Homogeneous metal alloys

Linear voltammetry is a powerful tool for investigating the kinetics of non-stationary electrode processes including anodic selective dissolution of homogeneous metal alloys, when the less noble component is predominantly oxidized. As a result, the surface layer of the dissolving alloy is enriched with a nobler metal and a solid-phase diffusion zone, in which the mass transfer is carried out by the vacancy mechanism, is formed. The concentration of dot defects formed on the alloy surface is much higher than an equilibrium value, however, despite the increased diffusion mobility of the conqronent atoms, the transient solid mass transfer often controls the selective dissolution of the whole. 

The properties of alloys are affected by their composition and structure. Not only is the crystalline structure important, but the size and texture of the individual grains also contribute to the properties of an alloy. Some metal alloys are one-phase homogeneous solutions. Examples are brass, bronze, and the gold coinage alloys. Other alloys are heterogeneous mixtures of different crystalline phases, such as tin-lead solder and the mercury-silver amalgams used to fill teeth. 

Now, suppose that we have a solid solution of two (2) elemental solids. Would the point defects be the same, or not An easy way to visualize such point defects is shown in the following diagram, given as 3.1.3. on the next page. It is well to note here that homogeneous lattices usually involve metals or solid solutions of metals (alloys) in contrast to heterogeneous lattices which involve compounds such as ZnS. 

Moving on from preparation of homogenous Pt alloy particles to tailoring of core-and-sheU alloy particles, targeting (i) further lowering of the mass of precious metal per unit power output and (ii) further boost of catalytic activity per square centimeter of catalyst area [Zhang et al., 2004]. 

Fig. 29. CO oxidation at 240°C over Pd-Rh alloy films as a function of apparent surface composition homogeneous alloys and pure metals ( ) alloys showing phase separation (3) (34).

H.I. Aaronson and F.K. LeGoues. An assessment of studies on homogeneous diffusional nucleation kinetics in binary metallic alloys. Metall. Trans. A, 23(7) 1915—1945, 1992. 

Complex metal cyanides decompose at fairly high temperatures. Decomposition in an oxidizing atmosphere (up to 600 K) results in the corresponding oxides, that in an inert or in a reducing atmosphere (up to 900 K) results in the metals or alloys. In either case, reaction of the oxides or of the metals/alloy with the support is minimized. The complex cyanide method can thus establish homogeneity of the constituent ions on a molecular scale and also prevent undcsircd reactions of the active precursors with the support. 

Wood is a complex composite of cellulose and lignin most sedimentary rocks are composites of particles bonded together by natural cement and many metallic alloys are composites of several quite different constituents. On a macro scale these are all homogeneous materials. 

This term might be used to describe a metal alloy sample known to be inherently stable, tested for homogeneity as part of routine production quality control and analysed by both the laboratory s routine method (say, XRF) and an alternative method (say, dissolution and measurement of the solution by ICP-OES). 

Atomization is particularly useful for the production of homogeneous powdered alloys, since the constituent metals are intimately mixed in the molten state. Further, this process is also useful to produce powders of difficult compositions. For instance. 

Moharil D. B. Jin I. Purdy G. R., The effect of h-ferrite formation on the post-solidification homogenization of alloy steels. Metall. Trans, 5 (1974), 59-63... 

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