Transformations of Solid Solutions

Pniim-Fniim transformations of solid solutions of CsCl with KC1 and CsBr exhibit different behaviours. With increasing percentages of KC1, the NaCl structure gets stabilized in the CsCl+KCl system. In the CsCl+CsBr system, the transformation temperature increases with % CsBr and AH essentially remains constant. Both these behaviours can be satisfactorily explained in terms of the Born treatment of ionic solids. The Pmlm-Fniim transformation retains its first-order characteristics in the CsCl+KCl system, but higher-order components seem to be present in the CsCl+CsBr system. Incorporation of vacancies do not affect the transformation of CsCl markedly. 

Characteristics and implementation of the treatments depend on the expected results and on the properties of the material considered a variety of processes are employed. In ferrous alloys, in steels, a eutectoid transformation plays a prominent role, and aspects described by time-temperature-transformation diagrams and martensite formation are of relevant interest. See a short presentation of these points in 5.10.4.5. Titanium alloys are an example of the formation of structures in which two phases may be present in comparable quantities. A few remarks about a and (3 Ti alloys and the relevant heat treatments have been made in 5.6.4.1.1. More generally, for the various metals, the existence of different crystal forms, their transformation temperatures, and the extension of solid-solution ranges with other metals are preliminary points in the definition of convenient heat treatments and of their effects. In the evaluation and planning of the treatments, due consideration must be given to the heating and/or cooling rate and to the diffusion processes (in pure metals and in alloys). 

Thermal transformation of solid phases in the dry state or via solution (Chap. 14)... 

A. G. Khachaturian, The Theory of Phase Transformations and Structure of Solid Solutions, Nauka, Moscow, 1974. 

Solgel processing specifies a type of solid material synthesis method performed in a liquid and at low temperatures [152], The produced inorganic solids, mostly oxides or hydroxides, are formed by chemical transformation of chemical solutes termed precursors. The solid is formed as the result of a polymerization process that involves the establishment of M-OH-M or M-O-M bridges between the metallic atoms M of the precursor molecules [152], The drying process, after the gel formation, is carried out at a relatively low temperature to produce a xerogel, or by a supercritical drying process. 

The solgel procedure, as was previously recognized, is a method for solid materials synthesis, carried out in a liquid at a low temperature (typically T < 100°C). The synthesized inorganic solids are formed by chemical transformation of chemical solutes termed precursors [39], More specifically... 

Recent structural studies of a number of surface alloy phases have revealed some surprising results. Here we have concentrated on just two issues. One is the formation of a stacking fault at the interface of the surface alloy layer and the underlying substrate which has been found for the (V3xV3)R30°-Sb phases formed on Cu(lll) and Ag(lll). A number of other fcc(lll) (V3xV3)R30° surface alloy phases, such as that formed by Pb on Ni(lll), do not show this effect, and it may be rather specific to the role of Sb on these two substrates for both Cu and Ag there are bulk hep phases of solid solutions containing a significant concentration of Sb, and this transformation may be effected at much lower concentrations near a surface. 

The new assessment for the Si-C system was primarily based on experimental SiC solubility data in liquid solution given by Scace and Slack [34], Hall [35], Iguchi [36], Kleykamp and Schumacher [37], Oden and McCune [38], and Ottem [14], Solid solubility data given by Nozaki et al. [39], Bean [40], and Newman [41] were used to determine the properties of solid solution. The eutectic composition reported by Nozaki et al. [39] and Hall [35] and peritec-tic transformation temperature determined by Scace [34] and Kleykamp [37] were also used in the thermodynamic optimization. Thermodynamic description of the SiC compound was taken from an early assessment [42]. The... 

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