnesium alloys  

SciTech Connect

This new handbook is the most comprehensive publication of engineering information on commercial magnesium alloys under one cover in the last sixty years. Prepared with the cooperation of the International Magnesium Association, it presents the industrial practices currently used throughout the world, as well as the properties of the products critical to their proper application. Contents include: general characteristics; physical metallurgy; melting, refining, alloying, recycling, and powder production; casting; heat treatment; forging, rolling, and extrusion; semisolid processing; forming; joining; cleaning and finishing; selection, application, and properties of grades and alloys; design considerations; mechanical behavior and wear resistance; fatigue and fracture-mechanics; high-temperature strength and creep; corrosion and stress-corrosion cracking; specification.

Avedesian, M.; Baker, H. [eds.

1998-12-31

375

Hydrogen in titanium alloys  

SciTech Connect

The titanium alloys that offer properties worthy of consideration for fusion reactors are Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo-Si (Ti-6242S) and Ti-5Al-6Sn-2Zr-1Mo-Si (Ti-5621S). The Ti-6242S and Ti-5621S are being considered because of their high creep resistance at elevated temperatures of 500/sup 0/C. Also, irradiation tests on these alloys have shown irradiation creep properties comparable to 20% cold worked 316 stainless steel. These alloys would be susceptible to slow strain rate embrittlement if sufficient hydrogen concentrations are obtained. Concentrations greater than 250 to 500 wppm hydrogen and temperatures lower than 100 to 150/sup 0/C are approximate threshold conditions for detrimental effects on tensile properties. Indications are that at the elevated temperature - low hydrogen pressure conditions of the reactors, there would be negligible hydrogen embrittlement.

Wille, G W; Davis, J W

1981-04-01

376

Ageing of zirconium alloy components  

NASA Astrophysics Data System (ADS)

India has two types (pressurized heavy water reactors (PHWRs) and boiling water reactors (BWRs)) of commercial nuclear reactors in operation, in addition to research reactors. Many of the life limiting critical components in these reactors are fabricated from zirconium alloys. The progressive degradation of these components caused by the cumulative exposure of high energy neutron irradiation with increasing period of reactor operation was monitored to assess the degree of ageing. The components/specimens examined included fuel element claddings removed from BWRs, pressure tubes and garter springs removed from PHWRs and calandria tube specimens used in PHWRs. The tests included tension test (for cladding, garter spring), fracture toughness test (for pressure tube), crush test (for garter spring), and measurement of irradiation induced growth (for calandria tube). Results of various tests conducted are presented and applications of the test results are elaborated for residual life estimation/life extension of the components.

Chatterjee, S.; Shah, Priti Kotak; Dubey, J. S.

2008-12-01

377

Gas-deposit-alloy corrosion interactions in simulated combustion environments  

NASA Astrophysics Data System (ADS)

High temperature corrosion in aggressive coal combustion environments involves simultaneous corrosion reactions between combustion gases, ash deposits, and alloys. This research investigated the behavior of a ferritic steel (SA387-Gr11) and three weld claddings (309L SS, Alloy 72, and Alloy 622) in five combustion environments beneath solid deposits at 500C for up to 1000 hours. The synthetic gases consisted of N2-CO-CO-H2-H2O-H 2S-SO2 mixtures that simulated a range of fuel-rich or fuel-lean combustion environments with a constant sulfur content. The synthetic deposits contained FeS2, FeS, Fe3O4 and/or carbon. Reaction kinetics was studied in individual gas-metal, gas deposit, and deposit-alloy systems. A test method was developed to investigate simultaneous gas-deposit-metal corrosion reactions. The results showed reaction kinetics varied widely, depending on the gas-alloy system and followed linear, parabolic, and logarithmic rate laws. Under reducing conditions, the alloys exhibited a range of corrosion mechanisms including carburization-sulfidation, sulfidation, and sulfidation-oxidation. Most alloys were not resistant to the highly reducing gases but offered moderate resistance to mixed oxidation-sulfidation by demonstrating parabolic or logarithmic behavior. Under oxidizing conditions, all of the alloys were resistant. Under oxidizing-sulfating conditions, alloys with high Fe or Cr contents sulfated whereas an alloy containing Mo and W was resistant. In the gas-deposit-metal tests, FeS2-bearing deposits were extremely corrosive to low alloy steel under both reducing and oxidizing conditions but they had little influence on the weld claddings. Accelerated corrosion was attributed to rapid decomposition or oxidation of FeS2 particles that generated sulfur-rich gases above the alloy surface. In contrast, FeS-type deposits had no influence under reducing conditions but they were aggressive to low alloy steel under oxidizing conditions. The extent of damage correlated with the initial sulfur content in the deposit. Fe3O4 in the deposit was beneficial because it acted as a sulfur getter or oxygen source. Carbon had a mixed effect. The reaction behavior was modeled using computational thermochemistry based on Gibbs free energy minimization. A calculation method was introduced to predict equilibrium corrosion microstructures and trace reaction paths in complex gas-deposit-metal environments. Kinetic factors were identified where equilibrium reaction products were not experimentally observed.

Luer, Kevin Raymond

378

Study of corrosion between a titanium implant and dental alloys.  

PubMed

The infiltration of saliva into the multi-metallic structures on titanium implants brings different types of alloys into temporary or permanent contact. In this way a galvanic cell is established as a result of their potential difference. The galvanic cell phenomenon is compounded by another type of corrosion resulting from the geometry of the assembly: localized crevice corrosion. Fifteen galvanic couples (Ti/gold-based alloys, Ti/palladium-based alloy and Ti/non-precious alloys) were studied. Various electrochemical parameters (Ecorr, Ecommon, Ecouple corr, Ecrevice, icorr, icouple corr and Tafel slopes) were analysed. The galvanic currents measured are of the same order of magnitude (except Ti/stainless steel). They remain low. Application of the mixed-potential theory shows that titanium in coupling with the alloys studied will be under either cathodic or anodic control. According to the results obtained, an alloy that is potentially usable for superstructures in a galvanic coupling with titanium must fulfil a certain number of parameters: in a coupling, titanium must have a weak anodic polarization; the current generated by the galvanic cell must also be weak; the crevice potential must be markedly higher than the common potential. PMID:8027459

Reclaru, L; Meyer, J M

1994-06-01

379

Iron aluminide alloys with improved properties for high temperature applications  

DOEpatents

An improved iron aluminide alloy of the DO.sub.3 type that has increased room temperature ductility and improved high elevated temperature strength. The alloy system further is resistant to corrosive attack in the environments of advanced energy corrosion systems such as those using fossil fuels. The resultant alloy is relatively inexpensive as contrasted to nickel based and high nickel steels currently utilized for structural components. The alloy system consists essentially of 26-30 at. % aluminum, 0.5-10 at. % chromium, 0.02-0.3 at. % boron plus carbon, up to 2 at. % molybdenum, up to 1 at. % niobium, up to 0.5 at. % zirconium, up to 0.1 at. % yttrium, up to 0.5 at. % vanadium and the balance iron.

McKamey, Claudette G. (Knoxville, TN) [Knoxville, TN; Liu, Chain T. (Oak Ridge, TN) [Oak Ridge, TN

1990-01-01

380

Aluminum alloys for satellite boxes : engineering guidelines for obtaining adequate strength while minimizing residual stresses and machining distortion.  

SciTech Connect

This report provides strategies for minimizing machining distortion in future designs of aluminum alloy satellite boxes, based in part on key findings from this investigation. The report outlines types of aluminum alloys and how they are heat treated, how residual stresses develop during heat treatment of age hardening alloys, ways residual stresses can be minimized, and the design of machining approaches to minimize distortion in parts that contain residual stresses. Specific recommendations are made regarding alloy selection, heat treatment, stress relieving, and machining procedures for boxes requiring various strength levels with emphasis on 6061 and 7075 aluminum alloys.

Younger, Mandy S.; Eckelmeyer, Kenneth Hall

2007-11-01

381

Surface modification of high temperature iron alloys  

DOEpatents

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.

Park, J.H.

1995-06-06

382

Work function of binary alloys  

NASA Astrophysics Data System (ADS)

By utilizing the field emission method, we have studied the composition dependence of work function in NiCu and PtRh alloys. In PtRh alloys, we find that the work function falls below the linear interpolation, in agreement with the experimental results on AgAu alloys [Fain and McDavid, Phys. Rev. B 9 (1974) 5099]. On the other hand, the work function of NiCu alloys is found to show little systematic deviation from the linear interpolation. The observed negative deviation in PtRh alloys is not compatible with a simple theoretical prediction based on the electronic density of states.

Ishii, Ryusuke; Matsumura, Katsunori; Sakai, Akira; Sakata, Toyo

2001-01-01

383

Stress-Corrosion and Corrosion-Fatigue Susceptibility of High-Strength Aluminum Alloys.  

National Technical Information Service (NTIS)

The 'stress-corrosion-fatigue' performance of several high strength-aluminum alloys was investigated by tests of hydraulic cylinders and other types of specimens. Specimens were prepared from forgings and forging stock of alloys 2014-T6, 7075-T6, 7075-T73...

B. W. Lifka G. E. Nordmark J. G. Kaufman M. S. Hunter

1970-01-01

384

Corrosion of Several Alloys in Superheated Steam at 482 and 538 exp 0 C.  

National Technical Information Service (NTIS)

The corrosion of several ferritic steels, Incoloy Alloy 800, Inconel 617, and type 304 stainless steel in superheated steam at 482 and 538 exp 0 C (755 and 811 K) was investigated. Specimens of the alloys, including welds and U-bends in some cases, are mo...

J. C. Griess W. A. Maxwell

1978-01-01

385

Theory of the resistivity and Hall effect in alloys during Guinier-Preston zone formation  

Microsoft Academic Search

The theory of the resistivity maximum, based on Bragg scattering of electrons from Guinier-Preston zones, is described and is used to construct semi-phenomenological formulae for the resistivity appropriate to various types of alloy configuration. When the parameters are determined from transport calculations the formulae will be useful in analysing the state of an alloy during ageing. It is shown, for

A. J. Hillel; J. T. Edwards; P. Wilkes

1975-01-01

386

Development of silicide coating over molybdenum based refractory alloy and its characterization  

Microsoft Academic Search

Molybdenum based refractory alloys are potential candidate materials for structural applications in high temperature compact nuclear reactors and fusion reactors. However, these alloys being highly susceptible to oxidation in air or oxygen at elevated temperature, undergoes severe losses from highly volatile molybdenum trioxide species. Present investigation, therefore, examines the feasibility of development of silicide type of coating over molybdenum base

S. P. Chakraborty; S. Banerjee; I. G. Sharma; A. K. Suri

2010-01-01

387

Modifying the properties of the Inconel 625 nickel alloy by glow discharge assisted nitriding  

Microsoft Academic Search

The nickel alloys of the Inconel type (containing above 15wt% of chromium), used in many industrial applications including the manufacture of aircraft, chemistry, power generation, and material processing, have advantageous mechanical properties, high plasticity and good corrosion resistance, but their frictional wear resistance is poor. This drawback can be obviated by subjecting the alloys to various surface treatments.The paper describes

Tomasz Borowski; Agnieszka Brojanowska; Marcin Kost; Halina Garbacz; Tadeusz Wierzcho?

2009-01-01

388

Low-temperature electrical resistivity study of deformed Inconel alloy 600  

Microsoft Academic Search

The electrical resistivity of a plastic deformed Inconel alloy 600 (alloy of Ni 72 Cr 16 Fe 8) as function of temperature between 25K and 300K was studied. The deformation does not affect the Curie temperature much; it is roughly near 176K of the deflected point at electrical resistivity, except for the sample with 75% deformation. The ?-type behavior of

Feng Shiu Chan; Yeong Der Yao; Shing Hoa Wang

2006-01-01

389

Self-adjustment of Young's modulus in biomedical titanium alloys during orthopaedic operation  

Microsoft Academic Search

In spinal fixation devices, the Young's modulus of the metallic implant rod should be not only sufficiently low to prevent stress shielding for the patient but also sufficiently high to suppress springback for the surgeon. This paper proposes a novel function of biomedical titanium alloysself-adjustment of Young's modulus. Deformation-induced ? phase transformation was introduced into ?-type titanium alloys so that

Masaaki Nakai; Mitsuo Niinomi; Xingfeng Zhao; Xiaoli Zhao

2011-01-01

390

Processing zirconium alloy used in light water reactors for specified creep rate  

Microsoft Academic Search

This patent describes a method for processing a zirconium alloy, material of a type wherein the material is subjected to a post extrusion meal, a series of an intermediate area reductions and intermediate recrystallization anneals possibly being a late stage beta, a final area reduction, and a final anneal. It comprises controlling creep rate in an alloy consisting essentially of

J. P. Foster; S. A. Worcester; R. J. Comstock

1992-01-01

391

Rapid solidification of copper alloys with high strength and high conductivity  

NASA Astrophysics Data System (ADS)

Rapid solidification has been employed to develop high-strength/high-conductivity copper alloys, because it offers advantages not achievable by conventional ingot metallurgy practice. The effect of rapid solidification on mechanical properties and electrical conductivity on copper alloys (with and without heat treatment) has been studied. Results indicated that alloys of the Cu-Cr-Zr type, rapidly solidified and aged, show a good combination of electrical conductivity [45.82 106(l/? m)] and microhardness Vickers (24.46 106 Pa) values. These values are superior to those of optimally aged conventional copper alloys for resistance welding electrode applications.

Lopez, F.; Reyes, J.; Campillo, B.; Aguilar-Sahagun, G.; Juarez-Lslas, J. A.

1997-10-01

392

Close Correlation between Enthalpy of Mixing and Internal Strain Energy in III V Compound Alloys  

NASA Astrophysics Data System (ADS)

The correlation of enthalpy of mixing and internal strain energy calculated by the elastic sphere model has been studied for III V ternary alloy semiconductors of the AB0.5C0.5 type. A plot of the enthalpy of mixing and the internal strain energy on a plane for 18 different alloy systems shows nearly linear correlation. This result strongly supports the conclusion drawn in our previous paper that the immiscibility domains, in which the alloys are not formed completely, for III V alloys can be predicted simply from the isoenergy chart obtained by the elastic sphere model.

Oyama, Katsushi; Uda, Hiroshi; Ikegami, Seiji; Sonomura, Hajimu

1999-11-01

393

Thermal coatings for titanium-aluminum alloys  

NASA Technical Reports Server (NTRS)

Titanium aluminides and titanium alloys are candidate materials for use in hot structure and heat-shield components of hypersonic vehicles because of their good strength-to-weight characteristics at elevated temperature. However, in order to utilize their maximum temperature capability, they must be coated to resist oxidation and to have a high total remittance. Also, surface catalysis for recombination of dissociated species in the aerodynamic boundary layer must be minimized. Very thin chemical vapor deposition (CVD) coatings are attractive candidates for this application because of durability and very light weight. To demonstrate this concept, coatings of boron-silicon and aluminum-boron-silicon compositions were applied to the titanium-aluminides alpha2 (Ti-14Al-21Nb), super-alpha2 (Ti-14Al-23-Nb-2V), and gamma (Ti-33Al-6Nb-1Ta) and to the titanium alloy beta-21S (Ti-15Mo-3Al-3Nb-0.2Si). Coated specimens of each alloy were subjected to a set of simulated hypersonic vehicle environmental tests to determine their properties of oxidation resistance, surface catalysis, radiative emittance, and thermal shock resistance. Surface catalysis results should be viewed as relative performance only of the several coating-alloy combinations tested under the specific environmental conditions of the LaRC Hypersonic Materials Environmental Test System (HYMETS) arc-plasma-heated hypersonic wind tunnel. Tests were also conducted to evaluate the hydrogen transport properties of the coatings and any effects of the coating processing itself on fatigue life of the base alloys. Results are presented for three types of coatings, which are as follows: (1) a single layer boron silicon coating, (2) a single layer aluminum-boron-silicon coating, and (3) a multilayer coating consisting of an aluminum-boron-silicon sublayer with a boron-silicon outer layer.

Cunnington, George R.; Clark, Ronald K.; Robinson, John C.

1993-01-01

394

Weldable ductile molybdenum alloy development  

SciTech Connect

Molybdenum and its alloys are attractive structural materials for high-temperature applications. However, various practical issues have limited its use. One concern relates to the loss of ductility occurring in the heat-affected weld zone caused by segregation of oxygen to grain boundaries. In this study, a series of arc melted molybdenum alloys have been produced containing controlled additions of B, C, Zr, and Al. These alloys were characterized with respect to their tensile properties, smooth bend properties, and impact energy for both the base metal and welds. These alloys were compared with a very high purity low carbon arc cast molybdenum reference. For discussion purposes the alloys produced are separated into two categories: Mo Al B alloys, and Mo Zr B alloys. The properties of Mo Zr B alloy welds containing higher carbon levels exhibited slight improvement over unalloyed molybdenum, though the base-metal properties for all Mo Zr B alloys were somewhat inconsistent with properties better, or worse, than unalloyed molybdenum. A Mo Al B alloy exhibited the best DBTT values for welds, and the base metal properties were comparable to or slightly better than unalloyed molybdenum. The Mo Al B alloy contained a low volume fraction of second-phase particles, with segregation of boron and carbon to grain boundaries believed to displace oxygen resulting in improved weld properties. The volume fractions of second-phase particles are higher for the Mo Zr B alloys, and these alloys were prone to brittle fracture. It is also noted that these Mo Zr B alloys exhibited segregation of zirconium, boron and carbon to the grain boundaries.

Cockeram, B. V. [Bettis Atomic Power Laboratory, West Mifflin, PA; Ohriner, Evan Keith [ORNL; Byun, Thak Sang [ORNL; Schneibel, Joachim H [ORNL; Miller, Michael K [ORNL; Snead, Lance Lewis [ORNL

2008-01-01

395

Shape Memory Alloy Actuator  

NASA Technical Reports Server (NTRS)

The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

Baumbick, Robert J. (Inventor)

2002-01-01

396

Shape Memory Alloy Actuator  

NASA Technical Reports Server (NTRS)

The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

Baumbick, Robert J. (Inventor)

2000-01-01

397

Quaternary Alloy Microwave MESFET.  

National Technical Information Service (NTIS)

Liquid phase epitaxial growth techniques have been used to grow quaternary alloys, Ga sub 1-x In sub x P sub 1-y As sub y, on InP substrates, using (100), (111) A and (111) B orientations. Liquidus and solidus data at 660 C have been used to determine dis...

J. W. Harrison S. B. Phatak M. A. Littlejohn G. Kelner H. H. Stadelmaier

1979-01-01

398

Superplasticity in aluminum alloys  

SciTech Connect

We have characterized in the Al-Mg system the microstructure and mechanical properties of a cold-rolled Al-6Mg-0.3Sc alloy. The alloy exhibited superplasticity at relatively high strain rates (about 10-2 s-1). At a strain rate of 10-2 s-1 there exists a wide temperature range (475-520`C) within which the tensile elongation is over 1000%. There also exists a wide strain rate range (10-3 - 10-1 s-1) within which the tensile elongation is over 500%. The presence of Sc in the alloy results in a uniform distribution of fine coherent Al3SC precipitates which effectively pin grain and subgrain boundaries during static and continuous recrystallization. As a result, the alloy retains its fine grain size (about 7 micron), even after extensive superplastic deformation (>1000%). During deformation, dislocations Mg with a high Schmidt factor slip across subgrains but are trapped by subgrain boundaries, as a result of the strong pining of Al3Sc. This process leads to the conversion of low-angled subgrain boundaries to high-angled grain boundaries and the subsequent grain boundary sliding, which produces superelasticity. A model is proposed to describe grain boundary sliding accommodated by dislocation glide across grains with a uniform distribution of coherent precipitates. The model predictions is consistent with experimental observations.

Nieh, T. G.

1997-12-01

399

Quinary metallic glass alloys  

DOEpatents

At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf).sub.a (Al,Zn).sub.b (Ti,Nb).sub.c (Cu.sub.x Fe.sub.y (Ni,Co).sub.z).sub.d wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d.multidot.y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

Lin, Xianghong (Pasadena, CA); Johnson, William L. (Pasadena, CA)

1998-01-01

400

Ferromagnetic bulk glassy alloys  

NASA Astrophysics Data System (ADS)

This paper deals with the review on the formation, thermal stability and magnetic properties of the Fe-based bulk glassy alloys in as-cast bulk and melt-spun ribbon forms. A large supercooled liquid region over 50 K before crystallization was obtained in Fe-(Al, Ga)-(P, C, B, Si), Fe-(Cr, Mo, Nb)-(Al, Ga)-(P, C, B) and (Fe, Co, Ni)-Zr-M-B (M=Ti, Hf, V, Nb, Ta, Cr, Mo and W) systems and bulk glassy alloys were produced in a thickness range below 2 mm for the Fe-(Al, Ga)-(P, C, B, Si) system and 6 mm for the Fe-Co-(Zr, Nb, Ta)-(Mo, W)-B system by copper-mold casting. The ring-shaped glassy Fe-(Al, Ga)-(P, C, B, Si) alloys exhibit much better soft magnetic properties as compared with the ring-shaped alloy made from the melt-spun ribbon because of the formation of the unique domain structure. The good combination of high glass-forming ability and good soft magnetic properties indicates the possibility of future development as a new bulk glassy magnetic material.

Inoue, Akihisa; Makino, Akihiro; Mizushima, Takao

2000-06-01

401

Theory of superconducting alloys  

Microsoft Academic Search

A theory is presented to describe disordered weak coupling superconductors. It is shown that the disorder problem can be treated completely within the CPA scheme without further approximations. In particular, the theory is applied to the calculation of the superconducting transition temperature as a function of the alloy parameters.

A. Weinkauf; J. Zittartz

1975-01-01

402

Quinary metallic glass alloys  

DOEpatents

At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3}K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf){sub a}(Al,Zn){sub b}(Ti,Nb){sub c}(Cu{sub x}Fe{sub y}(Ni,Co){sub z}){sub d} wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d{hor_ellipsis}y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

Lin, X.; Johnson, W.L.

1998-04-07

403

Silver alloy compositions  

SciTech Connect

This patent describes a silver alloy composition. It comprises essentially all of the following parts by weight: about 89-93.5% silver, about 0.01-2% silicon, about 0.001-2% boron, about 0.5-5% zinc, about 0.5-6% copper, about 0.25-2% tin, and about 0.01-1.25% indium.

Berhard, M.; Sivertsen, J.T.

1990-11-27

404

Microstructure and stress corrosion cracking of the fusion boundary region in an alloy 182-A533B low alloy steel dissimilar weld joint  

Microsoft Academic Search

Stress corrosion cracking (SCC) in the fusion boundary (FB) region of an Alloy 182-A533B low alloy steel (LAS) dissimilar weld joint in high temperature water doped with sulfate was studied following a microstructure characterization of the FB region. The microstructure characterization suggested the type-II and type-I boundaries in the dilution zone (DZ) adjacent to the FB had lower resistance to

Juan Hou; Qunjia Peng; Yoichi Takeda; Jiro Kuniya; Tetsuo Shoji

2010-01-01

405

Characterization of amorphous Co-P alloy coatings electrodeposited with pulse current using gluconate bath  

NASA Astrophysics Data System (ADS)

Co-P alloy coatings were electrodeposited with pulse current using gluconate bath and characterized by XRD, FESEM, AFM, DSC and XPS. Co-P alloy coatings are amorphous in nature as demonstrated by XRD. FESEM exhibits the "cauliflower type" morphology that is distinctive of nanocrystalline metals and alloys. Co-P alloys are found to follow instantaneous growth mechanism as revealed by AFM studies. Two exothermic peaks at 320 and 340 C in DSC profiles of Co-P deposit correspond to the crystallization of the deposit. Detailed XPS studies of these alloy coatings have shown that as-deposited coatings consist of Co metal as well as oxidized Co species. P has mostly been present as bulk alloy on the surface as P?- form. Increase in the amounts of Co metal and P?- are observed upon intermittent sputtering. No appreciable increase in microhardness is observed with increase in the phosphorous content, but it increases with heat treatment significantly.

Bera, Parthasarathi; Seenivasan, H.; Rajam, K. S.; William Grips, V. K.

2012-10-01

406

Mg Sheet Metal Forming: Lessons Learned from Deep Drawing Li and Y Solid-Solution Alloys  

SciTech Connect

The sheet formability of current magnesium alloys at ambient temperatures is poor; however, the formability at moderately elevated temperatures can be excellent. Cylindrical cup drawing tests are used to compare the warm forming characteristics of conventional alloy AZ31B with alloys containing lithium oryttrium solid solutions. While both types of experimental alloy can have better room-temperature ductility ({epsilon}{sub f}-25-30%) than AZ31B, only the lithium alloy has comparable or better deep-drawing capacity. The results are discussed in terms of the sheet anisotropy. Particular attention is drawn to the fact that magnesium alloys exhibit poor bending ductility due to their anisotropy and mechanical twinning-induced tension-compression strength asymmetry.

Agnew, Sean R [University of Virginia; Senn, Jeremy W. [University of Virginia; Horton Jr, Joe A [ORNL

2006-01-01

407

?=5/2 fractional quantum Hall state in the presence of alloy disorder.  

PubMed

We report quantitative measurements of the impact of alloy disorder on the ? = 5/2 fractional quantum Hall state. Alloy disorder is controlled by the aluminum content x in the Al(x)Ga(1-x)As channel of a quantum well. We find that the ? = 5/2 state is suppressed with alloy scattering. To our surprise, in samples with alloy disorder the ? = 5/2 state appears at significantly reduced mobilities when compared to samples in which alloy disorder is not the dominant scattering mechanism. Our results highlight the distinct roles of the different types of disorder present in these samples, such as the short-range alloy and the long-range Coulomb disorder. PMID:24702403

Deng, Nianpei; Gardner, G C; Mondal, S; Kleinbaum, E; Manfra, M J; Csthy, G A

2014-03-21

408

Tensile bond strength of a composite resin cement for bonded prosthesis to various dental alloys.  

PubMed

The development of composite resin cements that chemically bond to dental alloys has improved the construction of resin-bonded prostheses. Composite resins can be selected for various situations, but specific clinical situations may require different alloys. This study evaluated the ability of a composite resin cement to bond to various dental alloys of different compositions. Ten pairs of disks for each alloy (two NiCr, two NiCrBe, one CuAl, one gold type IV, and one gold for metal ceramic) were bonded to a composite resin cement after air abrasion was performed with aluminum oxide. The disks were then rinsed in tap water and were ultrasonically cleaned in distilled water for 2 minutes. The tensile tests exhibited greater values for alloys ultrasonically cleaned, and the best results were recorded by NiCr and NiCrBe alloys. PMID:7473275

Rubo, J H; Pegoraro, L F

1995-09-01

409

Environmental protection to 922K (1200 F) for titanium alloys  

NASA Technical Reports Server (NTRS)

Evaluations are presented of potential coating systems for protection of titanium alloys from hot-salt stress-corrosion up to temperatures of 755 K (900 F) and from oxidation embrittlement up to temperature of 922 K (1200 F). Diffusion type coatings containing Si, Al, Cr, Ni or Fe as single coating elements or in various combinations were evaluated for oxidation protection, hot-salt stress-corrosion (HSSC) resistance, effects on tensile properties, fatigue properties, erosion resistance and ballistic impact resistance on an alpha and beta phase titanium alloy (Ti-6Al-2Sn-4Zr-2Mo). All of the coatings investigated demonstrated excellent oxidation protectiveness, but none of the coatings provided protection from hot-salt stress-corrosion. Experimental results indicated that both the aluminide and silicide types of coatings actually decreased the HSSC resistance of the substrate alloy. The types of coatings which have typically been used for oxidation protection of refractory metals and nickel base superalloys are not suitable for titanium alloys because they increase the susceptibility to hot-salt stress-corrosion, and that entirely new coating concepts must be developed for titanium alloy protection in advanced turbine engines.

Groves, M. T.

1973-01-01

410

Rheological behavior of Al-Mg-Si-Cu alloys in the mushy state obtained by partial remelting and partial solidification at high cooling rate  

Microsoft Academic Search

This work investigates the mechanical behavior of two aluminum alloys in the mushy state, the alloy AA6056 and an alloy based\\u000a on mixing AA6056 and AA4047. These alloys have been studied to give insight into the susceptibility to hot tearing, which\\u000a occurs during laser welding of AA6056 with 4047 filler wire. Two types of isothermal tensile tests have been conducted:

D. Fabrgue; A. Deschamps; M. Sury; W. J. Poole

2006-01-01

411

Hydrogen absorption behavior of TA15 alloy  

NASA Astrophysics Data System (ADS)

The hydrogen absorption kinetics of TA15 titanium alloy at 973-1123 K was studied using a tube-type hydrogen treatment furnace. The hydrogen absorption kinetic curves obtained were analyzed according to a series of mechanism equations to reveal the kinetic parameters and mechanism of the hydrogen absorption process. The results show that both the hydrogen absorption rate and the equilibrium hydrogen pressure increase and the time to reach equilibrium is shortened with increasing temperature. It is found that only the second hydrogen absorption period exists in the hydrogen absorption process of TA15 alloy between 973 and 1123 K, and the activation energy is 54.889 kJ/mol for hydrogen absorption. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results demonstrate that ? hydride forms between 973 and 1123 K, and ? phase decreases with the increase of temperature. Orthorhombic ?? martensite is generated at 1073-1123 K, and their amount increases with increasing temperature.

Ren, Xue-Ping; Zhang, Fang-Fang; Guo, Qing-Miao; Hou, Hong-Liang; Wang, Yao-Qi

2011-04-01

412

Alloys for hydrogen storage in nickel/hydrogen and nickel/metal hydride batteries  

NASA Technical Reports Server (NTRS)

Since 1990, there has been an ongoing collaboration among the authors in the three laboratories to (1) prepare alloys of the AB(sub 5) and AB(sub 2) types, using arc-melting/annealing and mechanical alloying/annealing techniques; (2) examine their physico-chemical characteristics (morphology, composition); (3) determine the hydrogen absorption/desorption behavior (pressure-composition isotherms as a function of temperature); and (4) evaluate their performance characteristics as hydride electrodes (charge/discharge, capacity retention, cycle life, high rate capability). The work carried out on representative AB(sub 5) and AB(sub 2) type modified alloys (by partial substitution or with small additives of other elements) is presented. The purpose of the modification was to optimize the thermodynamics and kinetics of the hydriding/dehydriding reactions and enhance the stabilities of the alloys for the desired battery applications. The results of our collaboration, to date, demonstrate that (1) alloys prepared by arc melting/annealing and mechanical alloying/annealing techniques exhibit similar morphology, composition and hydriding/dehydriding characteristics; (2) alloys with the appropriate small amounts of substituent or additive elements: (1) retain the single phase structure, (2) improve the hydriding/dehydriding reactions for the battery applications, and (3) enhance the stability in the battery environment; and (3) the AB(sub 2) type alloys exhibit higher energy densities than the AB(sub 5) type alloys but the state-of-the-art, commercialized batteries are predominantly manufactured using Ab(sub 5) type alloys.

Anani, Anaba; Visintin, Arnaldo; Petrov, Konstantin; Srinivasan, Supramaniam; Reilly, James J.; Johnson, John R.; Schwarz, Ricardo B.; Desch, Paul B.

1993-01-01

413

Mechanical alloying of brittle materials  

NASA Astrophysics Data System (ADS)

Mechanical alloying by high energy ball milling has been observed in systems with nominally brittle components. The phases formed by mechanical alloying of brittle components include solid solutions (Si + Ge ? SiGe solid solution), intermetallic compounds (Mn + Bi ? MnBi), and amorphous alloys (NiZr2 + Ni11Zr9 ? amorphous Ni50Zr50). A key feature of possible mechanisms for mechanical alloying of brittle components is the temperature of the powders during milling. Experiments and a computer model of the kinetics of mechanical alloying were carried out in order to esti-mate the temperature effect. Temperature rises in typical powder alloys during milling in a SPEX mill were estimated to be ?350 K using the kinetic parameters determined from the computer model. The tempering response of fresh martensite in an Fe-1.2 wt pct C alloy during milling was consistent with the maximum results of the computer model, yielding temperatures in the pow-ders of ?575 K i.e., ?T ? 300 K). Thermal activation was required for mechanical alloying of Si and Ge powder. No alloying occurred when the milling vial was cooled by liquid nitrogen. The pos-sible mechanisms responsible for material transfer during mechanical alloying of brittle components are considered.

Davis, R. M.; McDermott, B.; Koch, C. C.

1988-12-01

414

Structure of dental gallium alloys.  

PubMed

The interest in gallium alloys as a replacement for amalgam has increased in recent years due to the risk of environmental pollution from amalgam. Alloy powders with compositions close to those for alloys of amalgam are mixed with a liquid gallium alloy. The mix is condensed into a prepared cavity in much the same way as for amalgam. The aim of the present work was to study the structure of: (1) two commercial alloy powders containing mainly silver, tin and copper, and (2) the phases formed by mixing these powders with a liquid alloy of gallium, indium and tin. One of the alloy powders contained 9 wt% palladium. Cross-sections of cylindrical specimens made by these gallium mixes were investigated by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Discrete grains of the following phases were found to be present in both gallium alloys: hexagonal Ag2Ga, tetragonal Cu(Pd)Ga2, cubic Ag9In4 and tetragonal beta-Sn. Indications of hexagonal or orthorhombic Ag2Sn were found in the remaining, unreacted alloy particles. In the palladium-containing alloy the X-ray reflections indicate a minor fraction of cubic Cu9Ga4 in addition to the Cu(Pd)Ga2 phase. Particles of beta-Sn are probably precipitated because Sn-Ga phases cannot be formed according to the binary phase diagram. PMID:8805980

Her, H; Simensen, C J; Jrgensen, R B

1996-07-01

415

Corrosion performance of structural alloys.  

SciTech Connect

Component reliability and long-term trouble-free performance of structural materials are essential in power-generating and gasification processes that utilize coal as a feedstock. During combustion and conversion of coal, the environments encompass a wide range of oxygen partial pressures, from excess-air conditions in conventional boilers to air-deficient conditions in 10W-NO{sub x} and gasification systems. Apart from the environmental aspects of the effluent from coal combustion and conversion, one concern from the systems standpoint is the aggressiveness of the gaseous/deposit environment toward structural components such as waterwall tubes, steam superheaters, syngas coolers, and hot-gas filters. The corrosion tests in the program described in this paper address the individual and combined effects of oxygen, sulfur, and chlorine on the corrosion response of several ASME-coded and noncoded structural alloys that were exposed to air-deficient and excess-air environments typical of coal-combustion and gasification processes. Data in this paper address the effects of preoxidation on the subsequent corrosion performance of structural materials such as 9Cr-1Mo ferritic steel, Type 347 austenitic stainless steel, Alloys 800, 825, 625, 214, Hastelloy X, and iron aluminide when exposed at 650 C to various mixed-gas environments with and without HCI. Results are presented for scaling kinetics, microstructural characteristics of corrosion products, detailed evaluations of near-surface regions of the exposed specimens, gains in our mechanistic understanding of the roles of S and Cl in the corrosion process, and the effect of preoxidation on subsequent corrosion.

Natesan, K.

1999-07-15

416

Mechanical behavior and properties of mechanically alloyed aluminum alloys  

Microsoft Academic Search

The fracture and deformation behaviors of several product forms produced from mechanically alloyed (MA) aluminum alloys 9052\\u000a and 905XL were studied. The main operative strengthening mechanism is strengthening due to the submicron grain size. Ductility\\u000a and toughness were found to be controlled by the morphology of the prior particle boundaries. We propose that the work-hardening\\u000a behavior of these MA alloys

H. R. Last; R. K. Jr. Garrett

1996-01-01

417

A Review on High-Speed Machining of Titanium Alloys  

NASA Astrophysics Data System (ADS)

Titanium alloys have been widely used in the aerospace, biomedical and automotive industries because of their good strength-to-weight ratio and superior corrosion resistance. However, it is very difficult to machine them due to their poor machinability. When machining titanium alloys with conventional tools, the tool wear rate progresses rapidly, and it is generally difficult to achieve a cutting speed of over 60m/min. Other types of tool materials, including ceramic, diamond, and cubic boron nitride (CBN), are highly reactive with titanium alloys at higher temperature. However, binder-less CBN (BCBN) tools, which do not have any binder, sintering agent or catalyst, have a remarkably longer tool life than conventional CBN inserts even at high cutting speeds. In order to get deeper understanding of high speed machining (HSM) of titanium alloys, the generation of mathematical models is essential. The models are also needed to predict the machining parameters for HSM. This paper aims to give an overview of recent developments in machining and HSM of titanium alloys, geometrical modeling of HSM, and cutting force models for HSM of titanium alloys.

Rahman, Mustafizur; Wang, Zhi-Gang; Wong, Yoke-San

418

Casting behavior of titanium alloys in a centrifugal casting machine.  

PubMed

Since dental casting requires replication of complex shapes with great accuracy, this study examined how well some commercial titanium alloys and experimental titanium-copper alloys filled a mold cavity. The metals examined were three types of commercial dental titanium [commercially pure titanium (hereinafter noted as CP-Ti), Ti-6Al-4V (T64) and Ti-6Al-7Nb (T67)], and experimental titanium-copper alloys [3%, 5% and 10% Cu (mass %)]. The volume percentage filling the cavity was evaluated in castings prepared in a very thin perforated sheet pattern and cast in a centrifugal casting machine. The flow behavior of the molten metal was also examined using a so-called "tracer element technique." The amounts of CP-Ti and all the Ti-Cu alloys filling the cavity were similar; less T64 and T67 filled the cavity. However, the Ti-Cu alloys failed to reach the end of the cavities due to a lower fluidity compared to the other metals. A mold prepared with specially designed perforated sheets was effective at differentiating the flow behavior of the metals tested. The present technique also revealed that the more viscous Ti-Cu alloys with a wide freezing range failed to sequentially flow to the end of the cavity. PMID:12593955

Watanabe, K; Miyakawa, O; Takada, Y; Okuno, O; Okabe, T

2003-05-01

419

Surface segregation in MCrAlY alloys  

NASA Astrophysics Data System (ADS)

This paper presents a study of surface segregation in NiCrAlY and FeCrAlY type alloys. The segre-gation was measured using Auger electron spectroscopy. Samples were heated in the spectrometer to temperatures between 800 and 1100 C, and segregation was measured at temperature as a function of time. The results show that when yttrium and sulfur were present in the alloy, they segregated to the surface where their concentrations were greatly enriched over their bulk concentrations. The presence of yttrium in the alloy did not eliminate sulfur segregation. The surface concentration of aluminum appeared, in most cases, to be greater than its bulk concentration. However, because of uncertainty in sensitivity factors for Auger emission, this point could not be conclusively proven. Cobalt and chromium, in contrast, were depleted from the surface. Sulfur segregation was also ex-amined in Ni-S, Cr-S, Al-S, and Y-S binary alloys. Sulfur was found to segregate extensively in the nickel and chromium alloys, but to a much less extent in aluminum. No sulfur segregation was ob-served in the yttrium alloy.

Briant, C. L.; Luthra, K. L.

1988-08-01

420

Low modulus Ti-Nb-Hf alloy for biomedical applications.  

PubMed

?-Type titanium alloys with a low elastic modulus are a potential strategy to reduce stress shielding effect and to enhance bone remodeling in implants used to substitute failed hard tissue. For biomaterial application, investigation on the mechanical behavior, the corrosion resistance and the cell response is required. The new Ti25Nb16Hf alloy was studied before and after 95% cold rolling (95% C.R.). The mechanical properties were determined by tensile testing and its corrosion behavior was analyzed by potentiostatic equipment in Hank's solution at 37C. The cell response was studied by means of cytotoxicity evaluation, cell adhesion and proliferation measurements. The stress-strain curves showed the lowest elastic modulus (42GPa) in the cold worked alloy and high tensile strength, similar to that of Ti6Al4V. The new alloy exhibited better corrosion resistance in terms of open circuit potential (EOCP), but was similar in terms of corrosion current density (iCORR) compared to Ti grade II. Cytotoxicity studies revealed that the chemical composition of the alloy does not induce cytotoxic activity. Cell studies in the new alloy showed a lower adhesion and a higher proliferation compared to Ti grade II presenting, therefore, mechanical features similar to those of human cortical bone and, simultaneously, a good cell response. PMID:25063170

Gonzlez, M; Pea, J; Gil, F J; Manero, J M

2014-09-01

421

Optical Properties of Molten Alloys  

NASA Astrophysics Data System (ADS)

This work concentrates on the metal non-metal (M-NM) transition that some binary systems undergo as their composition is changed. The purpose is to study the short range order that may produce localization in molten alloys. For this purpose three alloy systems have been considered: Se(,x)Te(,1-x), Cs(,x)Tl(,1-x), and Cs(,x)(CsCl)(,1-x). The idea behind the selection is to increase the electronegativity difference, or the charge transfer among the alloy components, going from a covalently bonded semiconductor Se(,x)Te(,1 -x), through a partially ionic system Cs(,x)Tl(,1-x), to an ionic system Cs(,x)(CsCl)(,1-x). The electromagnetic field at optical frequencies was chosen to probe the dielectric properties of these alloys. Normal reflectance data were collected for these alloys in an energy range of 0.65 to 5.50 eV behind a sapphire window. The optical data of the semiconducting alloys were analysed by adjusting the parameters of a model of the optical joint density of states. The optical data of the metallic alloys were analysed by adjusting the parameters of a free electron Drude model. For the Se(,x)Te(,1-x) alloys the measurements were made for 11 alloy compositions and 3 temperatures. The optical data support the existence of three regimes. One metallic, and two semiconducting with different band gaps. Transitions between the different regimes could be achieved by changes in alloy concentration and temperature. The model presented is consistent with previously reported dc transport measurements. Measurements were made for 12 Cs(,x)Tl(,1-x) alloys at 450(DEGREES)C. The measured reflectances show metallic characteristics for alloys rich in either component. The x = 0.50 and 0.60 alloys have reflectances with distinct semiconducting character. Some differences with less ionic alloys are noted. The Cs(,x)(CsCl)(,1 -x) alloys are the last previously studied of the selected alloy systems. Normal reflectance of 11 Cs(,x)(CsCl)(,1 -x) alloys were obtained. The measurements were made 25(DEGREES)C above the liquidus curve of the phase diagram. A large drop in reflectance was observed over a small range of concentration: from a metallic regime for x (GREATERTHEQ) 0.98 to an apparent insulating state for x (LESSTHEQ) 0.85. The M-NM transition was sharp and well marked in the optical data. However, reported transport measurements do not show a N-NM transition in this range.

Fainchtein, Raul

422

Influences of original alloy microstructure on magnetic properties of isotropic HDDR-treated Nd-Fe-B powder  

NASA Astrophysics Data System (ADS)

Influences of original alloy microstructure on magnetic properties of the isotropic hydrogenation-decomposition-desorption-recombination-treated Nd 12.6Fe 79.0Co 2.4B 6.0 powder were studied using two types of starting materials, i.e., the strip cast (SC) alloy and the conventional book-mold cast (BMC) alloy. It was found that the powder prepared from the SC alloy exhibits better I- H loop squareness and higher remanence than the powder from the BMC alloy. The powder obtained from the SC alloy consists of the recombined Nd 2Fe 14B grains with more uniform size, which is thought to be closely related to its good loop squareness. The effect of using the SC alloy could be attributed to the complete elimination of ?-Fe phase.

Morimoto, K.; Niizuma, E.; Nakayama, R.; Igarashi, K.

2003-07-01

423

Positron lifetime studies of decomposition in 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) alloys  

SciTech Connect

In the current paper, the decomposition behavior of the engineering alloys 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) is studied using positron lifetime measurements. Positrons probe open volume defects such as vacancies and dislocations. However, they may also be used to investigate coherent zones and incoherent precipitates. In order to understand the rather complicated precipitation sequences and the response of positrons to different type of precipitates occurring in 2024 and 7010 alloys, binary and ternary laboratory alloys were also investigated under the same experimental conditions as the engineering alloys. The interpretations of the results are based on experiences of the group from extensive positron studies of laboratory alloys such as Al-Zn, Al-Zn-Mg, Al-Cu, and further Al alloys (see also the review (4)). Their collected results are shown as lifetimes and curve-shape parameters S of the electron-positron momentum distribution curves characteristic for different precipitates in Al alloys.

Dlubek, G. [ITA Inst. fuer Innovative Technologien GmbH, Halle (Germany)] [ITA Inst. fuer Innovative Technologien GmbH, Halle (Germany); [Martin-Luther-Univ. Halle-Wittenberg, Halle (Germany). Fachbereich Physik; Lademann, P.; Krause, H.; Krause, S.; Unger, R. [Martin-Luther-Univ. Halle-Wittenberg, Halle (Germany). Fachbereich Physik] [Martin-Luther-Univ. Halle-Wittenberg, Halle (Germany). Fachbereich Physik

1998-09-04

424

New alloys for pressure vessels and piping  

SciTech Connect

This book describes new alloys for pressure vessels and piping applications. Topics include: Cr-Mo-Si alloys, HAZ liquation cracking in lean 316 stainless steels, copper bearing stainless steels, and Ni-Cr-W-Mo alloys.

Prager, M.; Cantzler, C. (Materials Properties Council, Inc., New York, NY (United States))

1990-01-01

425

Shape Memory Alloys  

NSDL National Science Digital Library

This experiment, presented by the National Nanotechnology Infrastructure Network, covers Shape Memory Alloys or Smart Materials. A Smart Material or Shape Memory Alloys belongs to a class of materials which displays the shape memory effect (SME); they possess the ability to radically change crystal structure or phase at a distinct temperature. The lab will "explore how smart materials work and what applications these materials are used in." Additionally, students will be provided with a brief history lesson about the origins of smart material. The experiment is quite fun, students will observe how smart materials can "think and do amazing things." A student and teacher guide is provided with the lab. Overall, this is a great exercise for any science classroom interested in the workings of nanotechnology.

2009-01-26

426

Shape memory alloys characterization techniques  

Microsoft Academic Search

Shape memory alloys are the generic class of alloys that show both thermal and mechanical memory. The basic physics involved\\u000a in the shape memory effect is the reversible thermoelastic martensitic transformation. In general, there exists two phases\\u000a in shape memory alloys, viz., a high-temperature phase or austenitic phase (A) and a low-temperature phase or martensitic\\u000a phase (M). In addition, an

Jayagopal Uchil

2002-01-01

427

Interfacial segregation and deformation of superplastically deformed Al-Mg-Mn alloys.  

National Technical Information Service (NTIS)

Microstructural and microchemical studies have been carried out on superplastically deformed Al-Mg-Mn (AA5083-type) alloys. Grain boundary composition was measured using a Scanning Auger Microprobe (SAM) and an Analytical Transmission Electron Microscope ...

J. S. Vetrano C. A. Lavender S. M. Bruemmer

1995-01-01

428

Copper and Copper Alloy Powders. Seminar Held on 18th December 1976.  

National Technical Information Service (NTIS)

This report contains the following papers: Types, Properties and Uses of Copper Powder; Production of Copper & Copper Alloy Powders for General Engineering Applications; Bronze Powders; Atomized Copper and Copper Based Powders; Process and Equipment for t...

1976-01-01

429

Intergranular Attack of Alloy 600: High-Temperature Electrochemical Tests. Final Report.  

National Technical Information Service (NTIS)

In some steam generators, intergranular attack (IGA) has occurred on Alloy 600 tubes in the tube-tube sheet crevice region. In order to evaluate the physico-chemical parameters which influence this type of corrosion, potentiostatic tests were implemented ...

G. Pinard-Legry G. Plante

1983-01-01

430

Corrosion behavior of cast and forged cobalt-based alloys for double-alloy joint endoprostheses.  

PubMed

An ideal combination of mechanical and corrosion properties of long-term implants such as joint endoprostheses has yet to be found. Besides being resistant to pitting and crevice attack, which can lead to corrosion fatigue and stress corrosion cracking failures, the implant material must be highly resistant to wear and abrasion. Two cobalt-based alloys, wrought CoNiMoTi and air-cast CoCrMo, were subjected to a number of selected in vitro electrochemically and chemically accelerated corrosion tests in chloride-containing solutions with wrought AISI-316L used as a reference alloy. A limited number of immersion tests in FeCl3 and acidified FeCl3 solutions were also conducted. It is found that the mechanical properties of wrought CoNiCrMoTi alloy qualify it as a substitute for cast CoCrMo alloy and wrought AISI-316L in anchorage shaft production for all types of joint endoprostheses. Wrought CoNiCrMoTi has a higher resistance to fatigue cracking compared with cast CoCrMo and is as resistant to selective corrosion phenomena such as stress corrosion cracking. PMID:701305

Sry, P; Semlitsch, M

1978-09-01

431

Effects of process-control agents on mechanical alloying of nanostructured aluminum alloys  

NASA Astrophysics Data System (ADS)

The effects of the process-control agents (PCAs) stearic acid and methanol on the mechanical alloying (MA) of a nanostructured aluminum alloy (Al93Fe3Ti2Cr2) have been investigated. The dependency of the powder-particle sizes, grain sizes, atomic-level strains, lattice parameters, formation of solid solutions, and microstructural evolution of the aluminum alloy on the types of PCAs and their concentrations have been studied using a variety of analytical instruments including X-ray diffraction scanning electron microscopy, and transmission electron microscopy. The results clearly indicate that prevention of excessive cold welding of Al particles can be achieved by the addition of a PCA at the expense of reductions in the grain size, formation rate of solid solutions, and rate of microstructural refinement, all of which are desired in MA of the Al alloy. Furthermore, a PCA that is more effective in preventing excessive cold welding will also impose more hindrance to the MA process. These phenomena have been discussed in the light of the adsorption of the PCA on the metal surface and the lubricating function of the PCA.

Shaw, L.; Villegas, J.; Luo, H.; Zawrah, M.; Miracle, D.

2003-01-01

432

Shape memory alloy actuator  

DOEpatents

An actuator for cycling between first and second positions includes a first shaped memory alloy (SMA) leg, a second SMA leg. At least one heating/cooling device is thermally connected to at least one of the legs, each heating/cooling device capable of simultaneously heating one leg while cooling the other leg. The heating/cooling devices can include thermoelectric and/or thermoionic elements.

Varma, Venugopal K. (Knoxville, TN)

2001-01-01

433

Nanocrystal dispersed amorphous alloys  

NASA Technical Reports Server (NTRS)

Compositions and methods for obtaining nanocrystal dispersed amorphous alloys are described. A composition includes an amorphous matrix forming element (e.g., Al or Fe); at least one transition metal element; and at least one crystallizing agent that is insoluble in the resulting amorphous matrix. During devitrification, the crystallizing agent causes the formation of a high density nanocrystal dispersion. The compositions and methods provide advantages in that materials with superior properties are provided.

Perepezko, John H. (Inventor); Allen, Donald R. (Inventor); Foley, James C. (Inventor)

2001-01-01

434

Evaluation of a hydrogen resistant titanium aluminide alloy  

NASA Technical Reports Server (NTRS)

The Ti-24Al-11Nb (Ti-24-11) alloy heat treated to the fine basketweave microstructure was shown previously to be hydrogen tolerant. In order to assess its limit of hydrogen tolerance, the tensile, creep, fracture toughness, and sustained load crack growth behaviors of this alloy were studied as a function of hydrogen content. All test specimens were thermally charged with internal hydrogen and tested at 25 and 600 C. Coupon specimens were used for developing the hydrogen charging procedures and for studying compatibility of the alloy with high temperature, high pressure gaseous hydrogen. The mechanical test results indicated that the fine basketweave microstructure was tolerant to hydride embrittlement for hydrogen contents up to approximately 1500 wt. ppm, providing that the hydride formed was of the TiH2 type. On the other hand, hydrogen charging experiments indicated that the Ti-24-11 alloy was severely cracked and pulverized under zero load when the hydrogen content exceeded 3000 wt. ppm. X-ray diffraction results revealed that the dichotomous behaviors might be due to the formation of TiH(1.924) type hydrides at higher hydrogen contents. Thus, hydrogen embrittlement in the Ti-24-11 alloy with the fine basketweave microstructure depends on hydrogen content and the nature of the hydrides formed.

Chan, K. S.

1991-01-01

435

The effect of grain size on environmental embrittlement of Co[sub 3]Ti alloy  

SciTech Connect

The environmental embrittlement of L1[sub 2]-type Co[sub 3]Ti ordered alloy has been studied by the present authors from various points of view. In this study, the effect of grain size on the moisture-induced embrittlement of L1[sub 2]-type Co[sub 3]Ti ordered alloy is investigated at room temperature by tensile test and fractography. Embrittlement/ductility property is assessed as functions of grain size, strain rate and environmental media.

Takasugi, T.; Hanada, S. (Tohoku Univ., Sendai (Japan). Inst. for Materials Research)

1999-06-18

436

Irradiation performance of Fast Flux Test Facility drivers using D9 alloy  

Microsoft Academic Search

In comparison with the Fast Flux Test Facility Type 316 stainless steel driver design, six test assemblies employing D9 alloy in place of stainless steel for duct, cladding, and wire wrap material were irradiated to demonstrate the improved performance and lifetime capability of an advanced D9 alloy driver design. A single pinhole-type breach occurred in one of the high-exposure tests

A. L. Pitner; B. C. Gneiting; F. E. Bard

1995-01-01

437

A comparison of tensile bond strengths of resin-retained prostheses made using five alloys.  

PubMed

This in vitro study evaluated the bond strength of metal frameworks cast using Ni-Cr, Ni-Cr-Be, Cu-Al, type IV gold, and noble metal ceramic alloy with and without tin electroplating. The castings were luted to human teeth using Panavia Ex resin. It was found that tin electroplating had a negative effect for the Cu-Al and type IV gold alloys and a positive effect for gold for metal ceramic restorations. The best results were obtained using the Ni-Cr alloy. PMID:8957864

Rubo, J H; Pegoraro, L F; Ferreira, P M

1996-01-01

438

Modeling of the thermomechanical behavior of porous shape memory alloys  

Microsoft Academic Search

Two methods are used in this work to estimate the porous shape memory alloy (SMA) thermomechanical behavior. The porous SMA is assumed to be made of two components, the dense SMA matrix and the pores. An existing rate-independent type constitutive model is employed to describe the matrix behavior. Two contrasting strategies are used to estimate the overall thermomechanical behavior: (1)

Muhammad A. Qidwai; Pavlin B. Entchev; Dimitris C. Lagoudas; Virginia G. DeGiorgi

2001-01-01

439

Characterization of aluminum-alloyed contacts by diode recovery measurements  

Microsoft Academic Search

On silicon diodes possessing a base width to minority carrier diffusion length ratio around one and aluminum-alloyed contacts, a dependence of storage times from absolute values of forward and reverse currents is observed which can be described by a constant leakage current. To explain this phenomena it is not possible to characterize this type of contact with a single recombination

W. Mielke; A. Katsura

1971-01-01

440

Early stages of fatigue damage in aluminium and aluminium alloys  

Microsoft Academic Search

In this paper fatigue damage initiation is considered as both microcrack nucleation from microheterogeneities within fatigued material and microcrack growth over distances corresponding to the size of the microstructure. A brief review of the literature shows that, depending on fatigue conditions and microstructure three different types of nucleation sites exist in aluminium and aluminium alloys : slip bands, grain boundaries

R. FOUGERES

1993-01-01

441

Quench modification of aluminium-silicon eutectic alloys  

Microsoft Academic Search

Directional solidification of aluminium-silicon eutectic alloys were carried out in order to investigate the mechanism by which the quench modification takes place. For this purpose a new type of Bridgman furnace was designed which can attain a high temperature gradient and a high interfacial growth velocity up to 1000 m-1. It is established that the fibrous structure is the result

S. Khan; R. Elliott

1996-01-01

442

Kinetics of chemical interactions between zirconium alloys and stainless steels.  

National Technical Information Service (NTIS)

The chemical interaction kinetics of reactor core component zirconium alloys and stainless steels at high temperatures was examined. Interaction of as-received and preoxidized Zr1%Nb with X18H10T stainless steel used in WWER type nuclear reactors, and als...

J. Frecska L. Maroti L. Matus

1995-01-01

443

Modification of alloy surfaces using pulsed energy  

SciTech Connect

A method to improve the quality and bonding of surface coatings is explored. The method involves application of radio frequency (rf) induction heating to coated metallic surfaces. By tailoring the rf frequency, depth of induction heating penetration can be controlled. Total heat input is a function of the duration of rf power application. Induction heating using high frequencies and short pulses provides a mechanism for controlled penetration heating. The objective of this project was to demonstrate coating consolidation and metallurgical alloying of an inductively coupled coating into the substrate material, without affecting the bulk substrate material properties. A metallurgically alloyed coating to substrate interface improves coating adherence and can provide graded properties in the interface region. Coating consolidation serves to improve the coating integrity through the elimination of porosity and cracks. This report details experimental studies to place palladium, nickel and chromium coatings over substrates of Inconel alloys 182 and 600, and Type 316NG stainless steel. Continuously bonded coatings of palladium were produced. Preliminary thermal cycling studies indicate coating stability.

Clark, R.A. (Failure Analysis Associates, Inc., Redmond, WA (United States))

1991-10-01

444

Aluminum Alloy and Article Cast Therefrom  

NASA Technical Reports Server (NTRS)

A cast article from an aluminum alloy, which has improved mechanical properties at elevated temperatures, has the following composition in weight percent: Silicon 14 - 25.0, Copper 5.5 - 8.0, Iron 0.05 - 1.2, Magnesium 0.5 - 1.5, Nickel 0.05 - 0.9, Manganese 0.05 - 1.0, Titanium 0.05 - 1.2, Zirconium 0.05 - 1.2, Vanadium 0.05 - 1.2, Zinc 0.05 - 0.9, Phosphorus 0.001 - 0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10 - 25, and the copper-to-magnesium ratio is 4 - 15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2, crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix and containing up to about 60% by volume of a secondary filler material.

Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

2003-01-01

445

Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings  

SciTech Connect

Fireside corrosion, caused by liquid alkali-iron trisulfates, has been an obstacle to higher steam temperatures and to efficient utilization of high-sulfur coals. Tests simulating the environment in the superheater bank of a pulverized-coal-fired boiler were conducted on several promising new alloys and claddings. Alloys were exposed to a variety of synthetic ash and simulated flue gas compositions at 650 and 700{degrees}C for times ranging up to 800 hours. Included in the testing program were new high-chromium/high-nickel alloys, modified commercial alloys, lean stainless steels (modified Type 316) clad with high-chromium/high-nickel alloys, and intermetallic aluminides. Thickness loss measurements indicated that resistance to attach improved with increasing chromium level. Silicon and aluminum were also helpful in resisting attack, while molybdenum was detrimental to the resistance of the alloys to attack. Three different attack modes were observed on the alloys tested. Alloys with low resistance to attack exhibited uniform wastage, while pitting was observed in more resistant alloys. In addition to surface fluxing by molten alkali-iron trisulfates, subsurface sulfur penetration and intergranular attack also occurred.

Van Weele, S. (Foster Wheeler Development Corp., Livingston, NJ (United States))

1991-08-01

446

Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings. Final report  

SciTech Connect

Fireside corrosion, caused by liquid alkali-iron trisulfates, has been an obstacle to higher steam temperatures and to efficient utilization of high-sulfur coals. Tests simulating the environment in the superheater bank of a pulverized-coal-fired boiler were conducted on several promising new alloys and claddings. Alloys were exposed to a variety of synthetic ash and simulated flue gas compositions at 650 and 700{degrees}C for times ranging up to 800 hours. Included in the testing program were new high-chromium/high-nickel alloys, modified commercial alloys, lean stainless steels (modified Type 316) clad with high-chromium/high-nickel alloys, and intermetallic aluminides. Thickness loss measurements indicated that resistance to attach improved with increasing chromium level. Silicon and aluminum were also helpful in resisting attack, while molybdenum was detrimental to the resistance of the alloys to attack. Three different attack modes were observed on the alloys tested. Alloys with low resistance to attack exhibited uniform wastage, while pitting was observed in more resistant alloys. In addition to surface fluxing by molten alkali-iron trisulfates, subsurface sulfur penetration and intergranular attack also occurred.

Van Weele, S. [Foster Wheeler Development Corp., Livingston, NJ (United States)

1991-08-01

447

Tensile and fatigue properties of two titanium alloys as candidate materials for fusion reactors  

NASA Astrophysics Data System (ADS)

Titanium alloys have been identified as candidate structural materials for the first wall, the blanket and the magnetic coil structures of fusion reactors. Titanium alloys are interesting materials because of their high specific strength and low elastic modulus, their low swelling tendency and their fast induced radioactivity decay. Other attractive properties are an excellent resistance to corrosion and good weldability, even in thick sections. Furthermore titanium alloys are suitable for components exposed to heat loads since they have a low thermal stress parameter. Titanium alloys with an ? structure are believed to have a good resistance against radiation embrittlement and ?+? alloys should possess the best tolerance to hydrogen embrittlement. Two classical industrially available alloys in the two families, the Ti5Al2.4Sn and the Ti6Al4V alloys have been used in this study. The tensile properties between room temperature and 450C are reported. A low cycle fatigue analysis has been performed under strain control at total strain ranges between 0.8% and 2% and at a temperature of 350C. The microstructure of both alloys was investigated before and after both types of deformation. Both alloys exhibit excellent mechanical properties comparable to or better than those of ferritic martensitic steels.

Marmy, P.; Leguey, T.; Belianov, I.; Victoria, M.

2000-12-01

448

The optimal condition of acidic electroless copper plating method for Ti, Zr-based hydrogen storage alloys for electrode use  

Microsoft Academic Search

An acidic electroless copper plating using HF for titanium and zirconium-based hydrogen storage alloys shows a significant improvement in activation and discharge capacity of the alloy electrodes even though the plating process is simple. In this paper, the optimal conditions of this acidic electroless copper plating have been investigated for Ti, Zr-based AB2-type alloy powders for a negative electrode of

S. J. Choi; J. Choi; C. Y. Seo; C. N. Park

2003-01-01

449

Welding Metallurgy of Alloy HR-160  

SciTech Connect

The solidification behavior and resultant solidification cracking susceptibility of autogenous gas tungsten arc fusion welds in alloy HR-160 was investigated by Varestraint testing, differential thermal analysis, and various microstructural characterization techniques. The alloy exhibited a liquidus temperature of 1387 {deg}C and initiated solidification by a primary L - {gamma} reaction in which Ni, Si, and Ti segregated to the interdendritic liquid and Co segregated to the {gamma} dendrite cores. Chromium exhibited no preference for segregation to the solid or liquid phase during solidification. Solidification terminated at {approx} 1162 {deg}C by a eutectic-type L - [{gamma}+ (Ni,Co){sub 16}(Ti,Cr){sub 6}Si{sub 7}] reaction. The (Ni,Co){sub 16}(Ti,Cr){sub 6}Si{sub 7} phase is found to be analogous to the G phase which forms in the Ni-Ti-Si and Co-Ti-Si ternary systems, and similarities are found to exist between the solidification behavior of this commercial multicomponent alloy and the simple Ni-Si and Ni-Ti binary systems. Reasonable agreement is obtained between the calculated and measured volume percent of the [{gamma} +(Ni,Co){sub l6}(Ti,Cr){sub 6}Si{sub 7}] eutectic-typr constituent with the Scheil equation using experimentally determined k values for Si and Ti from electron microprobe data. The alloy exhibited a very high susceptibility to solidification cracking in the Varestraint test. This is attributed to a large solidification temperature range of 225 {deg}C and the presence of 2 to 5 vol% solute rich interdendritic liquid which preferentially wets the grain boundaries and interdendritic regions.

DuPont, J.N.; Michael, J.R.; Newbury, B.D.

1999-05-28

450

Aluminum-Alloy-Matrix/Alumina-Reinforcement Composites  

NASA Technical Reports Server (NTRS)

Isotropic composites of aluminum-alloy matrices reinforced with particulate alumina have been developed as lightweight, high-specific-strength, less-expensive alternatives to nickel-base and ferrous superalloys. These composites feature a specific gravity of about 3.45 grams per cubic centimeter and specific strengths of about 200 MPa/(grams per cubic centimeter). The room-temperature tensile strength is 100 ksi (689 MPa) and stiffness is 30 Msi (206 GPa). At 500 F (260 C), these composites have shown 80 percent retention in strength and 95 percent retention in stiffness. These materials also have excellent fatigue tolerance and tribological properties. They can be fabricated in net (or nearly net) sizes and shapes to make housings, pistons, valves, and ducts in turbomachinery, and to make structural components of such diverse systems as diesel engines, automotive brake systems, and power-generation, mining, and oil-drilling equipment. Separately, incorporation of these metal matrix composites within aluminum gravity castings for localized reinforcement has been demonstrated. A composite part of this type can be fabricated in a pressure infiltration casting process. The process begins with the pla