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Showing papers on "Alloy published in 1998"


Journal ArticleDOI
TL;DR: In this article, the design of new β type titanium alloys composed of non-toxic elements like Nb, Ta, Zr, Mo or Sn with lower moduli of elasticity and greater strength were studied based on the d-electron alloy design method, and the basic mechanical properties of designed alloys of button ingots melted by tri-arc furnace in the laboratory were investigated.
Abstract: Pure titanium and Ti–6Al–4V alloy have been mainly used as implant materials. V-free titanium alloys like Ti–6Al–7Nb and Ti–5Al–2.5Fe have been then developed because toxicity of V has been pointed out. Al- and V-free titanium alloys as implant materials have been developed. Most of them are, however, α+β type alloys. β type titanium alloys with lower moduli of elasticity and greater strength have been developed recently. Design of new β type titanium alloys composed of non-toxic elements like Nb, Ta, Zr, Mo or Sn with lower moduli of elasticity and greater strength were, therefore, studied based on the d-electron alloy design method, and the basic mechanical properties of designed alloys of button ingots melted by tri-arc furnace in the laboratory were investigated in this study. β type alloys, Ti–Nb–Ta–Zr, Ti–Nb–Ta–Mo and Ti–Nb–Ta–Sn system alloys designed in this study are expected to have greater performance for implant materials. The Young's moduli of these alloys are lower compared with that of Ti–6Al–4V ELI which has been used as an implant material. The alloys on which some heat treatments have been conducted offer suitable tensile properties as implant materials. The tensile strength and elongation of designed alloys in this study are equivalent or greater than required values already reported.

1,068 citations


Journal ArticleDOI
TL;DR: In this paper, the corrosion behavior of 6056 T6 aluminium alloy was investigated in 1-M NaCl solution and it was found that pits first developed within the grains and grew up through microscopic crystallographic tunnels.

433 citations


Journal ArticleDOI
TL;DR: It is suggested that the good corrosion properties of the NiTi alloy and the related promising biological response, as reported in literature, may be ascribed to the presence of mainly a TiO2-based surface layer and its specific properties, including the formation of a calcium-phosphate layer after exposure to a bioenvironment.

407 citations


Journal ArticleDOI
TL;DR: In this article, the electro-oxidation of carbon monoxide and methanol on platinum-ruthenium bulk alloys was investigated by cyclic voltammetry and in situ FTIR reflectance spectroscopy.

385 citations


Journal ArticleDOI
TL;DR: In this paper, the basic mechanisms of irradiation embrittlement in reactor pressure vessel steels are reviewed and a detailed identity and etiology of the matrix defects and manganese-nickel-rich phases are discussed.
Abstract: This paper reviews the current understanding of the basic mechanisms of irradiation embrittlement in reactor pressure vessel steels. Radiation enhanced diffusiona at operating temperatures around 290°C leads to the formation of various ultrafine scale hardening phases, including copper rich and copper catalysed manganese-nickel rich precipitates. Other nanofeatures that do not require copper, so-called matrix defects, include alloy phosphides and carbonitrides as well as defect cluster-solute complexes. Matrix defects that are thermally unstable (anneal) under irradiation play a very important role in mediating flux and temperature effects. The balance of features depends on the composition of the steel and the irradiation conditions. Copper enriched phases, which are the dominant embrittling feature in alloys containing significant trace quantities of this element, are fairly well understood. In contrast, the detailed identity and etiology of the matrix defects and manganese-nickel rich phases t...

330 citations


Journal ArticleDOI
TL;DR: In this paper, the microstructure and mechanical properties of nanograin-sized WC-Co composites were investigated and compared with those of conventional cermets, and it was shown that the nanostructured composites have higher tungsten content in the binder phase and a higher FCC HCP ratio of the cobalt.

325 citations


Journal ArticleDOI
TL;DR: The effects of various metallic ions using various metallic powders on the relative growth ratio of fibroblasts L929 and osteoblasts MC3T3-E1 cells were carried out and the new Ti-15%Zr- 4%Nb-4%Ta-0.2%Pd alloy exhibited a higher corrosion resistance in physiological saline solution.

322 citations


Journal ArticleDOI
TL;DR: In this paper, the deformation, fracture and alloy design of B2 iron aluminides based on FeAl is reviewed and two other factors, namely intrinsic grain-boundary weakness and quenched-in vacancies become important in limiting the tensile ductility of FeAl alloys.
Abstract: This paper reviews the deformation, fracture and alloy design of B2 iron aluminides based on FeAl. Moisture-induced environmental embrittlement is shown to be a leading cause of low tensile ductility and brittle cleavage fracture of Ferich FeAl alloys at ambient temperatures. With increasing Al concentration, two other factors, namely intrinsic grain-boundary weakness and quenched-in vacancies become important in limiting the tensile ductility of FeAl alloys. FeAl alloys show a yield-strength anomaly at intermediate temperatures. Recent work indicates that the anomaly is a result of hardening by thermal vacancies at elevated temperatures. The understanding of the deformation and fracture behavior has led to the development of FeAl-base alloys and composites with improved metallurgical and mechanical properties for structural applications. These FeAl-based alloys can be prepared by melting and casting or by powder processing. The unique combination of the excellent oxidation and carburization/sulfidation resistance coupled with relatively low material density and good mechanical properties at room and elevated temperatures has sparked industrial interest in FeAl alloys and composites for a number of applications.

267 citations


Journal ArticleDOI
TL;DR: In this article, a wide supercooled liquid region exceeding 50K before crystallization was observed for melt-spun amorphous alloys with high glass-forming ability and good mechanical properties.
Abstract: A wide supercooled liquid region exceeding 50K before crystallization was observed for melt-spun Ti 50 Ni 25-x Cu 25 Sn x (x=3 and 5 at%) amorphous alloys. The temperature interval of the supercooled liquid region defined by the difference between crystallization temperature (T x ) and glass transition temperature (T g ), Δ T x (= T x -T g ) is 40 K for the 0%Sn alloy and increases to 50 K for the 3%Sn alloy and 60 K for the 5%Sn alloy. With increasing Sn content, the ΔT x value decreases significantly. A similar increase in thermal stability of the supercooled liquid was also recognized for the 3 at%Sb-containing alloy in the Ti 50 Ni 25-x Cu 25 Sb x system. The replacement by 3 to 5 at%Sn for Ni also induces an increase of mechanical strength, in addition to the increase in Δ T x . The tensile fracture strength (σ f ), Young's modulus (E) and Vickers hardness (H v ) increase from 1800 MPa, 93 GPa and 530, respectively, for the Ti 50 Ni 25 Cu 25 alloy to 2050 MPa, 102 GPa and 650, respectively, for the Ti 50 Ni 20 Cu 25 Sn 5 alloy. The crystallization takes place through a single exothermic reaction, accompanying the simultaneous precipitation of multiple (CuTi + Cu 4 Ti 3 + NiTi) phases. The crystallization mode requires long-range atomic rearrangements for precipitation of the crystalline phases, leading to the increase in the stability of supercooled liquid against crystallization. The high thermal stability of the supercooled liquid enabled the production of bulk amorphous alloys in the diameter range up to about 6 mm by copper mold casting. There is no appreciable difference in the stability of the supercooled liquid region between the melt-spun and cast bulk amorphous alloys. The first synthesis of the Ti-based amorphous alloys with high glass-forming ability and good mechanical properties allows us to expect the future development of bulk amorphous alloys as a new type of high specific strength material.

258 citations


Patent
09 Dec 1998
TL;DR: In this paper, the seed layer is annealed at about 100°C to about 400°C. to increase the grain size of the seed layers and impart a (111)-dominant crystallographic option before plating the Cu or Cu alloy interconnections thereon the seed-layer.
Abstract: The electromigration of a Cu or Cu alloy interconnection member is reduced by annealing the seed layer before electroplating or electroless plating the Cu or Cu alloy interconnection member on the seed layer. Embodiments include depositing a Cu or Cu alloy seed layer, annealing at about 100° C. to about 400° C. to increase the grain size of the seed layer and impart a (111)-dominant crystallographic option before plating the Cu or Cu alloy interconnect member thereon the seed layer

242 citations


Journal ArticleDOI
TL;DR: In this article, the influence of the physical and chemical deposition parameters on the nanostructure of the deposits and demonstrate that the grain size can be tuned to values between 13 and 93 nm, with rather narrow grain size distribution.
Abstract: Pulsed electrodeposition is a simple, yet versatile method for the production of nanostructured metals. For n-nickel we determine the influence of the physical and chemical deposition parameters on the nanostructure of the deposits and demonstrate that the grain size can be tuned to values between 13 and 93 nm, with rather narrow grain size distribution. The thermal stability of our n-nickel as studied by x-ray diffraction and differential thermal analysis exhibits no detectable grain growth up to temperatures of about 380 K and an initial $$\sqrt t $$ behavior at 503 K followed by a regime of anomalous grain growth. For nanocrystalline Ni1-x Cux (Monel-metal™) we demonstrate that alloy formation occurs at room temperature and that both chemical composition and grain size can be controlled by the pulse parameters and by appropriate organic additives.

Journal ArticleDOI
TL;DR: Polyaniline (PANi) films can be electrosynthesized by oxidation of aniline on iron and mild steel in a one-step process from an aqueous oxalic acid medium which passivates substrates as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this article, a microdendritic (second-phase), equiaxed, cell structure was friction-stir welded with a compositionally modified 1100 aluminum alloy.

Journal ArticleDOI
TL;DR: In this paper, a survey on metal dusting is given, where the mechanisms for metal carburization and graphitization in carbonaceous atmospheres at carbon activities a C > 1.
Abstract: A survey is given on recent research on metal dusting i.e. a catastrophic carburization or rather graphitization of metals and alloys occuring in carbonaceous atmospheres at carbon activities a C >1. The thermodynamics are explained, the mechanisms for iron, low and high alloy steels, nickel and Ni-base alloys are described and the kinetics derived for iron and low alloy steels. Protection against metal dusting is possible by the presence of sulfur in the atmosphere, since adsorbed sulfur retards carbon transfer and hems graphite nucleation. Also dense oxide layers are protective, the preconditions for the formation of Cr-rich protectivee layers on steels and Ni-base alloys are shortly presenteed.

Journal ArticleDOI
TL;DR: In this paper, the basic principles involved in the use of alloys as negative electrodes, as well as the conversion of oxides to alloys, are presented and available data on the behavior of a number of lithium alloys and binary oxides as negative electrode in lithium systems are also included.

Journal ArticleDOI
TL;DR: In this paper, composites of the Cu47Ti34Zr11Ni8 bulk metallic glass, reinforced with up to 30 vol % SiC particles are synthesized and characterized.
Abstract: Composites of the Cu47Ti34Zr11Ni8 bulk metallic glass, reinforced with up to 30 vol % SiC particles are synthesized and characterized. Results based on x-ray diffraction, optical microscopy, scanning Auger microscopy, and differential scanning calorimetry (DSC) are presented. During processing of the composites, a TiC layer forms around the SiC particles and Si diffuses into the Cu47Ti34Zr11Ni8 matrix stabilizing the supercooled liquid against crystallization. The small Si addition between 0.5 and 1 at. % increases the attainable maximum thickness of glassy ingots from 4 mm for Cu–Ti–Zr–Ni alloys to 7 mm for Cu–Ti–Zr–Ni–Si alloys. DSC analyses show that neither the thermodynamics nor the kinetics of the alloy are affected significantly by the Si addition. This suggests that Si enhances the glass forming ability by chemically passivating impurities such as oxygen and carbon that cause heterogeneous nucleation in the melt.

Journal ArticleDOI
TL;DR: In this paper, a new semiconductor alloy material, GaAs1-xBix, was created by metal organic vapor phase epitaxial (MOVPE) growth, and X-ray diffraction measurements of alloy layers reveal that the diffraction patterns are satisfactory.
Abstract: A new semiconductor alloy material, GaAs1-xBix has been created by Metal Organic Vapor Phase Epitaxial (MOVPE) growth. A low growth temperature, such as 365°C, is required to obtain the alloy. X-ray diffraction measurements of alloy layers reveal that the diffraction patterns are satisfactory. The maximum GaBi content in the GaAsBi alloy estimated from the lattice constant is around 2%, which is consistent with that estimated from secondary ion mass spectroscopy (SIMS) measurements. In a photoluminescence (PL) measurement, a single peak spectrum is observed from 10 to 300 K. The temperature variation of the PL peak energy is as small as 0.1 meV/K.

Journal ArticleDOI
TL;DR: The vortex-like structures are composed of dynamically recrystallized, fine-grained intercalation microstructures which have been observed by optical metallography, scanning electron microscopy and transmission electron microscopes as discussed by the authors.
Abstract: Dissimilar plates (0.6 cm thick) of copper and 6061 aluminum alloy; and 2024 aluminum alloy and 6061 aluminum alloy were friction-stir welded at various rotation speeds (400–1200 rpm) and traverse speeds of 1 to 3 mm/s, and produced variations of vortex and other swirl-like intercalations, especially near the weld-zone/work-piece interface. These vortex-like structures are composed of dynamically recrystallized, fine-grained intercalation microstructures which have been observed by optical metallography, scanning electron microscopy and transmission electron microscopy. They are similar to those characterizing mechanical alloying. Such microstructures are especially fascinating because although they resemble vortex instabilities which occur in turbulent fluids, they are formed by extreme deformation in the solid state since centerline temperatures through the weld zone are about 420°C, or ∼0.7 TM in the 6061 aluminum system.

Journal ArticleDOI
TL;DR: In this paper, an analytical impedance model of the metal hydride electrode was used to calculate the diffusion coefficient of hydrogen in the metal alloy, and the impedance response of cobalt microencapsulated LaNi4.27Sn0.24 electrode was measured at different hydrogen contents.

Journal ArticleDOI
TL;DR: In this paper, a rotating disk electrode technique was used to examine the electrochemical oxidation of hydrogen (H2), carbon monoxide (CO), and their mixtures (500 ppm−2%) on a well-characterized Pt70Mo30 bulk alloy.
Abstract: The electrochemical oxidation of hydrogen (H2), carbon monoxide (CO), and their mixtures (500 ppm−2%) on a well-characterized Pt70Mo30 bulk alloy was examined using the rotating disk electrode technique in 0.5 M H2SO4 at 333 K. The electrodes were transferred to and from a UHV chamber, where surface analyses were conducted using a combination of low-energy ion scattering (LEIS), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). The surface composition of this alloy after sputter-etching and annealing in UHV was slightly enriched in Pt to a composition of Pt77Mo23. The kinetics of H2 oxidation are not measurably affected by the presence of the Mo in the surface. The shapes of the polarization curves for the oxidation of the H2/CO mixtures are qualitatively similar to those for the Pt50Ru50 alloy examined previously: a high current−potential slope (ca. 0.5 V/dec) at low overpotential followed by a transition to a highly active state where the current approaches the diffusion-li...

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the creep behavior and deformation substructures of Mg-Y binary alloys containing 0.2-2.4 mol% Y and found that the effect of the yttrium concentration increases when the concentration exceeds 1.6 mol%.
Abstract: Creep behavior and deformation substructures of Mg–Y binary alloys containing 0.2–2.4 mol% Y have been investigated at 550 K under 50–200 MPa. Creep strength is remarkably improved by a small addition of yttrium as compared with aluminum and manganese. Two stress regions are recognized based on the stress dependence of the minimum creep rate. The lower-stress region, where the stress exponent n is about 5, corresponds to the H region (class M behavior) commonly observed in other solid solution alloys. The concentration dependence of solid-solution Mg–Y alloys is similar to that of Mg–Al solid solution alloys: the apparent concentration exponent m is about −2. The effect of the yttrium concentration increases when the concentration exceeds 1.6 mol%. Transmission electron microscopy reveals that the activation of the non-basal slip systems is enhanced and dynamic precipitation occurs during creep deformation in a concentrated Mg–Y alloy. The high creep resistance can be correlated with two mechanisms, i.e. forest dislocation-hardening (work hardening) and dynamic precipitation of fine pseudo-equilibrium β′ phase on the dislocation lines during creep.

Journal ArticleDOI
TL;DR: In this article, the effect of copper, zinc, and indium on the isothermal fatigue properties of Sn-3.5%Ag alloy has been investigated, and the relationship between fatigue life and crack propagation rate estimated from load drop curve during fatigue test is also discussed.
Abstract: In our previous study, the fatigue life of Sn-3.5Ag-Bi alloy was found to be dominated by the fracture ductility of the alloy and to obey a modified Coffin-Manson’s law: (Δep/2D)· Nfα, where Δep is plastic strain range, Nf is fatigue life, and α and=C are nondimensional constants. In this study, copper, zinc, and indium are selected as the third element, and the effect of these elements on the isothermal fatigue properties of Sn-3.5%Ag alloy has been investigated. The relationship between fatigue life and crack propagation rate estimated from load drop curve during fatigue test is also discussed. The addition of copper, indium, and zinc up to 2% slightly decreases the fatigue life of Sn-3.5Ag alloy due to the loss of ductility, while the life still remains higher than that of tin-lead eutectic alloy. The modified Coffin-Manson’s equation can also be applied to ternary Sn-3.5Ag-X. It is found that both ductility and fatigue life are significantly responsible for the load drop rate of the alloy, which reflects the extent of crack propagation. The fatigue life of Sn-3.5Ag-X alloy is therefore dominated not by the kinds and amount of third element but by the ductility of each alloy.

Journal ArticleDOI
TL;DR: In this paper, the S/N behavior of a bulk amorphous Zr-Ti-Cu-Ni-Be alloy was investigated, with the objective of examining the relationship between fatigue crack initiation and propagation in comparison to behavior in traditional crystalline alloys.

Journal ArticleDOI
TL;DR: Ti–6Al–7Nb alloy exhibited sufficient castability by a dental casting method for titanium alloys and enough mechanical properties for dental application and excellent corrosion resistance through an immersion test in 1.0% lactic acid and an anodic polarization test in 0.9% NaCl solution.
Abstract: With the aim of applying a novel titanium alloy, Ti-6Al-7Nb, to a dental casting material, a comprehensive research work was carried out on its characteristics, such as castability, mechanical properties and corrosion resistance in the present study. As a result, Ti-6Al-7Nb alloy exhibited sufficient castability by a dental casting method for titanium alloys and enough mechanical properties for dental application. It is also showed excellent corrosion resistance through an immersion test in 1.0% lactic acid and an anodic polarization test in 0.9% NaCl solution. From these results, it is concluded that this Ti-6Al-7Nb alloy is applicable as a dental material in place of Ti-6Al-4V alloy, which includes cytotoxic vanadium.

Journal ArticleDOI
TL;DR: In this paper, the susceptibility to stress corrosion cracking (SCC) of the Al-Zn-Mg-Cu French 7010 alloy of different temper has been investigated by Slow Strain Rate Testing.

Journal ArticleDOI
TL;DR: In this article, microstructural features in the lamellar structures were characterized by metallography, SEM and TEM, and the mechanical properties were determined by tensile tests at temperatures to 1000 °C.

Journal ArticleDOI
TL;DR: In this paper, the underlying mechanisms behind the reported high strength of titanium aluminide alloys containing a large addition of niobium has been investigated by determining the flow stresses and activation parameters of plastic deformation.

Journal ArticleDOI
TL;DR: In this article, an oxide dispersion strengthened (ODS) ferritic steel with high temperature strength has been developed in line with low activation criteria for application in fusion power systems and the composition Fe−13.5Cr−2W−0.25Y2O3 was chosen to provide a minimum chromium content to insure fully delta-ferrite stability.

Journal ArticleDOI
TL;DR: In this paper, the effect of ultrasonic treatment on the as-cast alloy microstructure can be summarized as follows: reduction of mean grain size, variation of phase distribution and better material homogeneity and segregation control.

Journal ArticleDOI
TL;DR: In this article, a melt-spun Mg 2 (Ni,Y) hydrogen storage alloy with exact composition Mg 63 Ni 30 Y 7 ) was prepared by rapid solidification, using a melting-spinning technique.