Showing papers on "Alloy published in 1975"

Stacking fault energies of seven commercial austenitic stainless steels

Abstract: The stacking fault energies of seven commercial austenitic Fe-Cr-Ni, Fe-Cr-Ni-Mn and Fe-Mn-Ni alloys have been determined by X-ray diffraction line profile analysis. From comparison with existing data on laboratory alloys with similar compositions, it is concluded that both Ni and C increase γ while Cr, Si, Mn, and N decrease γ. Regression analysis of data produced in this study provides an expression relating γ to commercial alloy composition in terms of Ni, Cr, Mn, and Mo alloy concentrations.

Separation of second phase particles in spheroidized 1045 steel, Cu-0.6pct Cr alloy, and maraging steel in plastic straining

Abstract: Experiments were performed on spheroidized 1045 steel, Cu-06 pct Cr alloy, and maraging steel containing respectively Fe3C, Cu-Cr, and TiC particles of nearly equiaxed shape The local interfacial stresses for separation of these particles during plastic deformation were evaluated by the methods described in the two preceding papers The results show that the interfacial strengths for these particles in their respective matrices are 242, 144, and 264 ksi In the spheroidized steel the average diam of the separated particles is distinctly larger than the average diam of the whole population This is quantitatively explained by the enhanced interfacial stresses developed in regions of above average volume fraction of second phase which frequently occur in very dense populations of particles No such effect was observed in the other two systems which is consistent with their much lower volume fraction of second phase Some tension experiments have also been performed with the spheroidized 1045 steel at elevated temperature, giving results qualitatively similar to those at room temperature

Magnetic Properties of Anodic Oxide Coatings on Aluminum Containing Electrodeposited Co and Co‐Ni

Abstract: Cobalt and Co‐Ni alloy were electrodeposited into the micropores of various kinds of anodic oxide films on aluminum. Fine granular metals precipitated on the barrier layer and formed columnar structures. Although the films of cobalt or nickel showed remarkable magnetic anisotropies perpendicular to the surface, the alloy films which consisted of approximately 50% cobalt showed a strong anisotropy along the horizontal direction. Coercive forces ranged from about 500 to about 1100 oe and the density of residual magnetization rose above 1000 gauss. The films may have applications in magnetic memories and recording devices.

The alloying behaviour and mechanical properties of polycrystalline Ni3Al (?? phase) with ternary additions

Abstract: A survey of the results from a variety of techniques has shown that the substitution behaviour of alloying additions is primarily determined by electronic considerations. Thus, Si, Ti, V, Mn, Nb, Hf and Ta substitute for aluminium; Co and Cu substitute for nickel and Cr, Fe, W, and Mo substitute for both species. A number of conclusions have been drawn from an analysis of compression test data, the most significant of which was that the mechanical properties of γ′ depended on both the substitution behaviour of the alloying addition and the degree of non-stoichiometry. Considerable strengthening is only obtained when (1) the alloying addition substitutes for aluminium and has a large size misfit parameter, and (2) the alloy is aluminium-rich or stoichiometric.

A comparison of palladium-silver and palladium-yttrium alloys as hydrogen separation membranes

Abstract: Some palladium-yttrium alloy diffusion membranes have been developed which are both significantly stronger and more permeable to hydrogen than the present, commercially used, Pd-Ag membrane. The permeabilities of these alloys as a function of both temperature and pressure are compared with that of the commercial Pd-25%Ag alloy. The effect of surface oxidation on the activity of the membranes has also been investigated.

Unique form of filamentous carbon

Abstract: CONSIDERABLE interest has been shown in the formation of carbon filaments from the catalytic decomposition of gases over metal surfaces at about 700° C (see refs 1,2). Detailed studies have been chiefly confined to the behaviour of pure metals, but technically and industrially the effect of alloying elements is also important. We have studied how additives to an iron catalyst modify the filament growth process during decomposition of acetylene. With acetylene decomposed on a Pt/Fe alloy a new mode of filament growth was identified in which the complete detachment of a catalyst particle from the surface of the metal was not a necessary prerequisite for growth3. Here we describe the effect of tin on the growth of filaments from the iron/acetylene system. The experimental technique used in this work, controlled atmosphere electron microscopy, has been described elsewhere4.

Surgical implant and alloy for use in making an implant

Abstract: Implant for bone surgery and for dental therapeutics, comprising an alloy containing defined critical amounts of titanium and/or zirconium, and other selected elements including niobium, tantalum, chromium, molybdenum and aluminum. Dissolved gases may also be included. The alloy is free from copper, cobalt, nickel, vanadium and tin, apart from the usual impurities.

In situ observations of crystalline oxide formation during aluminum and aluminum alloy oxidation

Abstract: Anin situ morphological study of the oxidation of electron transparent specimens of aluminum and aluminum alloys containing zinc and magnesium has been carried out in the temperature range 400 to 520°C using the hot stage of a 1 MeV transmission electron microscope. The structure and morphology of the crystalline oxide produced in each alloy has been carefully examined by selected area electron diffraction and stereomicroscopy. In pure aluminum, oxidation takes place after a temperature dependent induction period, by the nucleation of crystalline γ-Al2O3 at the amorphous oxide/metal interface. This process is delayed by additions of zinc which modify the structure of the oxide. In alloys containing magnesium, oxidation takes place by the rapid nucleation and growth of MgAl2O4 or MgO, with a secondary form of magnesia developing from the reduction of the amorphous γ-Al2O3 surface layer.

The formation and dissociation of magnesium alloy hydrides and their use for fuel storage in the hydrogen car

Abstract: The formation of hydrides by the reaction of high-pressure hydrogen (300 to 800 psi) with Mg-10Al and Mg-25Ni was studied at 400 and 450°C. Although the reaction kinetics for both alloys can be described by the Johnson-Mehl relationship, the morphology and nature of the reaction products were very different for the two alloys. The temperature dependence of the rates suggests that an interfacial reaction, possibly the transfer of hydrogen from the metal to the hydride, may be the rate-controlling step. One hydride, MgH2, formed internally in the Mg-10Al alloy as spherical particles of nearly constant size at any time, indicating that nucleation was rapid. The reaction involving Mg-25Ni resulted in two hydrides, MgH2 and Mg2NiH4, the former being more stable and forming first by consuming the primary magnesium phase of the eutectic structure. The hydride advanced into the alloy as a “front”, after which the eutectic plates of Mg2Ni reacted to form the ternary hydride. Finally, the larger primary plates of Mg2Ni reacted. Dehydriding of the Mg-10Al alloy hydride also followed the Johnson-Mehl relationship and was found to be complete in 90 min at 300°C, these conditions being favorable for the use of this hydride in vehicles combusting hydrogen. On the other hand, dehydriding of the hydrided Mg-25Ni alloy occurred by a twostep process in which some of the Mg2NiH4 dissociated followed by complete dissociation of this hydride and of the MgH2. Only a small fraction, 10 pct of the available hydrogen could be recovered in several hours at 300°C. The Mg-10Al alloy exhibited a much higher resistance to fragmentation during hydriding than did the Mg-25Ni alloy. An analysis of numerous factors required of hydrides for use in vehicular applications showed that Mg-10Al was much better than Mg-25Ni, although the charging time is much too long.

Novel silver compositions

Abstract: Compositions useful for making electrical conductor patterns on a nonconductive substrate, the compositions comprising metal powder and 1-5% glass-free inorganic binder. The binder consists essentially of certain amounts of bismuth oxide and oxides of copper and/or lead, and optionally MnB2 and/or MnO2. The metal powder is either silver or a mixture of silver with a second metal powder; the second metal powder is Pt, Pd, Au, or an alloy of Cu with one or more of Pt, Pd, Au, and Ag. The weight ratio of Ag to other metals is at least 17/1. These compositions are useful for making conductor patterns on substrates, which patterns have good adhesion to the substrate, both initially and after thermal aging (e.g., 150° C. for 48 hours).

Microstructural stability of titanium-modified type 316 and type 321 stainless steel

Abstract: Optical metallography, transmission electron microscopy, and X-ray diffraction from bulk extracted residues were used to investigate the microstructural stability in the temperature range 450°C to 950°C of a titanium-modified type 316 stainless steel and to compare this steel to a type 321 heat. The effect of cold deformation prior to aging was also investigated. Compared to standard type 316 stainless steel, the nucleation of M23C6 was delayed and its growth retarded in the titanium modified alloy due to early formation of TiC and Ti4C2S2 which reduced the carbon content in the matrix. Precipitation of the intermetallic σ and χ phases was faster in the titanium modified alloy. The type 321 material formed both M23C6 and the intermetallic phases less rapidly than either standard or titanium-modified type 316 steels. The relative tendencies toward intermetallic compound formation in various austentic stainless steels are discussed in terms of an “effective equivalent Cr content” remaining in the austenitic matrix after carbide precipitation. Cold work accelerated the precipitation rate of M23C6 and σ, but it suppressed χ formation due to preferential early σ formation. Early sigma formation was often associated with recrystallization of the cold worked matrix. Mechanisms accounting for this behavior are discussed.

Absorption of hydrogen by palladium–copper alloys. Part 1.—Experimental measurements

Abstract: Pressure against composition isotherms, and changes in the relative electrical resistance with hydrogen content, have been determined over the temperature range 303–373 K, for the absorption of hydrogen by palladium alloys containing 5, 10, 15 and 20 atom % copper. For each alloy, the relative resistance increases continuosly with hydrogen content. The pressure against composition isotherms all lie inside the isotherm for palladium, and the solubility at 1 atmosphere decreases continuously with increasing copper content. There is a marked hysteresis between the absorption and desorption data, both for the relative resistance relationships and for the pressure against composition isotherms.α-Phase absorption data, over the temperature range 423–573 K have also been obtained, and it is found that the solubility, at any reference pressure decreases with copper content.

The high-temperature oxidation of Ni-20%Cr alloys containing various oxide dispersions

Abstract: The oxidation behavior of Ni-20%Cr alloys containing approximately 3 vol.% Y2O3, ThO2, and A12O3 as dispersed particles has been examined in the temperature range 900 to 1200° C in slowly flowing oxygen at 100 Torr. The results show that the oxidation behavior of the Y2O3-, ThO2-, Al2O3-, and Ce02-containing alloys is very similar and that some anomalies in the behavior of the ThO2-containing alloy might be explained by the slower rate of chromium diffusion in this coarse-grained alloy. Two Al2O3-containing alloys were studied. One with a relatively coarse dispersoid size behaved in a manner analogous to a dispersion-free Ni-30% Cr alloy at 1100°C. The other alloy contained a dispersion of fine Al2O3 particles and behaved exactly like the Y2O3-containing alloy at 1000 and 1100°C, but at 1200° C oxidized at a faster rate. It has been shown that the adherent scales on dispersion-containing alloys have a stabilized fine grain size, whereas the nonadherent scales on dispersion-free alloys undergo grain growth.

Process for fabricating articles of tungsten-nickel-iron alloy

Abstract: A high density W--Ni--Fe alloy of composition 85-96% by weight W and the remainder Ni and Fe in a wt. ratio of 5:5-8:2 having enhanced mechanical properties is prepared by compacting the mixed powders, sintering the compact in reducing atmosphere to near theoretical density followed by further sintering at a temperature where a liquid phase is present, vacuum annealing, and cold working to achieve high uniform hardness.