Alloys related

Her0, H. and Valderhaug, J. Tarnishing in vivo and in vitro of a Low Gold Alloy Related to its Structure , Journal of Dental Research, 64, 139-143 (1985)... 

Amorphous alloys are in a thermodynamically metastable state, and hence essentially they are chemically more reactive than corresponding thermodynamically stable crystalline alloyIf an amorphous alloy crystallises to a single phase having the same composition as the amorphous phase, crystallisation results in a decrease in the activity of the alloy related to the active dissolution rate of the alloy . 

In these particular experiments it proved impossible to investigate the effect of copper concentration on the catalytic activity of alloys free of the hydride phase. Figure 10 69, 64a, 65) illustrates the changing values of the recombination coefficient on nickel-copper alloys related to the composition of the alloy at room temperature. The small amount of copper introduced into the nickel already distinctly decreased the catalytic ac-... 

The early papers usually assumed that surface concentration can be estimated from the normalized ratio of the Auger peaks (41,42). However, soon it appeared that this had led to incorrect conclusions on, e.g., Ni-Cu (43) or Pd-Ag (44) alloys. In particular, the progress with pure Ni-Cu alloy systems suffered very much from the uncertainties caused by improper procedures. The main point to keep in mind in this respect is that the ratio of peak intensities for metals A and B in alloys related to those in the pure metals, as seen by Auger electron spectroscopy (AES), is given by (45, 47) the following equation ... 

The following remarks, classified by alloy, relate primarily to cases in which long-term outdoor atmosphere exposure data are available some references are also made to accelerated test results, to assist investigators. 

Fig. 13. UCu4j,A1. j alloys relations between concentration x and (upper panel) coefficient of the electronic specific heat, y (middle panel) ratio between electric resistivities at and at RT, p /pnoxl (lower panel) Neel points, or temperature of maximum in p(T) plot,...

Implementation of these Pb-free alloys may require considerable effort in component, substrate, and final product qualification. This may include the elimination of Pb-containing solderable surfaces if there is substantial Bi content in the solders. Major costs may be associated with start-up and qualification costs. Alloy-related costs will probably not be a major factor [typically pennies (U.S.) per PWB]. 

Aru] Arutyunyan, S.V., Transition from Atomic Ordering to Disordering in Fc3(Al,Si) Alloys Related to the Formation of the K-Effect (in Russian), Izv. Akad. Nauk Arm. SSR, Ser. Tekh. Nauk, 32, 36-42 (1970) (Experimental, 4)... 

Besides the material based characteristics, the difference of density of the used particle/substrate combination is a very important criterion. The difference of density influences the contrast of the radiographic tests. Tungsten carbides were used as mechanically resistant particles and titanium based alloys as substrate. The substrate material is marked by an advantageous relation of strength to density. This material is often used in aeronautics, astronautics, and for modification of boundary layers. The density of tungsten carbide (15.7 g/cm ) is about 3.5 times higher than the density of titanium (4.45-4.6 g/cm ). 

Our discussion shows that the Ising model, lattice gas and binary alloy are related and present one and the same statistical mechanical problem. The solution to one provides, by means of the transcription tables, the solution to the others. Flistorically, however, they were developed independently before the analogy between the models was recognized. 

We now turn to a mean-field description of these models, which in the language of the binary alloy is the Bragg-Williams approximation and is equivalent to the Ciirie-Weiss approxunation for the Ising model. Botli these approximations are closely related to the van der Waals description of a one-component fluid, and lead to the same classical critical exponents a = 0, (3 = 1/2, 8 = 3 and y = 1. 

The metal has unusual superconductive properties. As little as 1 percent gadolinium improves the workability and resistance of iron, chromium, and related alloys to high temperatures and oxidation. 

AWS) has issued specifications covering the various filler-metal systems and processes (2), eg, AWS A5.28 which appHes to low alloy steel filler metals for gas-shielded arc welding. A typical specification covers classification of relevant filler metals, chemical composition, mechanical properties, testing procedures, and matters related to manufacture, eg, packaging, identification, and dimensional tolerances. New specifications are issued occasionally, in addition to ca 30 estabUshed specifications. Filler-metal specifications are also issued by the ASME and the Department of Defense (DOD). These specifications are usually similar to the AWS specification, but should be specifically consulted where they apply. 

Copper and Copper-Containing Alloys. Either sulfuric or hydrochloric acid may be used effectively to remove the oxide film on copper (qv) or copper-containing alloys. Mixtures of chromic and sulfuric acids not only remove oxides, but also brighten the metal surface. However, health and safety issues related to chromium(VT) make chromic acid less than desirable. 

Naphthenic acid corrosion has been a problem ia petroleum-refining operations siace the early 1900s. Naphthenic acid corrosion data have been reported for various materials of constmction (16), and correlations have been found relating corrosion rates to temperature and total acid number (17). Refineries processing highly naphthenic cmdes must use steel alloys 316 stainless steel [11107-04-3] is the material of choice. Conversely, naphthenic acid derivatives find use as corrosion inhibitors ia oil-weU and petroleum refinery appHcations. 

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