Showing papers on "Alloy published in 1969"

Magnesium-base alloy for use in bone surgery

Abstract: A magnesium-base alloy for use in bone surgery which contains the following components, wt.%: Rare earth element 0.4-4.0 Cadmium 0.05-1.2 An element from the group consisting of calcium and aluminum 0.05-1.0 Manganese 0.05.05 Silver 0-0.8 Zirconium 0-0.8 Silicon 0-0.3 Magnesium remainder

Solid-Solution Strengthening in Single Crystals of Iron Alloys

Abstract: To elucidate the mechanism of the substitutional solid-solution strengthening of iron, evaluation of the modulus parameter and the direct observation of dislocation configuration were made for six alloy systems; Fe–Be, Fe–Al, Fe–Si, Fe–V, Fe–Ge and Fe–Mo. The rate of the solid-solution strengthening at 300°K was best described as a function of the combined mismatch parameters by the equation d (τ/µ)/ d c =0.04( e µ '+1.5 e a ) 2 , where e a and e µ ' are the size and the modulus mismatch parameter, respectively. The dislocations observed at the lower yield point were almost of screw type in all the alloys but their densities were extensively different from alloy to alloy. It was concluded that the elastic interaction of screw dislocations with the solute atoms was the dominant cause of the solid-solution strengthening of iron at 300°K. The wide variety of dislocation density was well-explained by a proposed model that it is determined by the condition for the applied stress to be minimum in a constant str...

The thermal conductivity of sintered semiconductor alloys

Abstract: The thermal conductivity of sintered semiconductor alloys is calculated using the Klemens-Callaway model assuming that the boundary scattering can be adequately described by a mean free path. It is shown that the relative increase in thermal resistance increases with the amount of alloy disorder scattering and should be substantial in sintered germanium silicon alloys with particle sizes of the order of one micron.

Protective diffusion layer on nickel and/or cobalt-based alloys

Abstract: Nickel and/or cobalt-based alloys are given a protective coating by diffusing into the surface of the alloy metallic aluminum and one or more metals of the platinum groups.

The structure of directionally frozen Al–CuAl2 eutectic alloy

Abstract: The structure of Al–CuAl2 eutectic alloy has been examined by transmission electron microscopy. The orientations of phases and of preferred lamellar interfaces have been determined and it is shown how small deviations from these preferred orientations are accommodated by tilt and/or twist boundaries. The dislocation structures of sub-boundaries and of the semicoherent phase boundaries are illustrated. The hardness of the eutectic material is more sensitive to the rate of cooling in the solid state than it is to the lamellar spacing and the dislocation distribution in quenched and slowly cooled alloy is compared.

The equilibrium shapes of small liquid droplets in solid–liquid phase mixtures: metallic h.c.p. and metalloid systems

Abstract: Solid–liquid interfacial free energy is shown to be highly anisotropic in alloys of some h. c. p. metals and of two metalloids. This anisotropy is evaluated from a study of the equilibrium shapes of small droplets of alloy liquid entrained within solid grains. Factors affecting the attainment of equilibrium in such droplets are considered, and γ -plots are obtained for solid–liquid interfaces in the h. c. p. metals zinc and cadmium. In the magnesium alloys studied, spherical droplet shapes were observed, indicative of essentially isotropic interfacial energies. Droplet shapes were also analysed in some alloys of bismuth and of antimony. The results are related to current ideas of solid–liquid interfacial structure.

The determination of the diffusion constants of oxygen in nickel and α-iron by an internal oxidation method

Abstract: The diffusion constants of oxygen in nickel and α-iron are calculated from experimentally determined internal oxidation rates in dilute silicon-bearing alloys. A single crystal alloy of composition 0.058 wt % silicon in nickel and polycrystalline alloys of composition 0.48 wt % silicon in nickel and 0.072 wt % silicon in iron were oxidised and allowance is made for the absorption of oxygen in the reaction with silicon. For nickel the values of activation energy Q=73.9 kcal/g atom in the range 800 to 1200° C and Q=74.4 kcal/g atom in the range 900 to 1300° C are in good agreement with a previous result. The activation energy required for oxygen diffusion in α-iron was found to be 39.9 kcal/g atom in the range 700 to 850° C.

The Design of Iron-Chromium-Nickel Alloys for Use at High Temperatures

Abstract: The design of iron-chromium-nickel alloys for use at high temperatures ought to be based on a knowledge of the alloy compositions that will give rise to a chromic oxide scale. For this reason, the nickel-chromium and iron-chromium-nickel alloy systems have been investigated at 1000°C under oxidizing conditions, and the isothermal sections of the nickel-chromium-oxygen and the iron-chromium-nickel-oxygen equilibrium diagrams have been determined. On the basis of these determinations, several ternary compositions are recommended as being the most suitable to form the basis of high-temperature alloys for use in oxidizing environments.

Thermal Stability of Hastelloy Alloy C-276

Abstract: Hastelloy Alloy C has long been of major importance to the chemical process industry, but in many applications, vessels fabricated from Alloy C had to be solution heat treated to remove harmful weld heat affected zone precipitates which reduced corrosion resistance. Modification of the chemical composition produced Hastelloy Alloy C-276, which is more resistant to the precipitation of grain boundary particles than Alloy C. In order to fully utilize the improved alloy, and to understand its responses to fabrication techniques, it is helpful to understand the time-temperature-transformation characteristics. Grain boundary precipitates can form in Alloy C-276 when it is exposed to temperatures from 1200 to 2000 F (649 to 1093 C). The precipitation characteristics of Alloy C-276 compared to those of Alloy C can be shown through the use of a time-temperature-transformation curve (T-T-T). The precipitates have been identified as either “P” or Ni7Mo6-type phases. No M6C precipitate was found in Alloy C-...

Grain‐Boundary Fine Structure in an Iron Alloy

Abstract: Regular substructures were observed in grain boundaries of an annealed Fe‐0.75% Mn alloy by transmission electron microscopy. A detailed analysis was made on one of the grain boundaries. The result indicates that the analyzed grain boundary may be considered as a coincidence site grain boundary.

Thermal expansivities, thermal conductivities, and densities of vanadium, titanium, chromium and some vanadium-base alloys: A comparison with austenitic stainless steel

Abstract: Computer-fitted polynomial expressions are presented that define the linear thermal-expansion behavior of vanadium, titanium, chromium, certain VTi and VTiCr alloys, and AISI Types 304 and 316 stainless steels between 0 ° and 1000 °C. The mean expansion coefficients for the vanadium-base alloys differ only slightly from those for unalloyed vanadium (plus or minus 6%), and are 65% to 80% lower than the mean expansion coefficients for the austenitic stainless steels. Densities of the vanadium-base alloys and the austenitic stainless steels were determined at 25 °C by liquid displacement. The VTi alloys show a non-linear decrease in density with increasing titanium for titanium contents greater than 30 wt.%. The VTiCr alloys also exhibit a non-linear change in density for compositions containing greater than 15 wt.% titanium, and greater than 5 wt.% chromium. A comparison of the mechanical and thermal properties of two vanadium-base alloys and two austenitic stainless steels was made to determine their relative usefulness as reactor fuel jackets for service between 500 ° and 700 °C. This comparison shows that vanadium alloy fuel jackets would be subjected to only one-third the thermal stresses generated in austenitic stainless steel jackets during reactor excursions between 500 ° and 700 °C under conditions where the fuel is not in intimate contact with the jacket. This difference in thermal stresses in the two jacket materials is the result of the 37% higher tensile strength, 40% higher thermal conductivity, and 70% lower thermal expansivity exhibited by the vanadium alloys as compared with austenitic stainless steel.

Anodic Polarization of Titanium and Titanium Alloys in Hydrochloric Acid

Abstract: : Commercially pure titanium and the alloys studied exhibited active to passive transitions in HCl. Increasing the acid concentration increased the critical current for passivity and shifted the critical potential for passivity in the noble direction. Increasing the temperature served only to increase the critical current for passivity. Activation energies for the anodic polarization process were the right order of magnitude for a reaction controlled by reactivity at the metal surface. For the alpha-beta alloy 6Al-6V-2Sn the critical current for passivity increased as the ratio of amounts of beta-to-alpha phase decreased with increasing strength level. The addition of Fe(3+) and Cu(2+) (0.03 M) to the HCl facilitated passivation of the metal and its alloys. The maximum dissolution current densities for the metal and alloys in HCl were double those in H2SO4. Pitting of several of the alloys occurred in HCl but not in H2SO4. (Author)

Composite coating for the superalloys

Abstract: Improved operating lifetimes are provided for the superalloys through use of a composite coating comprising a chromium or chromium-rich interlayer adjacent the superalloy substrate surface and an oxidation-resistant outer layer comprising an alloy of iron, cobalt and/or nickel alloyed with selected amounts of chromium, aluminum and yttrium.

Method of forming metal alloys

Abstract: A method of forming superplastic metal alloys by heating the alloy to a temperature at which it is superplastic and then forming the alloy, in which the formed alloy is heated to a temperature above the superplastic temperature range in order to render it resistant to deformation before it is removed from the forming tool.

Carbide grain growth during the liquid-phase sintering of the alloys NbCFe, NbCNi, and NbCCo

Abstract: An investigation has been made of the microstructural changes which occur during the liquid-phase sintering of the alloys NbC-22 wt.% Fe andNbC-22 wt.% Ni. It was found that the growth of the carbide grains, dispersed in either of the liquid metals, is consistent with the theoretical equation, derived by Wagner, for a solution/ precipitation growth process controlled by the diffusion of the solid constituent through the liquid. The same growth behaviour has been observed earlier in a similar alloy of NbC in cobalt. The effect of temperature on grain growth was measured and “activation energies” of the growth rates were determined.

A study of dilute alloys of iron in gold using the Mössbauer effect

Abstract: A detailed analysis of Mossbauer absorption spectra of 57Fe in Au-Fe alloys has been carried through for the concentration range 05-128% at room temperature and for the 128% alloy from room temperature down to 04 °K. The results show that significantly different spectra are obtained for iron atoms with 0, 1, 2,... iron nearest neighbours. The concentration dependence of the mean isomer shift is consistent with the changes in charge density to be expected from the changes in atomic volume. As the temperature is reduced, measurable hyperfine fields appear first at iron sites with the largest number of iron nearest neighbours. The quadrupole splitting averaged over all iron sites tends to zero as the temperature is reduced, indicating that the angle between the spin direction and the electric field gradient has a mean value close to cos -1(1/radical3).

Precipitation in Ni-12 at. % Ti Alloy

Abstract: Precipitation behaviour in Ni-12 at. % Ti alloy was studied by means of thin foil transmission electron microscopy and electron diffraction technique. Hardness measurements showed two stage age-hardening at 500°C and 600°C. Thin foil observations revealed that the initial rapid increase in hardness was associated with the presence of superlattice. Slower second hardening was caused by the formation of modulated structure or periodic ordered structure. The increase in hardness by these periodic structures was found to be due to the internal strain hardening as originally suggested by Mott and Nabarro.

Electronic properties of liquid binary alloys

Abstract: The binary alloy systems In-Sb, Bi-Te, Sb-Te and In-Te have been investigated in respect of their electrical conduction propertics in the liquid state. Measurements of resistivity, thermoelectric power and Hall coefficient have been made and indicate the existence of strong positional correlation of ions in the liquid state. This occurs for a range of alloy compositions, not only in the stoichionietric phases.

Electroplating a ductile zinc-nickel alloy onto strip steel

Abstract: A METHOD OF ELECTROPLATING A NICKEL-ZINC ALLOY ON A STEEL STRIP IS DESCRIBED, IN WHICH THE PLATING BATH IS MAINTAINED WITHIN A SELECTED PH RANGE, THROUGH USE OF A PRESELECTED RATIO OF NICKEL TO ZINC IN THE BATH, AND A PRESELECTED PLATING CURRENT DENSITY, WHEREBY AN ELECTROPLATED COATING IS FORMED HAVING A NICKEL CONTENT OF FROM 9.5 TO 12.5%, WHICH COATING HAS A LOW INTERNAL STRESS, AND INCREASED RESISTANCE TO CORROSION.

The role of nickel in the high-temperature oxidation of Fe-Cr-Ni alloys in oxygen

Abstract: The oxidation of several largely austenitic Fe-Cr-Ni alloys in 1 atm oxygen at 800–1200°C has been studied thermogravimetrically, metallographically, and in detail by electron probe micro analysis. Fe-Cr-Ni alloys of this type are protected by Cr2O3-healed scale, which thickens slower than on the corresponding binary Fe-Cr and Ni-Cr alloys, presumably because nickel and iron ions dope the Cr2O3 more effectively together than singly and/or because the alloy composition and ability to absorb cation vacancies are such as to produce a smaller vacancy activity gradient or level in the scale, or voids within it. The scale adhesion, as on Ni-Cr alloys, is generally good after long times, at least partly due to the convoluted alloy-oxide interface, in some cases to large intergranular Cr2O3-rich stringers, and possibly to the general specimen mechanical properties. Nonprotective stratified scale development is relatively unusual and often produces nickel-rich, alloy-particle-containing nodules, as on Fe-Ni alloys. Careful selection of ternary and more complex alloys with appropriate alloy interdiffusion coefficients and oxygen solubilities and diffusivities should permit development of materials with the best compromise between ease of Cr2O3 establishment, avoidance of breakaway, and readiness of scale healing.