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1

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

Microsoft Academic Search

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.

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

2000-01-01

2

Development of techniques for welding V–Cr–Ti alloys  

Microsoft Academic Search

Welding vanadium alloys is complicated by interstitial impurity introduction and redistribution at elevated temperatures. Gas tungsten arc (GTA) welding, which will probably be required for the fabrication of large tokamak structures, must be done in a glove box environment. Welds were evaluated by Charpy testing. GTA welds could be made with a ductile to brittle transition temperature (DBTT) of 50°C

M. L. Grossbeck; J. F. King; D. J. Alexander; P. M. Rice; G. M. Goodwin

1998-01-01

3

Welding development for V-Cr-Ti alloys  

SciTech Connect

Welds have been produced and characterized using the gas-tungsten arc (GTA) and electron beam (EB) welding processes. Thin sheet (0.75 mm) welds were made with three levels of interstitial contamination, and hardness and tensile properties were found to be strongly affected by oxygen pickup. Thick-section (6 mm) welds have been produced using both processes, and no embrittlement is experienced when high purity atmosphere is maintained. Metallographic examination shows a narrow, but coarse grained, heat affected zone for the GTA welds. Transition joint welding development between vanadium alloy and stainless steel has shown encouraging results.

Goodwin, G.M.; King, J.F. [Oak Ridge National Lab., TN (United States)

1994-09-01

4

Development of techniques for welding V Cr Ti alloys  

NASA Astrophysics Data System (ADS)

Welding vanadium alloys is complicated by interstitial impurity introduction and redistribution at elevated temperatures. Gas tungsten arc (GTA) welding, which will probably be required for the fabrication of large tokamak structures, must be done in a glove box environment. Welds were evaluated by Charpy testing. GTA welds could be made with a ductile to brittle transition temperature (DBTT) of 50°C with a post-weld heat treatment (PWHT) or by using a heated Ti getter system on the glove box to reduce interstitial contamination. Titanium-O,N,C precipitates in the fusion zone were found to transform to a more oxygen-rich phase during a PWHT of 950°C/2 h. Hydrogen was found to promote cleavage cracking following welding in cases where the atmosphere was contaminated. Grain size and microstructure also affected weld embrittlement.

Grossbeck, M. L.; King, J. F.; Alexander, D. J.; Rice, P. M.; Goodwin, G. M.

1998-10-01

5

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 -28°C 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 -90°C 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

6

Subtask 12B1: Welding development for V-Cr-Ti alloys  

SciTech Connect

Development of the metallurgical and technological basis for the welding of thick sections of V-Cr-Ti alloys. The weldability and weldment properties of the V-5Cr-5Ti alloy have been evaluated. Results for the Sigmajig test of the vanadium alloy were similar to the cracking resistance of stainless steels, and indicates hot-cracking is unlikely to be a problem. Subsize Charpy test results for GTA weld metal in the as-welded condition have shown a significant reduction in toughness compared to the base metal. The weld metal toughness properties were restored to approximately that of the base metal after exposure to a PWHT 950{degrees}C. The subsize Charpy toughness results for the EB weld metal from this same heat of vanadium alloy has shown significant improvement in properties compared to the GTA weld metal and the base metal. Further testing and analysis will be conducted to more fully characterize the properties of weld metal for each welding process and develop a basic understanding of the cause of the toughness decrease in the GTA welds. 5 figs., 1 tab.

King, J.F.; Goodwin, G.M.; Grossbeck, M.L.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)

1995-03-01

7

Feasibility of correlating V-Cr-Ti alloy weld strength with weld chemistry. CRADA final report  

SciTech Connect

The mechanical properties of refractory metals such as vanadium are determined to a large extent by the interstitial impurities in the alloy. In the case of welding, interstitial impurities are introduced in the welding process from the atmosphere and by dissolution of existing precipitates in the alloy itself. Because of the necessity of having an ultra-pure atmosphere, a vacuum chamber or a glove box is necessary. In the V-Cr-Ti system, the titanium serves as a getter to control the concentration of oxygen and nitrogen in solid solution in the alloy. In this project the secondary ion mass spectrometry (SIMS) technique was used to detect, measure, and map the spacial distribution of impurity elements in welds in the alloy V-4Cr-4Ti. An attempt was then made to correlate the concentrations and distributions of the impurities with mechanical properties of the welds. Mechanical integrity of the welds was determined by Charpy V-notch testing. Welds were prepared by the gas-tungsten-arc (GTA) method. Charpy testing established a correlation between weld impurity concentration and the ductile to brittle transition temperature (DBTT). Higher concentrations of oxygen resulted in a higher DBTT. An exception was noted in the case of a low-oxygen weld which had a high hydrogen concentration resulting in a brittle weld. The concentrations and distributions of the impurities determined by SIMS could not be correlated with the mechanical properties of the welds. This research supports efforts to develop fusion reactor first wall and blanket structural materials.

Grossbeck, M.L. [Oak Ridge National Lab., TN (United States); Odom, R.W. [Charles Evans and Associates, Redwood City, CA (United States)

1998-06-01

8

Feasibility of correlating V-Cr-Ti alloy weld strength with weld chemistry. CRADA final report  

Microsoft Academic Search

The mechanical properties of refractory metals such as vanadium are determined to a large extent by the interstitial impurities in the alloy. In the case of welding, interstitial impurities are introduced in the welding process from the atmosphere and by dissolution of existing precipitates in the alloy itself. Because of the necessity of having an ultra-pure atmosphere, a vacuum chamber

M. L. Grossbeck; R. W. Odom

1998-01-01

9

Reactions of hydrogen with V–Cr–Ti alloys 1 Research sponsored by the Office of Fusion Energy Sciences, U.S. Department of Energy under contract DE-ACO5-96OR22464 with Lockheed Martin Energy Research Corporation. 1  

Microsoft Academic Search

The interest in vanadium alloys for use as a first-wall material in fusion reactor applications has led to a study to determine the effects of hydrogen on the mechanical properties of certain V–Cr–Ti alloys. Hydrogen uptake by the alloys is a function of temperature and pressure. In the absence of increases in oxygen concentration, additions of up to 400 wpm

J. R DiStefano; J. H De Van; D. H Röhrig; L. D Chitwood

1999-01-01

10

Research and development on vanadium alloys for fusion applications  

SciTech Connect

The current status of research and development on unirradiated and irradiated V-Cr-Ti alloys intended for fusion reactor structural applications is reviewed, with particular emphasis on the flow and fracture behavior of neutron-irradiated vanadium alloys. Recent progress on fabrication, joining, oxidation behavior, and the development of insulator coatings is also summarized. Fabrication of large (>500 kg) heats of V-4Cr-4Ti with properties similar to previous small laboratory heats has now been demonstrated. Impressive advances in the joining of thick sections of vanadium alloys using GTA and electron beam welds have been achieved in the past two years, although further improvements are still needed.

Zinkle, S.J.; Rowcliffe, A.F. [Oak Ridge National Lab., TN (United States); Matsui, H.; Abe, K. [Tohoku Univ. (Japan); Smith, D.L. [Argonne National Lab., IL (United States); Osch, E. van [NERF, Petten (Netherlands); Kazakov, V.A. [RIAR, Dimitrovgrad (Russian Federation)

1998-03-01

11

Wegner estimate for sparse and other generalized alloy type potentials  

E-print Network

Wegner estimate for sparse and other generalized alloy type potentials Werner Kirsch and Ivan on the occasion of his Sixtieth Birthday Abstract We prove a Wegner estimate for generalized alloy type models Generalized alloy type models 3 3 Selfadjointness 7 4 Wegner estimate for generalized alloy type potentials 9

12

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

13

DISCRETE SCHRODINGER OPERATORS WITH RANDOM ALLOY-TYPE POTENTIAL  

E-print Network

DISCRETE SCHR¨ODINGER OPERATORS WITH RANDOM ALLOY-TYPE POTENTIAL ALEXANDER ELGART, HELGE KR alloy- type models based on the multiscale analysis and the fractional mo- ment method, respectively. The discrete alloy-type model is a family of Schr¨odinger operators H = - + V on 2 (Zd ) where is the discrete

Krueger, Helge

14

Gas tungsten arc welding of vanadium alloys with impurity control  

NASA Astrophysics Data System (ADS)

Gas tungsten arc welding in vanadium alloys is controlled by interstitial impurities. Techniques have been developed to weld V-4Cr-4Ti in a high-purity argon atmosphere resulting in a DBTT of -20 °C. The atmosphere was controlled by a Zr-Al getter which is activated at high temperature to obtain a clean surface then cooled and allowed to absorb hydrogen and oxygen impurities. Through the use of low-oxygen base metal and high-purity weld filler wire, a DBTT of -145 °C was obtained. Experiments using electron beam welding have shown that grain size also has an important effect on weld ductility. Introduction of nitrogen and yttrium has been used to study their effect on grain size. Using a combination of atmosphere control, alloy purity control, and grain size control, it is anticipated that V-Cr-Ti alloys will be weldable in field conditions.

Grossbeck, M. L.; King, J. F.; Nagasaka, T.; David, S. A.

2002-12-01

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 8.35×10(-4)s(-1). However, when the strain rate is higher than 8.35×10(-4)s(-1), ??-?? and ?? increase, but ???-? decreased with increasing the strain rate. By cyclic loading and unloading to the maximum strain of 6% at 25°C under the strain rate of 1.67×10(-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  

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

17

Discrete Schrödinger operators with random alloy-type potential  

E-print Network

We review recent results on localization for discrete alloy-type models based on the multiscale analysis and the fractional moment method, respectively. The discrete alloy-type model is a family of Schr\\"odinger operators $H_\\omega = - \\Delta + V_\\omega$ on $\\ell^2 (\\ZZ^d)$ where $\\Delta$ is the discrete Laplacian and $V_\\omega$ the multiplication by the function $V_\\omega (x) = \\sum_{k \\in \\ZZ^d} \\omega_k u(x-k)$. Here $\\omega_k$, $k \\in \\ZZ^d$, are i.i.d. random variables and $u \\in \\ell^1 (\\ZZ^d ; \\RR)$ is a so-called single-site potential. Since $u$ may change sign, certain properties of $H_\\omega$ depend in a non-monotone way on the random parameters $\\omega_k$. This requires new methods at certain stages of the localization proof.

Alexander Elgart; Helge Krüger; Martin Tautenhahn; Ivan Veseli?

2011-07-14

18

Wegner estimate for alloy-type models with sign-changing exponentially decaying single-site  

E-print Network

Wegner estimate for alloy-type models with sign-changing exponentially decaying single(Rd) and 2(Zd) with a random potential of alloy-type. The single-site potential is assumed as an ingredient for a localisation proof via multiscale analysis. Keywords: random Schr¨odinger operators, alloy

19

The effect of cobalt content in U-700 type alloys on degradation of aluminide coatings  

NASA Technical Reports Server (NTRS)

The influence of cobalt content in U-700 type alloys on the behavior of aluminide coatings is studied in burner rig cyclic oxidation tests at 1100C. It is determined that aluminide coatings on alloys with higher cobalt offer better oxidation protection than the same coatings on alloys containing less cobalt.

Zaplatynsky, I.

1985-01-01

20

Calorimetric Studies of Palladium Alloy Cathodes Using Fleischmann-Pons Dewar Type Cells  

Microsoft Academic Search

My first three experiments conducted at NHE using the Fleischmann-Pons (F-P) Dewar type cells investigated the Pd-Ce-B, Pd-B, and Pd-Ce alloy cathodes. Significant excess power was produced from the cells using the Pd-B and Pd-Ce alloy cathodes. The Pd-Ce-B alloy, in contrast, showed no measureable excess power effects. Previous experiments at China Lake using similar Pd-B alloy cathodes prepared by

Melvin H. Miles

21

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

Microsoft Academic Search

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

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

2002-01-01

22

Spectral extrema and Lifshitz tails for non monotonous alloy type models  

E-print Network

In the present note, we determine the ground state energy and study the existence of Lifshitz tails near this energy for some non monotonous alloy type models. Here, non monotonous means that the single site potential coming into the alloy random potential changes sign. In particular, the random operator is not a monotonous function of the random variables.

Frédéric Klopp; Shu Nakamura

2008-04-25

23

Corrosion behavior of dental alloys in various types of electrolyzed water.  

PubMed

The corrosion behavior of dental alloys was examined in electrolyzed strong acid water, weak acid water and neutral water using a 7-day immersion test. The precious metal alloys, gold alloy. Au-Ag-Pd alloy and silver alloy showed the greatest surface color change and dissolution of constituents in the strong acid water and the smallest in the neutral water. The release of Au from gold alloy was especially marked in the strong acid water. Co-Cr alloy showed greater corrosion and tarnish resistance in the strong acid water rather than in the weak acid water and the neutral water. X-ray microanalysis revealed that the corrosion products on the precious metal alloys were silver chloride crystals and the thin brown products on Co-Cr alloy were cobalt and chromium oxides. Ti was sound in all three types of electrolyzed water. The neutral water appeared the least corrosive to metals among the three types showing equivalent bactericidal activity. PMID:15005226

Dong, Hongwei; Nagamatsu, Yuki; Chen, Ker-Kong; Tajima, Kiyoshi; Kakigawa, Hiroshi; Shi, Sizhen; Kozono, Yoshio

2003-12-01

24

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

25

Thermal and irradiation-induced phase separation in Fe-Ni based invar-type alloys  

NASA Astrophysics Data System (ADS)

We summarize and review critically the existing experimental and theoretical evidence concerning both thermal and irradiation-induced high-temperature miscibility gaps in Fe-Ni based Invar-type alloys. Independent data regarding phase separation are obtained from studies on magnetic, low-expansion Invar-type alloys and model austenitic Fe-Ni based alloys studied for potential nuclear applications. The response of these alloys to long-term thermal aging is found to be inconsistent with that of single-phase alloys predicted by most accepted or proposed phase diagrams. These alloys show anomalies in numerous properties which suggest compositional or magnetic heterogeneities or both. We herein model the kinetics and thermodynamics of spinodal decomposition and nucleation in these alloys under thermal conditions. The absence of models for surface energy and gradient energy in systems with negative departure from ideality severely limits our analysis of the kinetics of both nucleation and spinodal decomposition. We can combine our calculations with those of others and also with experimental studies of decomposition to reach a conclusion that suggests a high-temperature miscibility gap for Fe-Ni alloys in the Invar regime. The gap is found to be very narrow at high temperatures but to be broadened at low temperatures by magnetic effects. Alloys in the Invar composition range have been subjected to a variety of high fluence irradiation treatments in the 725 to 1000 K temperature range. The result in most cases was large-scale decomposition into approximately 25 and 50 pet Ni phases. The apparent miscibility gap under irradiation is much wider than that observed thermally. We discuss these observations in the light of existing theories of irradiation-induced or irradiation-altered alloy decomposition. We conclude that although irradiation-enhanced diffusion speeds up phase separation, other processes must be operating to produce the greatly widened miscibility gap.

Russell, K. C.; Garner, F. A.

1992-07-01

26

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

27

Discrete alloy-type models: Regularity of distributions and recent results  

E-print Network

We consider discrete random Schr\\"odinger operators on $\\ell^2 (\\mathbb{Z}^d)$ with a potential of discrete alloy-type structure. That is, the potential at lattice site $x \\in \\mathbb{Z}^d$ is given by a linear combination of independent identically distributed random variables, possibly with sign-changing coefficients. In a first part we show that the discrete alloy-type model is not uniformly $\\tau$-H\\"older continuous, a frequently used condition in the literature of Anderson-type models with general random potentials. In a second part we review recent results on regularity properties of spectral data and localization properties for the discrete alloy-type model.

Martin Tautenhahn; Ivan Veseli?

2014-03-28

28

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

29

Strain glass transition in a multifunctional ?-type Ti alloy  

NASA Astrophysics Data System (ADS)

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

2014-02-01

30

A linear Wegner estimate for alloy type Schroedinger operators on metric graphs  

E-print Network

We study spectra of alloy-type random Schr\\"odinger operators on metric graphs. For finite edge subsets of general graphs we prove a Wegner estimate which is linear in the volume (i.e. the number of edges) and the length of the considered energy interval. The single site potential of the alloy-type model needs to have fixed sign, but the considered metric graph does not need to have a periodic structure. The second result we obtain is an exhaustion construction of the integrated density of states for ergodic random Schr\\"odinger operators on metric graphs with a $\\ZZ^{\

Mario Helm; Ivan Veselic'

2006-11-20

31

Passivation behavior of AB 5-type hydrogen storage alloys for battery electrode application  

Microsoft Academic Search

In many applications, AB5 type hydrogen storage alloys show passivation behavior, i.e. when fully discharged, metal hydride electrodes show (especially at higher temperatures) a decrease in activity and therefore a decrease in capacity at normal discharge currents for ensuing cycles. Passivation may continue to the point where activity becomes so low that the capacity is no longer accessible. Electrochemical measurements

F. Meli; T. Sakai; A. Züttel; L. Schlapbach

1995-01-01

32

Anderson localization in a two-particle continuous model with an alloy-type external potential  

E-print Network

We establish exponential localization for a two-particle Anderson model in a Euclidean space ${\\mathbb R}^{d}$, $d\\ge 1$, in presence of a non-trivial short-range interaction and a random external potential of the alloy type. Specifically, we prove that all eigenfunctions with eigenvalues near the lower edge of the spectrum decay exponentially in $L^2$-norm.

A. Boutet de Monvel; V. Chulaevsky; P. Stollmann; Y. Suhov

2009-07-09

33

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

34

Lifshitz tails for alloy type models in a constant magnetic field  

E-print Network

In this note, we study Lifshitz tails for a 2D Landau Hamiltonian perturbed by a random alloy-type potential constructed with single site potentials decaying at least at a Gaussian speed. We prove that, if the Landau level stays preserved as a band edge for the perturbed Hamiltonian, at the Landau levels, the integrated density of states has a Lifshitz behavior of the type $e^{-\\log^2|E-2bq|}$.

Frédéric Klopp

2010-05-05

35

Atomistic simulation of the point defects in B 2-type MoTa alloy  

NASA Astrophysics Data System (ADS)

The formation and migration mechanisms of three different point defects (mono-vacancy, anti-site defect and interstitial atom) in B 2-type MoTa alloy have been investigated by combining molecular dynamics (MD) simulation with modified analytic embedded-atom method (MAEAM). From minimization of the formation energy, we find that the anti-site defects Mo Ta and Ta Mo are easier to form than Mo and Ta mono-vacancies, while Mo and Ta interstitial atoms are difficult to form in the alloy. In six migration mechanisms of Mo and Ta mono-vacancies, one nearest-neighbor jump (1NNJ) is the most favorable due to its lowest activation and migration energies, but it will cause a disorder in the alloy. One next-nearest-neighbor jump (1NNNJ) and one third-nearest-neighbor jump (1TNNJ) can maintain the ordered property of the alloy but require higher activation and migration energies, so the 1NNNJ and 1TNNJ should be replaced by straight [1 0 0] six nearest-neighbor cyclic jumps (S[1 0 0]6NNCJ) or bent [1 0 0] six nearest-neighbor cyclic jumps (B[1 0 0]6NNCJ) and [1 1 0] six nearest-neighbor cyclic jumps ([1 1 0]6NNCJ), respectively. Although the migrations of Mo and Ta interstitial atoms need much lower energy than Mo and Ta mono-vacancies, they are not main migration mechanisms due to difficult to form in the alloy.

Zhang, Jian-Min; Wang, Fang; Xu, Ke-Wei; Ji, Vincent

2009-08-01

36

Tensile and impact properties of vanadium-base alloys irradiated at <430°C  

NASA Astrophysics Data System (ADS)

Tensile and impact properties were investigated at <430°C on V-Cr-Ti, V-Ti-Si, and V-Ti alloys after irradiation to ?2-46 dpa at 205-430°C in lithium or helium in the fast flux test facility (FFTF), high flux isotope reactor (HFIR), experimental breeder reactor II (EBR-II), and advanced test reactor (ATR). A 500-kg heat of V-4Cr-4Ti exhibited high ductile-brittle transition temperature and minimal uniform elongation as a result of irradiation-induced loss of work-hardening capability. Work-hardening capabilities of 30- and 100-kg heats of V-4Cr-4Ti varied significantly with irradiation conditions, although the 30-kg heat exhibited excellent impact properties after irradiation at ?390-430°C. The origin of the significant variations in the work-hardening capability of V-4Cr-4Ti is not understood, although fabrication variables, annealing history, and contamination from the irradiation environment are believed to play important roles. A 15-kg heat of V-3Ti-1Si exhibited good work-hardening capability and excellent impact properties after irradiation at ?390-430°C. Helium atoms, either charged dynamically or produced via transmutation of boron in the alloys, promote work-hardening capability in V-4Cr-4Ti and V-3Ti-1Si.

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

1998-10-01

37

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

38

Multi-particle dynamical localization in a continuous Anderson model with an alloy-type potential  

E-print Network

This paper is a complement to our earlier work \\cite{BCSS10b}. With the help of the multi-scale analysis, we derive, from estimates obtained in \\cite{BCSS10b}, dynamical localization for a multi-particle Anderson model in a Euclidean space $\\D{R}^{d}$, $d\\geq 1$, with a short-range interaction, subject to a random alloy-type potential.

Victor Chulaevsky; Anne Boutet de Monvel; Yuri Suhov

2010-07-22

39

Twinning and detwinning of ?0?1?1? type II twin in shape memory alloy  

Microsoft Academic Search

?0?1?1? type II twin is a major twinning mode frequently observed in NiTi shape memory alloy. Its response to applied stresses is responsible for various inelastic deformation processes. In order to predict the shape recovery characteristic under various conditions, it is of primary importance to predict the martensite detwinning characteristic prior to the reverse transformation. However, due to its irrational

Yong Liu; Z. L. Xie

2003-01-01

40

Mechanical properties of L1{sub 2} type Zn{sub 3}Ti-based alloy  

SciTech Connect

An alloy composed of L1{sub 2}-type Zn{sub 3}Ti was investigated in terms of phase stability and mechanical properties. Zn and Ti powders were mixed at a composition of Zn-25mol%Ti using a ball mill in Ar, and an ingot was made by melting the powders. Optical microscopy, X-ray diffraction analysis and thermogravimetry--differential thermal analysis were carried out. Mechanical properties were investigated by Vickers hardness tests at room temperature (RT) and compression tests from RT to 703K in Ar. It is found that (1) the alloy is mainly composed of L1{sub 2}Zn{sub 3}Ti, (2) the alloy has weak positive temperature dependence of strength, and (3) normalized strength by melting point is comparable to that of L1{sub 2}Al{sub 3}Ti-Cr alloys. L1{sub 2}Zn{sub 3}Ti has HV178 and is brittle at RT. Reaction temperatures of Zn-rich portion of the Zn-Ti phase diagram were also reinvestigated and a peritectic-reaction temperature between Zn{sub 3}Ti and liquid + Zn{sub 2}Ti is determined to be at 880K.

Hosoda, Hideki; Hanada, Shuji

1999-07-01

41

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; Garcés, Gerardo; Pérez, Pablo; Adeva, Paloma

2014-07-01

42

Deformation behavior of metastable ?-type Ti-25Nb-2Mo-4Sn alloy for biomedical applications.  

PubMed

The deformation behavior of metastable ?-type Ti-25Nb-2Mo-4Sn (wt%) alloy subjected to different thermo-mechanical treatments was discussed by the combining results from transmission electron microscope, tensile test and in-situ synchrotron X-ray diffraction. Visible "double yielding" behavior, which is characterized by the presence of stress-plateau, was observed in the solution treated specimen. Upon a cold rolling treatment, the Ti-25Nb-2Mo-4Sn alloy performs nonlinear deformation because of the combined effects of elastic deformation and stress-induced ?? martensitic transformation. After the subsequent annealing, the ? phase is completely stabilized and no stress-induced martensitic transformation takes place on loading due to the inhibitory effect of grain boundaries and dislocations on martensitic transformation. As a result, the annealed specimen exhibits linear elastic deformation. PMID:25011015

Guo, S; Meng, Q K; Cheng, X N; Zhao, X Q

2014-10-01

43

P-type InGaN across the entire alloy composition range  

SciTech Connect

A systematic investigation on Mg doped and undoped InGaN epilayers grown by plasma-assisted molecular beam epitaxy has been conducted. Single phase InGaN alloys across the entire composition range were synthesized and Mg was doped into In{sub x}Ga{sub 1-x}N (0.1 {<=} x {<=} 0.88) epilayers up to {approx}10{sup 20}/cm{sup 3}. Hall effect, thermopower, and electrochemical capacitance voltage experimental results demonstrate the realization of p-type InGaN across the entire alloy composition range for properly Mg doped InGaN. Hole densities have been measured or estimated to be in the lower {approx}10{sup 18}/cm{sup 3} range when the net acceptor concentrations are in the lower {approx}10{sup 19}/cm{sup 3} range across the composition range.

Wang, K.; Araki, T.; Katsuki, T. [Department of Photonics, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga 525-8577 (Japan)] [Department of Photonics, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga 525-8577 (Japan); Yu, K. M.; Mayer, M. A.; Ager, J. W. III; Walukiewicz, W. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Alarcon-Llado, E. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States) [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland); Nanishi, Y. [Department of Photonics, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga 525-8577 (Japan) [Department of Photonics, Ritsumeikan University, 1-1-1 Noji Higashi, Kusatsu, Shiga 525-8577 (Japan); WCU Hybrid Materials Program, Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

2013-03-11

44

Structure fragmentation in Fe-based alloys by means of cyclic martensitic transformations of different types  

PubMed Central

The effect of martensite transformations of different types on the misorientation of austenite crystalline lattice, which characterizes the degree of structure fragmentation, was investigated for Fe-Ni and Fe-Mn alloys. As a result of multiple face-centered cubic (f.c.c.)-body-centered cubic (b.c.c.)-f.c.c. transformations, an austenite single-crystalline specimen is transformed in a polycrystalline one due to progressive fragmentation. It was shown that the degree of fragmentation depends on the magnitude of volume change and the density of dislocations generated on martensitic transformations. PMID:24565160

2014-01-01

45

Structure fragmentation in Fe-based alloys by means of cyclic martensitic transformations of different types.  

PubMed

The effect of martensite transformations of different types on the misorientation of austenite crystalline lattice, which characterizes the degree of structure fragmentation, was investigated for Fe-Ni and Fe-Mn alloys. As a result of multiple face-centered cubic (f.c.c.)-body-centered cubic (b.c.c.)-f.c.c. transformations, an austenite single-crystalline specimen is transformed in a polycrystalline one due to progressive fragmentation. It was shown that the degree of fragmentation depends on the magnitude of volume change and the density of dislocations generated on martensitic transformations. PMID:24565160

Bondar, Volodimir I; Danilchenko, Vitalij Ie; Dzevin, Ievgenij M

2014-01-01

46

Different types of discontinuous precipitation in Cu-15 wt % In alloy  

SciTech Connect

Discontinuous precipitation is a solid-state reaction in which an initially homogeneous solid solution, {alpha}{sub 0}, is decomposed into a lamellar two-phase microstructure, {alpha}+{beta}, in the region behind the migrating reaction front. Two types of discontinuous precipitation can be distinguished: the interfacial type reaction and the dislocation type. For the interfacial type reaction, generally the reaction front is a high-angle grain boundary. However, for the dislocation type reaction, it is highly probable that dislocations play a dominate role in nucleation and growth. Preferred nucleation sites are dislocation rich areas in the matrix. The dislocation type reaction is found principally in systems in which the specific volumes of the initial matrix and of the reaction product strongly differ. It is assumed that in the vicinity of the growing {beta} particles dislocations are produced and act as new nucleation sites. By this means the reaction front can further migrate in an autocatalytic fashion, and with isothermal conditions a constant migration velocity results. The dislocation type reaction does not occur as frequently as the interfacial type reaction. In several solid solutions both reactions can be observed simultaneously, but in Cu-In alloy only the interfacial one can appear.

Saheb, N.; Boumerzoug, Z.; Hamana, D. [Univ. of Constantine (Algeria). Research Unit in Materials Physic and Applications] [Univ. of Constantine (Algeria). Research Unit in Materials Physic and Applications; Laoui, T.; Van Der Biest, O. [Catholic Univ. of Leuven (Belgium). Metallurgical and Materials Engineering Dept.] [Catholic Univ. of Leuven (Belgium). Metallurgical and Materials Engineering Dept.

1995-05-01

47

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

SciTech Connect

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 (copper type texture), may be easily converted into the B-component of the alloy type texture (brass texture) due to shear banding induced during cross-rolling. It was proved that deformation in shear bands is a simple transgranular shear (micro-shearband) which makes the polycrystalline metal behave like a single crystal oriented for the single system slip. In view of these results, it seems necessary to re-examine the problem of the formation of the brass type texture during monotonic rolling. In particular, there is no experimental information about the spatial orientation of shear bands in the test piece of brass, except that they occurs on average on lateral face of sample, at 35{degree} with respect to the rolling direction. This does not suffice yet to conclude whether the position of shear in brass is the same as in copper. It may as well be expected, that if the deformation in shear bands in brass is not a plane strain deformation with respect to the sample reference system or, in other words, the sample transverse direction does not lie in the plane of shear, the formation of shear bands may systematically lead to splitting of the metal type texture (resulting from homogeneous deformation) according to the geometry of shear bands. The problem of the spatial orientation of shear bands in monotonically rolled brass and of the evolution of the texture pattern is discussed in this work.

Dobrzanski, F.; Bochniak, W. [Akademy of Mining and Metallurgy, Krakow (Poland). Dept. of Structure and Mechanics of Solids] [Akademy of Mining and Metallurgy, Krakow (Poland). Dept. of Structure and Mechanics of Solids

1995-06-15

48

A new type of Cu-Al-Ta shape memory alloy with high martensitic transformation temperature  

NASA Astrophysics Data System (ADS)

In this study, a new type of Cu-Al-Ta (Cu86Al12Ta2 wt%) shape memory alloy with high martensitic transformation temperature is explored. The microstructure, reversible martensitic transformation and shape memory properties are investigated by means of optical microscopy, back-scattered electron, electron probe microanalysis, x-ray diffraction, differential scanning calorimetry and tensile tests. It is proposed that Cu86Al12Ta2 alloy consists of a mixture of primarily {\\beta }_{1}^{\\prime} martensite and a little {\\gamma }_{1}^{\\prime} martensite and some different precipitates. The tiny thin-striped Ta2(Al,Cu)3 precipitate is predominant in the as-quenched condition, whereas the particle-shaped Cu(Al, Ta) precipitate is dominant after hot-rolling. Additionally, the dendritic-shaped ?1(Cu9Al4) phase begins to appear after hot-rolling, but it disappears when the sample is re-quenched. All studied samples have reversible martensitic transformation temperatures higher than 450?° C. The results show that two-step martensitic transformation behavior is observed for Cu86Al12Ta2 alloy in all three different conditions due to the transformations between ({\\beta }_{1}^{\\prime}+{\\gamma }_{1}^{\\prime}) martensites and the austenite parent phase. The results further show that the recovery ratios are almost 100% when the pre-strains are ?2.5%, then they gradually decrease with further increase of the pre-strains. The shape memory effects clearly increase as a result of increase of the pre-strains, up to a maximum value of 3.2%.

Wang, C. P.; Su, Y.; Y Yang, S.; Shi, Z.; Liu, X. J.

2014-02-01

49

Comparison of high efficiency solar cells on large area n-type and p-type silicon wafers with screen-printed Aluminum-alloyed rear junction  

Microsoft Academic Search

Low-cost, high-efficiency, and large area n-type silicon cells can be processed based on the screen printed Aluminum-alloyed rear junction concept. This process uses fabrication techniques which are very close to the current industry-standard screen printed mc-Si cell process. We compare, by experimental tests and modeling, the differences of using n-type wafers and p-type wafers with this process. An independently confirmed

D. S. Saynova; V. D. Mihailetchi; L. J. Geerligs; A. W. Weeber

2008-01-01

50

Adhesive strength of medical polymer on anodic oxide nanostructures fabricated on biomedical ?-type titanium alloy.  

PubMed

Anodic oxide nanostructures (nanopores and nanotubes) were fabricated on a biomedical ?-type titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), by anodization in order to improve the adhesive strength of a medical polymer, segmented polyurethane (SPU), to TNTZ. TNTZ was anodized in 1.0M H3PO4 solution with 0.5 mass% NaF using a direct-current power supply at a voltage of 20V. A nanoporous structure is formed on TNTZ in the first stage of anodization, and the formation of a nanotube structure occurs subsequently beneath the nanoporous structure. The nanostructures formed on TNTZ by anodization for less than 3,600s exhibit higher adhesive strengths than those formed at longer anodization times. The adhesive strength of the SPU coating on the nanoporous structure formed on top of TNTZ by anodization for 1,200s improves by 144% compared to that of the SPU coating on as-polished TNTZ with a mirror surface. The adhesive strength of the SPU coating on the nanotube structure formed on TNTZ by anodization for 3,600s increases by 50%. These improvements in the adhesive strength of SPU are the result of an anchor effect introduced by the nanostructures formed by anodization. Fracture occurs at the interface of the nanoporous structure and the SPU coating layer. In contrast, in the case that SPU coating has been performed on the nanotube structure, fracture occurs inside the nanotubes. PMID:24433910

Hieda, Junko; Niinomi, Mitsuo; Nakai, Masaaki; Cho, Ken; Mohri, Tomoyoshi; Hanawa, Takao

2014-03-01

51

Corrosion of high Ni-Cr alloys and Type 304L stainless steel in HNO/sub 3/-HF  

SciTech Connect

Nineteen alloys were evaluated as possible materials of construction for steam heating coils, the dissolver vessel, and the off-gas system of proposed facilities to process thorium and uranium fuels. Commercially available alloys were found that are satisfactory for all applications. With thorium fuel, which requires HNO/sub 3/-HF for dissolution, the best alloy for service at 130/sup 0/C when complexing agents for fluoride are used is Inconel 690; with no complexing agents at 130/sup 0/C, Inconel 671 is best. At 95/sup 0/C, six other alloys tested would be adequate: Haynes 25, Ferralium, Inconel 625, Type 304L stainless steel, Incoloy 825, and Haynes 20 (in order of decreasing preference); based on composition, six untested alloys would also be adequate. The ions most effective in reducing fluoride corrosion were the complexing agents Zr/sup 4 +/ and Th/sup 4 +/; Al/sup 3 +/ was less effective. With uranium fuel, modestly priced Type 304L stainless steel is adequate. Corrosion will be most severe in HNO/sub 3/-HF used occasionally for flushing and in solutions of HNO/sub 3/ and corrosion products (ferric and dichromate ions). HF corrosion can be minimized by complexing the fluoride ion and by passivation of the steel with strong nitric acid. Corrosion caused by corrosion products can be minimized by operating at lower temperatures.

Ondrejcin, R.S.; McLaughlin, B.D.

1980-04-01

52

CONCEPT: N-TYPE SILICON SOLAR CELLS WITH SURFACE-PASSIVATED SCREEN-PRINTED ALUMINUM-ALLOYED REAR EMITTER  

E-print Network

-ALLOYED REAR EMITTER Robert Bock 1 , Jan Schmidt 1 , Susanne Mau 1 , Bram Hoex 2 , Erwin Kessels 2 , and Rolf ABSTRACT Aluminum-doped p-type (Al-p + ) silicon emitters fabricated by means of screen-printing and firing nitride (SiNx) layer is deposited by PECVD. While the a-Si passivation of the Al-p+ emitter results

53

Bi1-xSbx under high pressure: Effect of alloying on the incommensurate Bi-III type composite structure  

Microsoft Academic Search

The high-pressure structural behavior of alloys Bi1-xSbx was investigated experimentally and by means of first-principles calculations in order to study the effect of alloying on the incommensurate Bi-III type composite structure, which is adopted by the high-pressure phases Bi-III and Sb-II of the pure elements. High-pressure experiments of Bi0.75Sb0.25 and Bi0.50Sb0.50 resulted in a decomposition into Sb-rich phases with the

U. Häussermann; O. Degtyareva; A. S. Mikhaylushkin; K. Söderberg; S. I. Simak; M. I. McMahon; R. J. Nelmes; R. Norrestam

2004-01-01

54

Reduced thermal conductivity due to scattering centers in p-type SiGe alloys  

NASA Technical Reports Server (NTRS)

Spark erosion was used to produce ultra-fine particles of SiGe thermoelectric material and boron nitride, an inert phonon-scattering material. A homogeneous powder was made by mixing the two powders. The mixture was hot pressed to produce a thermoelectric material with uniformity dispersed, ultra-fine, inert, phonon-scattering centers. It is shown that, in samples with inert boron nitride or silicon nitride, thermal conductivity of a SiGe alloy can be reduced by about 25 percent while maintaining the electrical properties of the samples. Annealing of all the samples at 1525 K caused grain growth to over a micron, eliminating the detrimental effect attributable to small grains. Only in the sample with boron nitride the thermal conductivity did remain well below that for standard p-type SiGe (about 25 percent), while the electrical resistivity and Seebeck coefficient were very close to the values for standard p-type 80/20 SiGe.

Beaty, John S.; Rolfe, Jonathon L.; Vandersande, Jan; Fleurial, Jean-Pierre

1992-01-01

55

Valence Band Structure of Highly Efficient p-type Thermoelectric PbTe-PbS Alloys  

SciTech Connect

New experimental evidence is given relevant to the temperature-dependence of valence band structure of PbTe and PbTe1-xSx alloys (0.04 x 0.12), and its effect on the thermoelectric figure of merit zT. The x = 0.08 sample has zT ~ 1.55 at 773K. The magnetic field dependence of the high-temperature Hall resistivity of heavily p-type (> 1019 cm-3) Na-doped PbTe1-xSx reveals the presence of high-mobility electrons. This put in question prior analyses of the Hall coefficient and the conclusion that PbTe would be an indirect gap semiconductor at temperatures where its zT is optimal. Possible origins for these electrons are discussed: they can be induced by photoconductivity, or by the topology of the Fermi surface when the L and -bands merge. Negative values for the low-temperature thermopower are also observed. Our data show that PbTe continues to be a direct gap semiconductor at temperatures where the zT and S2 of p-type PbTe are optimal e.g. 700-900K. The previously suggested temperature induced rapid rise in energy of the heavy hole LVB relative to the light hole UVB is not supported by the experimental data.

Jaworski, C. M. [Ohio State University; Nielsen, Mechele [Ohio State University; Wang, Hsin [ORNL; Girard, Steven N. [Northwestern University, Evanston; Cai, Wei [ORNL; Porter, Wallace D [ORNL; Kanatzidis, Mercouri G. [Northwestern University, Evanston; Heremans, J. P. [Ohio State University

2013-01-01

56

Galvanic effects accelerate crevice corrosion of type 316L SS flanges coupled to 6% Mo alloy. [Stainless Steel  

SciTech Connect

A service water system underwent a material replacement program in recent years. The service was a once-through system fed from the Delaware River. The original type 316L stainless steel (SS) and cement-lined carbon steel were replaced with 6% Mo alloy AL-6XN (UNS N08367). The majority of the system was 6% Mo piping connected to type 316L SS valves via gasketed flanges. During several years of operation, plant personnel observed localized crevice corrosion on the flange-face areas of the type 316L SS (UNS S31603) flanges. This area typically contains an insulation gasket material (a fibrous bound elastomeric material) that is sandwiched between flange joints. Galvanic effects, caused by the mixed alloy construction (i.e., type 316L SS to alloy 6% Mo), may be accelerating the observed crevice corrosion of type 316L SS. This possibility was of significant concern, and flange isolation kits typically used for isolating cathodic protection systems or dissimilar metals were being used. However, the plant grounding system caused the isolated flanges to have zero electrical resistance between them.

Krantz, B. (Corrosion Testing Labs., Inc. (United States))

1999-06-01

57

Stability of Febased alloys with structure type C 6 Cr 23 M. Widom and M. Mihalkovic #  

E-print Network

­planes connecting all pure elements in their lowest energy structures forms a useful reference for alloy energies. The distance #H for of an alloy energy from the tie­surface joining pure elements is known as its enthalpy to identify third elements that can e#ectively destabilize C6Cr23 . Yttrium appears optimal among transition

Widom, Michael

58

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

59

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 (<47°C) 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

60

Megabit bubble memory process using a new type resin and TaMo alloy-Au conductor  

NASA Astrophysics Data System (ADS)

A newly developed heat resistant resin, ladder type organosiloxane polymer, is applied to 8 ?m period 1 megabit bubble memory devices. Propagation bias margin and reliability are discussed, comparing with the conventional SiO lift-off planar process. TaMo alloy-Au system is also introduced for the conductor. Interdiffusion, electromigration, and corrosion resistance of Au and refractory metals are studied.

Majima, T.; Hirano, A.; Orihara, S.

1981-03-01

61

Megabit bubble memory process using a new type resin and TaMo alloy-Au conductor  

Microsoft Academic Search

A newly developed heat resistant resin, ladder type organosiloxane polymer, is applied to 8 ?m period 1 megabit bubble memory devices. Propagation bias margin and reliability are discussed, comparing with the conventional SiO lift-off planar process. TaMo alloy-Au system is also introduced for the conductor. Interdiffusion, electromigration, and corrosion resistance of Au and refractory metals are studied.

T. Majima; A. Hirano; S. Orihara

1981-01-01

62

p-Type Bismuth Telluride-Based Composite Thermoelectric Materials Produced by Mechanical Alloying and Hot Extrusion  

NASA Astrophysics Data System (ADS)

We produced six different composites of p-type bismuth antimony telluride alloys and studied their structure and thermoelectric properties. The components of the composites were obtained in powder form by mechanical alloying. Mixed powders of two different compositions were consolidated by hot extrusion to obtain each bulk composite. The minimum grain size of bulk composites as revealed by scanning electron microscopy shows a 50% reduction compared with the conventional (Bi0.2Sb0.8)2Te3. X-ray diffraction (XRD) analysis only shows peak broadening with no clear indication of separate phases, and indicates a systematic decrease of crystallite size in the composite materials. Scattering mechanisms of charge carriers were evaluated by Hall-effect measurements. The thermoelectric properties were investigated via the Harman method from 300 K up to 460 K. The composites show no significant degradation of the power factor and high peak ZT values ranging from 0.86 to 1.04. The thermal conductivity of the composites slightly increases with respect to the conventional alloy. This unexpected behavior can be attributed to two factors: (1) the composites do not yet contain a significant number of grains whose sizes are sufficiently small to increase phonon scattering, and (2) each of the combined components of the composites corresponds to a phase with thermal conductivity higher than the minimum value corresponding to the (Bi0.2Sb0.8)2Te3 alloy.

Keshavarz, M. K.; Vasilevskiy, D.; Masut, R. A.; Turenne, S.

2013-07-01

63

Influence of Product Type on Stress Corrosion Cracking of Alloy 600  

Microsoft Academic Search

Grain-boundary carbide coverage obtained from metallographic replications has been considered as an estimation of SCC susceptibility of alloy 600 components in pressurized-water reactor (PWR) primary water. Stress corrosion cracking (SCC) initiation tests were carried out on alloy 600 (UNS N06600) in primary water at 325 C and 360 C and in steam with hydrogen at 400 C to gain some

D. Gomez-Briceno; F. Blazquez; F. Hernandez

1999-01-01

64

Read/write characteristics of a new type of bit-patterned-media using nano-patterned glassy alloy  

NASA Astrophysics Data System (ADS)

The paper reports a feasibility study of new type bit-patterned-media using a nano-patterned glassy alloy template for ultra-high density hard disk applications. The prototype bit-patterned-media was prepared using a nano-hole array pattern fabricated on a Pd-based glassy alloy thin film and a Co/Pd multilayered film filled in the nano-holes. The prepared prototype bit-patterned-media had a smooth surface and isolated Co/Pd multilayer magnetic dots, where the average dot diameter, the average dot pitch and the average dot height were 30, 60 and 19 nm, respectively. MFM (magnetic force microscope) observation revealed that each dot was magnetized in a perpendicular direction and the magnetization could reverse when an opposite magnetic field was applied. Static read/write tester measurements showed that repeated writing and reading on isolated magnetic dots were possible in combination with conventional magnetic heads and high-accuracy positioning technologies. The present study indicates that the new type of bit-patterned-media composed of nano-hole arrays fabricated on glassy alloy film template and Co/Pd multilayer magnetic dots are promising for applications to next generation ultra-high density hard disk drives.

Takenaka, Kana; Saidoh, Noriko; Nishiyama, Nobuyuki; Ishimaru, Manabu; Futamoto, Masaaki; Inoue, Akihisa

2012-04-01

65

Alloying and coating strategies for improved Pb-Li compatibility in DEMO-type fusion reactors  

NASA Astrophysics Data System (ADS)

Two strategies were explored to improve the Pb-16Li compatibility of Fe-base alloys for a fusion energy blanket system. The use of thin (?50 ?m) Al-rich diffusion coatings on Grade 92 (9Cr-2W) substrates significantly reduced the mass loss in static Pb-Li capsule tests for up to 5000 h at 600 °C and 700 °C. However, significant Al loss was observed at 700 °C. Thicker coatings with Fe-Al intermetallic layers partially spalled after exposure at 700 °C, suggesting that coating strategies are limited to lower temperatures. To identify compositions for further alloy development, model FeCrAlY alloys with 10-20 wt.%Cr and 3-5%Al were exposed for 1000 h at 700 °C. There was little effect on mass change of varying the Cr content, however, alloys with <5% Al showed mass losses in these experiments. For both coatings and FeCrAl alloys, the surface reaction product was LiAlO2 after exposure and cleaning.

Unocic, K. A.; Pint, B. A.

2014-12-01

66

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

67

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

68

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

69

Characterization of corrosion products of AB{sub 5}-type hydrogen storage alloys for nickel-metal hydride batteries  

SciTech Connect

To better understand the decrease in storage capacity of AB{sub 5}-type alloys in rechargeable Ni/MH batteries undergoing repeated charge/discharge cycles, the corrosion of a MnNi{sub 3.55}Co{sub 0.75}Mn{sub 0.4}Al{sub 0.3} alloy in aqueous KOH electrolyte was studied. The crystal structure, chemical composition, and distribution of corrosion products were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Hollow and filed needles of a mixed rare earth hydroxide Mn(OH){sub 3} were found to cover a continuous nanocrystalline corrosion scale composed of metal (Ni, Co) solid solution, oxide (Ni,Co)O solid solution and rare earth hydroxide, and a Mn-depleted alloy subscale. Corrosion kinetics were measured for three different temperatures. Growth kinetics of the continuous corrosion scale and of the Mm(OH){sub 3} needles obeyed linear and parabolic rate laws, respectively. Models for the corrosion mechanism were developed on the basis of diffusional transport of Mn and OH through the hydroxide needles and subsequent diffusion along grain boundaries through the nanocrystalline scale.

Maurel, F.; Knosp, B.; Backhaus-Ricoult, M.

2000-01-01

70

Magsimal-59, an AlMgMnSi-type squeeze-casting alloy designed for temper F  

SciTech Connect

To get high mechanical properties using standard squeeze casting alloys (for example A356) it is indispensable to make a heat treatment. That means solution heat treatment and quenching and artificially aging. For this reason, the authors were challenged to develop an alloy that provides sophisticated mechanical properties without any heat treatment. Compared to A 356 T6 values in brackets, the new alloy has yield strength > 21 ksi (> 32 ksi) tensile strengths > 42 ksi (43 ksi) and elongation > 15% (10%) in temper F. fatigue strength (r = {minus}1, high frequency pulsation test) is > {+-} 16 ksi (13.5). To meet these properties, a casting process with high solidification velocity like squeeze casting or high pressure die-casting is necessary. Magsimal-59 is of the AlMgMnSi-type. The microstructure consists of {alpha}-Al and a very fine dispersed ternary eutectic. The microstructure and the influence of cooling rate on the mechanical properties will be discussed including some examples of castings.

Hielscher, U.; Sternau, H.; Koch, H.; Franke, A.J. [Aluminium Rheinfelden (Germany)

1996-10-01

71

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

SciTech Connect

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 FeV{sub 0.8}Ti{sub 0.4}Sb 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 Degree-Sign C, which is relatively high as for p-type half-Heusler alloys containing earth-abundant elements. - Graphical abstract: Fine-grained Ti-doped FeVSb alloys were prepared by the MA-SPS method. The maximum ZT value reaches 0.43 at 500 Degree-Sign C, which is relatively high for p-type half-Heusler alloys. Highlights: Black-Right-Pointing-Pointer Ti-doped FeVSb half-Heusler alloys were synthesized by combining MA and SPS. Black-Right-Pointing-Pointer Substituting V with Ti changes the electrical behavior from n-type to p-type. Black-Right-Pointing-Pointer Thermoelectric properties are improved by optimizing sintering temperature. Black-Right-Pointing-Pointer Thermoelectric properties are further improved by applying annealing treatment. Black-Right-Pointing-Pointer A high ZT value of 0.43 is obtained at 500 Degree-Sign C for p-type Ti-doped FeVSb alloys.

Zou, Minmin [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)] [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Li, Jing-Feng, E-mail: jingfeng@mail.tsinghua.edu.cn [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)] [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Kita, Takuji [Advanced Material Engineering Division, Vehicle Engineering Group, Higashifuji Technical Center, Toyota Motor Corporation, 1200, Mishuku, Susono, Shizuoka 410-1193 (Japan)] [Advanced Material Engineering Division, Vehicle Engineering Group, Higashifuji Technical Center, Toyota Motor Corporation, 1200, Mishuku, Susono, Shizuoka 410-1193 (Japan)

2013-02-15

72

CRFP-ALUMINUM ALLOY COMPOSITE STRUCTURES: A NEW TYPE OF COMPOSITE STRUCTURES IN FUTURE  

Microsoft Academic Search

High-strength, light-weight and durable materials are always desired by structure engineer. Although CFRP (carbon fiber reinforced-polymer) meets the demands, but its anisotropy makes the connection of structural elements considerably weak which is the main cause that make its high strength not be utilized fully. However, Al (aluminum alloy) is now becoming the structural material in civil engineering in recent years

Lieping Ye

73

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

74

The structural, electronic and dynamic properties of the L12- type Co3Ti alloy  

NASA Astrophysics Data System (ADS)

The structural, electronic and dynamic properties of the cubic Co3Ti alloy in L12 structure have been investigated using a pseudopotential plane wave (PP-PW) method within the generalized gradient approximation proposed by Perdew-Burke-Ernzerhof (GGA-PBE). The structural properties, including the lattice constant, the bulk modulus and its pressure derivative agree reasonably with the previous results. The density of state (DOS), projected density of state (PDOS) and electronic band structure are also reported. The DOS shows that Co3Ti alloy has a metallic character since the energy bands cross the Fermi level. The density of states at Fermi level mainly comes from the Co-3d states. Phonon dispersion curves and their corresponding total densities of states were obtained using a linear response in the framework of the density functional perturbation theory. All computed phonon frequencies are no imaginer and thus, Co3Ti alloy is dynamically stable. The zone center phonon modes have been founded to be 9.307, 9.626 and 13.891 THz for Co3Ti.

Arikan, Nihat; Özduran, Mustafa

2014-10-01

75

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

Microsoft Academic Search

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

Yavari

1993-01-01

76

Titanium alloy production technology, market prospects and industry development  

Microsoft Academic Search

Titanium alloy with a low density, high specific strength, corrosion resistance and good process performance, is the ideal structural materials for the aerospace engineering. Based on the microstructure of titanium alloys, it can be divided into ?-type titanium alloys (heat-resistant titanium alloys), ?-type titanium alloys and ?+?-type titanium alloys. The research scopes also include the fabrication technology of titanium alloys,

Chunxiang Cui; BaoMin Hu; Lichen Zhao; Shuangjin Liu

2011-01-01

77

Two types of the first cycle effects in copper based shape memory alloys  

SciTech Connect

The effects of thermo mechanical treatments on transformation temperatures and hysteresis are important for many shape memory applications. Depending on the field of application either a large or small hysteresis is required. A high hysteresis for the first cycle is especially important for one way applications, when the material has to be stored in the transformable martensitic condition. For this reason the material is deformed slightly in the martensitic state (T{sub MF}alloy. Treppman et al., Spielfeld et al. and also Zhang et al. found that the defects formed in martensite domain boundaries are able to induce a shift of austenite temperatures to significantly higher values and thus increase the transformation hysteresis of the first cycle. In this work it will be shown that a different first cycle effect occurs after ausforming of the Copper based shape memory alloy. For the first cycle the A{sub s} temperature is lowered. For the following DSC cycles it is increased nearly to its original value after betatising.

Hornbogen, E.; Mertinger, V.; Spielfeld, J.

1999-05-21

78

Wegner-type bounds for a two-particle continuous Anderson model with an alloy-type external potential  

E-print Network

We consider a two-particle quantum systems in a d-dimensional Euclidean space with interaction and in presence of a random external potential (a continuous two-particle Anderson model). We establish Wegner-type estimates (inequalities) for such models, assessing the probability that random spectra of Hamiltonians in finite volumes intersect a given set.

A. Boutet de Monvel; V. Chulaevsky; P. Stollmann; Y. Suhov

2008-12-14

79

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

80

The characterization of shape memory effect for low elastic modulus biomedical {beta}-type titanium alloy  

SciTech Connect

This work investigates the textures of biomedical TiNbTaZr alloy rolled by 99% cold reduction ratios in thickness. The relationship between textures and superelasticity of the specimens treated at 873 K and 1223 K for 1.2 ks is studied. The microstructure of tensile specimen is investigated by transmission electron microscopy. Textures of cold-rolled and heat-treated specimens are studied. During unloading, the anisotropy of superelastic strain and pure elastic strain in the heat-treated specimens is observed. Superelastic strain along rolling direction and transverse direction is larger than those along 45 deg. from rolling direction while pure elastic strain shows the highest value along 45 deg. from rolling direction in the specimen treated at 873 K. For the specimen treated at 1223 K, higher pure elastic strain is obtained along rolling direction. The maximum recovered strain around 2.11% is obtained along rolling direction.

Wang Liqiang [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China); Lu Weijie, E-mail: luweijie@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China); Qin Jining; Zhang Fan; Zhang Di [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China)

2010-05-15

81

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

82

Identification of a new pseudo-binary hydroxide during calendar corrosion of (La, Mg)2Ni7-type hydrogen storage alloys for Nickel-Metal Hydride batteries  

E-print Network

1 Identification of a new pseudo-binary hydroxide during calendar corrosion of (La, Mg)2Ni7-type hydrogen storage alloys for Nickel-Metal Hydride batteries J. Monnier 1 , H. Chen 1 , S. Joiret2,3 , J Abstract To improve the performances of Nickel-Metal Hydride batteries, an important step

Boyer, Edmond

83

Thermoelectric Properties of n-type Polycrystalline BixSb2-xTe3 Alloys N. Gerovac, G. J. Snyder, and T. Caillat  

E-print Network

Thermoelectric Properties of n-type Polycrystalline BixSb2-xTe3 Alloys N. Gerovac, G. J. Snyder their atomic composition. The thermoelectric properties were measured at room temperature in both directions. The thermoelectric figure-of-merit, ZT, was calculated from these properties. The best ZT was ~.5, given by annealed

84

Twinning in L1[sub 0] type Fe-Pt alloys  

SciTech Connect

Previously, twin systems of [111] <112> were reported in L1[sub 0] TiAl. No pseudo twinning was observed in TiAl. This is probably due to the fact that the pseudo twins, [111], [211] or [121], result in L1[sub 1] like structure which has a higher energy in TiAl. Nevertheless, it was suggested that the pseudo-twinning might be possible at high temperatures where a disordering occurs and the pseudo-twin energy becomes small. In current experiments, FePt alloy which was deformed at 600 C didn't show pseudo twinning. Since the order-disorder transformation occurs at 1,300 C, it is still likely that a high degree of disordering may occur above 1,100 C. Relatively easy twinning in FePt as compared to TiAl may be explained from two reasons. First, FePt may be characterized as having a metallic bonding while TiAl as having a covalent bonding. Also, the heat of formation indicates that a strong bonding exists in TiAl. The heat of formation for FePt is [minus]25 kJmol[sup [minus]1] (1,123 K) and that of TiAl is [minus]36 kJ[sup [minus]1]. Second, the twinning shear for FePt is 0.63 compared to 0.96 in TiAl. For these reasons, twinning shear in FePt would requires less energy than that required in TiAl.

Gao, Y.Q.; Whang, S.H. (Polytechnic Univ., Brooklyn, NY (United States). Dept. of Materials Science and Engineering)

1994-12-01

85

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. Methanol is also an important bulk chemical that is most efficiently formed over the industrial Cu/ZnO/Al2O3 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. 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

86

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

87

Electrometallurgical treatment of metal, oxide, and aluminum-alloy spent nuclear fuel types.  

SciTech Connect

Electrorefining uranium in a molten salt bath is the key step in the electrometallurgical treatment of spent nuclear fuels. The versatility of the electrometallurgical treatment suggests its use for a variety of spent fuel types, as well as for nonnuclear metal-separation applications.

McPheeters, C. C.; Gay, E. C.; Karell, E. J.; Ackerman, J. P.; Chemical Engineering

1997-01-01

88

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 A·m-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 g·m-2·h-1, respectively, in accelerated corrosion test for 8 h at 2000 A·m-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

89

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; Saatçi, Buket; Gündüz, Mehmet; Özdemir, Mehmet

2013-11-01

90

Fabrication of a maxillary posterior fixed partial denture with a type 4 gold alloy and a dual-polymerizing indirect composite.  

PubMed

The aim of the present study was to design and fabricate a maxillary posterior fixed partial denture (FPD) made of a type 4 gold alloy and an indirect composite. Unlike the conventional framework design of a resin veneered restoration, cut-back was extended approximately 1/4 to 1/3 width in the occlusal table of the buccal cusp. Multiple retentive beads 150-200 mum in diameter were placed on the metal surface to be veneered. The gold alloy was cast in a cristobalite mold using a centrifugal casting machine. The cut surface with the retentive beads was air-abraded with alumina, and a priming agent (Alloy Primer) that contained triazine dithione monomer (VTD) was applied. A tooth-colored veneer was then fabricated with a highly loaded light- and heat-cured composite material (Estenia). This design and procedure can be applied as a standardized laboratory technique for fabrication of maxillary posterior restorations and FPDs. PMID:18403895

Matsumura, Hideo; Mori, Shuichi; Tanoue, Naomi

2008-03-01

91

Stability of Fe-based alloys with structure type C6Cr23 M. Widom and M. Mihalkovic  

E-print Network

of an alloy energy from the tie-surface joining pure elements is known as its enthalpy of formation to identify third elements that can effectively destabilize C6Cr23. Yttrium appears optimal among transition together with metalloid elements such as B or C. Bulk Iron-based amorphous alloys could become important

Widom, Michael

92

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

93

Transformations and new PHACOMP analysis in weld metal of Hastelloy C-type alloys. [C-4, C-22, C-276  

SciTech Connect

The sequence of phase transformations occurring during solidification and cooling of weld metals in the Hastelloy C family (C-4, C-22, C-276) has been determined. An equivalent component chemistry model has been defined for these alloys which allows existing Ni-Cr-Mo ternary phase diagrams to be used to predict the transformation sequence (both liquid ..-->.. solid and solid ..-->.. solid) in these complex alloys. In the cases of Alloys C-22 and C-276, the solidification events terminate with the formation of a constituent containing a topologically-close-packed (TCP) phase (sigma in C-22; P in C-276). The New PHACOMP formalism developed by Morinaga et al. for predicting TCP phase precipitation by solid state transformation in superalloys is applied for the first time to measured weld solidification segregation profiles. This formalism correctly predicts the occurrence of terminal solidification TCP phases in Alloys C-22 and C-276 and correctly predicts the absence of such phases as terminal solidification products in Alloy C-4. Implications to analysis of other nickel alloy weld metals are suggested.

Cieslak, M.J.; Headley, T.J.; Romig, A.D. Jr.

1986-01-01

94

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

95

Thermoelectric Properties of Ag-Doped n-Type (Bi2- x Ag x Te3)0.96-(Bi2Se3)0.04 Pseudobinary Alloys  

NASA Astrophysics Data System (ADS)

n-Type thermoelectric powders of (Bi2- x Ag x Te3)0.96-(Bi2Se3)0.04 (0 ? x ? 0.05) have been synthesized by mechanical alloying and then consolidated by spark plasma sintering. The analysis results show that the grain size of pure Bi, Te, Ag, and Se powders is decreased to about 1 ?m to 0.5 ?m after they are mechanically alloyed for 2 h. The power factor of bulk material increases with increasing Ag-doping content, while the trend for the lattice thermal conductivity is the opposite. Bulk (Bi0.99Ag0.04)2(Te0.96Se0.04)3 after milling for 12 h exhibits a higher power factor, lower thermal conductivity, and thus a higher ZT of 0.74 at 373 K.

Zhang, Xin; Ma, Xu-Yi; Lu, Qing-Mei; Zhang, Fei-Peng; Liu, Yan-Qin; Zhang, Jiu-Xing; Wang, Lei

2011-05-01

96

Energy band engineering and controlled p-type conductivity of CuAlO2 thin films by nonisovalent Cu-O alloying  

NASA Astrophysics Data System (ADS)

The electronic band structure and p-type conductivity of CuAlO2 films were modified via synergistic effects of energy band offset and partial substitution of less-dispersive Cu+ 3d10 with Cu2+ 3d9 orbitals in the valence band maximum by alloying nonisovalent Cu-O with CuAlO2 host. The Cu-O/CuAlO2 alloying films show excellent electronic properties with tunable wide direct bandgaps (˜3.46-3.87 eV); Hall measurements verify the highest hole mobilities (˜11.3-39.5 cm2/Vs) achieved thus far for CuAlO2 thin films and crystals. Top-gate thin film transistors constructed on p-CuAlO2 films were presented, and the devices showed pronounced performance with Ion/Ioff of ˜8.0 × 102 and field effect mobility of 0.97 cm2/Vs.

Yao, Z. Q.; He, B.; Zhang, L.; Zhuang, C. Q.; Ng, T. W.; Liu, S. L.; Vogel, M.; Kumar, A.; Zhang, W. J.; Lee, C. S.; Lee, S. T.; Jiang, X.

2012-02-01

97

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

98

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

99

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

100

Amorphous metal alloy  

DOEpatents

Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

Wang, R.; Merz, M.D.

1980-04-09

101

Effect of grain size on high-cycle fatigue properties in alpha-type titanium alloy at cryogenic temperatures  

Microsoft Academic Search

High-cycle fatigue properties were investigated at 4, 77 and 293 K in Ti–5%Al–2.5%Sn ELI alloy which was used for liquid hydrogen turbo-pumps of Japanese-built launch vehicles. Mean grain size of specimens was controlled to be about 30 or 80 ?m. In the specimens with a grain size of 30 ?m, fatigue strengths at 106 cycles at 4 and 77 K

Y. Ono; T. Yuri; H. Sumiyoshi; S. Matsuoka; T. Ogata

2003-01-01

102

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

103

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

SciTech Connect

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. -- Highlights: ? Tungsten/nickel/cobalt, tungsten/nickel/iron, and pure tungsten were studied. ? Male Fischer rats implanted with pellets in gastrocnemius muscle of each hind leg. ? Aggressive rhabdomyosarcomas developed from tungsten/nickel/cobalt pellets only. ? Microarray gene expression analysis was carried out on selected tumors. ? Pellet degradation, urinary metal concentration, and sarcoma were correlated.

Schuster, B.E. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, B434 Mulberry Road, Aberdeen Proving Ground, MD 21005-5609 (United States)] [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, B434 Mulberry Road, Aberdeen Proving Ground, MD 21005-5609 (United States); Roszell, L.E. [U.S. Army Institute of Public Health, 5158 Blackhawk Road, Aberdeen Proving Ground, MD 21010?5403 (United States)] [U.S. Army Institute of Public Health, 5158 Blackhawk Road, Aberdeen Proving Ground, MD 21010?5403 (United States); Murr, L.E.; Ramirez, D.A. [Department of Metallurgical and Materials Engineering, University of Texas, El Paso, TX 79968 (United States)] [Department of Metallurgical and Materials Engineering, University of Texas, El Paso, TX 79968 (United States); Demaree, J.D. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, B434 Mulberry Road, Aberdeen Proving Ground, MD 21005-5609 (United States)] [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, B434 Mulberry Road, Aberdeen Proving Ground, MD 21005-5609 (United States); Klotz, B.R. [Dynamic Science Inc., Aberdeen Proving Ground, MD 21005?5609 (United States)] [Dynamic Science Inc., Aberdeen Proving Ground, MD 21005?5609 (United States); Rosencrance, A.B.; Dennis, W.E. [U.S. Army Center for Environmental Health Research, Department of Chemistry, Ft. Detrick, MD 21702?5010 (United States)] [U.S. Army Center for Environmental Health Research, Department of Chemistry, Ft. Detrick, MD 21702?5010 (United States); Bao, W. [SAS Institute, Inc. SAS Campus Drive, Cary, NC 27513 (United States)] [SAS Institute, Inc. SAS Campus Drive, Cary, NC 27513 (United States); Perkins, E.J. [U.S. Army Engineer Research and Development Center, 3909 Hall Ferry Road, Vicksburg MS 39180 (United States)] [U.S. Army Engineer Research and Development Center, 3909 Hall Ferry Road, Vicksburg MS 39180 (United States); Dillman, J.F. [U.S. Army Medical Research Institute of Chemical Defense, 3100 Ricketts Point Road, Aberdeen Proving Ground, MD 21010?5400 (United States)] [U.S. Army Medical Research Institute of Chemical Defense, 3100 Ricketts Point Road, Aberdeen Proving Ground, MD 21010?5400 (United States); Bannon, D.I., E-mail: desmond.bannon@us.army.mil [U.S. Army Institute of Public Health, 5158 Blackhawk Road, Aberdeen Proving Ground, MD 21010?5403 (United States)

2012-11-15

104

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

105

Combinatorial sputtering in planetary type systems for alloy libraries with perpendicular gradients of layer thickness and composition realised by a timing approach  

NASA Astrophysics Data System (ADS)

We present a combinatorial sputtering technique to fabricate alloy thin films with orthogonal gradients of thickness and stoichiometry in a planetary type sputtering system. Using this approach we prepared a library of planar Nb Josephson junctions with a magnetic compound layer made from Si and Fe on one wafer. The independent investigation of thickness and composition changes of the FeSi layer allows the identification of transition regions where the phase difference of the superconducting order parameter across the barrier changes from 0 to . A mapping technique which allows to identify the different coupling regimes depending on material properties might facilitate the fabrication of junctions with tailored critical current, damping and normal resistance parameters for applications.

Ruppelt, N.; Vavra, O.; Sickinger, H.; Goldobin, E.; Koelle, D.; Kleiner, R.; Kohlstedt, H.

2014-07-01

106

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

107

Design and fabrication of a locomotive mechanism for capsule-type endoscopes using shape memory alloys (SMAs)  

Microsoft Academic Search

Endoscopes are medical devices to diagnose various kinds of diseases throughout the whole gastrointestinal tracks. Generally, they are divided into conventional push-type endoscopes and more recently developed wireless capsule-type endoscopes. The conventional endoscopes cannot reach the small intestines and generate pain and discomfort to patients due to the stiffness of their body. Such disadvantages do not exist in wireless capsule-type

Byungkyu Kim; Sunghak Lee; Jong Heong Park; Jong-Oh Park

2005-01-01

108

Microstructural studies on Alloy 693  

NASA Astrophysics Data System (ADS)

Superalloy 693, is a newly identified ‘high-temperature corrosion resistant alloy’. Present study focuses on microstructure and mechanical properties of the alloy prepared by double ‘vacuum melting’ route. In general, the alloy contains ordered Ni3Al precipitates distributed within austenitic matrix. M6C primary carbide, M23C6 type secondary carbide and NbC particles are also found to be present. Heat treatment of the alloy at 1373 K for 30 min followed by water quenching (WQ) brings about a microstructure that is free from secondary carbides and Ni3Al type precipitates but contains primary carbides. Tensile property of Alloy 693 materials was measured with as received and solution annealed (1323 K, 60 min, WQ) and (1373 K, 30 min, WQ) conditions. Yield strength, ultimate tensile strength (UTS) and hardness of the alloy are found to drop with annealing. It is noted that in annealed condition, considerable cold working of the alloy can be performed.

Halder, R.; Dutta, R. S.; Sengupta, P.; Samajdar, I.; Dey, G. K.

2014-10-01

109

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

110

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

111

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 MââCâ can form in

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

1983-01-01

112

High efficient N-type interdigitated back contact silicon solar cells with screen-printed al-alloyed emitter  

Microsoft Academic Search

N-type interdigitated back contact (IBC) silicon solar cells have been successfully applied industrially with high-efficiency of 23.4% by Sunpower and are being investigated by several research groups. However, the formation of p+ emitter is still an issue. A traditional method is boron diffusion which needs high temperature processes to form the emitter and to remove the silicate glass boron skin.

Chun Gong; E. Van Kerschaver; J. Robbelein; N. E. Posthuma; S. Singh; J. Poortmans; R. Mertens

2010-01-01

113

Wetting Characteristics of Novel-type 63Sn-29.2Pb-6Zn-1Ag-0.38Cu-0.42Bi Solder Alloy  

NASA Astrophysics Data System (ADS)

6061 aluminum alloy has many advantages, and soldering is the most attractive joining method for 6061 aluminum alloy. In order to expand application of 6061 aluminum alloy, a novel 63Sn-29.2Pb-6Zn-1Ag-0.38Cu-0.42Bi solder alloy was prepared. The melting characteristic and microstructure of the solder were analyzed by differential scanning calorimetry and scanning electron microscope. Its spreading on the 6061 aluminum alloy was also studied. The results show that its melting temperature range is 456.34-463.68 K, and the temperature interval between the solidus and the liquidus is 6.34 K. The solder on 6061 aluminum alloy had better wetting characteristics. A precursor film appears ahead of the spreading droplet. The microstructure at the interface between the solder and the 6061 aluminum alloy was analyzed. It was clear that the intermetallic compound, Ag2Al phase, was formed at the interface between the solder and the 6061 aluminum alloy.

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

2010-07-01

114

Effect of small scattering centers on the thermoelectric properties of p-type SiGe alloys  

NASA Technical Reports Server (NTRS)

Theory predicts that the addition of ultra-fine, inert, phonon-scattering centers to thermoelectric materials will reduce their thermal conductivity. To investigate this prediction, ultrafine particulates (20 to 120 A) of silicon nitride have been added to boron-doped, p-type, 80/20 SiGe. All of the SiGe samples produced from ultrafine powder have lower thermal conductivities than standard SiGe, but high-temperature heat treatment increases the thermal conductivity back to the value for standard SiGe. However, the SiGe samples with silicon nitride, inert, phonon-scattering centers retained the lower thermal conductivity after several heat treatments. A reduction of approximately 25 percent in thermal conductivity has been achieved in these samples. The magnitude of the reduction agrees with theoretical predictions.

Beaty, John S.; Rolfe, Jonathan L.; Vandersande, Jan W.

1991-01-01

115

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 14.8–21.4 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 18–22 mass%

Satoru Nishikawa; Yukihiko Horii; Kenji Ikeuchi

2012-01-01

116

Grindability of dental magnetic alloys.  

PubMed

In this study, the grindability of cast magnetic alloys (Fe-Pt-Nb magnetic alloy and magnetic stainless steel) was evaluated and compared with that of conventional dental casting alloys (Ag-Pd-Au alloy, Type 4 gold alloy, and cobalt-chromium alloy). Grindability was evaluated in terms of grinding rate (i.e., volume of metal removed per minute) and grinding ratio (i.e., volume ratio of metal removed compared to wheel material lost). Solution treated Fe-Pt-Nb magnetic alloy had a significantly higher grinding rate than the aged one at a grinding speed of 750-1500 m x min(-1). At 500 m x min(-1), there were no significant differences in grinding rate between solution treated and aged Fe-Pt-Nb magnetic alloys. At a lower speed of 500 m x min(-1) or 750 m x min(-1), it was found that the grinding rates of aged Fe-Pt-Nb magnetic alloy and stainless steel were higher than those of conventional casting alloys. PMID:16022434

Hayashi, Eisei; Kikuchi, Masafumi; Okuno, Osamu; Kimura, Kohei

2005-06-01

117

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 -40°C.

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

2004-07-01

118

Producing a gradient-composition nanocrystalline structure on nitrided surfaces of invar-type Fe-Ni alloys using megaplastic deformation  

NASA Astrophysics Data System (ADS)

A nanocrystalline Fe-Ni matrix strengthened by dispersed CrN and TiN nitrides has been produced on the ion-plasma-nitrided surfaces of the austenitic Fe-Ni38-Cr15 and Fe-Ni36-Ti4 alloys using cyclic "nitride dissolution-nitride precipitation" phase transformations induced by megaplastic deformation. The high-pressure torsion of the nitrided alloys has led to the dissolution of the CrN nitrides and Ni3Ti intermetallic compounds, which appeared in the matrix, in the surface layer and to the mechanical alloying of the nitrided subsurface layer and the unnitriderd bulk of the specimens. Subsequent annealing has resulted in the formation of secondary nitrides, which propagated to a depth substantially exceeding the thickness of the original nitrided layer.

Shabashov, V. A.; Borisov, S. V.; Litvinov, A. V.; Kataeva, N. V.; Afanas'ev, S. V.; Titova, S. G.

2014-09-01

119

The structure, anisotropy and coercivity of rapidly quenched TbCu7-type SmCo7-xZrx alloys and the effects of post-treatments  

NASA Astrophysics Data System (ADS)

The effects of wheel speed, Zr content, post-ball milling process and heat treatment on the structure, anisotropy, magnetic properties and phase transition of the melt-spun SmCo7-xZrx alloys were investigated. The crystallographic c-axis is parallel to the ribbon plane for the ribbons prepared at low speeds of 5 and 15 m/s, and this orientation is reduced at higher speeds. The out-of-plane coercivity of SmCo6.8Zr0.2 ribbon increases from 123 kA/m for 5 m/s to 1076 kA/m for 60 m/s. Zr doping improves the hard magnetic properties and the in-plane coercivity of SmCo7-xZrx alloys increases with the Zr content from 592 kA/m for x=0.1 to 1376 kA/m for x=0.4. The Rietveld refinements and theoretical analysis reveal that Zr atoms occupy the 2e site. The coercivity mechanisms are different for the alloys with various Zr contents. The ball milling process could enhance the coercivity and remanence of the ribbons due to the grain refinement and the precipitation of Co phase. Heat treatment can further modify the magnetic properties of the alloys. SmCo6.7Zr0.3 alloy heat treated at 400 °C has the high maximum energy product (BH)max of 64.5 kJ/m3, where the coercivity was enhanced to 1560 kA/m by 650 °C heat treatment. In addition, the SmCo7-xZrx alloys exhibit excellent hard magnetic properties at elevated temperatures.

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

2013-12-01

120

Mechanical Alloying  

Microsoft Academic Search

A new technique of combining metals has been developed which overcomes many of the limitations of conventional alloying. Ball mills that generate higher energies than conventional ball mills are used to tumble a mixture of powders, such as WC and Co, in order to form a composite. Ni-base alloys can be dispersion-hardened in this way with an oxide such as

J. S. Benjamin

1976-01-01

121

Effect of phosphorus 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 intergranular stress corrosion cracking (IGSCC) susceptibility of shielded metal arc weld metals for Inconel alloy 600 has been investigated with particular reference to the influences of P and Nb contents on the basis of a creviced bent beam (CBB) test in pressurized hot water (corresponding to the service condition of boiling water reactor nuclear power plant). The IGSCC susceptibility

Satoru Nishikawa; Yukihiko Horii; Kenji Ikeuchi

2012-01-01

122

IEEE TRANSACTIONS ON MAGNETICS, VOL. 43, NO. 8, AUGUST 2007 3497 Co Alloy-SiO2 Granular-Type Longitudinal Media for Sputtered  

E-print Network

magnetic tape media. We used bias sputtering to achieve desirable properties (good in-plane orientation noise power compared to the CoCrPt-SiO2 media. Index Terms--Bias sputtering, Co alloy-SiO2 films. Secondly, as previously reported [7], bias sput- tering was used to achieve desirable media properties

Laughlin, David E.

123

Structural aspects of high performance Mg alloys design  

Microsoft Academic Search

Magnesium–gadolinium binary alloys exhibit good mechanical properties and high creep resistance comparable to or better than commercial WE type (Mg–Y–Nd–Zr) alloys. Combining scandium and manganese with a particular rare earth element (R.E.–Gd, Y, Ce) has a beneficial effect on the creep behaviour of complex Mg–R.E. alloys, at lower R.E. contents than in WE type alloys. They stabilise high creep resistance

B. Smola; I. Stul??ková; F. von Buch; B. L. Mordike

2002-01-01

124

[Composition and morphology of oxides on porcelain fused to Ni-Cr alloys. Be containing alloys].  

PubMed

Bonding strength between porcelain and Ni-Cr alloy for the porcelain fused-to metal crown in which Be is contained in the alloy is known to be higher than those in which Be is not contained. Since, bonding between porcelain and alloy is the reaction of oxides and porcelain, the bonding is thought to be influenced by the quality the oxides film which forms on the alloy surface. The purpose of this study was to determine the composition and morphology of the oxides formed on both Be containing and non-Be contained Ni-Cr alloys. The oxides analysis was done using an EPMA and Auger analysis. Also, the Porcelain/Ni-Cr alloy interface was observed by a scanning electron microscope (SEM). The following results are indicated from this investigation: 1. The oxides from the alloys not containing Be are corundum type Cr2O3 and spinel type NiCr2O4. These oxide layers are uniform, thick and porous and the adhesion to alloy is poor. 2. The oxides from alloy containing Be is BeO only. The BeO is uniform, thin and condensed. The adhesion to the alloy is good. 3. The oxide layer formed when the porcelain is fused to alloy containing Be is thin (1 micron average) and has good adhesion to alloy. 4. Be is selectively oxidized and controlled the form of Cr2O3 and NiO. PMID:2700282

Watanabe, T

1989-06-01

125

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 50-100°C, 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

126

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. PMID:19088892

Watanabe, Ikuya; Wallace, Cameron

2008-01-01

127

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

128

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.

129

Welding and brazing of nickel and nickel-base alloys  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

130

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.

131

Production of Aluminum Alloys: Status and Prospects  

Microsoft Academic Search

Due to their physico-mechanical properties, aluminum alloys are one of the most important structural materials presently in use. Aluminum alloys are second only to steel in terms of volume of production and substantially outstrip other nonferrous metals in this regard. For example, the worldwide production of different types of metals at the end of the last century broke down as

G. S. Makarov

2002-01-01

132

Iron aluminide alloys with improved properties for high temperature applications  

Microsoft Academic Search

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

Claudette G. McKamey; Chain T. Liu

1990-01-01

133

Modeling of diffusion processes during carburization of alloys  

Microsoft Academic Search

A Model was developed for the finite-difference calculation of carburization profiles in high-temperature alloys. The method includes the ternary crossdiffusion effect due to substitutional alloying elements that are preferentially oxidized. It can be used to treat cases such as carburization of preoxidized alloys or simultaneous oxidation and carburization. Up to three distinct types of carbide precipitation reactions can be included

D. Farkas; K. Ohla

1983-01-01

134

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

135

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

136

Corrosion fatigue of die-cast and extruded magnesium alloys  

Microsoft Academic Search

To study the fatigue life of die-cast and extruded AZ91D, AM50 and AZ31 magnesium alloys, corrosion fatigue tests were carried out using a rotating beam type fatigue machine. Corrosive environment (3.5% NaCl) significantly decreases fatigue life of alloys, especially for extruded alloys. The fatigue data at high stresses were analyzed using fitting equations. Extruded alloys show a higher sensitivity to

A Eliezer; E. M Gutman; E Abramov; Ya Unigovski

2001-01-01

137

Advanced cutting conditions for the milling of aeronautical alloys  

Microsoft Academic Search

This paper deals with possible improvement aspects on the chip cutting milling of two alloys that are used frequently in the aerospace industry, in particular the titanium alpha–beta-based alloy Ti6Al4V and the nickel alloy usually known as type 718. Both alloys are used widely in the manufacture of different turbo-engine parts, considering their excellent mechanic features, and their resistance to

L. N López de lacalle; J Pérez; J. I Llorente; J. A Sánchez

2000-01-01

138

The Development of the Low-Cost Titanium Alloy Containing Cr and Mn Alloying Elements  

NASA Astrophysics Data System (ADS)

The ? + ?-type Ti-4.5Al-6.9Cr-2.3Mn alloy has been theoretically designed on the basis of assessment of the Ti-Al-Cr-Mn thermodynamic system and the relationship between the molybdenum equivalent and mechanical properties of titanium alloys. The alloy is successfully prepared by the split water-cooled copper crucible, and its microstructures and mechanical properties at room temperature are investigated using the OM, SEM, and the universal testing machine. The results show that the Ti-4.5Al-6.9Cr-2.3Mn alloy is an ? + ?-type alloy which is consistent with the expectation, and its fracture strength, yield strength, and elongation reach 1191.3, 928.4 MPa, and 10.7 pct, respectively. Although there is no strong segregation of alloying elements under the condition of as-cast, the segregation of Cr and Mn is obvious at the grain boundary after thermomechanical treatment.

Zhu, Kailiang; Gui, Na; Jiang, Tao; Zhu, Ming; Lu, Xionggang; Zhang, Jieyu; Li, Chonghe

2014-04-01

139

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

140

Electron mobility in n-type Hg(1-x)Cd(x)Te and Hg(1-x)Zn(x)Te alloys  

NASA Technical Reports Server (NTRS)

Calculations of electron mobility in n-type mercury cadmium telluride (MCT), a candidate material for IR detectors, and n-type mercury zinc telluride (MZT) are compared. It is found that electron mobilities in MCT and MZT are nearly the same for equivalent energy gaps. The results are also found to compare will with experimental data. Directions of future research are briefly discussed.

Patterson, J. D.; Gobba, Wafaa A.; Lehoczky, S. L.

1992-01-01

141

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

142

Amorphous metal alloys produced by mechanical alloying  

SciTech Connect

Mechanical alloying is a powder metallurgy method used in commercial production of high temperature superalloys. Under specific conditions, mechanical alloying allows the synthesis of amorphous metal alloys from mixtures of pure metal powders or from the powders of intermetallic compounds. Because the amorphizing transformation during mechanical alloying is a solid state reaction, most of the difficulties related to the amorphization by rapid solidification of melts can be avoided. Mechanical alloying allows the synthesis of amorphous alloys from metals with high melting temperatures and the resulting alloys have interesting properties such as high hardness and high crystallization temperatures. We used mechanical alloying for the synthesis of amorphous alloys in the binary alloy systems Nl-Sn, Nb-Si and Al-Hf. The amorphous alloy powders were characterized by x-ray diffraction, differential scanning calorimetry, scanning and transmission electron microscopy and hardness measurements. Produced alloys were compacted by hot pressing and the obtained compacts were characterized by x-ray diffraction, density and hardness measurements and by optical and scanning electron microscopy. The results of the amorphization and compaction studies are presented and discussed together with the characteristics of the mechanical alloying process. 15 refs., 5 figs.

Tiainen, T.J.; Schwarz, R.B.

1989-01-01

143

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

144

Comparison of A15 Stoichiometry and Grain Morphology in Internal sn and Tube Type Strands; Influence of Strand Design, HTs and Alloying  

NASA Astrophysics Data System (ADS)

A15 stoichiometry was investigated and compared for two different Nb3Sn strand designs, "tube type" and high-performance, distributed-barrier RIT type. The focus of the study was to attain fine grain A15 with maximal Sn stoichiometry. Tube type conductors were compared to RIT conductors, each after the application of two-step HTs with plateaus ranging from 615° C to 675° C for various times. The resulting transport values were compared to those arising from standard HTs, namely 3476 A/mm2 for the RIT conductors and 2231 A/mm2 for the tube type conductors. The influence of strand geometry and reaction route was related to the resulting A15 stoichiometries. Short sections of strand were encapsulated and then HT, after which SEM (BSE) and EDS were used to observe the structures and obtain Sn concentration profiles. Fractography was performed to investigate the effect of a two-step reaction on the morphology, the ratio of coarse/fine grain area and grain size of fine grain A15.

Bhartiya, S.; Sumption, M. D.; Peng, X.; Gregory, E.; Tomsic, M. J.; Doll, D.; Collings, E. W.

2010-04-01

145

Thermoelectric Properties of Doped BiSb Alloy Thin Films  

Microsoft Academic Search

It is well known that undoped BiSb alloys are good n-type thermoelements. We have observed that the power factor (S^2 sigma) for MBE-grown BiSb thin films grown on CdTe(111) peak at a significantly higher temperature (250K) than previous results for the bulk alloy (80K), possibly due to an enhanced bandgap. In order to achieve p-type BiSb alloy thin films for

S. Cho; A. Divenere; G. K. Wong; J. B. Ketterson; J. R. Meyer; C. A. Hoffman

1998-01-01

146

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

147

Anodizing of aluminium alloys  

Microsoft Academic Search

Anodizing is used widely in the surface treatment of aluminium alloys for aerospace applications. Considers recent advances in understanding of the influences of alloying elements in anodizing of aluminium alloys and, in particular, their applicability to second phase particles during anodizing of commercial alloys. Through more precise knowledge of the response of second phase materials to anodic polarization, improved anodizing

G. E. Thompson; H. Habazaki; K. Shimizu; M. Sakairi; P. Skeldon; X. Zhou; G. C. Wood

1999-01-01

148

A New Ion-coating Surface Treatment of Alloys for Dental Adhesive Resins  

Microsoft Academic Search

4-META and new phosphate-methacrylate resins adhere strongly to dental alloys. However, for strengthening the water durability of the adhesive interface, the oxidation of the alloy surface is indispensable. A new oxidation method using ion-sputtering was developed, and the effectiveness of this surface treatment on two dental alloys-a type IV gold alloy and Ni-Cr-Be alloy-was investigated. As an endurance test, thermocycling

T. Tanaka; M. Hirano; M. Kawahara; H. Matsumura; M. Atsuta

1988-01-01

149

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

150

Tellurium n-type doping of highly mismatched amorphous GaN1-xAsx alloys in plasma-assisted molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

In this paper we report our study on n-type Te doping of amorphous GaN1-xAsx layers grown by plasma-assisted molecular beam epitaxy. We have used a low temperature PbTe source as a source of tellurium. Reproducible and uniform tellurium incorporation in amorphous GaN1-xAsx layers has been successfully achieved with a maximum Te concentration of 9×1020 cm-3. Tellurium incorporation resulted in n-doping of GaN1-xAsx layers with Hall carrier concentrations up to 3×1019 cm-3 and mobilities of ~1 cm2/V s. The optimal growth temperature window for efficient Te doping of the amorphous GaN1-xAsx layers has been determined.

Novikov, S. V.; Ting, M.; Yu, K. M.; Sarney, W. L.; Martin, R. W.; Svensson, S. P.; Walukiewicz, W.; Foxon, C. T.

2014-10-01

151

Structural alloys for high field superconducting magnets  

SciTech Connect

Research toward structural alloys for use in high field superconducting magnets is international in scope, and has three principal objectives: the selection or development of suitable structural alloys for the magnet support structure, the identification of mechanical phenomena and failure modes that may influence service behavior, and the design of suitable testing procedures to provide engineering design data. This paper reviews recent progress toward the first two of these objectives. The structural alloy needs depend on the magnet design and superconductor type and differ between magnets that use monolithic and those that employ force-cooled or ICCS conductors. In the former case the central requirement is for high strength, high toughness, weldable alloys that are used in thick sections for the magnet case. In the latter case the need is for high strength, high toughness alloys that are used in thin welded sections for the conductor conduit. There is productive current research on both alloy types. The service behavior of these alloys is influenced by mechanical phenomena that are peculiar to the magnet environment, including cryogenic fatigue, magnetic effects, and cryogenic creep. The design of appropriate mechanical tests is complicated by the need for testing at 4/sup 0/K and by rate effects associated with adiabatic heating during the tests. 46 refs.

Morris, J.W. Jr.

1985-08-01

152

Hydrogen solubility in inhomogeneous Pd alloys  

SciTech Connect

As-cast, arc-melted Pd-Ni alloys are inhomogeneous and the H{sub 2} isotherms for these differ from their homogeneous counterparts in the two phase, (dilute + hydride), regions but not in the dilute phase regions. Pd-Ni alloys, which become inhomogeneous via a ternary (Pd + Ni + H) equilibrium phase change, have H{sub 2} isotherms which differ from those of the homogeneous alloy in both the two-phase and the dilute phase regions. These results are discussed with respect to the expected type of inhomogeneities.

Flanagan, T.B.; Wang, D.; Clewley, J.D. [Univ. of Vermont, Burlington, VT (United States). Chemistry Dept.

1998-12-31

153

Discoloration of titanium alloy in acidic saline solutions with peroxide.  

PubMed

The objective of this study was to compare corrosion behavior in several titanium alloys with immersion in acidulated saline solutions containing hydrogen peroxide. Seven types of titanium alloy were immersed in saline solutions with varying levels of pH and hydrogen peroxide content, and resulting differences in color and release of metallic elements determined in each alloy. Some alloys were characterized using Auger electron spectroscopy. Ti-55Ni alloy showed a high level of dissolution and difference in color. With immersion in solution containing hydrogen peroxide at pH 4, the other alloys showed a marked difference in color but a low level of dissolution. The formation of a thick oxide film was observed in commercially pure titanium showing discoloration. The results suggest that discoloration in titanium alloys immersed in hydrogen peroxide-containing acidulated solutions is caused by an increase in the thickness of this oxide film, whereas discoloration of Ti-55Ni is caused by corrosion. PMID:23370866

Takemoto, Shinji; Hattori, Masayuki; Yoshinari, Masao; Kawada, Eiji; Oda, Yutaka

2013-01-01

154

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

155

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

156

Austenitic stainless steel alloy  

Microsoft Academic Search

This patent describes a stainless steel alloy composition for service exposed to irradiation, having resistance to irradiation promoted stress corrosion cracking and reduced long term irradiation induced radioactivity. The alloy consisting of a low carbon content austenitic stainless steel alloy composition comprising about 18 to 20 percent weight of chromium, about 9 to 11 percent weight of nickel, about 1.5

D. J. Coates; G. M. Gordon; A. J. Jacobs; D. W. Sandusky

1989-01-01

157

Alloys for aerospace  

Microsoft Academic Search

Aerospace industries require special allows with many properties tailored to meet specific needs. Prerequisites include clean melting techniques to maintain low impurity levels, tight control of alloy chemistry, and the analytical capability to characterize the product. Teledyne Wah Chang (TWC) produces specially refractory metals, including zirconium, hafnium, titanium, niobium and vanadium, which are essential components of many aerospace alloys. Alloys

S. Tuominen; C. Wojcik

1995-01-01

158

Superplasticity in powder metallurgy aluminum alloys and composites  

SciTech Connect

Superplasticity in powder metallurgy Al alloys and composites has been reviewed through a detailed analysis. The stress-strain curves can be put into 4 categories: classical well-behaved type, continuous strain hardening type, continuous strain softening type and complex type. The origin of these different types of is discussed. The microstructural features of the processed material and the role of strain have been reviewed. The role of increasing misorientation of low angle boundaries to high angle boundaries by lattice dislocation absorption is examined. Threshold stresses have been determined and analyzed. The parametric dependencies for superplastic flow in modified conventional aluminum alloys, mechanically alloyed alloys and Al alloy matrix composites is determined to elucidate the superplastic mechanism at high strain rates. The role of incipient melting has been analyzed. A stress exponent of 2, an activation energy equal to that for grain boundary diffusion and a grain size dependence of 2 generally describes superplastic flow in modified conventional Al alloys and mechanically alloyed alloys. The present results agree well with the predictions of grain boundary sliding models. This suggests that the mechanism of high strain rate superplasticity in the above-mentioned alloys is similar to conventional superplasticity. The shift of optimum superplastic strain rates to higher values is a consequence of microstructural refinement. The parametric dependencies for superplasticity in aluminum alloy matrix composites, however, is different. A true activation energy of superplasticity in aluminum alloy matrix composites, however, is different. A true activation energy of 313 kJ/mol best describes the composites having SiC reinforcements. The role of shape of the reinforcement (particle or whisker) and processing history is addressed. The analysis suggests that the mechanism for superplasticity in composites is interface diffusion controlled grain boundary sliding.

Mishra, R.S. [Defence Metallurgical Research Lab., Hyderabad (India)] [Defence Metallurgical Research Lab., Hyderabad (India); Bieler, T.R. [Michigan State Univ., East Lansing, MI (United States). Dept. of Materials Science and Mechanics] [Michigan State Univ., East Lansing, MI (United States). Dept. of Materials Science and Mechanics; Mukherjee, A.K. [Univ. of California, Davis, CA (United States). Dept. of Mechanical, Aeronautical and Materials Engineering] [Univ. of California, Davis, CA (United States). Dept. of Mechanical, Aeronautical and Materials Engineering

1995-03-01

159

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

160

Recovery of uranium alloy  

SciTech Connect

A method is described of recovery of uranium alloy from a mixture of uranium alloy with magnesium fluoride comprising: (a) pretreating uranium fluoride with magnesium at 400/sup 0/-1250/sup 0/C. to form a pretreated mixture of uranium and magnesium fluoride, (b) introducing the pretreated mixture into a molten-salt bath floating on a molten-uranium-alloy trap, (c) allowing the bath to transfer heat to the pretreated mixture to cause the magnesium fluoride to dissolve into the molten-salt bath and the uranium alloy to be molten, (d) allowing molten uranium alloy from the pretreated mixture in the bath to separate from the bath into the trap, (e) discharging separated molten-uranium alloy from the trap, and (f) discharging non-alloy components of the pretreated mixture along with excess molten salt from the bath.

Elliott, G.R.B.

1987-01-13

161

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

162

CD2Alloy: Class Diagrams Analysis Using Alloy Revisited  

E-print Network

CD2Alloy: Class Diagrams Analysis Using Alloy Revisited Shahar Maoz , Jan Oliver Ringert present CD2Alloy, a novel, powerful translation of UML class diagrams (CDs) to Alloy. Unlike existingAlloy uses a deeper embedding strategy. Rather than mapping each CD construct to a semantically

Maoz, Shahar

163

Research on mechanically alloyed aluminum alloy products for aerospace applications  

Microsoft Academic Search

Mechanically alloyed (MA) aluminum alloys represent an advanced aluminum powder metallurgy technology. Chemically homogeneous alloy powders containing a fine distribution of oxide and carbide dispersoids are manufactured by mechanical alloying, an INCO propriety process involving high energy milling of elemental powders. This process allows a desirable chemistry\\/microstructure\\/property combination to be engineered into the alloy. Consolidation by canless vacuum hot pressing

R. D. Schelleng; P. S. Gilman; A. D. Jatkar; S. J. Donachie

2008-01-01

164

Weldability of High Alloys  

SciTech Connect

The purpose of this study was to investigate the effect of silicon and iron on the weldability of HAYNES HR-160{reg_sign} alloy. HR-I60 alloy is a solid solution strengthened Ni-Co-Cr-Si alloy. The alloy is designed to resist corrosion in sulfidizing and other aggressive high temperature environments. Silicon is added ({approx}2.75%) to promote the formation of a protective oxide scale in environments with low oxygen activity. HR-160 alloy has found applications in waste incinerators, calciners, pulp and paper recovery boilers, coal gasification systems, and fluidized bed combustion systems. HR-160 alloy has been successfully used in a wide range of welded applications. However, the alloy can be susceptible to solidification cracking under conditions of severe restraint. A previous study by DuPont, et al. [1] showed that silicon promoted solidification cracking in the commercial alloy. In earlier work conducted at Haynes, and also from published work by DuPont et al., it was recognized that silicon segregates to the terminal liquid, creating low melting point liquid films on solidification grain boundaries. Solidification cracking has been encountered when using the alloy as a weld overlay on steel, and when joining HR-160 plate in a thickness greater than19 millimeters (0.75 inches) with matching filler metal. The effect of silicon on the weldability of HR-160 alloy has been well documented, but the effect of iron is not well understood. Prior experience at Haynes has indicated that iron may be detrimental to the solidification cracking resistance of the alloy. Iron does not segregate to the terminal solidification product in nickel-base alloys, as does silicon [2], but iron may have an indirect or interactive influence on weldability. A set of alloys covering a range of silicon and iron contents was prepared and characterized to better understand the welding metallurgy of HR-160 alloy.

Maroef, I

2003-01-22

165

Wear behaviour of cast hypereutectic aluminium silicon alloys  

Microsoft Academic Search

In the present paper, influence of alloying elements on wear behaviour of binary (Al–17%Si) and multi-component (Al–17Si–0.8Ni–0.6Mg–1.2Cu–0.6Fe) cast hypereutectic aluminium alloys has been reported. Experimental alloys were prepared via foundry technique. Wear behaviour of Al–17Si and Al–17Si–X {X=Ni, Cu, Mg, Fe} alloys was studied using pin on disc (ASTM: G99) type of friction and wear testing machine. Dry sliding wear

Dheerendra Kumar Dwivedi

2006-01-01

166

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

167

Alloy 10: A 1300F Disk Alloy  

NASA Technical Reports Server (NTRS)

Gas turbine engines for future subsonic transports will probably have higher pressure ratios which will require nickel-base superalloy disks with 13000 to 1400 F temperature capability. Several advanced disk alloys are being developed to fill this need. One of these, Allied Signal's Alloy 10, is a promising candidate for gas turbine engines to be used on smaller, regional aircraft. For this application, compressor/turbine disks must withstand temperatures of 1300 F for several hundred hours over the life of the engine. In this paper, three key properties of Alloy 10--tensile, 0.2% creep, and fatigue crack growth--will be assessed at 1300 F.

Gayda, John

2000-01-01

168

46 CFR 54.25-15 - Low temperature operation-high alloy steels (modifies UHA-23(b) and UHA-51).  

Code of Federal Regulations, 2011 CFR

...Carbon, Alloy, and Heat Treated Steels § 54.25-15 Low temperature operation—high alloy steels (modifies UHA-23(b) and UHA-51...than 0.10 percent) austenitic stainless steel type, produced according...

2011-10-01

169

46 CFR 54.25-15 - Low temperature operation-high alloy steels (modifies UHA-23(b) and UHA-51).  

Code of Federal Regulations, 2010 CFR

...Carbon, Alloy, and Heat Treated Steels § 54.25-15 Low temperature operation—high alloy steels (modifies UHA-23(b) and UHA-51...than 0.10 percent) austenitic stainless steel type, produced according...

2010-10-01

170

46 CFR 54.25-15 - Low temperature operation-high alloy steels (modifies UHA-23(b) and UHA-51).  

Code of Federal Regulations, 2012 CFR

...Carbon, Alloy, and Heat Treated Steels § 54.25-15 Low temperature operation—high alloy steels (modifies UHA-23(b) and UHA-51...than 0.10 percent) austenitic stainless steel type, produced according...

2012-10-01

171

46 CFR 54.25-15 - Low temperature operation-high alloy steels (modifies UHA-23(b) and UHA-51).  

Code of Federal Regulations, 2013 CFR

...Carbon, Alloy, and Heat Treated Steels § 54.25-15 Low temperature operation—high alloy steels (modifies UHA-23(b) and UHA-51...than 0.10 percent) austenitic stainless steel type, produced according...

2013-10-01

172

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

173

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

174

Catalyst Alloys Processing  

NASA Astrophysics Data System (ADS)

Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

Tan, Xincai

2014-10-01

175

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, David S. (West Richland, WA); Ghoniem, Nasr M. (Granada Hills, CA); Powell, Roger W. (Pasco, WA)

1986-01-01

176

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

177

Translating Z to Alloy  

Microsoft Academic Search

\\u000a Few tools are available to help with the difficult task of validating that a Z specification captures its intended meaning.\\u000a One tool that has been proven to be useful for validating specifications is the Alloy Analyzer, an interactive tool for checking\\u000a and visualising Alloy models. However, Z specifications need to be translated to Alloy notation to make use of the

Petra Malik; Lindsay Groves; Clare Lenihan

2010-01-01

178

Advanced aerospace Al alloys  

Microsoft Academic Search

SiC particulate or whisker-reinforced aluminum alloys are very attractive for applications requiring high stiffness coupled with a comparatively light weight. The dispersion strengthened Al alloys produced through the rapid solidification processing\\/powder metallurgy route demonstrate superior elevated temperature strength and microstructural stability, extending the useful service temperature of Al alloys to 350 C. However, low ductility and poor fracture toughness levels

K. S. Ravichandran; E. S. Dwarakadasa

1987-01-01

179

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

180

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

181

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

182

Electrical characterization of germanium-silicon alloy  

E-print Network

Samples of strained germanium-silicon (Ge-Si) alloy were electrically characterized using resistivity and Hall-mobility measurements. The samples were obtained from a n-type Ge-Si strained epi-layer which was grown on a ptype substrate using MBE...

Kishore, Kumar P.

2012-06-07

183

ALUMINUM ALLOY VACUUM CHAMBERS FOR SSRF  

Microsoft Academic Search

The antechamber type vacuum system design is chosen in the SSRF storage ring. Each vacuum chamber is machined from two thick plates of A5083-H321 aluminum alloy and welded at their perimeter. The complex structure and the high dimensional precision requirement are the features of these chambers. Some new ideas are adopted in the structure design to decrease the deflection. The

Lixin Yin; Dikui Jiang; Hanwen Du; Xiaoli Jiang

184

Plating on stainless steel alloys  

SciTech Connect

Quantitative adhesion data are presented for a variety of electroplated stainless steel type alloys. Results show that excellent adhesion can be obtained by using a Wood's nickel strike or a sulfamate nickel strike prior to final plating. Specimens plated after Wood's nickel striking failed in the deposit rather than at the interface between the substrate and the coating. Flyer plate quantitative tests showed that use of anodic treatment in sulfuric acid prior to Wood's nickel striking even further improved adhesion. In contrast activation of stainless steels by immersion or cathodic treatment in hydrochloric acid resulted in very reduced bond strengths with failure always occurring at the interface between the coating and substrate.

Dini, J.W.; Johnson, H.R.

1981-09-11

185

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

186

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

187

Surface composition of alloys  

NASA Astrophysics Data System (ADS)

In equilibrium, the composition of the surface of an alloy will, in general, differ from that of the bulk. The broken-bond model is applicable to alloys with atoms of virtually equal size. If the heat of alloy formation is zero, the component of lower heat of atomization is found enriched in the surface. If both partners have equal heats of sublimination, the surface of a diluted alloy is enriched with the minority component. Size effects can enhance or weaken the electronic effects. In general, lattice strain can be relaxed by precipitating atoms of deviating size on the surface. Two-phase alloys are described by the "cherry model", i.e. one alloy phase, the "kernel" is surrounded by another alloy, the "flesh", and the surface of the outer phase, the "skin" displays a deviating surface composition as in monophasic alloys. In the presence of molecules capable of forming chemical bonds with individual metal atoms, "chemisorption induced surface segregation" can be observed at low temperatures, i.e. the surface becomes enriched with the metal forming the stronger chemisorption bonds.

Sachtler, W. M. H.

1984-11-01

188

Aluminum battery alloys  

DOEpatents

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.

1984-09-28

189

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

190

Alloys for aerospace  

SciTech Connect

Aerospace industries require special allows with many properties tailored to meet specific needs. Prerequisites include clean melting techniques to maintain low impurity levels, tight control of alloy chemistry, and the analytical capability to characterize the product. Teledyne Wah Chang (TWC) produces specially refractory metals, including zirconium, hafnium, titanium, niobium and vanadium, which are essential components of many aerospace alloys. Alloys are prepared by vacuum-arc-remelting (VAR) or electron beam (EB) melting, and ingots are processed to products ranging from bar and tube stock to wire and foil. Chemical, mechanical, and microstructural tests are all conducted at TWC`s in-house laboratory facilities. Of the alloys described here, Ti-3Al-2.5V, Tiadyne 3515 (Alloy C), NiTiFe, and C-103 are produced commercially, while orthorhombic titanium aluminides are promising candidates for future light-weight composite matrices.

Tuominen, S.; Wojcik, C. [Teledyne Wah Chang, Albany, OR (United States)

1995-04-01

191

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

192

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 640°C. At temperatures above 640°C, 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 (540°C and 300°C) 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

193

Small diameter active catheter using shape memory alloy  

Microsoft Academic Search

Three kinds of active catheters whose outside diameters are less than 2 mm were fabricated. One uses polymer links, the other two are linkless active catheters using adhesive. Distributed shape memory alloy (SMA) coil were used as actuators for the active motion. There are endoskeletal type and exoskeletal type in the linkless active catheters. We have applied the endoskeletal type

Y. Hagal; Y. Tanahashi; M. Esashi

1998-01-01

194

Technology status of tantalum alloys for space nuclear power applications  

NASA Technical Reports Server (NTRS)

Tantalum alloys have a variety of properties which make them attractive candidates for application in nuclear power systems required to operate in space at elevated temperatures (1200 to 1600 K) for extended time periods. Most of the technology development on this class of alloys which is pertinent to space system application occurred during the 1960 to 1972 time period under NASA sponsorship. The most extensive data bases resulting from this earlier work were obtained on the alloys T-111 (Ta-8W-2Hf) and ASTAR 811C (Ta-8W-1Re-0.7Hf-0.025C). Emphasis in this paper is directed at the following technical factors: producibility, creep strength, weldability and compatibility. These factors are considered to be the most important elements in the selection of alloys for this application. Review of the available information indicates that alloys of this type are appropriate for application in many systems, particularly those utilizing alkali metals as the working fluid.

Hoffman, E. E.

1985-01-01

195

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

196

Turning of gamma TiAl Intermetallic alloys  

NASA Astrophysics Data System (ADS)

In the present work the turning of two different aluminium titanium of the so-called gamma TiAl (or titanium aluminides) is presented. These alloys are solidified in gamma phase, being this a uncommon case in the industrial materials. This kind of titanium alloy presents improved mechanical properties even at high temperatures, the ratio between resistance and weight and resistance and low corrosion is greater than the more known alfa-beta type titanium alloys. However an absolute lack of recommendation for machining alters the material production is delaying a lot the use of gamma TiAl in car and aeronautical applications. This work presents the main results of a long testing program on three alloys, with different application fields. The main conclusion is that they are difficult-to-cut materials, even harder to machining that titanium alloys.

Beranoagirre, A.; López de Lacalle, L. N.

2012-04-01

197

XVII. The structure and properties of some ternary alloys of manganese, zinc and carbon  

Microsoft Academic Search

Single phase ternary alloys of Mn, Zn and C have been prepared. These alloys have an ordered structure of the perovskite type and show a spontaneous magnetization at room temperature. The observed magnetic properties are exceptional and indicate a new type of ferrimagnetic behaviour postulated by Néel but hitherto unobserved in experiment.

R. G. Butters; H. P. Myers

1955-01-01

198

A comparative study on the bond strength of porcelain to the millingable Pd-Ag alloy  

PubMed Central

PURPOSE The porcelain fused to gold has been widely used as a restoration both with the natural esthetics of the porcelain and durability and marginal fit of metal casting. However, recently, due to the continuous rise in the price of gold, an interest towards materials to replace gold alloy is getting higher. This study compared the bond strength of porcelain to millingable palladium-silver (Pd-Ag) alloy, with that of 3 conventionally used metal-ceramic alloys. MATERIALS AND METHODS Four types of metal-ceramic alloys, castable nonprecious nickel-chrome alloy, castable precious metal alloys containing 83% and 32% of gold, and millingable Pd-Ag alloy were used to make metal specimens (n=40). And porcelain was applied on the center area of metal specimen. Three-point bending test was performed with universal testing machine. The bond strength data were analyzed with a one-way ANOVA and post hoc Scheffe's tests (?=.05). RESULTS The 3-point bending test showed the strongest (40.42 ± 5.72 MPa) metal-ceramic bond in the nonprecious Ni-Cr alloy, followed by millingable Pd-Ag alloy (37.71 ± 2.46 MPa), precious metal alloy containing 83% of gold (35.89 ± 1.93 MPa), and precious metal alloy containing 32% of gold (34.59 ± 2.63 MPa). Nonprecious Ni-Cr alloy and precious metal alloy containing 32% of gold showed significant difference (P<.05). CONCLUSION The type of metal-ceramic alloys affects the bond strength of porcelain. Every metal-ceramic alloy used in this study showed clinically applicable bond strength with porcelain (25 MPa). PMID:25352959

Hong, Jun-Tae

2014-01-01

199

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

200

Tensile and impact properties of iron-aluminum alloys  

SciTech Connect

Tensile and impact tests have been conducted on specimens from a series of five heats of iron-aluminum alloys. These results have been compared to data for the iron aluminide alloy FA-129. The transition temperatures of all of the Fe{sub 3}Al-based alloys were similar, but the simple ternary alloy had a much higher upper-shelf energy. The reduced aluminum alloys [based on Fe-8Al (wt %)] had lower transition temperatures and higher upper-shelf energy levels than the Fe{sub 3}Al-type alloys. The reduced aluminum alloy with yttrium showed excellent tensile properties, with a room temperature total elongation of 40%, and a very high upper-shelf energy level. Despite the high tensile ductility at room temperature, the transition temperature of the yttrium-containing alloy was still about 150 C, compared to approximately 300 C for FA-129. In general, the microstructures were coarse and anisotropic. The fracture processes were dominated by second-phase particles.

Alexander, D.J.; Sikka, V.K.

1993-12-31

201

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

202

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

203

Controlled expansion alloy  

Microsoft Academic Search

In an age hardenable controlled expansion alloy essentially devoid of chromium, the combination of short term tensile properties and elevated temperature properties, particularly notch rupture strength, are improved by the inclusion therein of silicon in an amount leass than 1%.

J. S. Smith; D. F. Jr. Smith

1984-01-01

204

Manufacture of Superplastic Alloys.  

National Technical Information Service (NTIS)

The requirements in a superplastic sheet material are either to possess a fine uniform grain size or to be capable of developing such a grain structure during the course of superplastic deformation. Alloys that are currently being commercially exploited f...

R. Grimes

1989-01-01

205

Solidification and foundry studies of Zn/Al alloys  

NASA Astrophysics Data System (ADS)

It is well known that the commercial Zn/Al alloys, particularly the Zn-11%Al and Zn-27%Al alloys, segregate markedly during founding and also that an "inverted pipe" is commonly present. A detailed study of the solidification of 8, 11 and 27% aluminum alloys has been carried-out to investigate the manner of an extent to which segregation arises in order to develop better foundry procedures to exploit the considerable potential of these alloys. This work has involved the uni-directional solidification of many samples under a wide variety of conditions selected to exploit naturally-induced and forced fluid flow in the melt. The results of this work are being applied to develop various foundry procedures aimed at the production of sound homogeneous castings. Since it is possible to eliminate the major foundry problem with these alloys, namely, underside shrinkage, in the case of the Zn-8%Al and Zn-11%Al by adjusting such casting variables as pouring temperature, mold type and riser volume and placement, discussion of the results will be confined to the Zn-27%Al alloys. This alloy type displays the greatest mechanical strength and is most prone to underside shrinkage in "chunky" castings.

Ayik, O.; Ghoreshy, M.; Sahoo, M.; Smith, R. W.

1986-12-01

206

Mechanical alloying and milling  

Microsoft Academic Search

Mechanical alloying (MA) is a solid-state powder processng technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill. Originally developed to produce oxide-dispersion strengthened (ODS) nickel- and iron-base superalloys for applications in the aerospace industry, MA has now been shown to be capable of synthesizing a variety of equilibrium and non-equilibrium alloy phases starting from

C. Suryanarayana

2001-01-01

207

CRC Handbook of Electrical Resistivitives of Binary Metallic Alloys  

SciTech Connect

Material design engineers often require a tabulation of physical properties in order to select the appropriate material for use, while developmental engineers need to be aware of basic principles and systemic trends that can be utilized as a guide for developing future materials and alloys. The trade-off in conductivity that results when metals are replaced by alloys for strength and stability purposes becomes an important consideration for both types of engineers. This handbook presents an extensive, updated and comprehensive compilation of the electrical resistivities of metallic alloys.

Schroder, K.

1983-01-01

208

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.

209

Investigation of surface oxides on aluminum alloys by valence band photoemission  

NASA Astrophysics Data System (ADS)

Core level and valence band x-ray photoelectron spectroscopy are used to study the chemical composition of the surface films on aluminum alloys. Certain alloying elements may preferentially migrate to the surface of an alloy, thereby altering the composition and consequently the chemistry of the surface. The behavior of a 6061 aluminum alloy is compared with that of pure aluminum. It is shown that the type of magnesium film formed at the alloy surface can be determined by comparing the valence band spectra of the aluminum alloy surface with that of known magnesium and aluminum compounds. The experimental valence band spectra of these compounds are supported by spectra generated from band structure calculations. The effect of boiling water on the surface film is discussed, with significant differences in surface chemistry being seen for the metal and the alloy. copyright 2002 American Vacuum Society.

Claycomb, Gregory D.; Sherwood, Peter M. A.

2002-07-01

210

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

211

A review of laser welding techniques for magnesium alloys  

Microsoft Academic Search

Laser welding will be an important joining technique for magnesium alloys with their increasing applications in aerospace, aircraft, automotive, electronics and other industries. In this document the research and progress in laser welding of magnesium alloys are critically reviewed from different perspectives. To date, two types of industrial lasers, carbon dioxide (CO2) and neodymium-doped yttrium aluminum garnet (Nd:YAG), have been

X. Cao; M. Jahazi; J. P. Immarigeon; W. Wallace

2006-01-01

212

Devitrification of Hf–Pd–Ni glassy alloy on heating  

Microsoft Academic Search

The thermal expansion and volume change in a Hf70Pd20Ni10 glassy alloy were studied by X-ray diffractometry using in situ heating in a high energy monochromatic Synchrotron beam radiation. Devitrification behavior of the Hf70Pd20Ni10 glassy alloy was investigated by using conventional X-ray diffractometry, transmission electron microscopy, differential scanning and isothermal calorimetries. The formation of nanoscale cF96 Ti2Ni-type particles embedded in the

Dmitri V. Louzguine-Luzgin; Larissa V. Louzguina-Luzgina; Alain Reza Yavari; Katsumi Ota; Gavin Vaughan; Akihisa Inoue

2006-01-01

213

Stress corrosion cracking control measures. 5. Titanium alloys  

Microsoft Academic Search

The practical SCC hazards to titanium involve a wide range of environments. For some groups of environments, such as natural waters and nearly neutral aqueous solutions, the cracking occurs only in the presence of a pre-existing crack-like flaw, and fracture mechanics type tests readily characterize the SCC behavior of alloys. Unalloyed titanium and the widely used Ti-6%al-4%V alloy are reasonably

1975-01-01

214

Passivity of high corrosion resistant Cu-Al-Sn alloys  

SciTech Connect

In a work studying the corrosion and tarnishing properties of a variety of copper alloys, the alloy Cu-A110-Sn5 was found to show an excellent corrosion resistance in neutral solutions, where copper and most conventional Cu alloys are covered by thick nonprotective surface layers. The passive films formed on this alloy were characterized with electrochemical and photoelectrochemical methods. The pH dependence of the passivation and of the photocurrent behavior of the Cu-A110-Sn5 alloy clearly indicates that the passivity of this alloy in neutral solutions is due to a formation of passive film enriched with aluminum oxide. At corrosion potential a strong increase in the corrosion resistance with time is due to a gradual enrichment of the surface with aluminum oxide. This can be seen in the photocurrent spectra which change from cooper-type to aluminum-type with time. At higher applied potentials the formation of an aluminum-type oxide film is strongly accelerated.

Virtanen, S.; Wojtas, H.; Schmuki, P.; Boehni, H. (Swiss Federal Inst. of Technology, Zuerich (Switzerland). Inst. of Materials Chemistry and Corrosion)

1993-10-01

215

Adhesive bonding of noble metal alloys with a triazine dithiol derivative primer and an adhesive resin.  

PubMed

The purpose of this study was to evaluate the bond strength and durability of a metal adhesive system bonded to noble metal alloys. Disc specimens were cast from type IV gold (type IV, Casting Gold M. C., metal-ceramic gold (Au-Pt-Pd, Degudent Universal, metal-ceramic palladium (Pd-Ga-Co, PTM 88 silver-indium (Ag-In-Zn, Salivan Hard and silver-palladium-copper-gold (Ag-Pd-Cu, S12) alloys and pure silver (pure Ag). The specimens were air-abraded with 50 micron alumina, conditioned with a thiol-based primer designed for noble alloys (V-Primer), and then bonded with an adhesive resin (Super-Bond Opaque Ivory). Shear bond strengths were determined after repeated thermocycling (4-60 degrees C, 1 min each, 100 000 cycles). The average bond strengths in MPa (n=8) were 30.9 for the type IV alloy, 29.0 for the Ag-Pd-Cu alloy, 28.0 for the Au-Pt-Pd alloy, 26.3 for the pure Ag, 26.0 for the Pd-Ga-Co alloy and 9.3 for the Ag-In-Zn alloy. The Ag-In-Zn alloy exhibited significantly lower bond strength than the other alloys, whereas the bond strengths of the other four alloys and pure Ag were comparable (P<0.05). It is concluded that the combined use of the thiol derivative primer and the adhesive resin is effective for bonding the noble metal alloys examined, with the exception of the Ag-In-Zn alloy. PMID:10583738

Matsumura, H; Taira, Y; Atsuta, M

1999-11-01

216

Compositional dependence of the direct and indirect band gaps in Ge1?ySny alloys from room temperature photoluminescence: implications for the indirect to direct gap crossover in intrinsic and n-type materials  

NASA Astrophysics Data System (ADS)

The compositional dependence of the lowest direct and indirect band gaps in Ge1?ySny alloys has been determined from room-temperature photoluminescence measurements. This technique is particularly attractive for a comparison of the two transitions because distinct features in the spectra can be associated with the direct and indirect gaps. However, detailed modeling of these room temperature spectra is required to extract the band gap values with the high accuracy required to determine the Sn concentration yc at which the alloy becomes a direct gap semiconductor. For the direct gap, this is accomplished using a microscopic model that allows the determination of direct gap energies with meV accuracy. For the indirect gap, it is shown that current theoretical models are inadequate to describe the emission properties of systems with close indirect and direct transitions. Accordingly, an ad hoc procedure is used to extract the indirect gap energies from the data. For y < 0.1 the resulting direct gap compositional dependence is given by ?E0 = ?(3.57 ± 0.06)y (in eV). For the indirect gap, the corresponding expression is ?Eind = ?(1.64 ± 0.10)y (in eV). If a quadratic function of composition is used to express the two transition energies over the entire compositional range 0 ?? y ?? 1, the quadratic (bowing) coefficients are found to be b0 = 2.46 ± 0.06 eV (for E0) and bind = 1.03 ± 0.11 eV (for Eind). These results imply a crossover concentration yc = 0.073-0.006+0.007, much lower than early theoretical predictions based on the virtual crystal approximation, but in better agreement with predictions based on large atomic supercells.

Jiang, L.; Gallagher, J. D.; Senaratne, C. L.; Aoki, T.; Mathews, J.; Kouvetakis, J.; Menéndez, J.

2014-11-01

217

Localized corrosion resistance of corrosion-resistant Ni based alloys in hot concentrated seawater  

SciTech Connect

Localized corrosion resistance of stainless steel (Type 316L), a titanium-based alloy (Ti-0.15Pd) and corrosion-resistant nickel-based alloys (a new alloy MAT-21 (Alloy T) and Alloy C-276) was evaluated in four simulated seawater solutions containing 1.8 to 22.0 wt% of chloride ions concentrated by evaporation. Stress corrosion cracking was observed on the 316L stainless steel but not on Alloy T and Alloy C-276 in the solutions. Pitting attack occurred on the surface of the 316L stainless steel base metal in all the solutions. Alloy C-276 suffered pitting attack on the surface including the welded section only in the solutions containing 18.9 and 22.0 wt% of chloride ions, respectively. No pitting attack occurred over any part of the surface including the welded section of Alloy T in any of the solutions. No crevice corrosion was observed in an immersion test of Alloy T and the Ti-0.15 5Pd alloy using test pieces with crevices although crevice corrosion was seen the creviced test pieces of Alloy C-276 and the 316L stainless steel. It was found that both Alloy T and the Ti-0.15Pd alloy, which exhibit high repassivation potentials for crevice corrosion (E{sub r,CREV})corresponding to crevice corrosion potentials, have excellent crevice corrosion resistance, while these alloys which exhibit corrosion potentials greater than E{sub r,CREV}in a solution with a high chloride ion concentration and a high dissolved oxygen concentration in open air may be corroding in the crevices.

Sugahara, Katsuo; Takizawa, Yoshio [Mitsubishi Materials Corp., Omiya, Saitama (Japan). Central Research Inst.

1998-12-31

218

Translating alloy using Boolean circuits  

E-print Network

Alloy is a automatically analyzable modelling language based on first-order logic. An Alloy model can be translated into a Boolean formula whose satisfying assignments correspond to instances in the model. Currently, the ...

Daitch, Samuel Isaac

2004-01-01

219

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; Wróbel, M; Witczak, Z; Blicharski, M

2010-03-01

220

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

221

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

222

Structural and Mössbauer 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. Mössbauer 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

223

Some features of the transgranular embrittlement of ?-titanium alloys under the influence of the environment  

Microsoft Academic Search

Some common features of the transgranular embrittlement of a-titanium alloys in chloride solutions, hot salts, liquid metals, and air are established. These types of brittle fracture are typical symptoms of trans-granular embrittlement along the basal (near-basal) cleavage planes of metals (alloys) with hcp crystal lattices with various values of the ratioc\\/a. In this connection, the role of alloying elements and

A. I. Igolkin

1995-01-01

224

Analysis Of Transport Properties of Mechanically Alloyed Lead Tin Telluride  

NASA Astrophysics Data System (ADS)

The work described in this thesis had two objectives. The first objective was to develop a physically based computational model that could be used to predict the electronic conductivity, Seebeck coefficient, and thermal conductivity of Pb1-xSnxTe alloys over the 400 K to 700 K temperature as a function of Sn content and doping level. The second objective was to determine how the secondary phase inclusions observed in Pb1-xSn xTe alloys made by consolidating mechanically alloyed elemental powders impact the ability of the material to harvest waste heat and generate electricity in the 400 K to 700 K temperature range. The motivation for this work was that though the promise of this alloy as an unusually efficient thermoelectric power generator material in the 400 K to 700 K range had been demonstrated in the literature, methods to reproducibly control and subsequently optimize the materials thermoelectric figure of merit remain elusive. Mechanical alloying, though not typically used to fabricate these alloys, is a potential method for cost-effectively engineering these properties. Given that there are deviations from crystalline perfection in mechanically alloyed material such as secondary phase inclusions, the question arises as to whether these defects are detrimental to thermoelectric function or alternatively, whether they enhance thermoelectric function of the alloy. The hypothesis formed at the onset of this work was that the small secondary phase SnO2inclusions observed to be present in the mechanically alloyed Pb1-xSnxTe would increase the thermoelectric figure of merit of the material over the temperature range of interest. It was proposed that the increase in the figure of merit would arise because the inclusions in the material would not reduce the electrical conductivity to as great an extent as the thermal conductivity. If this were to be true, then the experimentally measured electronic conductivity in mechanically alloyed Pb1-xSnxTe alloys that have these inclusions would not be less than that expected in alloys without these inclusions while the portion of the thermal conductivity that is not due to charge carriers (the lattice thermal conductivity) would be less than what would be expected from alloys that do not have these inclusions. Furthermore, it would be possible to approximate the observed changes in the electrical and thermal transport properties using existing physical models for the scattering of electrons and phonons by small inclusions. The approach taken to investigate this hypothesis was to first experimentally characterize the mobile carrier concentration at room temperature along with the extent and type of secondary phase inclusions present in a series of three mechanically alloyed Pb1-xSnxTe alloys with different Sn content. Second, the physically based computational model was developed. This model was used to determine what the electronic conductivity, Seebeck coefficient, total thermal conductivity, and the portion of the thermal conductivity not due to mobile charge carriers would be in these particular Pb1-x SnxTe alloys if there were to be no secondary phase inclusions. Third, the electronic conductivity, Seebeck coecient and total thermal conductivity was experimentally measured for these three alloys with inclusions present at elevated temperatures. The model predictions for electrical conductivity and Seebeck coefficient were directly compared to the experimental elevated temperature electrical transport measurements. The computational model was then used to extract the lattice thermal conductivity from the experimentally measured total thermal conductivity. This lattice thermal conductivity was then compared to what would be expected from the alloys in the absence of secondary phase inclusions. Secondary phase inclusions were determined by X-ray diraction analysis to be present in all three alloys to a varying extent. The inclusions were found not to significantly degrade electrical conductivity at temperatures above 400 K in these alloys, though they do dramatically impact elect

Krishna, Rajalakshmi

225

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

226

Semiconductor alloys - Structural property engineering  

NASA Technical Reports Server (NTRS)

Semiconductor alloys have been used for years to tune band gaps and average bond lengths to specific applications. Other selection criteria for alloy composition, and a growth technique designed to modify their structural properties, are presently considered. The alloys Zn(1-y)Cd(y)Te and CdSe(y)Te(1-y) are treated as examples.

Sher, A.; Van Schilfgaarde, M.; Berding, M.; Chen, A.-B.

1987-01-01

227

De-alloyed platinum nanoparticles  

SciTech Connect

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

228

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

229

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

230

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

231

Effects of alloying elements, Cr, Mo and N on repassivation characteristics of stainless steels using the abrading electrode technique  

Microsoft Academic Search

Cr, Mo and N are important alloying elements for passive film formation and repassivation but their roles in passive film still need explainable. In order to investigate effects of alloying elements on the stability of passive film and its repassivation, ferritic stainless steels such as Fe–Cr and Fe–Cr–Mo alloys and austenitic stainless steels such as type 316L, and type 316LN

Jae-Bong Lee

2006-01-01

232

Atomistic Method Applied to Computational Modeling of Surface Alloys  

NASA Technical Reports Server (NTRS)

The formation of surface alloys is a growing research field that, in terms of the surface structure of multicomponent systems, defines the frontier both for experimental and theoretical techniques. Because of the impact that the formation of surface alloys has on surface properties, researchers need reliable methods to predict new surface alloys and to help interpret unknown structures. The structure of surface alloys and when, and even if, they form are largely unpredictable from the known properties of the participating elements. No unified theory or model to date can infer surface alloy structures from the constituents properties or their bulk alloy characteristics. In spite of these severe limitations, a growing catalogue of such systems has been developed during the last decade, and only recently are global theories being advanced to fully understand the phenomenon. None of the methods used in other areas of surface science can properly model even the already known cases. Aware of these limitations, the Computational Materials Group at the NASA Glenn Research Center at Lewis Field has developed a useful, computationally economical, and physically sound methodology to enable the systematic study of surface alloy formation in metals. This tool has been tested successfully on several known systems for which hard experimental evidence exists and has been used to predict ternary surface alloy formation (results to be published: Garces, J.E.; Bozzolo, G.; and Mosca, H.: Atomistic Modeling of Pd/Cu(100) Surface Alloy Formation. Surf. Sci., 2000 (in press); Mosca, H.; Garces J.E.; and Bozzolo, G.: Surface Ternary Alloys of (Cu,Au)/Ni(110). (Accepted for publication in Surf. Sci., 2000.); and Garces, J.E.; Bozzolo, G.; Mosca, H.; and Abel, P.: A New Approach for Atomistic Modeling of Pd/Cu(110) Surface Alloy Formation. (Submitted to Appl. Surf. Sci.)). Ternary alloy formation is a field yet to be fully explored experimentally. The computational tool, which is based on the BFS (Bozzolo, Ferrante, and Smith) method for the calculation of the energetics, consists of a small number of simple PCbased computer codes that deal with the different aspects of surface alloy formation. Two analysis modes are available within this package. The first mode provides an atom-by-atom description of real and virtual stages 1. during the process of surface alloying, based on the construction of catalogues of configurations where each configuration describes one possible atomic distribution. BFS analysis of this catalogue provides information on accessible states, possible ordering patterns, and details of island formation or film growth. More importantly, it provides insight into the evolution of the system. Software developed by the Computational Materials Group allows for the study of an arbitrary number of elements forming surface alloys, including an arbitrary number of surface atomic layers. The second mode involves large-scale temperature-dependent computer 2. simulations that use the BFS method for the energetics and provide information on the dynamic processes during surface alloying. These simulations require the implementation of Monte-Carlo-based codes with high efficiency within current workstation environments. This methodology capitalizes on the advantages of the BFS method: there are no restrictions on the number or type of elements or on the type of crystallographic structure considered. This removes any restrictions in the definition of the configuration catalogues used in the analytical calculations, thus allowing for the study of arbitrary ordering patterns, ultimately leading to the actual surface alloy structure. Moreover, the Monte Carlo numerical technique used for the large-scale simulations allows for a detailed visualization of the simulated process, the main advantage of this type of analysis being the ability to understand the underlying features that drive these processes. Because of the simplicity of the BFS method for e energetics used in these calculations, a detailed atom-by-atom analysis can be performed at any

Bozzolo, Guillermo H.; Abel, Phillip B.

2000-01-01

233

Laser assisted high entropy alloy coating on aluminum: Microstructural evolution  

NASA Astrophysics Data System (ADS)

High entropy alloy (Al-Fe-Co-Cr-Ni) coatings were synthesized using laser surface engineering on aluminum substrate. Electron diffraction analysis confirmed the formation of solid solution of body centered cubic high entropy alloy phase along with phases with long range periodic structures within the coating. Evolution of such type of microstructure was a result of kinetics associated with laser process, which generates higher temperatures and rapid cooling resulting in retention of high entropy alloy phase followed by reheating and/or annealing in subsequent passes of the laser track giving rise to partial decomposition. The partial decomposition resulted in formation of precipitates having layered morphology with a mixture of high entropy alloy rich phases, compounds, and long range ordered phases.

Katakam, Shravana; Joshi, Sameehan S.; Mridha, Sanghita; Mukherjee, Sundeep; Dahotre, Narendra B.

2014-09-01

234

Iron aluminide alloys with improved properties for high temperature applications  

DOEpatents

An improved iron aluminide alloy of the DO[sub 3] type is described 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 conversion 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. 3 figs.

McKamey, C.G.; Liu, C.T.

1990-10-09

235

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); Liu, Chain T. (Oak Ridge, TN)

1990-01-01

236

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

237

Extrusion Die Design and Process Simulation of High Strength Aluminium Alloy  

Microsoft Academic Search

Aluminium alloy 7075 is an excellent metal with the features of high strength and light weight. The solid extruded parts of AL 7075 are commonly used in the structure members of airplanes and bicycles. The seamless tubes of AL 7075 are also used, while tubes with welding line (seamed) are mainly made by the other types of aluminium alloy. This

Jinn-Jong Sheu; Yan-Hong Chen; Guan-Cheng Su

2011-01-01

238

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

239

High Strength Ferritic Alloy.  

National Technical Information Service (NTIS)

A high-strength ferritic alloy is described which is useful for fast reactor duct and cladding applications. An iron base contains from about 9% to about 13% by weight chromium, from about 4% to about 8% by weight molybdenum, from about 0.2% to about 0.8%...

W. C. Hagel, F. A. Smidt, M. K. Korenko

1977-01-01

240

Molybdenum-based alloy  

SciTech Connect

A molybdenum-based alloy improved in mechanical strength and hot workability, which consists of 0.01 to 5.0% by weight of vanadium, 10 to 100 ppm of boron, 10 to 1,000 ppm of carbon, and the balance of molybdenum.

Koizumi, H.; Ishihara, H.; Kawakita, K.; Matsumoto, T.

1984-02-07

241

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

242

Titanium alloy development  

Microsoft Academic Search

Over the last decade, the focus of titanium alloy development has shifted from aerospace to industrial applications. The titanium industry has been very dependent on the aerospace market, and this sector will constitute a significant percentage of total consumption for years to come. However, titanium is increasingly being selected for industrial products as a result of value analyses based on

1996-01-01

243

Thermal coatings for titanium-aluminum alloys  

SciTech Connect

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, G.R.; Clark, R.K.; Robinson, J.C.

1993-04-01

244

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

245

The shape memory capability and life of Cu-Al-Be-X alloys  

SciTech Connect

The shape memory capacity and the shape memory life of three alloys of the Cu-11.6Al-0.4Be-X type have been investigated using the strain angle restoration method and compared with the alloy Cu-25Zn-4Al. The alloys were subjected to various normalizing and normalizing plus aging treatments, and all were found to possess excellent shape memory properties. The alloy Cu-11.6Al-0.4Be-0.2Cr demonstrated the best shape memory capacity and life.

Dong, Y.Y.; Dar, K.Z. (Gansu Mechanical Engineering Academy, Lanzhou (China)); Wang, T.M. (Lanzhou Univ. (China)); Zin, S.J. (Lanzhou High Pressure Valve Co. (China))

1994-09-01

246

Theoretical Studies of Hydrogen Storage Alloys.  

SciTech Connect

Theoretical calculations were carried out to search for lightweight alloys that can be used to reversibly store hydrogen in mobile applications, such as automobiles. Our primary focus was on magnesium based alloys. While MgH{sub 2} is in many respects a promising hydrogen storage material, there are two serious problems which need to be solved in order to make it useful: (i) the binding energy of the hydrogen atoms in the hydride is too large, causing the release temperature to be too high, and (ii) the diffusion of hydrogen through the hydride is so slow that loading of hydrogen into the metal takes much too long. In the first year of the project, we found that the addition of ca. 15% of aluminum decreases the binding energy to the hydrogen to the target value of 0.25 eV which corresponds to release of 1 bar hydrogen gas at 100 degrees C. Also, the addition of ca. 15% of transition metal atoms, such as Ti or V, reduces the formation energy of interstitial H-atoms making the diffusion of H-atoms through the hydride more than ten orders of magnitude faster at room temperature. In the second year of the project, several calculations of alloys of magnesium with various other transition metals were carried out and systematic trends in stability, hydrogen binding energy and diffusivity established. Some calculations of ternary alloys and their hydrides were also carried out, for example of Mg{sub 6}AlTiH{sub 16}. It was found that the binding energy reduction due to the addition of aluminum and increased diffusivity due to the addition of a transition metal are both effective at the same time. This material would in principle work well for hydrogen storage but it is, unfortunately, unstable with respect to phase separation. A search was made for a ternary alloy of this type where both the alloy and the corresponding hydride are stable. Promising results were obtained by including Zn in the alloy.

Jonsson, Hannes

2012-03-22

247

Electrical transport properties of (BN)-rich hexagonal (BN)C semiconductor alloys  

NASA Astrophysics Data System (ADS)

The layer structured hexagonal boron nitride carbon semiconductor alloys, h-(BN)C, offer the unique abilities of bandgap engineering (from 0 for graphite to ˜6.4 eV for h-BN) and electrical conductivity control (from semi-metal for graphite to insulator for undoped h-BN) through alloying and have the potential to complement III-nitride wide bandgap semiconductors and carbon based nanostructured materials. Epilayers of (BN)-rich h-(BN)1-x(C2)x alloys were synthesized by metal-organic chemical vapor deposition (MOCVD) on (0001) sapphire substrates. Hall-effect measurements revealed that homogeneous (BN)-rich h-(BN)1-x(C2)x alloys are naturally n-type. For alloys with x = 0.032, an electron mobility of about 20 cm2/Vs at 650 °K was measured. X-ray photoelectron spectroscopy (XPS) was used to determine the chemical composition and analyze chemical bonding states. Both composition and chemical bonding analysis confirm the formation of alloys. XPS results indicate that the carbon concentration in the alloys increases almost linearly with the flow rate of the carbon precursor (propane (C3H8)) employed during the epilayer growth. XPS chemical bonding analysis showed that these MOCVD grown alloys possess more C-N bonds than C-B bonds, which possibly renders the undoped h-(BN)1-x(C2)x alloys n-type and corroborates the Hall-effect measurement results.

Uddin, M. R.; Doan, T. C.; Li, J.; Ziemer, K. S.; Lin, J. Y.; Jiang, H. X.

2014-08-01

248

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

249

High-temperature property data: Ferrous alloys  

Microsoft Academic Search

In this book over 250 alloys are organized by AISI number into 10 major sections: Irons, Carbon Steels, Alloy Steels, Low Alloy Constructional Steels, Ultra High Strength Steels, Tool Steels, Maraging Steels, Wrought Stainless Steels, Heat Resistnat Casting Alloys, and Iron Based Rought Superalloys. Each alloy record lists the designation, specifications, UNS number, composition, product forms and a comment on

Rothman

1987-01-01

250

Advanced ordered intermetallic alloy deployment  

SciTech Connect

The need for high-strength, high-temperature, and light-weight materials for structural applications has generated a great deal of interest in ordered intermetallic alloys, particularly in {gamma}-based titanium aluminides {gamma}-based TiAl alloys offer an attractive mix of low density ({approximately}4g/cm{sup 3}), good creep resistance, and high-temperature strength and oxidation resistance. For rotating or high-speed components. TiAl also has a high damping coefficient which minimizes vibrations and noise. These alloys generally contain two phases. {alpha}{sub 2} (DO{sub 19} structure) and {gamma} (L 1{sub 0}), at temperatures below 1120{degrees}C, the euticoid temperature. The mechanical properties of TiAl-based alloys are sensitive to both alloy compositions and microstructure. Depending on heat-treatment and thermomechanical processing, microstructures with near equiaxed {gamma}, a duplex structure (a mix of the {gamma} and {alpha}{sub 2} phases) can be developed in TiAl alloys containing 45 to 50 at. % Al. The major concern for structural use of TiAl alloys is their low ductility and poor fracture resistance at ambient temperatures. The purpose of this project is to improve the fracture toughness of TiAl-based alloys by controlling alloy composition, microstructure and thermomechanical treatment. This work is expected to lead to the development of TiAl alloys with significantly improved fracture toughness and tensile ductility for structural use.

Liu, C.T.; Maziasz, P.J.; Easton, D.S. [Oak Ridge National Lab., TN (United States)

1997-04-01

251

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

252

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

253

Filler metal alloy for welding cast nickel aluminide alloys  

DOEpatents

A filler metal alloy used as a filler for welding cast nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and cast in copper chill molds. 3 figs.

Santella, M.L.; Sikka, V.K.

1998-03-10

254

Ohmic contact to p-type indium phosphide  

NASA Technical Reports Server (NTRS)

Low-Series-resistance ohmic contact to p-type InP semiconductor material is achieved in technique utilizing Au-Ge-Zn eutectic alloy. Alloy sets and adheres well to semiconductor surface with higher acceptor concentration at metal semiconductor interface. Technique has provided satisfactory for pn junction LED's and lasers.

Hawrylo, F. Z.

1980-01-01

255

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 37°C. 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

González, M; Peña, J; Gil, F J; Manero, J M

2014-09-01

256

Magnesium-lithium casting alloys  

NASA Technical Reports Server (NTRS)

The strength properties of magnesium-lithium alloys at room, low, and high temperatures are investigated. It is found that the alloys may have practical application at ambient temperatures up to 100 C, that negative temperatures have a favorable influence on the alloy strength, and that cyclic temperature variations have practically no effect on the strength characteristics. The influence of chemical coatings on corrosion resistance of the MgLi alloys is examined. Several facilities based on pressure casting machines, low-pressure casting machines, and magnetodynamic pumps were designed for producing MgLi alloy castings. Results were obtained for MgLi alloys reinforced with fibers having a volumetric content of 15%.

Latenko, V. P.; Silchenko, T. V.; Tikhonov, V. A.; Maltsev, V. P.; Korablin, V. P.

1974-01-01

257

On the precipitation of magnesium silicide in irradiated aluminum-magnesium alloys  

SciTech Connect

Thermal neutron irradiation of aluminium or its alloys causes the production of silicon by transmutation. In aluminium-magnesium alloys, the transmutation-produced silicon reacts with magnesium and forms small precipitates. The precipitation in irradiated Al-Mg alloys is similar to the early stage of aging in thermally treated Al-Mg-Si alloys. This study evidences the simultaneous generation of two crystallographically different precipitate types. On the basis of electron diffraction patterns, unit cell parameters are derived and compared with structures found in thermally aged alloys. One of the two precipitate types has an Mg{sub 2}Si composition, while the other is an Al-Si-Mg intermetallic compound with high aluminium and silicon but low magnesium content. The formation of magnesium poor precipitates is important since it indicates that the threshold neutron fluence for grain boundary precipitation of silicon may be much higher than estimated in the past.

Verwerft, M.

2000-03-14

258

The effect of tensile stress on hydrogen diffusion in metal alloys  

NASA Technical Reports Server (NTRS)

The effect of tensile stress on hydrogen diffusion has been determined for Type 303 stainless steel, A286 CRES, and Waspaloy and IN100 nickel-base alloys. It was found that hydrogen diffusion coefficients are not significantly affected by stress, while the hydrogen permeabilities are greatly affected in Type 303 stainless steel and A286 CRES (iron-based alloys), but are affected little in Waspaloy (nickel-base) and not affected in all in IN100 (nickel base). These observations might be taken as an indication that hydrogen permeabilities are affected by stress in iron-based alloys, but only slightly affected in nickel-based alloys. However, it is too early to make such a generalization based on the study of only these four alloys.

Danford, M. D.

1992-01-01

259

Materials data handbook, aluminum alloy 7075  

NASA Technical Reports Server (NTRS)

Materials data handbook on aluminum alloy 7075 includes data on the properties of the alloy at cryogenic, ambient, and elevated temperatures, and other pertinent engineering information required for the design and fabrication of components and equipment utilizing this alloy.

Sessler, J.; Weiss, V.

1967-01-01

260

Alchemy: Transmuting Base Alloy Specifications into Implementations  

E-print Network

Alchemy: Transmuting Base Alloy Specifications into Implementations Shriram Krishnamurthi Brown University Daniel J. Dougherty WPI Kathi Fisler WPI Daniel Yoo WPI ABSTRACT Alloy specifications are used to define lightweight models of systems. We present Alchemy, which compiles Alloy specifi- cations

Krishnamurthi, Shriram

261

Alloy Interface Interdiffusion Modeled  

NASA Technical Reports Server (NTRS)

With renewed interest in developing nuclear-powered deep space probes, attention will return to improving the metallurgical processing of potential nuclear fuels so that they remain dimensionally stable over the years required for a successful mission. Previous work on fuel alloys at the NASA Glenn Research Center was primarily empirical, with virtually no continuing research. Even when empirical studies are exacting, they often fail to provide enough insight to guide future research efforts. In addition, from a fundamental theoretical standpoint, the actinide metals (which include materials used for nuclear fuels) pose a severe challenge to modern electronic-structure theory. Recent advances in quantum approximate atomistic modeling, coupled with first-principles derivation of needed input parameters, can help researchers develop new alloys for nuclear propulsion.

Bozzolo, Guillermo H.; Garces, Jorge E.; Abel, Phillip B.

2003-01-01

262

Titanium alloy development  

SciTech Connect

Over the last decade, the focus of titanium alloy development has shifted from aerospace to industrial applications. The titanium industry has been very dependent on the aerospace market, and this sector will constitute a significant percentage of total consumption for years to come. However, titanium is increasingly being selected for industrial products as a result of value analyses based on life cycle cost rather than initial price. This shift in development emphasis is not unique to Timet, and efforts to diversify titanium usage are evident throughout the industry. Today, very little producer-industry research is aimed at fundamentally new alloys. Strategy is centered on developing or improving manufacturing processes that offer new product forms, or more cost-effective products. The goal is to expand current non-aerospace markets, or penetrate new ones. This article reviews developments in the various market sectors, together with the future thrust of research.

Allen, P. [Titanium Metals Corp., Henderson, NV (United States)

1996-10-01

263

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

264

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

265

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

Süry, P; Semlitsch, M

1978-09-01

266

Nondestructive evaluation of an environmentally friendly conversion coating for magnesium alloys using optical measurement techniques  

E-print Network

these harmful chromates out of the coating system and continue to use magnesium alloys, an environmentally friendly conversion coating has been developed. This paper explores the best types of methods used to evaluate the thickness and coating coverage...

Zuniga, David

2006-10-30

267

High temperature shape memory alloys  

SciTech Connect

Several alloy systems can be selected for high-temperature shape memory alloys, defined as alloys with stable reverse transformation temperatures above 120 C. However, due to the lack of minimum quality standards for stability, ductility, functional behavior and reliability, no successful applications have been realized so far. Research on high temperature shape memory alloys (HTSMA) is, nevertheless, an important topic not only for scientific reasons but also due to the market pull. This paper reviews existing systems of HTSMA pointing out their weak and strong parts.

Humbeeck, J. van [K.U. Leuven, Heverlee (Belgium). Dept. of Metallurgy and Materials Engineering

1999-01-01

268

Better Alloys with Quantum Design  

NASA Astrophysics Data System (ADS)

Alloy discovery and development is slowed by trial and error methods used to identify beneficial alloying elements. This fact has led to suggestions that integrating quantum theory and modeling with traditional experimental approaches might accelerate the pace of alloy discovery. We report here on one such effort, using advances in first principles computation along with an evolving theory that allows for the partitioning of charge density into chemically meaningful structures, alloying elements that improve the adhesive properties of interfaces common to high strength steels have been identified.

Jones, Travis E.; Eberhart, Mark E.; Imlay, Scott; Mackey, Craig; Olson, Greg B.

2012-09-01

269

Alloy Design Data Generated for B2-Ordered Compounds  

NASA Technical Reports Server (NTRS)

Developing alloys based on ordered compounds is significantly more complicated than developing designs based on disordered materials. In ordered compounds, the major constituent elements reside on particular sublattices. Therefore, the addition of a ternary element to a binary-ordered compound is complicated by the manner in which the ternary addition is made (at the expense of which binary component). When ternary additions are substituted for the wrong constituent, the physical and mechanical properties usually degrade. In some cases the resulting degradation in properties can be quite severe. For example, adding alloying additions to NiAl in the wrong combination (i.e., alloying additions that prefer the Al sublattice but are added at the expense of Ni) will severely embrittle the alloy to the point that it can literally fall apart during processing on cooling from the molten state. Consequently, alloying additions that strongly prefer one sublattice over another should always be added at the expense of that component during alloy development. Elements that have a very weak preference for a sublattice can usually be safely added at the expense of either element and will accommodate any deviation from stoichiometry by filling in for the deficient component. Unfortunately, this type of information is not known beforehand for most ordered systems. Therefore, a computational survey study, using a recently developed quantum approximate method, was undertaken at the NASA Glenn Research Center to determine the preferred site occupancy of ternary alloying additions to 12 different B2-ordered compounds including NiAl, FeAl, CoAl, CoFe, CoHf, CoTi, FeTi, RuAl, RuSi, RuHf, RuTi, and RuZr. Some of these compounds are potential high temperature structural alloys; others are used in thin-film magnetic and other electronic applications. The results are summarized. The italicized elements represent the previous sum total alloying information known and verify the computational method used to establish the table. Details of the computational procedures used to determine the preferred site occupancy can be found in reference 2. As further substantiation of the validity of the technique, and its extension to even more complicated systems, it was applied to two simultaneous alloying additions in an ordered alloy.

Noebe, Ronald D.; Bozzolo, Guillermo; Abel, Phillip B.

2003-01-01

270

Alloys by Microwave-Activated Hot Pressing  

NASA Astrophysics Data System (ADS)

The p-type Bi0.4Sb1.6Te3 alloys are prepared using a new method of mechanical alloying followed by microwave-activated hot pressing (MAHP). The effect of sintering temperature on the microstructure and thermoelectric properties of Bi0.4Sb1.6Te3 alloys is investigated. Compared with other sintering techniques, the MAHP process can be used to produce relatively compact bulk materials at lower sintering temperatures owing to its unique sintering mechanism. The grain size of the MAHP specimens increases gradually with the sintering temperature and a partially oriented lamellar structure can be formed in some regions of specimens obtained. The formation of the in situ-generated nano-phase is induced by the arcing effect of the MAHP process, which enhances the phonon scattering effect and decreases the lattice thermal conductivity. A minimum lattice thermal conductivity of 0.41 W/(m·K) and a maximum figure of merit value of 1.04 are obtained at 100°C for the MAHP specimen sintered at 325°C. This technique may also be extended to other functional materials to obtain ultrafine microstructures at low sintering temperatures.

Yang, Fan; Fan, Xi An; Rong, Zhen Zhou; Cai, Xin Zhi; Li, Guang Qiang

2014-11-01

271

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

272

Alloy Phase Formation by Mechanical Alloying:. Constraints and Mechanisms  

Microsoft Academic Search

Alloy phase formation in binary metallic systems by mechanical alloying (MA) of elemental powders is briefly reviewed. Our recent results indicate the inadequacy of the current understanding of the MA process, which has been depicted as an isothermal solid-state interdiffusion reaction under interfacial, metastable, equilibrium in layered composites. A structural and thermodynamic analysis of the supersaturation followed by amorphization in

E. Ma; M. Atzmon

1992-01-01

273

Procurement and screening test data for advanced austenitic alloys for 650 degrees C steam service (Part 1, 14Cr16Ni steels and 20Cr30NiFe alloys)  

Microsoft Academic Search

Tests were initiated to evaluate the potential of a group of developmental iron-nickel-chromium alloys for service at 700°C with a target design stress of 60 MPa. Tensile, creep, stress rupture, weldability, and microstructural stability tests were conducted on one group of alloys, which are essentially modifications of type 316 stainless steel. The data for the alloys were compared to data

R. W. Swindeman; G. M. Goodwin; P. J. Maziasz

1987-01-01

274

Loss of Alloy in Cast Restorations Fabricated by Dental Students.  

ERIC Educational Resources Information Center

A study investigated the quantity of alloy lost in the fabrication of three types of cast restoration by dental students, and identified the proportion of loss at each of the four principal stages of the fabrication process. Suggestions for reducing metal loss and related costs in dental schools are offered. (MSE)

Soh, George

1991-01-01

275

Differential equation of hysteresis: Application to partial martensitic transformation in shape-memory alloys. [NiTi alloy  

SciTech Connect

Many unusual thermomechanical properties of shape-memory alloys are directly connected with martensitic type phase transitions in these systems. Because the martensitic transformations, as a rule, are the first order transitions, a special attention should be given to a hysteretic behavior of shape-memory alloys. The most important characteristics of the temperature- or stress-induced martensitic transformation, have been previously studied in detail. It has been shown that such macroscopic state variables as inelastic strain or volume fraction of the martensite are always complex multi-valued functions of the temperature and external stress. Therefore, the shape-memory alloys should be considered as systems having an infinite number of state equations, representing inelastic strain and volume fraction of martensite as functions of the external stress and temperature, correspondingly. Some of the phenomenological approaches for the thermomechanical state equations for shape memory alloys were recently published. In particular, a special type of differential equation describing evolution of the inelastic macroscopic strain and volume fraction of martensite as a function of the temperature has been proposed. Its application to partial temperature cycling processes in shape-memory alloys and some other problems associated with the irreversible processes caused by hysteresis are discussed in the present paper.

Likhachev, A.A. (Ukrainian Academy of Sciences, Kiev (Ukraine). Inst. of Metal Physics)

1995-02-15

276

Status of studies on high-temperature oxidation and quench behaviour of Zircaloy4 and E110 cladding alloys  

Microsoft Academic Search

SUMMARY This paper gives an overview on the status of knowledge of high-temperature oxidation of the two zirconium alloys Zircaloy-4 and E110 with special emphasis on results obtained during the SARNET period. The tin-bearing alloy Zircaloy-4 and the niobium-bearing alloy E110 are the materials for cladding and structures recently mainly used in pressurised water reactors of the Western type and

M. Steinbrück; J. Birchley; A. V. Goryachev; M. Grosse; T. J. Haste; Z. Hozer; A. E. Kisselev; V. I. Nalivaev; V. P. Semishkin; L. Sepold; J. Stuckert; N. Vér; M. S. Veshchunov

277

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 placement of a mold with alumina particulate preform of net or nearly net size and shape in a crucible in a vacuum furnace. A charge of the alloy is placed in the crucible with the preform. The interior of the furnace is evacuated, then the furnace heaters are turned on to heat the alloy above its liquidus temperature. Next, the interior of the furnace is filled with argon gas at a pressure about 900 psi (approximately equal to 6.2 MPa) to force the molten alloy to infiltrate the preform. Once infiltrated, the entire contents of the crucible can be allowed to cool in place, and the composite part recovered from the mold.

Kashalikar, Uday; Rozenoyer, Boris

2004-01-01

278

Atomic engineering of platinum alloy surfaces.  

PubMed

A major practical challenge in heterogeneous catalysis is to minimize the loading of expensive platinum group metals (PGMs) without degrading the overall catalytic efficiency. Gaining a thorough atomic-scale understanding of the chemical/structural changes occurring during catalyst manufacture/operation could potentially enable the design and production of "nano-engineered" catalysts, optimized for cost, stability and performance. In the present study, the oxidation behavior of a Pt-31 at% Pd alloy between 673-1073 K is investigated using atom probe tomography (APT). Over this range of temperatures, three markedly different chemical structures are observed near the surface of the alloy. At 673 K, the surface oxide formed is enriched with Pd, the concentration of which rises further following oxidation at 773 K. During oxidation at 873 K, a thick, stable oxide layer is formed on the surface with a stoichiometry of PdO, beneath which a Pd-depleted (Pt-rich) layer exists. Above 873 K, the surface composition switches to enrichment in Pt, with the Pt content increasing further with increasing oxidation temperature. This treatment suggests a route for tuning the surfaces of Pt-Pd nanoparticles to be either Pd-rich or Pt-rich, simply by adjusting the oxidation temperatures in order to form two different types of core-shell structures. In addition, comparison of the oxidation behavior of Pt-Pd with Pt-Rh and Pd-Rh alloys demonstrates markedly different trends under the same conditions for these three binary alloys. PMID:23276526

Li, Tong; Bagot, P A J; Marquis, E A; Edman Tsang, S C; Smith, G D W

2013-09-01

279

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

280

Shape memory alloy actuators and their reliability  

NASA Astrophysics Data System (ADS)

We have developed two types of shape memory alloy (SMA) actuator and estimated the long-term reliability of SMA microcoils. A tube type tip articulator consists of 4 sets of SMA microcoil (wire diameter: 0.125 mm, coil diameter: 0.5 mm) for driving source and super elastic alloy (SEA) microcoils (wire diameter: 0.1 mm, coil diameter: 0.5 mm) for bias springs, support plates and flexible outer tube. The tube type tip articulator was bent approximately 90 degrees in any directions when a 200 mA current was applied. The joint mechanism consists of base plate, universal joint, reflection plate (diameter: 170 mm), SMA microcoil springs (wire diameter: 0.1 mm, coil diameter: 0.9 mm) and bias spring. The joint mechanism showed good response for control values with maximum tilt angle of 3.2 degrees. We also estimated the thermal cycling behavior of SMA microcoil actuators with the resistance monitoring method. SMA microcoil actuators (wire diameter: 0.1 mm, coil diameter: 0.5 mm) were given 3.0% shear stress and heated by current. For 10,000 cycles, the force of SMA microcoil actuators was approximately constant and showed good long-term reliability. Since the results show good characteristics and reliability, SMA microcoil actuators can be used in a wide range of industrial and medical applications.

Tohyama, Osamu; Maeda, Shigeo; Abe, Kazuhiro; Murayama, Manabu

2001-11-01

281

Shape memory alloy thaw sensors  

DOEpatents

A sensor permanently indicates that it has been exposed to temperatures exceeding a critical temperature for a predetermined time period. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the Austenitic temperature of the shape memory alloy. The shape change of the SMA element causes the sensor to change between two readily distinguishable states.

Shahinpoor, Mohsen (Albuquerque, NM); Martinez, David R. (Albuquerque, NM)

1998-01-01

282

Fatigue behavior of titanium alloys  

Microsoft Academic Search

This symposium was international in nature, with leaders in the fields of fatigue technology and the metallurgy of titanium from the US, Europe and Asia. It covered basic research, development, applications and modeling--life predictions and design of both fatigue crack initiation and propagation of titanium alloys. There were presentations on the full range of titanium alloy systems, from commercially pure

R. R. Boyer; D. Eylon; G. Luetjering

1999-01-01

283

Heat storage in alloy transformations  

NASA Astrophysics Data System (ADS)

The feasibility of using metal alloys as thermal energy storage media was determined. The following major elements were studied: (1) identification of congruently transforming alloys and thermochemical property measurements; (2) development of a precise and convenient method for measuring volume change during phase transformation and thermal expansion coefficients; (3) development of a numerical modeling routine for calculating heat flow in cylindrical heat exchangers containing phase change materials; and (4) identification of materials that could be used to contain the metal alloys. Several eutectic alloys and ternary intermetallic phases were determined. A method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation from data obtained during one continuous experimental test. The method and apparatus are discussed and the experimental results are presented. The development of the numerical modeling method is presented and results are discussed for both salt and metal alloy phase change media.

Birchenall, C. E.; Gueceri, S. I.; Farkas, D.; Labdon, M. B.; Nagaswami, N.; Pregger, B.

1981-03-01

284

Equivalent crystal theory of alloys  

NASA Technical Reports Server (NTRS)

Equivalent Crystal Theory (ECT) is a new, semi-empirical approach to calculating the energetics of a solid with defects. The theory has successfully reproduced surface energies in metals and semiconductors. The theory of binary alloys to date, both with first-principles and semi-empirical models, has not been very successful in predicting the energetics of alloys. This procedure is used to predict the heats of formation, cohesive energy, and lattice parameter of binary alloys of Cu, Ni, Al, Ag, Au, Pd, and Pt as functions of composition. The procedure accurately reproduces the heats of formation versus composition curves for a variety of binary alloys. The results are then compared with other approaches such as the embedded atom and lattice parameters of alloys from pure metal properties more accurately than Vegard's law is presented.

Bozzolo, Guillermo; Ferrante, John

1991-01-01

285

Normal evaporation of binary alloys  

NASA Technical Reports Server (NTRS)

In the study of normal evaporation, it is assumed that the evaporating alloy is homogeneous, that the vapor is instantly removed, and that the alloy follows Raoult's law. The differential equation of normal evaporation relating the evaporating time to the final solute concentration is given and solved for several important special cases. Uses of the derived equations are exemplified with a Ni-Al alloy and some binary iron alloys. The accuracy of the predicted results are checked by analyses of actual experimental data on Fe-Ni and Ni-Cr alloys evaporated at 1600 C, and also on the vacuum purification of beryllium. These analyses suggest that the normal evaporation equations presented here give satisfactory results that are accurate to within an order of magnitude of the correct values, even for some highly concentrated solutions. Limited diffusion and the resultant surface solute depletion or enrichment appear important in the extension of this normal evaporation approach.

Li, C. H.

1972-01-01

286

Heat storage in alloy transformations  

NASA Technical Reports Server (NTRS)

The feasibility of using metal alloys as thermal energy storage media was determined. The following major elements were studied: (1) identification of congruently transforming alloys and thermochemical property measurements; (2) development of a precise and convenient method for measuring volume change during phase transformation and thermal expansion coefficients; (3) development of a numerical modeling routine for calculating heat flow in cylindrical heat exchangers containing phase change materials; and (4) identification of materials that could be used to contain the metal alloys. Several eutectic alloys and ternary intermetallic phases were determined. A method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation from data obtained during one continuous experimental test. The method and apparatus are discussed and the experimental results are presented. The development of the numerical modeling method is presented and results are discussed for both salt and metal alloy phase change media.

Birchenall, C. E.; Gueceri, S. I.; Farkas, D.; Labdon, M. B.; Nagaswami, N.; Pregger, B.

1981-01-01

287

Thermomechanical treatment of alloys  

DOEpatents

An article of an alloy of AISI 316 stainless steel is reduced in size to predetermined dimensions by cold working in repeated steps. Before the last reduction step the article is annealed by heating within a temperature range, specifically between 1010.degree. C. and 1038.degree. C. for a time interval between 90 and 60 seconds depending on the actual temperature. By this treatment the swelling under neutron bombardment by epithermal neutrons is reduced while substantial recrystallization does not occur in actual use for a time interval of at least of the order of 5000 hours.

Bates, John F. (Ogden, UT); Brager, Howard R. (Richland, WA); Paxton, Michael M. (Gaithersburg, MD)

1983-01-01

288

Improved activation cross sections for vanadium and titanium  

SciTech Connect

Vanadium alloys such as V-20Ti and V-Cr-Ti are attractive candidates for use as structural materials in fusion-reactor blankets. The virtual absence of long-lived activation products in these alloys suggest the possibility of reprocessing on an intermediate time scale. We have employed the modern Hauser-Feshbach nuclear-model code GNASH to calculate cross sections for neutron-activation reactions in /sup 50/V and /sup 51/V, to allow a more accurate assessment of induced radioactivity in vanadium alloys. In addition, cross sections are calculated for the reactions /sup 46/Ti(n,2n) and /sup 45/Ti(n,2n) in order to estimate the production of /sup 44/Ti, a 1.2-MeV gamma-ray source with a half-life of 47 years.

Muir, D.W.; Arthur, E.D.

1983-01-01

289

Investigation of austenitic alloys for advanced heat recovery and hot-gas cleanup systems  

SciTech Connect

Materials properties were collected for the design and construction of structural components for use in advanced heat recovery and hot gas cleanup systems. Alloys systems included 9Cr-1Mo-V steel, modified 316 stainless steel, modified type 310 stainless steel, modified 20Cr-25Ni-Nb stainless steel, and modified alloy 800. Experimental work was undertaken to expand the databases for potentially useful alloys. Types of testing included creep, stress-rupture, creep-crack growth, fatigue, and post-exposure short-time tensile tests. Because of the interest in relatively inexpensive alloys for service at 700 C and higher, research emphasis was placed on a modified type 310 stainless steel and a modified 20Cr-25Ni-Nb stainless steel. Both steels were found to have useful strength to 925 C with good weldability and ductility.

Swindeman, R.W. [Oak Ridge National Lab., TN (United States)

1997-12-01

290

Continuous Displacement Formulation of Alloys  

NASA Astrophysics Data System (ADS)

The conventional permutational statistics of cooperative phenomena is extended to include displacement of atoms from their reference lattice points. The formulation is done in the cluster variation method (CVM) framework, by changing summations in energy and entropy to integrals. It is demonstrated for the pair approximation of CVM on phase-separating fcc binary alloys. The treatment can take into account local lattice distortion due to atomic size difference, the elastic effects, and the pressure effects. To compare stability of states under pressure, the grand potential ?( T, V, { ? i}) is extended to Z( T, p, { ? i}) by a Legendre transform. Although the new function Z( T, p, { ? i}) vanishes in equilibrium, and is called the ZERO-potential in the paper, it remains nonzero and is used to determine the coexisting phases when the chemical potentials are modified. Numerical calculations are done using the natural iteration technique on model inter-atomic potentials of the Lennard-Jones type. The numerical results of using ?( T, V, { ? i}) and Z( T, p, { ? i}) potentials for phase-separating diagrams, for composition and pressure dependence of the lattice constant, and for the bulk modulus are reported and discussed.

Kikuchi, Ryoichi

1999-06-01

291

Silicon Solar Cells with Front Hetero-Contact and Aluminum Alloy Back Junction: Preprint  

SciTech Connect

We prototype an alternative n-type monocrystalline silicon (c-Si) solar cell structure that utilizes an n/i-type hydrogenated amorphous silicon (a-Si:H) front hetero-contact and a back p-n junction formed by alloying aluminum (Al) with the n-type Si wafer.

Yuan, H.-C.; Page, M. R.; Iwaniczko, E.; Xu, Y.; Roybal, L.; Wang, Q.; Branz, H. M.; Meier, D. L.

2008-05-01

292

Recent advances and developments in refractory alloys  

Microsoft Academic Search

Refractory metal alloys based on Mo, W, Re, Ta, and Nb (Cb) find applications in a wide range of aerospace applications because of their high melting points and high-temperature strength. This paper, presents recent progress in understanding and applications of these alloys. Recent studies to improve the oxidation and mechanical behavior of refractory metal alloys, and particularly Nb alloys, are

T. G. Nieh; J. Wadsworth

1993-01-01

293

High-Alloy Materials for Offshore Applications  

Microsoft Academic Search

High-alloy materials possessing good corrosion resistance in hot, sour brines are being seriously considered for offshore applications. These alloys are available in a wide range of strength levels which can be attained by the methods of cold working or precipitation hardening. Results of testing INCONEL alloys 625 and 718 and INCOLOY alloys 825 and 925 for resistance to general corrosion,

T. F. Lemke; J. A. Harris

1983-01-01

294

Microstructures and mechanical properties of Ti-Mo alloys cold-rolled and heat treated  

SciTech Connect

In this study, the microstructures and mechanical properties of Ti-10Mo and Ti-20Mo alloys (mass%) are investigated to assess the potential use in biomedical applications. The microstructures are examined by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The mechanical properties are determined from uniaxial tensile tests. The experimental results indicate that the microstructures and mechanical properties of Ti-Mo alloys are dependent upon the cold rolling, solution heat treatment, and Mo content. The Ti-10Mo alloy exhibits ({alpha}'' + {beta}) and ({beta} + {omega}) phases under the cold rolling (CR) and solution treatment (ST), respectively. By contrast, the Ti-20Mo alloy comprises only {beta} phase under such conditions. The quenched Ti-20Mo alloy has the lowest elastic modulus and CR Ti-20Mo alloy has the highest tensile strength. The quenched Ti-10Mo alloy exhibits the excellent ductility and two-stage yielding from stress-strain curves due to the stress-induced martensite transformation from {beta} to {alpha}'' during tensile deformation. These Ti-Mo alloys exhibit low yield strength and good ductility, and they are more suitable for biomedical applications than the conventional metallic biomaterials from the viewpoint of better mechanical compatibility. The quenched Ti-10Mo alloy has some advantages over the other {beta} binary Ti-Mo alloys for biomedical applications. {beta} type Ti-Mo-Sn alloys are expected to be promising candidates for novel metallic biomaterials. - Highlights: {yields} The microstructures and mechanical properties of Ti-Mo alloys are dependent upon the cold rolling, solution heat treatment, and Mo content. {yields} The quenched Ti-10Mo alloy exhibits the excellent ductility and two-stage yielding due to stress-induced martensite transformation from beta to alpha double prime during tensile deformation. {yields} The Ti-Mo alloys are more suitable for biomedical applications than the conventional metallic biomaterials from the viewpoint of better mechanical compatibility. {yields} The quenched Ti-10Mo alloy has more advantages over the other beta binary Ti-Mo alloys for biomedical applications.

Zhou Yinglong, E-mail: yinglongzhou@126.com [Department of Mechatronics Engineering, Foshan University, 18 Jiangwan Yi Rd, Foshan 528000, Guangdong Province (China); Luo Dongmei [Department of Civil Engineering, Foshan University, 18 Jiangwan Yi Rd, Foshan 528000, Guangdong Province (China)

2011-10-15

295

SCC Initiation in Alloy 600 Heat Affected Zones Exposed to High Temperature Water  

SciTech Connect

Studies have shown that grain boundary chromium carbides improve the stress corrosion cracking (SCC) resistance of nickel based alloys exposed to high temperature, high purity water. However, thermal cycles from welding can significantly alter the microstructure of the base material near the fusion line. In particular, the heat of welding can solutionize grain boundary carbides and produce locally high residual stresses and strains, reducing the SCC resistance of the Alloy 600 type material in the heat affected zone (HAZ). Testing has shown that the SCC growth rate in Alloy 600 heat affected zone samples can be {approx}30x faster than observed in the Alloy 600 base material under identical testing conditions due to fewer intergranular chromium rich carbides and increased plastic strain in the HAZ [1, 2]. Stress corrosion crack initiation tests were conducted on Alloy 600 HAZ samples at 360 C in hydrogenated, deaerated water to determine if these microstructural differences significantly affect the SCC initiation resistance of Alloy 600 heat affected zones compared to the Alloy 600 base material. Alloy 600 to EN82H to Alloy 600 heat-affected-zone (HAZ) specimens where fabricated from an Alloy 600 to Alloy 600 narrow groove weld with EN82H filler metal. The approximate middle third of the specimen gauge region was EN82H such that each specimen had two HAZ regions. Tests were conducted with in-situ monitored smooth tensile specimens under a constant load, and a direct current electric potential drop was used for in-situ detection of SCC. Test results suggest that the SCC initiation resistance of Alloy 600 and its weld metal follows the following order: EN82H > Alloy 600 HAZ > Alloy 600. The high SCC initiation resistance observed to date in Alloy 600 heat affected zones compared to wrought Alloy 600 is unexpected based on the microstructure of HAZ versus wrought material and based on prior SCC growth rate studies. The observed behavior for the HAZ specimens is likely not related to differences in the environment, differences in surface stress/strain between the various specimen regions (weld, HAZ, wrought), differences in surface residual stress, or differences in the microstructure of the various specimen regions (weld, HAZ, wrought). The behavior may be related to differences in the creep behavior of the various weld regions or differences in the surface area of the various materials (weld, HAZ, wrought) exposed to high temperature water.

E Richey; DS Morton; RA Etien; GA Young; RB Bucinell

2006-11-03

296

High performance alloy electroforming  

NASA Technical Reports Server (NTRS)

Electroformed copper and nickel are used in structural applications for advanced propellant combustion chambers. An improved process has been developed by Bell Aerospace Textron, Inc. wherein electroformed nickel-manganese alloy has demonstrated superior mechanical and thermal stability when compared to previously reported deposits from known nickel plating processes. Solution chemistry and parametric operating procedures are now established and material property data is established for deposition of thick, large complex shapes such as the Space Shuttle Main Engine. The critical operating variables are those governing the ratio of codeposited nickel and manganese. The deposition uniformity which in turn affects the manganese concentration distribution is affected by solution resistance and geometric effects as well as solution agitation. The manganese concentration in the deposit must be between 2000 and 3000 ppm for optimum physical properties to be realized. The study also includes data regarding deposition procedures for achieving excellent bond strength at an interface with copper, nickel-manganese or INCONEL 718. Applications for this electroformed material include fabrication of complex or re-entry shapes which would be difficult or impossible to form from high strength alloys such as INCONEL 718.

Malone, G. A.; Winkelman, D. M.

1989-01-01

297

B Alloy Melt  

NASA Astrophysics Data System (ADS)

The solidification of undercooled Ni-4.5 wt pct B alloy melt was investigated by using the glass fluxing technique. The alloy melt was undercooled up to ? T p ~ 245 K (245 °C), where a mixture of ?-Ni dendrite, Ni3B dendrite, rod eutectic, and precipitates was obtained. If ? T p < 175 K ± 10 K (175 °C ± 10 °C), the solidification pathway was found as primary transformation and eutectic transformation (L ? Ni3B and L ? Ni/Ni3B); if ? T p ? 175 K ± 10 K (175 °C ± 10 °C), the pathway was found as metastable eutectic transformation, metastable phase decomposition, and residual liquid solidification (L ? Ni/Ni23B6, Ni23B6 ? Ni/Ni3B, and Lr ? Ni/Ni3B). A high-speed video system was adopted to observe the solidification front of each transformation. It showed that for residual liquid solidification, the solidification front velocity is the same magnitude as that for eutectic transformation, but is an order of magnitude larger than for metastable eutectic transformation, which confirms the reaction as Lr ? Ni/Ni3B; it also showed that this velocity decreases with increasing ? T r, which can be explained by reduction of the residual liquid fraction and decrease of Ni23B6 decomposition rate.

Liu, Feng; Xu, Junfeng; Zhang, Di; Jian, Zengyun

2014-10-01

298

Oxidation resistant alloys, method for producing oxidation resistant alloys  

DOEpatents

A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800.degree. C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800.degree. C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700.degree. C. at a low cost

Dunning, John S. (Corvallis, OR); Alman, David E. (Salem, OR)

2002-11-05

299

Oxidation resistant alloys, method for producing oxidation resistant alloys  

DOEpatents

A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800 C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800 C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700 C. at a low cost

Dunning, John S.; Alman, David E.

2002-11-05

300

Temperature dependence of the mechanical properties of a Ti-Al-Cr alloy  

SciTech Connect

TiAl based intermetallics are considered as potential high-temperature structural materials due to their attractive properties at high temperatures. Previous studies of the mechanical behavior of single phase and dual phase TiAl alloys revealed that these types of alloys have good ductility at high temperatures, but poor ductility at ambient and lower temperatures. Recently some triple phase TiAl alloys were developed by the addition of [beta] stabilizing elements, and the [beta] phase was found not to improve the room temperature ductility. However, few reports have been made about the high temperature behavior of the triple phase TiAl alloys. This research is concentrated on the temperature dependence of the mechanical properties of a triple phase Ti-Al-Cr alloy.

Chen, W.R.; Zhang, B.; Chen, W.J.; Wang, J.; Wan, X. (Shanghai Univ. of Technology (China). Inst. of Materials Science)

1994-11-15

301

Thermal and microstructural investigation of Cu-Al-Mn-Mg shape memory alloys  

NASA Astrophysics Data System (ADS)

There are many studies to improve the properties of Cu-Al-Mn shape memory alloys, such as high transformation temperatures, ductility and workability. Most of them have been performed by adding a quaternary component to the alloy. In this study, the effect of trace Mg addition on transformation temperatures and microstructures of three different quaternary Cu-Al-Mn-Mg alloys has been investigated using thermal analysis, optical microscopy and XRD techniques. The transformation temperatures are within the range of 120-180 °C, and they have not changed significantly on decreasing the Mn content, replacing with Mg. The fine precipitates have been observed in the alloys with the Mg content up to 1.64 at%. Calculated entropy change and XRD analysis reveal that the alloys with high Al content have mainly 18R-type structure which could be responsible for good ductility and workability.

Canbay, Canan Aksu; Ozgen, Soner; Genc, Zuhal Karagoz

2014-07-01

302

Dental casting of titanium and Ni-Ti alloys by a new casting machine.  

PubMed

The purpose of this study was to develop a new casting machine for titanium and Ni-Ti alloys. Properties of cast pure titanium and Ni-Ti alloys were studied by means of the tensile and casting tests. As gas in the mold was removed by the mold being heated under a high vacuum, the reaction between the molten metal and the mold decreased. The new control system and the two types of crucibles developed proved very useful for prevention of internal macro-defects in castings and for improvement of castability. Mechanical properties and castability of pure titanium were improved. Ni-Ti alloys could be cast without loss of their shape-memory effect or super-elasticity characteristics. The new casting machine is thought to be promising for the casting of titanium and Ni-Ti alloys. Furthermore, we can cast these alloys using conventional techniques and investments. PMID:2685069

Hamanaka, H; Doi, H; Yoneyama, T; Okuno, O

1989-11-01

303

Fatigue of die cast zinc alloys  

SciTech Connect

The rotating bending fatigue limit of die cast zinc alloy 2, alloy 3, alloy 5, AcuZinc 5, and ZA-8 were determined as a part of an on-going program by ILZRO into the mechanical properties of die cast zinc. The stress-life (S-N) curves of alloys 3, 5, AcuZinc 5, and ZA-8 were determined previously. This presentation reports the results of the S-N curve for Alloy 2 and the calculated fatigue limits for all five alloys. During the previous stress-life testing, the samples were stopped at 10 million cycles and the fatigue limit for alloy 3, alloy 5, and AcuZinc 5 appeared to be higher and the fatigue limit for ZA-8 appeared to be lower than the values reported in the literature. This was further investigated in alloy 5 and ZA-8 by testing continuous cast bulk alloy 5 and ZA-8.

Schrems, K.K.; Dogan, O.N.; Goodwin, F.E. (International Lead Zinc Research Organization, Inc.)

2006-04-01

304

Thermodynamic prediction of thixoformability in alloys based on the Al–Si–Cu and Al–Si–Cu–Mg systems  

Microsoft Academic Search

Most commercial semi-solid processing (of which thixoforming is one type) utilises the conventional casting alloys A356 and A357. There is, however, a demand to widen the range of alloys, including those with higher performance which tend to show poor characteristics for thixoforming. Thermodynamic calculation packages, such as MTDATA, provide a tool for predicting thixoformability. Here, the effects of compositional variations,

D. Liu; H. V. Atkinson; H. Jones

2005-01-01

305

Effects of Nb and Al on the microstructures and mechanical properties of high Nb containing TiAl base alloys  

Microsoft Academic Search

The influence of Nb and Al contents on the microstructure and yield strength of high Nb containing TiAl base alloys was investigated. The experimental results show that the yield strength at 900 °C of the alloys with the same type of microstructure, such as fully lamellar (FL), nearly lamellar (NL) and degraded fully lamellar (DFL), increases with increasing Nb content and

Z. C. Liu; J. P. Lin; S. J. Li; G. L. Chen

2002-01-01

306

Ab initio calculations of cohesive energies of Fe-based glass-forming alloys M. Mihalkovic* and M. Widom  

E-print Network

­10 list known stable and metastable structures. Chemically similar alloy systems provide hypo- thetical glass-forming alloys, which often contain three or more chemical elements, provide a useful test case of the struc- ture types CFe3 (Pearson symbol oP16) and C6Cr23 (Pearson symbol cF116) as the two main

Widom, Michael

307

The site occupancies of alloying elements in TiAl and Ti{sub 3}Al alloys  

SciTech Connect

The site occupancies of V, Cr, Mn, Fe, Ni, Zr, Nb, Mo, Ta, Ga and Sn (1--5 at.%) in TiAl alloys with different compositions, and in Ti{sub 3}Al with the compositions of Ti-26 at.%Al-(1--2 at.%)X, were measured by the atom location channeling enhanced microanalysis (ALCHEMI) method. For TiAl alloys, the results show that Zr, Nb and Ta atoms invariably occupy Ti sites, while Fe, Ni, Ga and Sn atoms occupy Al sites, the alloy composition having no significant influence on their site preference. By contrast, the site preference of V, Cr, and Mn changes considerably with alloy composition (the Ti/Al ratio in particular), the probability of these elements substituting for Ti decreasing in the above order. For quaternary Ti-Al-V-Cr alloys, the site occupancies of V and Cr do not show much mutual influence. In general, with increasing atomic number, elements in the same period show increasing tendency to substitute for Al, as is the tendency to substitute for Ti for elements in the same group of the periodic table. For Ti{sub 3}Al alloys, Ga and Sn atoms occupy Al sites, while V, Cr, Mn, Zr, Nb, Mo and Ta atoms occupy Ti sites, the site preference of V, Cr, Mn and Mo in TiAl alloys being different from that in Ti{sub 3}Al. The experimental results are interpreted in terms of a Bragg-Williams-type model and bond-order data obtained from electronic structure calculation. Qualitative agreement between the model and measurements is reached.

Hao, Y.L.; Xu, D.S.; Cui, Y.Y.; Yang, R.; Li, D. [Chinese Academy of Sciences, Shenyang (China). Inst. of Metal Research] [Chinese Academy of Sciences, Shenyang (China). Inst. of Metal Research

1999-03-10

308

Functionally Graded Al Alloy Matrix In-Situ Composites  

NASA Astrophysics Data System (ADS)

In the present work, functionally graded (FG) aluminum alloy matrix in-situ composites (FG-AMCs) with TiB2 and TiC reinforcements were synthesized using the horizontal centrifugal casting process. A commercial Al-Si alloy (A356) and an Al-Cu alloy were used as matrices in the present study. The material parameters (such as matrix and reinforcement type) and process parameters (such as mold temperature, mold speed, and melt stirring) were found to influence the gradient in the FG-AMCs. Detailed microstructural analysis of the composites in different processing conditions revealed that the gradients in the reinforcement modify the microstructure and hardness of the Al alloy. The segregated in-situ formed TiB2 and TiC particles change the morphology of Si particles during the solidification of Al-Si alloy. A maximum of 20 vol pct of reinforcement at the surface was achieved by this process in the Al-4Cu-TiB2 system. The stirring of the melt before pouring causes the reinforcement particles to segregate at the periphery of the casting, while in the absence of such stirring, the particles are segregated at the interior of the casting.

Kumar, S.; Subramaniya Sarma, V.; Murty, B. S.

2010-01-01

309

Directly smelted lead-tin alloys: A historical perspective  

NASA Astrophysics Data System (ADS)

This paper discusses evidence related to the genesis and occurrence of mixed lead-tin ore deposit consisting of cassiterite and the secondary minerals formed from galena. These evidences belong to a very long time period ranging from pre-historic to as late as the nineteenth century a.d. This type of mixed ore deposits was smelted to prepare lead-tin alloys. The composition of the alloy depended on the composition of the starting ore mixture. A nineteenth century evidence for the production of directly smelted lead-tin alloys in southern Thailand is discussed. A unique and rather uncommon metallurgical terminology in Sanskrit language— N?gaja—was introduced in India for the tin recovered from impure lead. This suggests that Indians developed a process for recovering tin from lead-tin alloys, which in all probability was based on the general principle of fire refining. It has been shown that in the context of India the possibility of connection between the word N?gaja and the directly smelted lead-tin alloys cannot be ruled out.

Dube, R. K.

2010-08-01

310

Heat storage in alloy transformations  

NASA Technical Reports Server (NTRS)

The feasibility of using metal alloys as thermal energy storage media was investigated. The elements selected as candidate media were limited to aluminum, copper, magnesium, silicon, zinc, calcium, and phosphorus on the basis of low cost and latent heat of transformation. Several new eutectic alloys and ternary intermetallic phases were determined. A new method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation. The method and apparatus are discussed and the experimental results are presented for aluminum and two aluminum-eutectic alloys. Candidate materials were evaluated to determine suitable materials for containment of the metal alloys. Graphite was used to contain the alloys during the volume change measurements. Silicon carbide was identified as a promising containment material and surface-coated iron alloys were also evaluated. System considerations that are pertinent if alloy eutectics are used as thermal energy storage media are discussed. Potential applications to solar receivers and industrial furnaces are illustrated schematically.

Birchenall, C. E.

1980-01-01

311

Cast alloys for gas turbine vanes  

Microsoft Academic Search

1.The investigation of the casting properties and manufacture of turbine vanes showed that it is possible to use investment casting for gas turbine vanes of the experimental alloys tested.2.In alloys hardened with aluminum and titanium (alloys 1 and 2) the maximum short-term strength was retained to higher temperatures than for the alloys hardened with aluminum and niobium (alloy 3) or

M. N. Efimova; E. N. Masaleva

1971-01-01

312

New Al–Mg–Sc alloys  

Microsoft Academic Search

Data on new 01515, 01523, 01535, 01545, 01570 and 01571 wrought weldable alloys based on the Al–Mg–Sc system are presented. These alloys differ from each other, mainly, by magnesium content and belong to the family of non-heat-treatable alloys. Wrought Al–Mg–Sc alloy semiproducts as-hot worked or as-annealed show much higher properties (especially yield strength) than those made from conventional Al–Mg alloys

Yu. A Filatov; V. I Yelagin; V. V Zakharov

2000-01-01

313

Advances in nickel alloys for aerospace applications  

Microsoft Academic Search

Recent advances in several areas of alloy development are examined, with emphasis on the application of these alloys to aerospace usage. Two mechanically alloyed materials are described, with emphasis on the outstanding high-temperature features of such alloys. A low-expansion high-strength alloy is described, with examples of its use in gas turbines and the Space Shuttle main engine. Properties of a

Tillack

1977-01-01

314

High-temperature ordered intermetallic alloys II; Proceedings of the Second Symposium, Boston, MA, Dec. 2-4, 1986  

NASA Technical Reports Server (NTRS)

The papers presented in this volume provide on overview of recent theoretical and experimental research in the field of high-temperature ordered intermetallic alloys. The papers are gouped under the following headings: ordering behavior and theory, microstructures, mechanical behavior, alloy design and microstructural control, and metallurgical properties. Specific topics discussed include antiphase domains, disordered films and the ductility of ordered alloys based on Ni3Al; kinetics and mechanics of formation of Al-Ni intermetallics; deformability improvements of L1(2)-type intermetallic compounds; B2 aluminides for high-temperature applications; and rapidly solidified binary TiAl alloys.

Stoloff, N. S. (editor); Koch, C. C. (editor); Liu, C. T. (editor); Izumi, O. (editor)

1987-01-01

315

Dendritic Alloy Solidification Experiment (DASE)  

NASA Technical Reports Server (NTRS)

A space experiment, and supporting ground-based research, is proposed to study the microstructural evolution in free dendritic growth from a supercooled melt of the transparent model alloy succinonitrile-acetone (SCN-ACE). The research is relevant to equiaxed solidification of metal alloy castings. The microgravity experiment will establish a benchmark for testing of equiaxed dendritic growth theories, scaling laws, and models in the presence of purely diffusive, coupled heat and solute transport, without the complicating influences of melt convection. The specific objectives are to: determine the selection of the dendrite tip operating state, i.e. the growth velocity and tip radius, for free dendritic growth of succinonitrile-acetone alloys; determine the growth morphology and sidebranching behavior for freely grown alloy dendrites; determine the effects of the thermal/solutal interactions in the growth of an assemblage of equiaxed alloy crystals; determine the effects of melt convection on the free growth of alloy dendrites; measure the surface tension anisotropy strength of succinon itrile -acetone alloys establish a theoretical and modeling framework for the experiments. Microgravity experiments on equiaxed dendritic growth of alloy dendrites have not been performed in the past. The proposed experiment builds on the Isothermal Dendritic Growth Experiment (IDGE) of Glicksman and coworkers, which focused on the steady growth of a single crystal from pure supercooled melts (succinonitrile and pivalic acid). It also extends the Equiaxed Dendritic Solidification Experiment (EDSE) of the present investigators, which is concerned with the interactions and transients arising in the growth of an assemblage of equiaxed crystals (succinonitrile). However, these experiments with pure substances are not able to address the issues related to coupled heat and solute transport in growth of alloy dendrites.

Beckermann, C.; Karma, A.; Steinbach, I.; deGroh, H. C., III

2001-01-01

316

Development of lead-free copper alloy graphite castings. Annual report, January--December 1995  

SciTech Connect

The distribution of graphite particles in graphite containing copper alloy was further improved very significantly using several procedures and technological modifications. The developed techniques attacked the graphite distribution problem in two ways. Realizing that clustering of very fine (5um) graphite particles is one of the two major problems, a pretreatment process has been developed using aluminum powders to deagglomerate graphite particles. Along with this, a two-stage stirring technique was used to first incorporate and then to distribute uniformly the deagglomerated particles in the melt. During this year, based on these developments, several components were cast to evaluate the castability of Cu alloy-graphite melts. In addition, machinability tests were done to clearly established that addition of graphite particles improve the machinability of copper MMC alloys over and above that of monolithic copper alloys. The results show that the machining chip sizes and cutting forces of Cu alloys containing graphite particles are smaller than these of the corresponding monolithic Cu alloys. This clearly establishes that the presence of graphite particles in copper alloy improves the machinability in a fashion similar to lead additions to copper alloys. Centrifugal casting of shapes of different sizes appear to be a very attractive method for casting graphite containing copper alloys, since all the graphite particles (regardless of their distribution in the melt) are forced to segregate to the inner periphery of the castings where they impart a very desirable solid lubrication property for bushing and bearing use. A very large number of cylindrical elements of lead bearing copper alloys are now used for similar bearing bushing applications and the manufacturers of these type of bearings are under safety and health hazard pressure to remove lead. This year several parameters for centrifugal casting of copper graphite alloys have been established.

Rohatgi, P.K.

1996-10-01

317

Nucleation of shear bands in amorphous alloys  

PubMed Central

The initiation and propagation of shear bands is an important mode of localized inhomogeneous deformation that occurs in a wide range of materials. In metallic glasses, shear band development is considered to center on a structural heterogeneity, a shear transformation zone that evolves into a rapidly propagating shear band under a shear stress above a threshold. Deformation by shear bands is a nucleation-controlled process, but the initiation process is unclear. Here we use nanoindentation to probe shear band nucleation during loading by measuring the first pop-in event in the load–depth curve which is demonstrated to be associated with shear band formation. We analyze a large number of independent measurements on four different bulk metallic glasses (BMGs) alloys and reveal the operation of a bimodal distribution of the first pop-in loads that are associated with different shear band nucleation sites that operate at different stress levels below the glass transition temperature, Tg. The nucleation kinetics, the nucleation barriers, and the density for each site type have been determined. The discovery of multiple shear band nucleation sites challenges the current view of nucleation at a single type of site and offers opportunities for controlling the ductility of BMG alloys. PMID:24594599

Perepezko, John H.; Imhoff, Seth D.; Chen, Ming-Wei; Wang, Jun-Qiang; Gonzalez, Sergio

2014-01-01

318

Nucleation of shear bands in amorphous alloys.  

PubMed

The initiation and propagation of shear bands is an important mode of localized inhomogeneous deformation that occurs in a wide range of materials. In metallic glasses, shear band development is considered to center on a structural heterogeneity, a shear transformation zone that evolves into a rapidly propagating shear band under a shear stress above a threshold. Deformation by shear bands is a nucleation-controlled process, but the initiation process is unclear. Here we use nanoindentation to probe shear band nucleation during loading by measuring the first pop-in event in the load-depth curve which is demonstrated to be associated with shear band formation. We analyze a large number of independent measurements on four different bulk metallic glasses (BMGs) alloys and reveal the operation of a bimodal distribution of the first pop-in loads that are associated with different shear band nucleation sites that operate at different stress levels below the glass transition temperature, Tg. The nucleation kinetics, the nucleation barriers, and the density for each site type have been determined. The discovery of multiple shear band nucleation sites challenges the current view of nucleation at a single type of site and offers opportunities for controlling the ductility of BMG alloys. PMID:24594599

Perepezko, John H; Imhoff, Seth D; Chen, Ming-Wei; Wang, Jun-Qiang; Gonzalez, Sergio

2014-03-18

319

Evaluation of surface modifications for oxidation protection of vanadium-base alloys in helium-cooled blanket designs  

NASA Astrophysics Data System (ADS)

Vanadium-base alloys are currently being considered for application to high-temperature helium-cooled fusion reactor blanket designs. A major drawback is their known sensitivity to low levels of oxidizing impurities that would normally be present as water vapor in the helium coolant gas. Although baseline data on the oxidation resistance of vanadium alloys are lacking, protection of vanadium alloy surfaces exposed to the helium coolant will probably be necessary for contiuous blanket operation at temperatures above 875 K. Surface alloying of vanadium-base alloys appears to be a feasible method of creating an oxidation-resistant surface. To examine this approach, a series of V-15Cr-5Ti alloy sheet specimens was surface alloyed with chromium. Oxidation tests were then conducted in flowing helium containing up to 100 vppm H 2O. Temperatures up to 925 K and times up to 1000 h were utilized. Control samples of unmodified V-15Cr-5Ti and a Type 316 stainless steel were also included. Significant reductions in oxygen pickup were observed with surface-alloyed specimens. These results suggest that surface alloying techniques offer great promise for protecting vanadium alloy surfaces against oxidation at blanket operating temperatures.

Tobin, A.; Busch, G.

1986-11-01

320

The effect of copper, chromium, and zirconium on the microstructure and mechanical properties of Al-Zn-Mg-Cu alloys  

NASA Technical Reports Server (NTRS)

The present study evaluates the effect of the systematic variation of copper, chromium, and zirconium contents on the microstructure and mechanical properties of a 7000-type aluminum alloy. Fracture toughness and tensile properties are evaluated for each alloy in both the peak aging, T8, and the overaging, T73, conditions. Results show that dimpled rupture essentially characterize the fracture process in these alloys. In the T8 condition, a significant loss of toughness is observed for alloys containing 2.5 pct Cu due to the increase in the quantity of Al-Cu-Mg-rich S-phase particles. An examination of T8 alloys at constant Cu levels shows that Zr-bearing alloys exhibit higher strength and toughness than the Cr-bearing alloys. In the T73 condition, Cr-bearing alloys are inherently tougher than Zr-bearing alloys. A void nucleation and growth mechanism accounts for the loss of toughness in these alloys with increasing copper content.

Wagner, John A.; Shenoy, R. N.

1991-01-01

321

Microstructural characterization of low and high carbon CoCrMo alloy nanoparticles produced by mechanical milling  

NASA Astrophysics Data System (ADS)

CoCrMo alloys are utilised as the main material in hip prostheses. The link between this type of hip prosthesis and chronic pain remains unclear. Studies suggest that wear debris generated in-vivo may be related to post-operative complications such as inflammation. These alloys can contain different amounts of carbon, which improves the mechanical properties of the alloy. However, the formation of carbides could become sites that initiate corrosion, releasing ions and/or particles into the human body. This study analysed the mechanical milling of alloys containing both high and low carbon levels in relevant biological media, as an alternative route to generate wear debris. The results show that low carbon alloys produce significantly more nanoparticles than high carbon alloys. During the milling process, strain induces an fcc to hcp phase transformation. Evidence for cobalt and molybdenum dissolution in the presence of serum was confirmed by ICP-MS and TEM EDX techniques.

Simoes, T. A.; Goode, A. E.; Porter, A. E.; Ryan, M. P.; Milne, S. J.; Brown, A. P.; Brydson, R. M. D.

2014-06-01

322

The effects of corrosion products from copper dental alloys on lymphocyte proliferation  

SciTech Connect

Copper dental alloys currently being used for dental applications possess mechanical properties similar to the traditional gold alloys. However, it is reported that these alloys have high corrosion rates, cause decreases in gingival fibroblast proliferation and release significant levels of Cu which have been associated with oral inflammatory responses in dogs. The authors investigated the effects of the commercial copper alloys, Goldent and Trindium, on human blood mononuclear cell proliferation. Fresh, human peripheral blood mononuclear cells, the CEM and HSB T-cell lines and the Raji B-cell line were exposed to the copper alloys for 24 hours. While the authors observed decreases in the proliferation of human blood mononuclear cells, as measured by {sup 3}H-thymidine uptake, these decreases were highly variable. The copper dental alloys caused 41-47% reductions in the proliferation of the CEM T-cell line while reducing proliferation in the Raji B-cell line and the HSB T-cell line by 20% or less. In conclusion, the effect of copper dental alloys is highly variable depending upon the cell type. These results indicate that further studies are warranted to adequately determine the biocompatibility of these alloys.

Bumgardner, J.D.; Lucas, L.C.; Tilden, A.B. (Veterans Administration, Birmingham, AL (United States))

1990-02-26

323

Laser surface alloying of silicon into aluminum casting alloys.  

SciTech Connect

Aluminum alloys that are easily castable tend to have lower silicon content, and hence, lower wear resistance. The use of laser surface alloying to improve the surface wear resistance of 319 and 320 aluminum alloys was examined. A silicon layer was painted onto the surface to be treated. A high power pulsed Nd:yttrium-aluminum-garnet laser with fiber-optic beam delivery was used to carry out the laser surface treatment to enhance the silicon content and produce a very fine silicon-rich phase. One advantage of using a pulsed laser beam to carry out the surface alloying is it provides a vigorous turbulence in the molten pool and enhances the dissolution of the fine silicon into the molten bath and its dispersal in a short process time. Process parameters were varied to obtain smooth single treated tracks and minimize the surface roughness from overlap of the treated tracks. Our goal is to take advantage of the vigorous turbulence characteristic of the pulsed beam to obtain desired microstructure of laser-alloyed layers, and at the same time to employ the pulse parameters that mimic continuous wave operation as closely as possible to produce the smooth surface. The surface-alloyed layer was characterized and the silicon content and microhardness profile were determined.

Xu, Z.; Leong, K. H.; Sanders, P. G.; Technology Development

2000-08-01

324

Metallic alloy stability studies  

NASA Technical Reports Server (NTRS)

The dimensional stability of candidate cryogenic wind tunnel model materials was investigated. Flat specimens of candidate materials were fabricated and cryo-cycled to assess relative dimensional stability. Existing 2-dimensional airfoil models as well as models in various stages of manufacture were also cryo-cycled. The tests indicate that 18 Ni maraging steel offers the greatest dimensional stability and that PH 13-8 Mo stainless steel is the most stable of the stainless steels. Dimensional stability is influenced primarily by metallurgical transformations (austenitic to martensitic) and manufacturing-induced stresses. These factors can be minimized by utilization of stable alloys, refinement of existing manufacturing techniques, and incorporation of new manufacturing technologies.

Firth, G. C.

1983-01-01

325

Magnesium Alloys and their Applications  

NASA Astrophysics Data System (ADS)

In the recent years there has been a dramatic increase in research activity and also applications of magnesium alloys. The driving force is the growing demand by the automobile industry resulting from the pressure to reduce weight and hence to reduce the fuel consumption. The U.S. car industry incorporates the largest amount of magnesium at the present time. In Europe, Volkswagen had a history of using magnesium in the VW Beetle. Volkswagen, in common with other major car producers has initiated a major research and development programme for advanced magnesium materials. The main emphasis of this book is in the field of general physical metallurgy and alloy development refelcting the need to provide a wider range of alloys both casting and wrought alloys to meet the increasing demands of industry. Other topics are nevertheless well represented such as casting, recycling, joining, corrosion, and surface treatment.

Kainer, Karl U.

1999-04-01

326

Copper alloys for industrial hardware  

SciTech Connect

Copper and its alloys are widely used because of their excellent electrical and thermal conductivities, outstanding resistance to corrosion, and ease of fabrication. Lifecycle costs are another important reason for new and expanding applications for copper and copper alloys. For example, lifecycle cost analyses favor the use of copper-nickel for automotive brake tubes, and copper alloys in molds for plastic parts. However, copper also competes very well on a first-cost basis in the brazed copper-and-brass radiator, and in free-cutting brass machined components. This article highlights four specific applications in which advanced copper alloys and fabrication techniques enhance the performance of industrial hardware, based largely on conductivity, corrosion resistance, and lifecycle costs.

Peters, D.T. [Copper Development Association Inc., New York, NY (United States)

1996-10-01

327

Technical Seminar "Shape Memory Alloys"  

NASA Video Gallery

Shape memory alloys are a unique group of materials that remember their original shape and return to that shape after being strained. How could the aerospace, automotive, and energy exploration ind...

328

An imperative extension to Alloy  

E-print Network

We extend the Alloy language with the standard imperative constructs; we show the mix of declarative and imperative constructs to be useful in modeling dynamic systems. We present a translation from our extended language ...

Near, Joseph Paul

329

Carbide Formation and Dissolution in Biomedical Co-Cr-Mo Alloys with Different Carbon Contents during Solution Treatment  

NASA Astrophysics Data System (ADS)

The microstructures of as-cast and heat-treated biomedical Co-Cr-Mo (ASTM F75) alloys with four different carbon contents were investigated. The as-cast alloys were solution treated at 1473 to 1548 K for 0 to 43.2 ks. The precipitates in the matrix were electrolytically extracted from the as-cast and heat-treated alloys. An M23C6 type carbide and an intermetallic ? phase (Co(Cr,Mo)) were detected as precipitates in the as-cast Co-28Cr-6Mo-0.12C alloy; an M23C6 type carbide, a ? phase, an ? phase (M6C-M12C type carbide), and a ? phase (M2T3X type carbide with a ?-manganese structure) were detected in the as-cast Co-28Cr-6Mo-0.15C alloy; and an M23C6 type carbide and an ? phase were detected in the as-cast Co-28Cr-6Mo-0.25C and Co-28Cr-6Mo-0.35C alloys. After solution treatment, complete precipitate dissolution occurred in all four alloys. Under incomplete precipitate dissolution conditions, the phase and shape of precipitates depended on the heat-treatment conditions and the carbon content in the alloys. The ? phase was detected in the alloys with carbon contents of 0.15, 0.25, and 0.35 mass pct after heat treatment at high temperature such as 1548 K for a short holding time of less than 1.8 ks. The presence of the ? phase in the Co-Cr-Mo alloys has been revealed in this study for the first time.

Mineta, Shingo; Namba, Shigenobu; Yoneda, Takashi; Ueda, Kyosuke; Narushima, Takayuki

2010-08-01

330

In vitro degradation behavior and cytocompatibility of Mg-Zn-Zr alloys  

PubMed Central

Zinc and zirconium were selected as the alloying elements in biodegradable magnesium alloys, considering their strengthening effect and good biocompatibility. The degradation rate, hydrogen evolution, ion release, surface layer and in vitro cytotoxicity of two Mg–Zn–Zr alloys, i.e. ZK30 and ZK60, and a WE-type alloy (Mg–Y–RE–Zr) were investigated by means of long-term static immersion testing in Hank’s solution, non-static immersion testing in Hank’s solution and cell-material interaction analysis. It was found that, among these three magnesium alloys, ZK30 had the lowest degradation rate and the least hydrogen evolution. A magnesium calcium phosphate layer was formed on the surface of ZK30 sample during non-static immersion and its degradation caused minute changes in the ion concentrations and pH value of Hank’s solution. In addition, the ZK30 alloy showed insignificant cytotoxicity against bone marrow stromal cells as compared with biocompatible hydroxyapatite (HA) and the WE-type alloy. After prolonged incubation for 7 days, a stimulatory effect on cell proliferation was observed. The results of the present study suggested that ZK30 could be a promising material for biodegradable orthopedic implants and worth further investigation to evaluate its in vitro and in vivo degradation behavior. PMID:20532960

Huan, Z. G.; Leeflang, M. A.; Fratila-Apachitei, L. E.; Duszczyk, J.

2010-01-01

331

Erosion of iron-chromium alloys by glass particles  

NASA Technical Reports Server (NTRS)

The material loss upon erosion was measured for several iron-chromium alloys. Two types of erodent material were used: spherical glass beads and sharp particles of crushed glass. For erosion with glass beads the erosion resistance (defined as the reciprocal of material loss rate) was linearly dependent on hardness. This is in accordance with the erosion behavior of pure metals, but contrary to the erosion behavior of alloys of constant composition that were subjected to different heat treatments. For erosion with crushed glass, however, no correlation existed between hardness and erosion resistance. Instead, the erosion resistance depended on alloy composition rather than on hardness and increased with the chromium content of the alloy. The difference in erosion behavior for the two types of erodent particles suggested that two different material removal mechanisms were involved. This was confirmed by SEM micrographs of the eroded surfaces, which showed that for erosion with glass beads the mechanism of material removal was deformation-induced flaking of surface layers, or peening, whereas for erosion with crushed glass it was cutting or chopping.

Salik, J.; Buckley, D. H.

1984-01-01

332

Ordered Magnesium-Lithium alloys  

Microsoft Academic Search

Emerging technologies increasingly depend on the production of ultra-lightweight materials. Magnesium-lithium (MgLi) alloys are the lightest metallic alloys, having densities near that of plastics, and are strong enough to be used in a variety of high- performance applications. Although considerable work has been done on the MgLi system, little is known regarding potential ordered phases. An analysis of the system

Richard Taylor; Stefano Curtarolo; Gus Hart

2009-01-01

333

IMPROVEMENTS RELATING TO ZIRCONIUM ALLOYS  

Microsoft Academic Search

A Zr alloy suitable for use in aqueous media at high temperatures, e.g., ; in pressurized or boiling water reactors, is one containing 0.75to 1.25 wt% Cu ; and 0.25to 0.75 wt % Sn, the balance being Zr and impurities. The preferred ; alloy contains 1.0 wt % Cu and 0.5 wt % Sn and was found to have a

T. Raine; J. A. Robinson

1961-01-01

334

Overview of ODS Alloy Development  

Microsoft Academic Search

The overall goal of this effort is to address the materials-related barriers to expediting the use of oxide dispersion-strengthened (ODS) alloys in components required in the U.S. Department of Energy's (DOE's) Office of Fossil Energy's advanced coal combustion, gasification, and utilization processes to operate at temperatures higher than are possible with conventionally-strengthened alloys. The project is focused on the needs

Ian G Wright; Bruce A Pint

2005-01-01

335

The mechanism of mechanical alloying  

Microsoft Academic Search

The mechanical alloying process is a new method for producing composite metal powders with controlled microstructures. It\\u000a is unique in that it is an entirely solid state process, permitting dispersion of insoluble phases such as refractory oxides\\u000a and addition of reactive alloying elements such as aluminum and titanium. Interdispersion of the ingredients occurs by repeated\\u000a cold welding and fracture of

J. S. Benjamin; T. E. Volin

1974-01-01

336

Shape memory alloy thaw sensors  

DOEpatents

A sensor permanently indicates that it has been exposed to temperatures exceeding a critical temperature for a predetermined time period. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the austenitic temperature of the shape memory alloy. The shape change of the SMA element causes the sensor to change between two readily distinguishable states. 16 figs.

Shahinpoor, M.; Martinez, D.R.

1998-04-07

337

Type Classes with Existential Types  

Microsoft Academic Search

Abstract Weargue,that the novel combination,of type classes and existential types in a single language yields significant expressive,power. Weexplore,this combination,in the context of higher-order functional languages with static typing, parametric polymorphism, algebraic data types, and Hindley-Milner type inference. Adding existential types to an existing functional language,that already features type classes requires only a minor syntactic extension. Wef irst demonstrate,how,to provide existential

Konstantin Läufer

1996-01-01

338

Casting Characteristics of Aluminum Die Casting Alloys  

SciTech Connect

The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

Makhlouf M. Makhlouf; Diran Apelian

2002-02-05

339

Microstructure in the cubic to monoclinic transition in titanium-nickel shape memory alloys  

SciTech Connect

Microstructure in the cubic to monoclinic transition in the technologically important Ti-Ni shape memory alloys is considered. Using a geometrically nonlinear theory of martensitic transformations, the twinned martensite, austenite-martensite, wedge, triangle, and diamond microstructures are studied. Specifically, compound, type 1, and type 2 twins are possible for any choice of the lattice parameters; while, non-standard twins may exist with special lattice parameters only. In addition, 192 habit planes are found for a particular Ti-Ni alloy, but only 24 have been unambiguously observed in experiments. Further, the twinned wedge is possible in this alloy, but the triangle and diamond are not. These latter three are special microstructures, which provide a mechanism through which a specimen can easily transform and are possible only for alloys with specific lattice parameters. A complete enumeration of the various microstructures is given, and algorithms are presented so that the calculations can be repeated with different lattice parameters.

Hane, K.F.; Shield, T.W. (Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Aerospace Engineering and Mechanics)

1999-07-09

340

Application of Fe–16Cr ferritic alloy to interconnector for a solid oxide fuel cell  

Microsoft Academic Search

Iron-base scaling-resistant alloys (Fe–Cr) as materials for interconnectors of planar-type solid oxide fuel cells (SOFC) are proposed for application in automobile industry because of their advantages in comparison with other Ni- or Co-based alloys and ceramic materials (e.g. (La,Sr)CrO3). The oxidation kinetics of Fe–16Cr alloy (SUS 430) has been studied in H2–H2O gas mixtures (pH2\\/pH2O=94\\/6 and 97\\/3), and in air

Tomasz Brylewski; Makoto Nanko; Toshio Maruyama; Kazimierz Przybylski

2001-01-01

341

Unirradiated characteristics of U-Si alloys as dispersed-phase fuels  

SciTech Connect

To satisfy the power demands of many research reactors, a new LEU fuel with a high density and U content was needed. Any fuel must be compatible with Al and its alloys so that it may be fabricable as a dispersed-phase in Al alloy and Al matrix plate-type elements following, as nearly as possible, established commercial manufacturing techniques. U-Si and U-Si-Al alloys at or near the composition of U/sub 3/Si were immediately attractive because of work documented by the Canadians. 8 refs., 2 figs.

Domagala, R.F.; Wiencek, T.C.

1987-06-01

342

A study of Fe-30Mn-6Si shape memory alloys prepared from different melting techniques  

SciTech Connect

Newly developed shape memory alloys Ge-Mn-Si, governed by the stress-induced {gamma} {yields} {epsilon} martensitic transformation, are attracting attention due to their low cost and excellent workability. The shape memory effect (SME), although only a one way type, can be nearly perfect for alloys containing suitable amounts of manganese and silicon. However, there are few papers reporting the effect of the melting process, although it is an important factor affecting the material properties. Therefore, in the present study, the authors aim to investigate the casting morphology, shape memory effect, tensile property and fracture behavior for the Fe-30Mn-6Si alloys which are prepared by two melting techniques.

Lin, H.C.; Lin, K.M. [Feng Chia Univ., Taichung (Taiwan, Province of China). Dept. of Materials Science] [Feng Chia Univ., Taichung (Taiwan, Province of China). Dept. of Materials Science; Chou, T.S. [China Steel Corp., Kaoshiung (Taiwan, Province of China). Steel and Aluminum R and D Dept.] [China Steel Corp., Kaoshiung (Taiwan, Province of China). Steel and Aluminum R and D Dept.

1996-10-01

343

Materials data handbook: Stainless steel type 301  

NASA Technical Reports Server (NTRS)

A summary of the materials property information for stainless steel type 301 is presented. The scope of the information includes physical and mechanical properties at cryogenic, ambient, and elevated temperatures. Information on material procurement, metallurgy of the alloy, corrosion, environmental effects, fabrication, and bonding is developed.

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

1972-01-01

344

Ohmic contact for P type indium phosphide  

NASA Technical Reports Server (NTRS)

A body including P type indium phosphide has an ohmic contact thereon of an alloy of by weight 81% to 86% gold (Au), 11% to 14% germanium (Ge) and 2% to 5% zinc (Zn). This contact has a low resistance and good adhesion to the indium phosphide body.

Hawrylo, Frank Z. (Inventor)

1980-01-01

345

Crystal structure of martensitic phases in Ni–Mn–Ga shape memory alloys  

Microsoft Academic Search

The crystal structures of the different martensitic phases observed in a wide variety of Ni–Mn–Ga alloy compositions have been studied in detail. Similarly to the Ni–Al alloys, the non-modulated martensite can be well described by the L10 lattice, although it must be “doubled” in order to account for the L21 type of order of the parent phase. Concerning the well

J. Pons; V. A. Chernenko; R. Santamarta; E. Cesari

2000-01-01

346

The investigations of hot-deformability and structure of high-temperature Fe-Ni alloy  

Microsoft Academic Search

Purpose: This study describes the influence of initial austenite grain size and parameters of hot plastic deformation on the deformability and structure of high-temperature Fe-Ni austenitic alloy of A-286 type. Design\\/methodology\\/approach: The hot deformation characteristics of the alloy were investigated by hot torsion tests using torsion plastometer. The tests were executed at constant strain rates of 0.1 and 1.0 s-1,

K. J. Ducki; D. Kuc

347

Strip casting of A5182 alloy using a melt drag twin-roll caster  

Microsoft Academic Search

The melt drag twin-roll caster (MDTRC) was devised for the high-speed strip casting of mushy solidification type aluminium alloys. The MDTRC enables A5182 aluminium alloy to be cast at a speed of up to 60m\\/min. The MDTRC combines a low separating force, semi-solid forming at the upper side of the strip and the use of copper rolls and requires no

T Haga; T Nishiyama; S Suzuki

2003-01-01

348

Release of elements from dental casting alloys into cell-culture medium over 10 months  

Microsoft Academic Search

Objective: The release of elements from eight types of commonly used dental casting alloys into cell-culture medium was measured over a 10-month period. The release of elements was determined to provide information about the long-term biological risk these alloys may pose to the oral tissues. The current work extends previous studies of shorter time periods, and is more relevant to

John C Wataha; Petra E Lockwood

1998-01-01

349

Evaluation of copper alloys for fusion reactor divertor and first wall components  

Microsoft Academic Search

This paper presents a critical analysis of the main factors of radiation damage limiting the possibility to use copper alloys in the ITER divertor and first wall structure. In copper alloys the most significant types of radiation damage in the proposed temperature-dose operation range are swelling, creep, and low-temperature radiation embrittlement. Low-temperature radiation embrittlement at Tirr < 150°C presents considerable

S. A. Fabritsiev; S. J. Zinkle; B. N. Singh

1996-01-01

350

Warm Forming of Aluminum Alloys using a Coupled ThermoMechanical Anisotropic Material Model  

Microsoft Academic Search

Temperature-dependant anisotropic material models for two types of automotive aluminum alloys (5754-O and 5182-O) were developed and implemented in LS-Dyna as a user material subroutine (UMAT) for coupled thermo-mechanical finite element analysis (FEA) of warm forming of aluminum alloys. The anisotropy coefficients of the Barlat YLD2000 plane stress yield function for both materials were calculated for the range of temperatures

Nader Abedrabbo; Farhang Pourboghrat; John E. Carsley

2005-01-01

351

Flow behavior and microstructure evolution of TB8 alloy during hot deformation process  

Microsoft Academic Search

Hot compression tests of metastable ? titanium alloy TB8 were carried out using a Gleeble-1500 thermal simulation testing machine in the temperature range of 750–1 100 °C, at constant strain rate from 0.01 s?1 to 1 s?1 and with height direction reduction of 60%. Flow stress behavior and microstructure evolution during hot compression of TB8 alloy were investigated. The hyperbolic-sine-type

Yuan-pei DUAN; Ping LI; Ke-min XUE; Qing ZHANG; Xiao-xi WANG

2007-01-01

352

Microstructure of a pressure die cast magnesium—4wt.% aluminium alloy modified with rare earth additions  

Microsoft Academic Search

Addition of cerium-rich mixtures of rare earth (RE) elements to aluminium-containing magnesium pressure die cast alloys is known to improve the creep properties at elevated temperatures. In the present investigation, a detailed description of the microstructure of a magnesium-4 wt.% aluminium alloy containing 1.4 wt.% of a cerium-rich mixture of RE elements is presented. Particle types occurring and their distribution

G. Pettersen; H. Westengen; R. Høier; O. Lohne

1996-01-01

353

Growth and properties of low bandgap amorphous (Si, Ge) alloy materials and devices  

Microsoft Academic Search

The properties of low bandgap a-(Si,Ge):H alloy materials and devices prepared using low pressure, high dilution ECR plasma deposition techniques have been investigated. Significant reduction in dihydride type bonding have been achieved by using low pressure, high ion flux conditions for alloys with Tauc gaps ranging from 1.1 to 1.4 eV. The defect density was measured using space charge limited

Vikram L Dalal; Yong Liu; Zhiyang Zhou; Keqin Han

2002-01-01

354

High-Thermoelectric Performance of Nanostructured Bismuth Antimony Telluride Bulk Alloys  

Microsoft Academic Search

The dimensionless thermoelectric figure of merit (ZT) in bismuth antimony telluride (BiSbTe) bulk alloys has remained around 1 for more than 50 years. We show that a peak ZT of 1.4 at 100°C can be achieved in a p-type nanocrystalline BiSbTe bulk alloy. These nanocrystalline bulk materials were made by hot pressing nanopowders that were ball-milled from crystalline ingots under

Bed Poudel; Qing Hao; Yi Ma; Yucheng Lan; Austin Minnich; Xiao Yan; Dezhi Wang; Andrew Muto; Daryoosh Vashaee; Xiaoyuan Chen; M. S. Dresselhaus; Mildred S. Dresselhaus; Gang Chen; Zhifeng Ren

2008-01-01

355

Laser alloying and cladding of metallic substrates  

NASA Astrophysics Data System (ADS)

This paper describes the microstructure and properties (chemical composition and microhardness) of the surface laser alloyed layer with tantalum as well as coatings, made of Tribaloy T-400 and Stellite 6 powders, deposited by laser cladding. The surface alloyed zones varied in microstructure, zones depth and width, as well as Ta content related to the thickness of the coated layer, bonding paint type and the process parameters (power and scanning velocity). The electron microprobe analysis of melts shows that higher tantalum content in the melted zone resulted from the thicker original Ta coating as well as slower scanning velocity. Scanning electron microscopy examinations show that dendritic structure is typically martensitic when silicon-containing binder was used for powder deposition. Samples covered with Ta and the carbon containing binder showed after laser alloying higher hardness than in case of using silicon-containing binder. Defect free coatings, made of Tribaloy T-400 and Stellite 6 powders, deposited by laser cladding on iron and nickel based substrates are described. The proper selection of the cladding process parameters permitted to get coatings with low dilution of the base material. Cross-sections of such coatings have been examined revealing their microstructure using optical, SEM and TEM electron microscopy, chemical (EDS microanalysis) and phase composition (XRD), hardness and microhardness testing methods. As compared with other deposition techniques the microstructure of the laser coatings showed a high degree of refinement and chemical homogeneity. The grain coarsening was observed in the heat- affected zones and was explained as to be due to the overlapping of subsequent tracks during the coatings deposition. The erosive wear resistance of the coatings has been investigated. In general, the laser deposited coatings turned out to be susceptible for an extensive erosive wear. The effect was explained by lack of feasibility of the coated material to plastic deformation during erosion.

Kusinski, Jan P.; Przybylowicz, Janusz; Woldan, Agnieszka

2000-11-01

356

Thermophysical property measurements on low alloy high strength carbon steels  

SciTech Connect

The alloys of interest in this study were AISI Type 4230 and Type 4320 low alloy high strength carbon steels. They are heat-treatable steels and are usually used in the quenched and tempered condition. The Type 4130 has about 0.3% (wt.)C, 0.95%Cr, and 0.2% Mo. The Type 4320 has about 0.2%C, 1.7%Ni, 0.7%Cr, and 0.3% Mo. They are among the most popular alloy steels because of their excellent combination of mechanical properties and are used in both cast and wrought forms for many applications requiring high strength and toughness. However, during the casting operation, carbon segregation to the part surface forms a high carbon content surface layer in the part, which will induce surface cracking in the subsequent quenching process. And, during the welding operation, the critical cooling rate in the heat-affected zone (HAZ) will determine if the weldment is crack-free or not. Thus, the numerical effort to study the thermal history, microstructure evolution and residual stress development during welding and casting is critical to the application of these steels. This modeling effect requires the accurate knowledge of thermophysical properties, such as thermal expansion, solidus and liquidus temperatures, specific heat capacity, and heat of fusion. Unfortunately, these thermophysical properties are unavailable for temperatures over 1,000 C (1,2), thus the need for this study.

Li, M.; Brooks, J.A. [Sandia National Labs., Livermore, CA (United States)] [Sandia National Labs., Livermore, CA (United States); Atteridge, D.G. [Oregon Graduate Inst., Portland, OR (United States). Dept. of Materials Science and Engineering] [Oregon Graduate Inst., Portland, OR (United States). Dept. of Materials Science and Engineering; Porter, W.D. [Oak Ridge National Lab., TN (United States). Physical Properties User Center] [Oak Ridge National Lab., TN (United States). Physical Properties User Center

1997-06-15

357

Zinc Alloys for the Fabrication of Semiconductor Devices  

NASA Technical Reports Server (NTRS)

ZnBeO and ZnCdSeO alloys have been disclosed as materials for the improvement in performance, function, and capability of semiconductor devices. The alloys can be used alone or in combination to form active photonic layers that can emit over a range of wavelength values. Materials with both larger and smaller band gaps would allow for the fabrication of semiconductor heterostructures that have increased function in the ultraviolet (UV) region of the spectrum. ZnO is a wide band-gap material possessing good radiation-resistance properties. It is desirable to modify the energy band gap of ZnO to smaller values than that for ZnO and to larger values than that for ZnO for use in semiconductor devices. A material with band gap energy larger than that of ZnO would allow for the emission at shorter wavelengths for LED (light emitting diode) and LD (laser diode) devices, while a material with band gap energy smaller than that of ZnO would allow for emission at longer wavelengths for LED and LD devices. The amount of Be in the ZnBeO alloy system can be varied to increase the energy bandgap of ZnO to values larger than that of ZnO. The amount of Cd and Se in the ZnCdSeO alloy system can be varied to decrease the energy band gap of ZnO to values smaller than that of ZnO. Each alloy formed can be undoped or can be p-type doped using selected dopant elements, or can be n-type doped using selected dopant elements. The layers and structures formed with both the ZnBeO and ZnCdSeO semiconductor alloys - including undoped, p-type-doped, and n-type-doped types - can be used for fabricating photonic and electronic semiconductor devices for use in photonic and electronic applications. These devices can be used in LEDs, LDs, FETs (field effect transistors), PN junctions, PIN junctions, Schottky barrier diodes, UV detectors and transmitters, and transistors and transparent transistors. They also can be used in applications for lightemitting display, backlighting for displays, UV and visible transmitters and detectors, high-frequency radar, biomedical imaging, chemical compound identification, molecular identification and structure, gas sensors, imaging systems, and for the fundamental studies of atoms, molecules, gases, vapors, and solids.

Ryu, Yungryel; Lee, Tae S.

2009-01-01

358

Lifshitz Tails for Generalized Alloy Type Random Schrodinger Operators  

E-print Network

V(x) = Zd V (x - ) on Rd, d 1, where · V0 is a periodic potential; · V is a compactly supported of studies. In particular, it is well known that the integrated density of states of the Hamiltonian admits a Lifshitz tail near E-, i.e., lim EE+ - log | log N(E)| log(E - E-)

Paris-Sud XI, Université de

359

Weldability of Fe[sub 3]Al-type Aluminide  

SciTech Connect

An investigation was carried out to determine the weldability of a series of Fe[sub 3]Al-type alloys. Autogenous welds were made on thin sheets of iron aluminide alloys using gas tungsten arc (GTA) and electron beam (EB) welding processes at different travel speeds and power levels. The results indicate that although these alloys can be successfully welded using the EB welding process, some compositions may hot crack during GTA welding. Boron and zirconium additions have been found to promote hot cracking in these alloys. Among the alloys investigated, Fe[sub 3]Al modified with chromium, niobium and carbon (FA-129) showed the most promise for good weldability. Hot-cracking severity of this alloy was further investigated using the Sigmajig test. The minimum threshold stress of 25 ksi measured is within the material range of other aluminides and some commercial stainless steels. Also, some of these alloys exhibited a tendency for cold cracking. This is related to severe hydrogen embrittlement associated with this class of alloys.

David, S.A.; Zacharia, T. (Oak Ridge National Lab., TN (United States))

1993-05-01

360

Nickel-based gadolinium alloy for neutron adsorption application in RAM packages.  

SciTech Connect

The National Spent Nuclear Fuel Program, located at the Idaho National Laboratory (INL), coordinates and integrates national efforts in management and disposal of US Department of Energy (DOE)-owned spent nuclear fuel. These management functions include development of standardised systems for long-term disposal in the proposed Yucca Mountain repository. Nuclear criticality control measures are needed in these systems to avoid restrictive fissile loading limits because of the enrichment and total quantity of fissile material in some types of the DOE spent nuclear fuel. This need is being addressed by development of corrosion-resistant, neutron-absorbing structural alloys for nuclear criticality control. This paper outlines results of a metallurgical development programme that is investigating the alloying of gadolinium into a nickel-chromium-molybdenum alloy matrix. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross section and low solubility in the expected repository environment. The nickel-chromium-molybdenum alloy family was chosen for its known corrosion performance, mechanical properties, and weldability. The workflow of this programme includes chemical composition definition, primary and secondary melting studies, ingot conversion processes, properties testing, and national consensus codes and standards work. The microstructural investigation of these alloys shows that the gadolinium addition is present in the alloy as a gadolinium-rich second phase. The mechanical strength values are similar to those expected for commercial Ni-Cr-Mo alloys. The alloys have been corrosion tested with acceptable results. The initial results of weldability tests have also been acceptable. Neutronic testing in a moderated critical array has generated favourable results. An American Society for Testing and Materials material specification has been issued for the alloy and a Code Case has been submitted to the American Society of Mechanical Engineers for code qualification.

Mizia, Ronald A. (Idaho National Laboratory, Idaho Falls, ID); Dupont, John Neuman (Lehigh University, Bethlehem, PA); McConnell, Paul E.; Robino, Charles Victor

2005-02-01

361

Nickel-based gadolinium alloy for neutron adsorption application in ram packages.  

SciTech Connect

The National Spent Nuclear Fuel Program, located at the Idaho National Laboratory (INL), coordinates and integrates national efforts in management and disposal of US Department of Energy (DOE)-owned spent nuclear fuel. These management functions include development of standardized systems for long-term disposal in the proposed Yucca Mountain repository. Nuclear criticality control measures are needed in these systems to avoid restrictive fissile loading limits because of the enrichment and total quantity of fissile material in some types of the DOE spent nuclear fuel. This need is being addressed by development of corrosion-resistant, neutron-absorbing structural alloys for nuclear criticality control. This paper outlines results of a metallurgical development program that is investigating the alloying of gadolinium into a nickel-chromium-molybdenum alloy matrix. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross section and low solubility in the expected repository environment. The nickel-chromium-molybdenum alloy family was chosen for its known corrosion performance, mechanical properties, and weldability. The workflow of this program includes chemical composition definition, primary and secondary melting studies, ingot conversion processes, properties testing, and national consensus codes and standards work. The microstructural investigation of these alloys shows that the gadolinium addition is present in the alloy as a gadolinium-rich second phase. The mechanical strength values are similar to those expected for commercial Ni-Cr-Mo alloys. The alloys have been corrosion tested with acceptable results. The initial results of weldability tests have also been acceptable. Neutronic testing in a moderated critical array has generated favorable results. An American Society for Testing and Materials material specification has been issued for the alloy and a Code Case has been submitted to the American Society of Mechanical Engineers for code qualification.

Mizia, Ronald A. (Idaho National Engineering & Environmental Laboratory, Idaho Falls, ID); McConnell, Paul E.; Robino, Charles Victor

2004-09-01

362

Microstructure and properties of a titanium alloy-orthorhombic titanium aluminide layered composite  

NASA Astrophysics Data System (ADS)

The microstructure and tensile properties of a layered composite material fabricated by solid-state bonding of its components using pressure welding are studied at room and elevated temperatures. The components are made of a high-temperature VT25U titanium alloy and an intermetallic alloy ( O alloy) based on orthorhombic titanium aluminide of the composition Ti-23Al-22.7Nb-1.1V-0.6Zr-0.2Si-0.3C (at %). The study of the microstructure and chemical composition of the composite by scanning electron microscopy and energy dispersive X-ray analysis demonstrates that this method of producing a layered composite provides high-quality poreless bonding of materials of different types. The solid-state bonding zone has an intermediate chemical composition. Mechanical tests demonstrate that the room-temperature strength of the composite is comparable with that of the O alloy and is higher than that of the titanium alloy; as the fraction of the titanium alloy in the composite decreases, this strength increases. The relative elongation of the layered composite is found to be higher than that of the O alloy and lower than that of the titanium alloy. In the temperature range 500-700°C, the strength of the composite material is 25% higher than that of the titanium alloy, and its plasticity is lower than that of the titanium alloy. Our method is shown to be promising for producing layered composite materials that have high mechanical properties over a wide temperature range.

Galeev, R. M.; Valiakhmetov, O. R.; Safiullin, R. V.; Imaev, V. M.; Imaev, R. M.

2009-03-01

363

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

SciTech Connect

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

Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

1998-03-10

364

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

NASA Astrophysics Data System (ADS)

The Al-12 pctSi alloy and aluminum-based composites reinforced with TiB2 and Al3Ti intermetallics exhibit good wear resistance, strength-to-weight ratio, and strength-to-cost ratio when compared to equivalent other commercial Al alloys, which make them good candidates as coating materials. In this study, structural AA 6028 alloy is used as the base material. Four different coating materials were used. The first one is Al-Si alloy that has Si content near eutectic composition. The second, third, and fourth ones are Al-6 pctSi-based reinforced with TiB2 and Al3Ti nano-particles produced by addition of Al-Ti5-B1 master alloy with different weight percentages (1, 2, and 3 pct). The coating treatment was carried out with the aid of GTAW process. The microstructures of the base and coated materials were investigated using optical microscope and scanning electron microscope equipped with EDX analyzer. Microhardness of the base material and the coated layer were evaluated using a microhardness tester. GTAW process results in almost sound coated layer on 6028 aluminum alloy with the used four coating materials. The coating materials of Al-12 pct Si alloy resulted in very fine dendritic Al-Si eutectic structure. The interface between the coated layer and the base metal was very clean. The coated layer was almost free from porosities or other defects. The coating materials of Al-6 pct Si-based mixed with Al-Ti5-B1 master alloy with different percentages (1, 2, and 3 pct), results in coated layer consisted of matrix of fine dendrite eutectic morphology structure inside ?-Al grains. Many fine in situ TiAl3 and TiB2 intermetallics were precipitated almost at the grain boundary of ?-Al grains. The amounts of these precipitates are increased by increasing the addition of Al-Ti5-B1 master alloy. The surface hardness of the 6028 aluminum alloy base metal was improved with the entire four used surface coating materials. The improvement reached to about 85 pct by the first type of coating material (Al-12 pctSi alloy), while it reached to 77, 83, and 89 pct by the coating materials of Al-6 pct Si-based mixed with Al-Ti5-B1 master alloy with different percentages 1, 2, and 3 pct, respectively.

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

2014-10-01

365

Application of MO-Type Flange for Accelerator Beam Ducts 3  

Microsoft Academic Search

Based on experiences in the precedent stain-less steel case, a possibility of employing copper-alloy and aluminum-alloy Matsumoto-Ohtsuka (MO)-type flanges in a vacuum beam pipes for a particle accelerator is experimentally studied. They can mitigate the heating problems found in the case of stainless-steel flanges under high-intensity beams, and also simplify the manufacturing procedure of beam pipes. Copper-alloy flanges show a

Yusuke Suetsugu; Mitsuru Shirai; Michio Ohtsuka; Toshiro Nishidono; Kazuhiko Watanabe; Yasuaki Suzuki; Akira Morishige; Masao Tsuchiya; Tomohiro Yonemoto

2010-01-01

366

Solidification behavior and structure of Al-Cu alloy welds  

SciTech Connect

The microsegregation behavior of electron beam (EB) and gas tungsten arc (GTA) welds of Al-Cu alloys covering a range from 0.19 to 7.74 wt% Cu were characterized for dendrite core concentrations and fraction eutectic solidification. Although a single weld speed of 12.7 mm/sec was used, some differences were observed in the segregation behavior of the two weld types. The microsegregation behavior was also modeled using a finite differences technique considering dendrite tip and eutectic undercooling and solid state diffusion. Fairly good agreement was observed between measured and calculated segregation behavior although differences between the two weld types could not be completely accounted for. The concept of dendrite tip undercooling was used to explain the formation of a single through thickness centerline grain in the higher alloy content GTA welds.

Brooks, J.A.; Li, M.; Yang, N.C.Y.

1997-09-01

367

Light weight alloys for aerospace applications  

Microsoft Academic Search

This book contains the proceedings of this 1989 TMS annual meeting. Topics covered include: High temperature and high strength aluminum alloys; Aluminum-lithium alloys; Metal matrix composites; and Superplasticity and joining.

E. W. Lee; E. H. Chia; N. J. Kim

1989-01-01

368

Alloy hardening and softening in binary molybdenum alloys as related to electron concentration  

NASA Technical Reports Server (NTRS)

An investigation was conducted to determine the effects of alloy additions of hafnium, tantalum, tungsten, rhenium, osmium, iridium, and platinum on hardness of molybdenum. Special emphasis was placed on alloy softening in these binary molybdenum alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to molybdenum, while those elements having an equal number or fewer s+d electrons that molybdenum failed to produce alloy softening. Alloy softening and alloy hardening can be correlated with the difference in number of s+d electrons of the solute element and molybdenum.

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

1972-01-01

369

Quasicrystal-reinforced Mg alloys  

NASA Astrophysics Data System (ADS)

The formation of the icosahedral phase (I-phase) as a secondary solidification phase in Mg-Zn-Y and Mg-Zn-Al base systems provides useful advantages in designing high performance wrought magnesium alloys. The strengthening in two-phase composites (I-phase + ?-Mg) can be explained by dispersion hardening due to the presence of I-phase particles and by the strong bonding property at the I-phase/matrix interface. The presence of an additional secondary solidification phase can further enhance formability and mechanical properties. In Mg-Zn-Y alloys, the co-presence of I and Ca2Mg6Zn3 phases by addition of Ca can significantly enhance formability, while in Mg-Zn-Al alloys, the co-presence of the I-phase and Mg2Sn phase leads to the enhancement of mechanical properties. Dynamic and static recrystallization are significantly accelerated by addition of Ca in Mg-Zn-Y alloy, resulting in much smaller grain size and more random texture. The high strength of Mg-Zn-Al-Sn alloys is attributed to the presence of finely distributed Mg2Sn and I-phase particles embedded in the ?-Mg matrix.

Kim, Young Kyun; Kim, Won Tae; Hyang Kim, Do

2014-04-01

370

Influence of rare-earth metals on the high-temperature strength of Ni3Al-based alloys  

NASA Astrophysics Data System (ADS)

The influence of the content of reaction- and surface-active alloying elements (rare-earth metals (REMs)) and the method of their introduction into cast high-temperature ?'-Ni3Al-based intermetallic alloys, which are thermally stable natural eutectic composites, on their structure-phase state and the mechanical properties is studied. The life of low-alloy heterophase ?' + ? cast high-temperature light Ni3Al-based alloys is shown can be increased at temperatures exceeding 0.8 T m ( T m is the melting temperature of Ni3Al) due to additional stabilization of the single-crystal structure of these alloys with submicron and nanometer-sized particles of the phases formed by refractory and active REMs. It is also shown that stage-by-stage fractional introduction of all components into alloys during vacuum induction melting with allowance for their reaction activities (most refractory metals are introduced in the form of low-melting-point master alloys at the first stage of vacuum induction melting, and lanthanum is introduced with a master alloy in the optimal contents of 0.1-2 wt % into the charge of VKNA-1V and VKNA-25 alloys at the final stage) leads to the formation of a modified structure stabilized by nanoprecipitates of nickel and aluminum lanthanides and the phases formed by refractory metals. This method increases the life of VKNV-1V-type alloys (0.5 wt % Re) at 1000-1200°C by a factor of ˜1.7 and that of VKNA-25-type alloys (1.2 wt % Re and Co) by a factor of ˜3.

Povarova, K. B.; Kazanskaya, N. K.; Drozdov, A. A.; Bazyleva, O. A.; Kostina, M. V.; Antonova, A. V.; Morozov, A. E.

2011-01-01

371

Compositional variation of hydrogen permeability in ferritic alloys and steels  

Microsoft Academic Search

From a compilation of permeation data of hydrogen in ferritic\\/martensitic alloys and steels dependences are derived of activation energies and prefactors in Arrhenius-type relations on concentration of constituents. By most constituents the prefactor is reduced and the activation energy is increased compared to pure iron. The permeabilities of ferritic\\/martensitic stainless steels can be approximated within the scatter of data by

P. Jung

1996-01-01

372

Corrosion of ferrous alloys in eutectic lead-lithium environments  

Microsoft Academic Search

Corrosion data have been obtained on austenitic prime candidate alloy (PCA) and Type 316 stainless steel and ferritic HT-9 and Fe-9Cr-1Mo steels in a flowing Pb-17 at. % Li environment at 727 and 700 K (454 and 427°C). The results indicate that the dissolution rates for both austenitic and ferritic steels in Pb-17Li are an order of magnitude greater than

O. K. Chopra; D. L. Smith

1983-01-01

373

Nickel aluminide alloys with improved weldability  

DOEpatents

Weldable nickel aluminide alloys which are essentially free, if not entirely free, of weld hot cracking are provided by employing zirconium concentrations in these alloys of greater than 2.6 wt. % or sufficient to provide a substantial presence of Ni--Zr eutectic phase in the weld so as to prevent weld hot cracking. Weld filler metals formed from these so modified nickel aluminide alloys provide for crack-free welds in previously known nickel aluminide alloys. 5 figs.

Santella, M.L.; Goodwin, G.M.

1995-05-09

374

Nickel aluminide alloys with improved weldability  

DOEpatents

Weldable nickel aluminide alloys which are essentially free, if not entirely free, of weld hot cracking are provided by employing zirconium concentrations in these alloys of greater than 2.6 wt. % or sufficient to provide a substantial presence of Ni--Zr eutectic phase in the weld so as to prevent weld hot cracking. Weld filler metals formed from these so modified nickel aluminide alloys provide for crack-free welds in previously known nickel aluminide alloys.

Santella, Michael L. (Knoxville, TN); Goodwin, Gene M. (Lenior City, TN)

1995-05-09

375

Research on Alloying Tecniques of Mischmetal in Die Casting Magnesium Alloy  

Microsoft Academic Search

An aim of the experiments is to study alloying techniques of dollop-like MM, as-cast and extruded Mg-MM master alloy in die casting AZ91D magnesium alloy at conventional cold chamber die casting temperature. The as-cast AZ91D-1.2wt%MM alloys were prepared and MM was added by different way at 720°C. The results showed that the efficiency of alloying achieved less than 50% within

Yulei Xu; Kui Zhang; Xinggang Li; Kang Zhang; Jian Lei; Haibo Yuan

2009-01-01

376

Diffusion bonding of Al7075 alloy to titanium aluminum vanadate alloy  

Microsoft Academic Search

The aluminum alloy (Al7075) and titanium alloy (Ti-6Al-4V) are used in a variety of applications in the aerospace industry. However, the high cost of Ti-6Al-4V alloy has been a major factor which has limited its use and therefore, the ability to join Al7075 alloy to Ti-6Al-4V alloy can provide a product that is less costly, but retains the high strength

Abdulaziz Nasser Alhazaa

2010-01-01

377

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

NASA Astrophysics Data System (ADS)

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 cast using sand and metallic chill mould with and without strontium addition. Machining on each cast product, was carried out using recommended cutting parameters for Al-Si alloys. Strontium modified samples have recorded a reduction in average flank wear, an increase in shear plane angles and a reduction in chip thickness. The main reason for this improvement is the refining effect of strontium, which reduces the size of the hard silicon particles. As a result, their abrasive action on the tool face has reduced a lot. Dramatic reductions in tool wear rate were recorded when the microstructures were refined. On the other hand, when no refinement of microstructure occurs, tool wear rate becomes high. Chip analysis showed that strontium modified sample produced a thinner chip thickness with a larger shear plane angle, requiring less cutting forces. The tool wear depends not only on the phases present in the work material, but also on their sizes and distribution over entire structure. Thus, strontium modification has better effect on machinability of die cast alloy compared to that of the sand cast LM-6 alloy.

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

378

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

379

Mechanical properties and microstructure of $alpha;-particle irradiated Fe-12% Cr-15, 30% Mn alloys  

NASA Astrophysics Data System (ADS)

The effect of helium injection on the mechanical properties of Fe?Cr?Mn alloys has been investigated. Materials used are Fe-12%Cr-15%Mn alloy and Fe-12%Cr-30%Mn alloy. The elongation of these alloys decreased with alpha particle irradiation. Intergranular-ductile fracture was observed on the Fe-12%Cr-30%Mn alloy in which alpha particles had been injected in amounts up to 2.1 × 10 17 cm -2 at the depth of range, whereas transgranular-ductile fracture occurred on the Fe-12%Cr-15%Mn alloy. These phenomena are, however, in contrast to the authors' previous result of Type 316 stainless steel which showed intergranular-brittle fracture in the helium deposited zone. The difference of formation and distribution of helium bubbles among the two Fe?Cr?Mn alloys and the 316 stainless steel was recognized, and this difference is considered to be an important factor to determine the fracture modes of these materials.

Miyahara, K.; Okazaki, Y.; Mochizukl, M.; Hosoi, Y.; Kayano, H.

1988-07-01

380

Formation and Applications of Bulk Glassy Alloys in Late Transition Metal Base System  

SciTech Connect

This paper reviews our recent results of the formation, fundamental properties, workability and applications of late transition metal (LTM) base bulk glassy alloys (BGAs) developed since 1995. The BGAs were obtained in Fe-(Al,Ga)-(P,C,B,Si), Fe-(Cr,Mo)-(C,B), Fe-(Zr,Hf,Nb,Ta)-B, Fe-Ln-B(Ln=lanthanide metal), Fe-B-Si-Nb and Fe-Nd-Al for Fe-based alloys, Co-(Ta,Mo)-B and Co-B-Si-Nb for Co-based alloys, Ni-Nb-(Ti,Zr)-(Co,Ni) for Ni-based alloys, and Cu-Ti-(Zr,Hf), Cu-Al-(Zr,Hf), Cu-Ti-(Zr,Hf)-(Ni,Co) and Cu-Al-(Zr,Hf)-(Ag,Pd) for Cu-based alloys. These BGAs exhibit useful properties of high mechanical strength, large elastic elongation and high corrosion resistance. In addition, Fe- and Co-based glassy alloys have good soft magnetic properties which cannot be obtained for amorphous and crystalline type magnetic alloys. The Fe- and Ni-based BGAs have already been used in some application fields. These LTM base BGAs are promising as new metallic engineering materials.

Inoue, Akihisa; Shen Baolong [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

2006-05-05

381

Electromagnetic stirring of aluminium-silicon alloys  

Microsoft Academic Search

A laboratory-scale electromagnetic stirrer was designed, constructed and tested on two aluminium-silicon alloys with silicon contents of seven and twenty mass per cent. The effect of stirring intensity on the structure of the hypoeutectic alloy was studied and also thermal analysis was performed. For the case of the hypereutectic alloy, the distribution of silicon was determined. The results demonstrate that

D. A. Currey; C. A. Pickles

1988-01-01

382

Alloy rotary kilns for hazardous waste disposal  

Microsoft Academic Search

The major conclusions of the study of rotary kilns for processing abrasive, energetic or corrosive hazardous wastes are: Alloy kilns are preferable to smaller refractory lined kilns for abrasive and\\/or explosive feed materials. Alloy construction and bolted sections make alloy kilns transportable; a pyrolysis operating mode can reduce the equipment size for wastes with a high energy release rate. However,

J. V. Del Bene; J. K. Shah; E. F. Colburn

1987-01-01

383

Welding high-strength aluminum alloys  

NASA Technical Reports Server (NTRS)

Handbook has been published which integrates results of 19 research programs involving welding of high-strength aluminum alloys. Book introduces metallurgy and properties of aluminum alloys by discussing commercial alloys and heat treatments. Several current welding processes are reviewed such as gas tungsten-arc welding and gas metal-arc welding.

Parks, P. G.; Hoppes, R. V.; Hasemeyer, E. A.; Masubuchi, K.

1974-01-01

384

UML2Alloy: A Challenging Model Transformation  

E-print Network

UML2Alloy: A Challenging Model Transformation Kyriakos Anastasakis1 , Behzad Bordbar1 , Geri Georg2,iray]@cs.colostate.edu Abstract. Alloy is a formal language, which has been applied to mod- elling of systems in a wide range of application domains. It is supported by Alloy Analyzer, a tool, which allows fully automated analysis

Bordbar, Behzad

385

HIGHLY DISPERSED ALLOY CATHODE CATALYST FOR DURABILITY  

E-print Network

HIGHLY DISPERSED ALLOY CATHODE CATALYST FOR DURABILITY T. D. Jarvi UTC Power Corporation This presentation does not contain any proprietary or confidential information #12;HIGHLY DISPERSED ALLOY CATALYSTVRHE (IR-Free) 720 A/cm2 Cost $8/kW #12;HIGHLY DISPERSED ALLOY CATALYST CurrentStateofArtcathodes (e

386

Fatigue crack propagation in aerospace aluminum alloys  

Microsoft Academic Search

This article reviews fracture mechanics-based, damage tolerant characterizations and predictions of fatigue crack growth in aerospace aluminum alloys. The results of laboratory experimentation and micromechanical modeling are summarized in the areas of 1) the wide range crack growth rate response of conventional aluminum alloys, 2) fatigue crack closure, 3) the fatigue behavior of advanced monolithic aluminum alloys and metal matrix

Richard P. Gangloff; Robert S. Piascik; Dennis L. Dicus; James C. Newman Jr.

1994-01-01

387

Environmental behavior of beta titanium alloys  

Microsoft Academic Search

Stemming from their unique combination of elevated strength, low density, and good overall corrosion resistance, beta titanium alloys have become attractive candidate materials for critical, high-stress components in corrosive services. An overview of the comparative corrosion resistance of beta alloys to conventional alpha and alpha\\/beta titanium alloys in common industrial and aerospace service environments generally reveals attractive behavior depending on

Schutz

1994-01-01

388

Creep degradation in oxide-dispersion-strengthened alloys  

NASA Technical Reports Server (NTRS)

Oxide dispersion strengthened Ni-base alloys in wrought bar form are studied for creep degradation effects similar to those found in thin gage sheet. The bar products evaluated included ODS-Ni, ODS-NiCr, and three types of advanced ODS-NiCrAl alloys. Tensile test specimens were exposed to creep at various stress levels at 1365 K and then tensile tested at room temperature. Low residual tensile properties, change in fracture mode, the appearance of dispersoid-free bands, grain boundary cavitation, and internal oxidation in the microstructure were interpreted as creep degradation effects. This work showed that many ODS alloys are subject to creep damage. Degradation of tensile properties occurred after very small amounts of creep strain, ductility being the most sensitive property. All the ODS alloys which were creep damaged possessed a large grain size. Creep damage appears to have been due to diffusional creep which produced dispersoid-free bands around boundaries acting as vacancy sources. Low angle and possibly twin boundaries acted as vacancy sources.

Whittenberger, J. D.

1977-01-01

389

Mechanically alloyed metal hydride systems  

NASA Astrophysics Data System (ADS)

Mechanosynthesis of metal hydrides is a new field in which important progress has been reported. In this paper, we present recent developments in mechanosynthesis of magnesium-based hydrides for storage applications. The effect of intense milling on magnesium and magnesium hydrides is presented. The influence of various additives on hydrogen-sorption properties is discussed with special emphasis on nanocomposite MgH2+5 at.%V, where hydrogen-storage characteristics, cycling properties and the mechanism of hydrogen desorption are presented. The production of novel nanocrystalline porous structures by mechanical alloying followed by a leaching technique is discussed. Hot ball-milling, as a new method for rapid synthesis of alloys, is also presented. Finally, two other methods of production of metal hydrides are discussed. One is reactive milling where metal hydrides are synthesized by mechanical alloying under hydrogen pressure, while the other is milling elemental hydrides to produce complex hydrides.

Huot, J.; Liang, G.; Schulz, R.

2001-04-01

390

Alloy Semiconductor Crystal Growth Under Microgravity  

SciTech Connect

Microgravity studies on the dissolution and crystallization of In{sub x}Ga{sub 1-x}Sb have been done using a sandwich combination of InSb and GaSb as the starting material using the Chinese recoverable satellite. The same type of experiment was performed under 1G gravity condition for comparison. From these experiments and the numerical simulation, it is found that the shape of the solid/liquid interface and composition profile in the solution was found to be significantly affected by gravity. GaSb seed was dissolved faster than GaSb feed even though the GaSb feed temperature was higher than that of GaSb seed temperature. These results clearly indicate that solute transport due to gravity affects dissolution and growth processes of alloy semiconductor bulk crystals.

Hayakawa, Yasuhiro; Arivanandhan, Mukannan; Rajesh, Govindasamy; Tanaka, Akira [Research Institute of Electronics, Shizuoka University, Johoku 3-5-1, Naka-Ku, Hamamatsu, Shizuoka 432-8011 (Japan); Ozawa, Tetsuo [Shizuoka Institute of Science and Technology, 2200-2 Toyozawa, Fukuroi, Shizuoka 437-8555 (Japan); Okano, Yasunori [Graduate School of Engineering Science, Osaka University, 1-3 Machiganeyama, Osaka 560-8531 (Japan); Sankaranarayanan, Krishnasamy [Alagappa University, Karaikudi, Tamilnadu (India); Inatomi, Yuko [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan)

2010-12-01

391

Diffusion phase transitions in alloys  

NASA Astrophysics Data System (ADS)

We present a critical analysis of research on the thermodynamics, kinetics, and morphology of diffusion phase transitions in alloys. We show that diffusion phase transitions are mainly driven by the chemical potential difference due to a change in the sign of the chemical interaction among the component atoms. We explain how the sign of the chemical interaction energy can be obtained from experimental measurements. Examples are given to illustrate the kinetics and morphology of the ordering-separation phase transition in Ni- and Co-based alloys. We show how introducing the concept of the ordering-separation phase transition may affect our thinking in this area.

Ustinovshchikov, Yu I.

2014-07-01

392

Understanding the Cu-Zn brass alloys using a short-range-order cluster model: significance of specific compositions of industrial alloys  

PubMed Central

Metallic alloys show complex chemistries that are not yet understood so far. It has been widely accepted that behind the composition selection lies a short-range-order mechanism for solid solutions. The present paper addresses this fundamental question by examining the face-centered-cubic Cu-Zn ?-brasses. A new structural approach, the cluster-plus-glue-atom model, is introduced, which suits specifically for the description of short-range-order structures in disordered systems. Two types of formulas are pointed out, [Zn-Cu12]Zn1~6 and [Zn-Cu12](Zn,Cu)6, which explain the ?-brasses listed in the American Society for Testing and Materials (ASTM) specifications. In these formulas, the bracketed parts represent the 1st-neighbor cluster, and each cluster is matched with one to six 2nd-neighbor Zn atoms or with six mixed (Zn,Cu) atoms. Such a cluster-based formulism describes the 1st- and 2nd-neighbor local atomic units where the solute and solvent interactions are ideally satisfied. The Cu-Ni industrial alloys are also explained, thus proving the universality of the cluster-formula approach in understanding the alloy selections. The revelation of the composition formulas for the Cu-(Zn,Ni) industrial alloys points to the common existence of simple composition rules behind seemingly complex chemistries of industrial alloys, thus offering a fundamental and practical method towards composition interpretations of all kinds of alloys. PMID:25399835

Hong, H. L.; Wang, Q.; Dong, C.; Liaw, Peter K.

2014-01-01

393

Understanding the Cu-Zn brass alloys using a short-range-order cluster model: significance of specific compositions of industrial alloys.  

PubMed

Metallic alloys show complex chemistries that are not yet understood so far. It has been widely accepted that behind the composition selection lies a short-range-order mechanism for solid solutions. The present paper addresses this fundamental question by examining the face-centered-cubic Cu-Zn ?-brasses. A new structural approach, the cluster-plus-glue-atom model, is introduced, which suits specifically for the description of short-range-order structures in disordered systems. Two types of formulas are pointed out, [Zn-Cu12]Zn1~6 and [Zn-Cu12](Zn,Cu)6, which explain the ?-brasses listed in the American Society for Testing and Materials (ASTM) specifications. In these formulas, the bracketed parts represent the 1(st)-neighbor cluster, and each cluster is matched with one to six 2(nd)-neighbor Zn atoms or with six mixed (Zn,Cu) atoms. Such a cluster-based formulism describes the 1(st)- and 2(nd)-neighbor local atomic units where the solute and solvent interactions are ideally satisfied. The Cu-Ni industrial alloys are also explained, thus proving the universality of the cluster-formula approach in understanding the alloy selections. The revelation of the composition formulas for the Cu-(Zn,Ni) industrial alloys points to the common existence of simple composition rules behind seemingly complex chemistries of industrial alloys, thus offering a fundamental and practical method towards composition interpretations of all kinds of alloys. PMID:25399835

Hong, H L; Wang, Q; Dong, C; Liaw, Peter K

2014-01-01

394

Structure formed in two-phase (? + ?) field and mechanical properties of a cryogenic alloy 10N7  

NASA Astrophysics Data System (ADS)

The effect of different types of structures produced by quenching from the intercritical temperature range on the strength, plasticity, and impact toughness of the Fe-6.9Ni-0.1C alloy has been studied. Two structures—ferrite + globular cementite and lath martensite—have been used as the initial state. The rate of heating into the two-phase (? + ?) field has been selected such that four morphological types of twophase structures, namely, ferritic-martensitic (Widmanstäten or globular) and duplex (lamellar or lamellarglobular), could be formed in a single alloy as a result of partial ? ? ? and ? ? ? transformations. It has been found that the mechanical properties of the alloy depend on the type of the initial structure and on the rate and temperature of heating to the intercritical temperature range. It has been shown that the alloy with a Widmanstätten ferritic-martensitic structure has a more favorable combination of the strength and plasticity properties than the alloy with a globular structure. The alloy with a lamellar duplex structure offers a much higher level of the impact toughness, plasticity, and strength at low temperatures than the alloy with a Widmanstätten ferritic-martensitic structure.

Khomskaya, I. V.

2010-08-01

395

Microstructure-property relationships in Al-Cu-Li-Ag-Mg Weldalite (tm) alloys, part 2  

NASA Technical Reports Server (NTRS)

The microstructure and mechanical properties of the ultrahigh strength Al-Cu-Li-Ag-Mg alloy, Weldalite (tm) 049, were studied. Specifically, the microstructural features along with tensile strength, weldability, Young's modulus and fracture toughness were studied for Weldalite (tm) 049 type alloys with Li contents ranging from 1.3 to 1.9 wt. pct. The tensile properties of Weldalite 049 and Weldalite 049 reinforced with TiB2 particles fabricated using the XD (tm) process were also evaluated at cryogenic, room, and elevated temperatures. In addition, an experimental alloy, similar in composition to Weldalite 049 but without the Ag+Mg, was fabricated. The microstructure of this alloy was compared with that of Weldalite 049 in the T6 condition to assess the effect of Ag+Mg on nucleation of strengthening phases in the absence of cold work.

Langan, T. J.; Pickens, J. R.

1991-01-01

396

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

SciTech Connect

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

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

2007-08-10

397

[Structural changes in bronze (Gaudent) and Palliag alloys following corrosion effects].  

PubMed

Due to socio-economic considerations the use of two new types of non-oxydable alloys satisfactory for practical necessities should be examined more closely with a view to acquire a better knowledge of their behaviour. The present study investigates the behaviour of Gaudent and Palliag alloys under the effects of corroding agents. An analysis with an electronic micro-probe of the samples of ally exposed to corroding effects has evidenced various reactions in the buccal cavity and in the environment. In the buccal cavity the bronze alloy (Gaudent) has, in most of the cases, a satisfactory reaction from the macroscopical viewpoint. However, when exposed to hydrochloric acid and sodium hydroxide solutions it undergoes an intercrystalline corrosion and its surface aspect is changed. The Palliag alloy has an evident microscopic stability against these corroding agents. PMID:2535073

Serb, H; Rînda?u, I; Donciu, V

1989-01-01

398

The localized corrosion resistance and mechanical properties of alloy 22 waste package outer containers  

NASA Astrophysics Data System (ADS)

The proposed waste packages for the disposal of high-level radioactive waste at the potential repository at Yucca Mountain, Nevada, consist of an outer container and inner container. The outer container is made of alloy 22, a corrosion-resistant Ni-Cr-Mo-W alloy, while the inner container is made of type 316 nuclear-grade stainless steel. Fabrication processes such as welding and postweld heat treatments can induce changes to the microstructure of alloy 22. Such microstructural changes can reduce ductility and impact strength and promote localized corrosion. Environmental conditions within the emplacement drifts, such as composition of solutions contacting the waste packages, can also affect localized corrosion susceptibility. In this study, the effects of fabrication processes on impact strength, fracture toughness, and crevice-corrosion resistance of alloy 22 were investigated.

Dunn, D. S.; Pan, Y.-M.; Chiang, K. T.; Yang, L.; Cragnolino, G. A.; He, X.

2005-01-01

399

Microstructural characterization of selected AEA/UCSB model FeCuMn alloys  

SciTech Connect

A set of 22 model ferritic alloys was purchased as part of a collaborative research program by the AEA Harwell Laboratory and the University of California at Santa Barbara. Nine of these alloys were selected by the Oak Ridge National Laboratory for use in a series of ion irradiation experiments investigating dispersed barrier hardening. These nine alloys contain varying amounts of copper, manganese, titanium, carbon, and nitrogen. The alloys have been characterized by transmission electron microscopy in the as-received condition to provide a baseline for comparison with the irradiated specimens. A description of the microstructural observations is provided for future reference. This summary focuses on the type and size distributions of the precipitates present; grain size and dislocation measurements are also included.

Rice, P.M.; Stoller, R.E.

1996-06-01

400

In vitro studies of biomedical magnesium alloys in a simulated physiological environment: a review.  

PubMed

In spite of the immense potential of biodegradable magnesium alloys, the fast degradation rates of Mg-based biomedical implants in the physiological environment impose severe limitations in many clinical applications. Consequently, extensive in vitro studies have been carried out to investigate the materials' performance and fathom the associated mechanisms. Here, an up-to-date review of the in vitro studies on biomedical magnesium alloys in a simulated physiological environment is provided. This review focuses on four topics: (1) materials selection and in vitro biocompatibility of biomedical magnesium alloys; (2) in vitro degradation of biomedical magnesium alloys in simulated physiological environments, specifically discussing corrosion types, degradation rates, corrosion products and impact of the constituents in body fluids on materials degradation; (3) selection of suitable test media for in vitro assessment; and (4) future research trends. PMID:21145436

Xin, Y; Hu, T; Chu, P K

2011-04-01

401

In-situ SEM observation on the fracture of V-5Cr-5Ti alloy  

NASA Astrophysics Data System (ADS)

The damage and fracture characteristic of V-5Cr-5Ti (wt.%) alloy was investigated using scanning electron microscope (SEM) with a micro-tension holder. Two types of specimen were used: smooth sheet and single-edge notched sheet. Results show that the microscopic fracture mechanism of smooth sheet alloy is microvoid coalescence and sliding off. What the fracture process shows is that the damage of smooth specimen stems from the inside. The alloy can be strengthened by single-edge notch but still remains considerable ductility. The main fracture mechanism of notched specimens is sliding off and quasi-cleavage. The main crack initiates at the root of notch and propagates along a zig-zag path. Grain boundary is a main barrier for crack propagation. Finite element method (FEM) simulation shows that the crack growth relaxes the stress of notched specimen, which in turn changes the fracture mechanism of alloy.

Li, Yufei; Dong, Ping; Li, Ruiwen; Yang, Jiangrong; Xie, Jijia

2012-02-01

402

Phase transformation of Mg-Fe alloys  

SciTech Connect

An Mg-Fe alloy system prepared through mechanical alloying (MA) was structurally analyzed. MA can produce single-phase bcc alloys using Mg concentrations up to about 15 mol %. Use of conventional average structure analysis and x-ray pair-distribution function method enabled the long-range and short-range order structures of the Mg-Fe alloys to be bridged. The substituted Mg atoms were randomly arranged in the low-Mg composition but started to have an order structure. The partially ordered Mg-Fe alloy undergoes an austenitic (cubic) to martensitic (orthorhombic) phase change, as increasing Mg composition.

Yoneda, Yasuhiro [Synchrotron Radiation Research Unit, Japan Atomic Energy Agency, 1-1-1 Kouto, Sayo-cho Sayo-gun, Hyogo 679-5148 (Japan); Abe, Hiroshi; Ohshima, Takeshi [Department of Material development, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Uchida, Hirohisa [Department of Applied Physics, Graduate and Undergraduate Schools of Engineering, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan)

2010-05-15

403

Alloy softening in binary iron solid solutions  

NASA Technical Reports Server (NTRS)

An investigation was conducted to determine softening and hardening behavior in 19 binary iron-alloy systems. Microhardness tests were conducted at four temperatures in the range 77 to 411 K. Alloy softening was exhibited by 17 of the 19 alloy systems. Alloy softening observed in 15 of the alloy systems was attributed to an intrinsic mechanism, believed to be lowering of the Peierls (lattice friction) stress. Softening and hardening rates could be correlated with the atomic radius ratio of solute to iron. Softening observed in two other systems was attributed to an extrinsic mechanism, believed to be associated with scavenging of interstitial impurities.

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

1976-01-01

404

Protective claddings for high strength chromium alloys  

NASA Technical Reports Server (NTRS)

The application of a Cr-Y-Hf-Th alloy as a protective cladding for a high strength chromium alloy was investigated for its effectiveness in inhibiting nitrogen embrittlement of a core alloy. Cladding was accomplished by a combination of hot gas pressure bonding and roll cladding techniques. Based on bend DBTT, the cladding alloy was effective in inhibiting nitrogen embrittlement of the chromium core alloy for up to 720 ks (200hours) in air at 1422 K (2100 F). A significant increase in the bend DBTT occurred with longer time exposures at 1422 K or short time exposures at 1589 K (2400 F).

Collins, J. F.

1971-01-01

405

Semiempirical Analysis of Surface Alloy Formation  

NASA Technical Reports Server (NTRS)

The BFS method for alloys is applied to the study of surface alloy formation. This method was previously used to examine the experimental STM observation of surface alloying of Au on Ni(110) for low Au coverages by means of a numerical simulation. In this work, we extend the study to include other cases of surface alloying for immiscible as well as miscible metals. All binary combinations of Ni, Au, Cu, and Al are considered and the simulation results are compared to experiment when data is available. The driving mechanisms of surface alloy formation are then discussed in terms of the BFS method and the available results.

Bozzolo, Guillermo; Ferrante, John; Ibanez-Meier, Rodrigo

1995-01-01

406

High-alloy materials for offshore applications  

SciTech Connect

High-alloy materials possessing good corrosion resistance in hot, sour brines are being seriously considered for offshore applications. These alloys are available in a wide range of strength levels which can be attained by the methods of cold working or precipitation hardening. Results of testing INCONEL alloys 625 and 718 and INCOLOY alloys 825 and 925 for resistance to general corrosion, hydrogen embrittlement, and stress-corrosion cracking (SCC) are presented. This paper also contrasts the range of mechanical properties available in precipitation-hardened materials with properties of cold-worked alloys.

Lemke, T.F.; Harris, J.A.

1983-05-01

407

Creep Behavior of Hydrogenated Zirconium Alloys  

NASA Astrophysics Data System (ADS)

Zirconium (Zr) alloys are the primary structural materials of most water reactors. Creep is considered to be one of the important degradation mechanisms of Zr alloys during reactor operating and repository conditions. Zr alloys pick up hydrogen (H2) during their service from the coolant water. Hydrogen can be present in solid solution or precipitated hydride form in Zr alloys depending upon the temperature and concentration. This study reviews the effect of hydrogen on creep behavior of Zr alloys used in the water reactors.

Sarkar, A.; Boopathy, K.; Eapen, J.; Murty, K. L.

2014-10-01

408

The Effects of Test Temperature, Temper, and Alloyed Copper on the Hydrogen-Controlled Crack Growth Rate of an Al-Zn-Mg-(Cu) Alloy  

SciTech Connect

The hydrogen embrittlement controlled stage II crack growth rate of AA 7050 (6.09 wt.% Zn, 2.14 wt% Mg, 2.19 wt.% Cu) was investigated as a function of temper and alloyed copper level in a humid air environment at various temperatures. Three tempers representing the underaged, peak aged, and overaged conditions were tested in 90% relative humidity (RH) air at temperatures between 25 and 90 C. At all test temperatures, an increased degree of aging (from underaged to overaged) produced slower stage II crack growth rates. The stage II crack growth rate of each alloy and temper displayed Arrhenius-type temperature dependence with activation energies between 58 and 99 kJ/mol. For both the normal copper and low copper alloys, the fracture path was predominantly intergranular at all test temperatures (25-90 C) in each temper investigated. Comparison of the stage II crack growth rates for normal (2.19 wt.%) and low (0.06 wt.%) copper alloys in the peak aged and overaged tempers showed the beneficial effect of copper additions on stage II crack growth rate in humid air. In the 2.19 wt.% copper alloy, the significant decrease ({approx} 10 times at 25 C) in stage II crack growth rate upon overaging is attributed to an increase in the apparent activation energy for crack growth. IN the 0.06 wt.% copper alloy, overaging did not increase the activation energy for crack growth but did lower the pre-exponential factor, {nu}{sub 0}, resulting in a modest ({approx} 2.5 times at 25 C) decrease in crack growth rate. These results indicate that alloyed copper and thermal aging affect the kinetic factors that govern stage II crack growth rate. Overaged, copper bearing alloys are not intrinsically immune to hydrogen environment assisted cracking but are more resistant due to an increased apparent activation energy for stage II crack growth.

G.A. Young, Jr.; J.R. Scully

2000-09-17

409

Stress corrosion cracking behavior of irradiated model austenitic stainless steel alloys.  

SciTech Connect

Slow-strain-rate tensile tests (SSRTs) and posttest fractographic analyses by scanning electron microscopy were conducted on 16 austenitic stainless steel (SS) alloys that were irradiated at 289 C in He. After irradiation to {approx}0.3 x 10{sup 21} n{center_dot}cm{sup {minus}2} and {approx}0.9 x 10{sup 21} n{center_dot}cm{sup {minus}2} (E >1 MeV), significant heat-to-heat variations in the degree of intergranular and transgranular stress corrosion cracking (IGSCC and TGSCC) were observed. Following irradiation to a fluence of {approx}0.3 x 10{sup 21} n{center_dot}cm{sup {minus}2}, a high-purity laboratory heat of Type 316L SS (Si {approx} 0.024 wt%) exhibited the highest susceptibility to IGSCC. The other 15 alloys exhibited negligible susceptibility to IGSCC at this low fluence. The percentage of TGSCC on the fracture surfaces of SSRT specimens of the 16 alloys at {approx}0.3 x 10{sup 21} n{center_dot}cm{sup {minus}2} (E > 1 MeV) could be correlated well with N and Si concentrations; all alloys that contained <0.01 wt.% N and <1.0 wt. % Si were susceptible, whereas all alloys that contained >0.01 wt.% N or >1.0 wt.% Si were relatively resistant. High concentrations of Cr were beneficial. Alloys that contain <15.5 wt.% Cr exhibited greater percentages of TGSCC and IGSCC than those alloys with {approx}18 wt.% Cr, whereas an alloy that contains >21 wt.% Cr exhibited less susceptibility than the lower-Cr alloys under similar conditions.

Chung, H. M.; Karlsen, T. M.; Ruther, W. E.; Shack, W. J.; Strain, R. V.

1999-07-16

410

Multi-Freedom Tube Type Manipulator with SMA Plate  

Microsoft Academic Search

The tube type multiple link micromanipulator using SMA (Shape Memory Alloy) has been conducted. The conceptual model of this manipulator has five linked pipes with 1 mm in diameter. On each link, a temperature\\/strain sensor and a control IC chip are equipped for position and\\/or force feedback control. We have successfully fabricated a prototype. This tube type manipulator, which is

Shinji Kaneko; Shinji Aramaki; Kazuhiko Arai; Yuichiro Takahashi; Hideyuki Adachi; Kazuhisa Yanagisawa

1996-01-01

411

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

412

Eutectic nucleation in Al-Si alloys  

SciTech Connect

In addition to a change in silicon morphology, modification of aluminium-silicon alloys with strontium or sodium increases the size of the eutectic grains. To determine the mechanism responsible, eutectic solidification in commercial purity and ultra-high purity aluminium-silicon alloys, with and without strontium additions, was examined by a quenching technique. In the commercial unmodified alloy, nucleation was prolific while in the high-purity unmodified alloy few eutectic grains nucleated. The addition of strontium to the commercial alloy reduced the number of eutectic grains that nucleated. Addition of strontium to the high-purity alloy did not significantly alter nucleation. It is concluded that commercial purity alloys contain a large number of potent nuclei that are susceptible to poisoning by impurity modification. The flake-to-fibre transition that occurs with impurity modification is shown to be independent of any change in eutectic nucleation mode and frequency.

McDonald, Stuart D.; Nogita, Kazuhiro; Dahle, Arne K

2004-08-16

413

Fractal characteristics of dendrite in aluminum alloys  

NASA Astrophysics Data System (ADS)

The fractal dimensions of dendrites in Al-Si and Al-Cu binary alloys were measured under furnace cooling and casting experiments. The fractal dimension of the Al-Si alloy increased from 1.275 to 1.495 along with increase in Si content. The fractal dimension of the Al-Cu alloy increased from 1.139 to 1.486 along with increase in Cu content. The fractal dimension of the binary alloys also increased with increase in cooling rate during solidification. Phase-field simulations for the evolution of the dendrites in the binary aluminium alloys were carried out and a same tendency as the experimental results was obtained. The permeability of an Al-5mass%Si alloy was estimated from the measured fractal dimension of an experimentally observed dendrite structure. The estimated permeability agreed well with reported permeability of an Al-Si alloy.

Ohsasa, K.; Katsumi, T.; Sugawara, R.; Natsume, Y.

2012-07-01

414

Environmental fatigue in aluminum-lithium alloys  

NASA Technical Reports Server (NTRS)

Aluminum-lithium alloys exhibit similar environmental fatigue crack growth characteristics compared to conventional 2000 series alloys and are more resistant to environmental fatigue compared to 7000 series alloys. The superior fatigue crack growth behavior of Al-Li alloys 2090, 2091, 8090, and 8091 is due to crack closure caused by tortuous crack path morphology and crack surface corrosion products. At high R and reduced closure, chemical environment effects are pronounced resulting in accelerated near threshold da/dN. The beneficial effects of crack closure are minimized for small cracks resulting in rapid growth rates. Limited data suggest that the 'chemically small crack' effect, observed in other alloy system, is not pronounced in Al-Li alloys. Modeling of environmental fatigue in Al-Li-Cu alloys related accelerated fatigue crack growth in moist air and salt water to hydrogen embrittlement.

Piascik, Robert S.

1992-01-01

415

Environmental fatigue in aluminum-lithium alloys  

NASA Astrophysics Data System (ADS)

Aluminum-lithium alloys exhibit similar environmental fatigue crack growth characteristics compared to conventional 2000 series alloys and are more resistant to environmental fatigue compared to 7000 series alloys. The superior fatigue crack growth behavior of Al-Li alloys 2090, 2091, 8090, and 8091 is due to crack closure caused by tortuous crack path morphology and crack surface corrosion products. At high R and reduced closure, chemical environment effects are pronounced resulting in accelerated near threshold da/dN. The beneficial effects of crack closure are minimized for small cracks resulting in rapid growth rates. Limited data suggest that the 'chemically small crack' effect, observed in other alloy system, is not pronounced in Al-Li alloys. Modeling of environmental fatigue in Al-Li-Cu alloys related accelerated fatigue crack growth in moist air and salt water to hydrogen embrittlement.

Piascik, Robert S.

1992-07-01

416

Alcoa: the alloy constraint analyzer  

Microsoft Academic Search

Alcoa is a tool for analyzing object models. It has a range of uses. At one end, it can act as a support tool for object model diagrams, checking for consistency of multiplicities and generating sample snapshots. At the other end, it embodies a lightweight formal method in which subtle properties of behaviour can be investigated.Alcoa's input language, Alloy, is

Daniel Jackson; Ian Schechter; Hya Shlyahter

2000-01-01

417

Alcoa: the Alloy constraint analyzer  

Microsoft Academic Search

Alcoa is a tool for analyzing object models. It has a range of uses. At one end, it can act as a support tool for object model diagrams, checking for consistency of multiplicities and generating sample snapshots. At the other end, it embodies a lightweight formal method in which subtle properties of behaviour can be investigated. Alcoa's input language, Alloy,

Daniel Jackson; Ian Schechter; Ilya Shlyakhter

2000-01-01

418

Dispersion-strengthened chromium alloy  

NASA Technical Reports Server (NTRS)

Finely divided powder mixture produced by vapor deposition of CR on small ThO2 particles was hot pressed or pressure bonded. Resulting alloy has lower ductile-to-brittle transition temperature than pure chromium, and high strength and oxidation resistance at elevated temperatures, both in as-rolled condition and after annealing.

Blocker, J. M., Jr.; Veigel, N. D.

1972-01-01

419

Machining of aerospace titanium alloys  

Microsoft Academic Search

The performance of PCBN (AMBORITE*) and PCD (SYNDITE) has been compared with that of coated tungsten carbide tool currently being used to machine titanium aerospace alloy. Tests confirm that SYNDITE gives a better surface finish, longer tool life and more manageable swarf than other tools. In addition, the “quick-stop” technique establishes that, for all three cutting tools, a layer is

Farhad Nabhani

2001-01-01

420

Welding of TZM molybdenum alloy  

Microsoft Academic Search

Molybdenum and TZM alloy are not too difficult to form or weld if the proper procedures are employed. Consistently good welds can be obtained by controlling the area of heating by ensuring full penetration of the welded pieces and by reducing the stresses. A large percentage of the problems incurred in welding TZM can be corrected by good weld joint

Hanks

1970-01-01

421

Volcano Types  

NSDL National Science Digital Library

This site lists the basic types of volcanoes: scoria cone, shield volcano, and stratovolcano. Each is described in terms of shape, composition, and eruption type, and links are available to additional information. Subordinate types listed include fissure eruptions, spatter cones, hornitos, and hydrovolcanic eruptions. The site also explains when a volcano is considered active, dormant, or extinct. In addition, generic features such as vent, central vent, edifice, magma chamber, parasitic cones, and fumaroles are listed and described.

Camp, Victor

422

Iron alloys with new functional properties obtained during reverse martensitic transformation  

NASA Astrophysics Data System (ADS)

It was shown that different types of the austenite (homogeneous and inhomogeneous polyhedral, or submicrocrystalline and nanocrystalline plate austenite) can be formed, providing new functional properties of various steels and alloys. The austenite formed during a partial ?to? transformation increases considerably the strength of the martensite, enhances the coercive force and improves the square shape of the hysteresis loop of maraging steels. The thermal expansion coefficient of the austenitic alloy type 32Ni can be adjusted over broad limits thanks to different ?to? transformation conditions. A stainless steel with a structure of alternating laths of the martensite and the austenite has a high resistance to radiation void formation.

Sagaradze, V. V.; Danilchenko, V. E.; L'Heritier, P.; Sagaradze, I. V.

2003-10-01

423

Microstructure and Strength Characteristics of Alloy 617 Welds  

SciTech Connect

Three types of high-temperature joints were created from alloy 617 base metal: fusion welds, braze joints, and diffusion bonds. The microstructures of all joint types and tensile properties of fusion welds and braze joints were characterized. Sound fusion welds were created by the GTAW process with alloy 617 filler wire. Cross-weld tensile strengths were equal to the parent metal at temperatures of 25, 800, and 1000°C; ductilities of the joints were only slightly lower than that of the parent metal. Failure occurred in the weld fusion zone at room temperature and in the parent metal at elevated temperatures. Incomplete wetting occurred in joints produced by vacuum brazing using AWS BNi-1 braze alloy, believed to be due to tenacious Al and Ti oxide formation. Incompletely bonded butt joints showed relatively poor tensile properties. A second set of braze joints has been created with faying surfaces electroplated with pure Ni prior to brazing; characterization of these joints is in progress. Conditions resulting in good diffusion bonds characterized by grain growth across the bondline and no porosity were determined: vacuum bonding at 1150°C for 3 hours with an initial uniaxial stress of 20 MPa (constant ram displacement). A 15 µm thick pure Ni interlayer was needed to achieve grain growth across the bondline. Tensile testing of diffusion bonds is in progress

T.C. Totemeier; H. Tian; D.E. Clark; J.A. Simpson

2005-06-01

424

Strainhardening and softening of vanadium-alloyed ferrite  

Microsoft Academic Search

This investigation into the softening of alloyed ferrlte was concerned with the changes in mechanical properties and microstructure of alloys. G. Tammann [1] alloyed solid solutions with small amounts of alloy elements producing equiatomic concentrations, this permitting a comparison os the effects of various elements in the most correct fashion. Austin in [2, 3] showed that alloy additions ~ncrease the

L. I. Mirkin

1959-01-01

425

Cloud Types  

NSDL National Science Digital Library

This tutorial explains common cloud classifications and the Latin root words that have been adapted to create the various names of clouds. The classification is subdivided into high-, low-, and mid-level types, clouds with vertical development, and other, less common types. Each description is accompanied by an example photograph.

2005-03-10

426

CORROSION OF HIGH-TEMPERATURE ALLOYS  

SciTech Connect

Five alloys were tested in the presence of water vapor and water vapor with HCl for 1000 hours using simulated combustion gas. Samples were removed at intervals during each test and measured for determination of corrosion rates. One sample of each alloy was examined with a SEM after the completion of each test. Cumulative corrosion depths were similar for the superstainless alloys. Corrosion for Alloy TP310 roughly doubled. Corrosion for the enhanced stainless alloys changed dramatically with the addition of chlorine. Corrosion for Alloy RA85H increased threefold, whereas Alloy TP347HFG showed an eightfold increase. SEM examination of the alloys revealed that water vapor alone allowed the formation of chromium oxide protective layers on the superstainless alloys. The enhanced stainless alloys underwent more corrosion due to greater attack of sulfur. Iron-rich oxide layers were more likely to form, which do not provide protection from further corrosion. The addition of chlorine further increased the corrosion because of its ability to diffuse through the oxide layers and react with iron. This resulted in a broken, discontinuous, and loose oxide layer that offered less protection. Niobium, although added to aid in creep strength, was found to be detrimental to corrosion resistance. The niobium tended to be concentrated in nodules and was easily attacked through sulfidation, providing conduits for further corrosion deep into the alloy. The alloys that displayed the best corrosion resistance were those which could produce chromium oxide protective layers. The predicted microstructure of all alloys except Alloy HR3C is the same and provided no further information relating to corrosion resistance. No correlation can be found relating corrosion resistance to the quantity of minor austenite-or ferrite-stabilizing elements. Also, there does not appear to be a correlation between corrosion resistance and the Cr:Ni ratio of the alloy. These alloys were tested for their corrosion resistance alone. Strength and creep tests were not performed. Based only their corrosion resistance, Alloys RA310 and TP310 were shown to be the best suited to resist chlorine in a combustion environment. These alloys produced protective chromium oxide layers, displayed more general rather than localized corrosion, and their additives did not react to provide conduits for further corrosion.

John P. Hurley; John P. Kay

1999-10-01

427

Optical absorption properties of dispersed gold and silver alloy nanoparticles.  

PubMed

The oldest topic in nanoscience is the size-dependent optical properties of gold and silver colloids or nanoparticles, first investigated scientifically by Michael Faraday in 1857. In the modern era, advances in both synthesis and characterization have resulted in new insights into the size-dependent absorbance of Au and Ag nanoparticles with sizes below the classical limit for Mie theory. In this paper we discuss the synthesis and properties of core/shell and nanoalloy particles of Au and Ag, compare them to particles of pure gold and silver, and discuss how alloying affects nanoparticle chemical stability. We show that composition, size, and nanostructure (e.g., core/shell vs quasi-random nanoalloy) can all be employed to adjust the optical absorbance properties. The type of nanostructure--core/shell vs alloy--is reflected in their optical absorbance features. PMID:19708105

Wilcoxon, Jess

2009-03-01

428

The Weathering of Aluminum Alloy Sheet Materials Used in Aircraft  

NASA Technical Reports Server (NTRS)

This report presents the results of an investigation of the corrosion of aluminum alloy sheet materials used in aircraft. It has for its purpose to study the causes of corrosion embrittlement in duralumin-type alloys and the development of methods for its elimination. The report contains results, obtained in an extensive series of weather-exposure tests, which reveal the extent to which the resistance of the materials to corrosion was affected by variable factors in their heat treatment and by the application of various surface protective coatings. The results indicate that the sheet materials are to be regarded as thoroughly reliable, from the standpoint of their permanence in service, provided proper precautions are taken to render them corrosion-resistant.

Mutchler, Willard

1935-01-01

429

Substitutional alloying and deformation modes in high chromium ferritic alloys  

Microsoft Academic Search

The effect of microalloying additions of between 0.05 and 2 wt pct Ni, Ru, Nb, and Ti on the plastic deformation of alloys\\u000a based on Fe-40 wt pct Cr has been studied. The dislocation sub-structures in the deformed and recovered conditions have been\\u000a characterized for a series of isothermal annealing cycles. Unalloyed Fe-40Cr deforms at room temperature by mixed twinning

I. M. Wolff; A. Ball

1992-01-01

430

Thermoelectric properties of p-type pseudo-binary (Ag{sub 0.365}Sb{sub 0.558}Te) {sub x} -(Bi{sub 0.5}Sb{sub 1.5}Te{sub 3}){sub 1-} {sub x} (x=0-1.0) alloys prepared by spark plasma sintering  

SciTech Connect

In this paper, pseudo-binary (Ag{sub 0.365}Sb{sub 0.558}Te) {sub x} -(Bi{sub 0.5}Sb{sub 1.5}Te{sub 3}){sub 1-} {sub x} (x=0-1.0) alloys were prepared using spark plasma sintering technique, and the composition-dependent thermoelectric properties were evaluated. Electrical conductivities range from 7.9x10{sup 4} to 15.6x10{sup 4} {omega}{sup -1} m{sup -1} at temperatures of 507 and 318 K, respectively, being about 3.0 and 8.5 times those of Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} alloy at the corresponding temperatures. The optimal dimensionless figure of merit (ZT) of the sample with molar fraction x=0.025 reaches 1.1 at 478 K, whereas that of the ternary Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} alloy is 0.58 near room temperature. The results also reveal that a direct introduction of Ag{sub 0.365}Sb{sub 0.558}Te in the Bi-Sb-Te system is much more effective to the property improvement than naturally precipitated Ag{sub 0.365}Sb{sub 0.558}Te in the Ag-doped Ag-Bi-Sb-Te system. - Graphical abstract: The temperature dependence of the dimensionless thermoelectric figure of merit ZT for different (Ag{sub 0.365}Sb{sub 0.558}Te) {sub x} -(Bi{sub 0.5}Sb{sub 1.5}Te{sub 3}){sub 1-} {sub x} (x=0-1.0) 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; Xue, H.F. [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); 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); Jiang, L. [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221008 (China); Ying, P.Z. [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221008 (China)

2006-12-15

431

First principles theory of disordered alloys and alloy phase stability  

SciTech Connect

These lecture notes review the LDA-KKR-CPA method for treating the electronic structure and energetics of random alloys and the MF-CF and GPM theories of ordering and phase stability built on the LDA- KKR-CPA description of the disordered phase. Section 2 lays out the basic LDA-KKR-CPA theory of random alloys and some applications. Section 3 reviews the progress made in understanding specific ordering phenomena in binary solid solutions base on the MF-CF and GPM theories of ordering and phase stability. Examples are Fermi surface nesting, band filling, off diagonal randomness, charge transfer, size difference or local strain fluctuations, magnetic effects; in each case, an attempt is made to link the ordering and the underlying electronic structure of the disordered phase. Section 4 reviews calculations of electronic structure of {beta}-phase Ni{sub c}Al{sub 1-c} alloys using a version of the LDA-KKR-CPA codes generalized to complex lattices.

Stocks, G.M.; Nicholson, D.M.C.; Shelton, W.A. [and others

1993-06-05

432

Use of alloy 117 as a liquid-metal current collector. Research and development report, January-March 1986  

SciTech Connect

Low-melting-point, bismuth-based alloys are potential replacements for NaK78 as liquid-metal slip-ring material because of their lower reactivity and potentially greater hydrodynamic stability. This paper describes experiments with one such alloy in a model of a 300-kW superconducting homopolar motor using close-clearance braid-type collectors. Slip-ring tip velocities varied from 5 to 20 m/s and currents ranging from 500 to 2000 A. Viscous power losses tend to follow a simple turbulent mode. In all, the data support the use of low-melting-point alloys as an alternative to Na78.

Maribo, D.; Sondergaard, N.

1987-09-01

433

Interfacial interaction of solid nickel with liquid Pb-free Sn–Bi–In–Zn–Sb soldering alloys  

Microsoft Academic Search

The dissolution process of nickel in liquid Pb-free 87.5% Sn–7.5% Bi–3% In–1% Zn–1% Sb and 80% Sn–15% Bi–3% In–1% Zn–1% Sb soldering alloys has been investigated by the rotating disc technique at 250–450°C. The temperature dependence of the nickel solubility in soldering alloys obeys a relation of the Arrhenius type cs=4.94×102exp(?39500\\/RT)% for the former alloy and cs=4.19×102exp(?40200\\/RT)% for the latter,

V. I. Dybkov; V. G. Khoruzha; V. R. Sidorko; K. A. Meleshevich; A. V. Samelyuk; D. C. Berry; K. Barmak

2008-01-01

434

Evaluation of zirconium-iron-rhenium alloys as surrogates for a technetium alloy waste form  

E-print Network

Stainless steel – zirconium alloys were developed by the US Department of Energy Laboratories as metallic waste forms for noble metal fission products. This thesis evaluates iron–zirconium–rhenium alloys to establish a technical basis for using...

Mews, Paul Aaron

2009-05-15

435

Effects of Substitutional Alloy Elements in an Fe-10Cr Ferritic Alloy.  

National Technical Information Service (NTIS)

The objective of this effort is to determine the effects of substitutional alloying elements in an Fe-10Cr base composition on microstructural development due to neutron irradiation. The alloying elements selected are of interest in reduced activation app...

D. S. Gelles, W. L. Beems

1984-01-01

436

BAs-GaAs Semiconductor Alloys as a Photovoltaic Alternative to Nitride Alloys  

SciTech Connect

Nitrogen alloyed III-V semiconductor compounds have been intensely studied in recent years due to unusual effects caused by nitrogen alloying. These effects are exploited in band gap engineering for specific applications such as solar cells and blue lasers.

Hart, G. L. W.; Zunger, A.

2000-01-01

437

High nickel, chromium-molybdenum alloys - are some new alloys more corrosion resistant than the old  

SciTech Connect

Within the past decade, several highly corrosion resistant, proprietary alloys have had their patients expire, and have been produced by others who wish to enter this competitive market. As such, research and development began in earnest for really new corrosion resistant alloys which could receive their own patents, and hopefully, premium prices or single source appropriation. Some limited corrosion test results have made these newer alloys appear outstanding. However, these alloys have not yet established a long or impressive track record within the Chemical Process Industry that has been generated by the older alloys over many years of intensive in-plant service. Therefore, a comparative alloy corrosion resistance testing program was performed to evaluate some of these newer alloys versus older alloys in four different acid environments and some aqueous solutions based on sodium chloride-ferric chloride.

Corbett, R.A.; Morrison, W.S.

1988-01-01

438

An investigation of reheat cracking in the weld heat affected zone of type 347 stainless steel  

Microsoft Academic Search

Reheat cracking has been a persistent problem for welding of many alloys such as the stabilized stainless steels: Types 321 and 347 as well as Cr-Mo-V steels. Similar problem occurs in Ni-base superalloys termed \\

Isaratat Phung-On

2007-01-01

439

Corrosion in Magnesium and a Magnesium Alloy  

NASA Astrophysics Data System (ADS)

Magnesium and a magnesium alloy (AZ91C) have been ion implanted over a range of ions energies (50 to 150 keV) and doses (1 x 10('16) to 2 x 10('17) ions/cm('2)) to modify the corrosion properties of the metals. The corrosion tests were done by anodic polarization in chloride -free and chloride-containing aqueous solutions of a borated -boric acid with a pH of 9.3. Anodic polarization measurements showed that some implantations could greatly reduce the corrosion current densities at all impressed voltages and also increased slightly the pitting potential, which indicated the onset of the chloride attack. These improvements in corrosion resistance were caused by boron implantations into both types of samples. However, iron implantations were found to improve only the magnesium alloy. To study the corrosion in more detail, Scanning Auger Microprobe Spectrometer (SAM), Scanning Electron Microscope (SEM) with an X-ray Energy Spectrometry (XES) attachment, and Transmission Electron Microscope (TEM) measurements were used to analyze samples before, after, and at various corrosion stages. In both the unimplanted pure magnesium and AZ91C samples, anodic polarization results revealed that there were three active corrosion stages (Stages A, C, and E) and two passivating stages (Stages B and D). Examination of Stages A and B in both types of samples showed that only a mild, generalized corrosion had occurred. In Stage C of the TD samples, a pitting breakdown in the initial oxide film was observed. In Stage C of the AZ91C samples, galvanic and intergranular attack around the Mg(,17)Al(,12) intermetallic islands and along the matrix grain boundaries was observed. Stage D of both samples showed the formation of a thick, passivating oxygen containing, probably Mg(OH)(,2) film. In Stage E, this film was broken down by pits, which formed due to the presence of the chloride ions in both types of samples. Stages A through D of the unimplanted samples were not seen in the boron or iron implanted samples. Instead one low current density passivating stage was formed, which was ultimately broken down by the chloride attack. It is believed that the implantation of boron modified the initial surface film to inhibit corrosion, whereas the iron implantation modified the intermetallic (Mg(,17)Al(,12)) islands to act as sacrificial anodes.

Akavipat, Sanay

440

Corrosion behavior and fatigue of alloy 625, alloy 33 and alloy 31 under conditions of decouplers in automotive exhaust systems  

SciTech Connect

The alloys 625, 31, 33 and in some tests the newly developed alloy 626Si have been investigated with respect to their mechanical properties and their corrosion resistance against alkali salts containing chlorides at temperatures of 550 C, 65O C, 7OO C and 750 C. Concerning strength in the sensitized condition, all alloys are suitable as decoupler materials. The mechanical properties of alloys 625, 626Si and probably 31 indicate adequate manufacturing possibilities of bellows. All alloys investigated suffer accelerated corrosion in the presence of alkali salt containing chlorides at temperatures ranging from 550 C to 750 C. At 750 C alloy 626Si shows the lowest corrosion rate. At 75O C, 7OO C and 650 C no difference between the solution annealed and the sensitized specimens was found. At 55O C, however, the corrosion rate of the alloys 625 and 33 increased significantly, when the material was sensitized prior to corrosion testing. Alloy 31 does not suffer significant corrosion attack at 55O C both in the solution annealed and in the sensitized condition, thus making it a potential cost effective alternative to the more expensive alloy 625 for decoupler applications.

Agarwal, D.C. [Krupp VDM GmbH, Houston, TX (United States); Kloewer, J.; Koehler, M.; Kolb-Telieps, A. [Krupp VDM GmbH, Werdohl (Germany)

1998-12-31