Experimental precipitation techniques description

Chapter 10 provides an exhaustive description of how these techniques can be applied to a large number of industrial alloys and other materials. This includes a discussion of solution and substance databases and step-by-step examples of multi-component calculations. Validation of calculated equilibria in multi-component alloys is given by a detailed comparison with experimental results for a variety of steels, titanium- and nickel-base alloys. Further selected examples include the formation of deleterious phases, complex precipitation sequences, sensitivity factor analysis, intermetallic alloys, alloy design, slag, slag-metal and other complex chemical equilibria and nuclear applications. 

Phase separation is frequently observed in polymer solutions and it is mainly due to their low entropy of mixing. At a state of equilibrium each species of the mixture is partitioned between two phases, namely, the supernatant (extremely dilute) and precipitated (moderately dilute) phases [78]. Theoretical models and experimental techniques have been developed to predict the solubility behavior of polymer solutions, polymer blends, and other related systems [79, 80]. Simple theories only permit a rather qualitative description of this phenomenon [78]. Refined and improved theoretical and semiempirical models allow a more accurate prediction of the demixing phenomena and related thermodynamic properties [57, 81]. 

The principles of fractionation by precipitation and extraction are too well known to need description here. Earlier reviews (2—5) dealing with most of the experimental and theoretical aspects, we shall only consider some recent developments. The systems dealt with contain linear macromolecules built up of identical segments. Molecular structure differences other than chain length will be left out of consideration. The phase separations involved in fractionation are described as liquid-liquid separations, and the calculations related to the latter will be based on equations valid for phase equilibrium. A brief discussion of the comparatively new technique of fractional crystallization is given in Section 2. 

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