Phase diagram binary eutectic

Fig. 1 Simple binary-phase diagram with eutectic formation. Ta is melting point of pure A Th is melting point of pure B and E is eutectic point.

Fig. 12 Binary phase diagram with eutectic, and DSC curve of the composition X2-...

In Figure 8.2-9 the phase diagram for an eutectic solidifying binary nrixture is shown. According to the given phase diagram (binary system without formation of mixed crystals) this soUd should contain less A than the feed. In this case the thermodynamic distribution coefficient for an impurity component i is defined by... 

Binary Alloys. Aluminum-rich binary phase diagrams show tliree types of reaction between liquid alloy, aluminum solid solution, and otlier phases eutectic, peritectic, and monotectic. Table 16 gives representative data for reactions in tlie systems Al—Al. Diagrams are shown in Figures 10—19. Compilations of phase diagrams may be found in reference 41. 

The distribution-coefficient concept is commonly applied to fractional solidification of eutectic systems in the ultrapure portion of the phase diagram. If the quantity of impurity entrapped in the solid phase for whatever reason is proportional to that contained in the melt, then assumption of a constant k is valid. It should be noted that the theoretical yield of a component exhibiting binary eutectic behavior is fixed by the feed composition and position of the eutectic. Also, in contrast to the case of a solid solution, only one component can be obtained in a pure form. 

OC10H21)], in which rearrangement does not occur. All the mixtures studied display liquid crystal behavior with improved properties with respect to the pure components. A representative binary phase diagram and their corresponding DSCtraces are presented in Figures 8.24 and 8.25 respectively, and reveal the eutectic nature ofthese systems. 

A brief discussion of sohd-liquid phase equihbrium is presented prior to discussing specific crystalhzation methods. Figures 20-1 and 20-2 illustrate the phase diagrams for binary sohd-solution and eutectic systems, respectively. In the case of binary solid-solution systems, illustrated in Fig. 20-1, the liquid and solid phases contain equilibrium quantities of both components in a manner similar to vapor-hquid phase behavior. This type of behavior causes separation difficulties since multiple stages are required. In principle, however, high purity... 

There are many types of phase diagrams in addition to the two cases presented here these are summarized in detail by Zief and Wilcox (op. cit., p. 21). Solid-liquid phase equilibria must be determined experimentally for most binary and multicomponent systems. Predictive methods are based mostly on ideal phase behavior and have limited accuracy near eutectics. A predictive technique based on extracting liquid-phase activity coefficients from vapor-liquid equilibria that is useful for estimating nonideal binary or multicomponent solid-liquid phase behavior has been reported by Muir (Pap. 71f, 73d ann. meet., AIChE, Chicago, 1980). 

Figure 2.13. Building blocks of binary phase diagrams examples of three-phase (invariant) reactions. In the upper part the general appearance, inside a phase diagram, of the two types of invariant equilibria is presented, that is, the so-called 1 st class (or eutectic type) and the 2nd class (or peritectic type) equilibria. In the lower part the various invariant equilibria formed by selected binary alloys for well-defined values of temperature and composition are listed. In the Hf-Ru diagram, for instance, three 1 st class equilibria may be observed, 1 (pHf) — (aHf) + HfRu (eutectoid, three solid phases involved), 2 L — (3Hf + HfRu (eutectic), 3 L —> HfRu + (Ru) (eutectic).

Figure 6.10. A generic binary phase diagram is shown for an A-B system in which two compounds, AB and ABm, are formed. Different parts of the liquidus line are indicated. 1 is the line of primary crystallization of the terminal solid-solution based on the component A (which, on cooling, will be followed by the peritectic formation of AB ) 2 is the line of primary crystallization of the compound AB (to be followed by the eutectic crystallization of AB + ABm) 3 and 4 are lines of primary crystallization of ABm (to be followed, respectively, by the crystallization of the eutectic AB + ABm or of the eutectic AB, + B-based solid solution).

Figure 15.4. Phase diagrams for binary systems (E - eutectic, L - liquid)...

A melt is a liquid or a liquid mixture at a temperature near its freezing point and melt crystallisation is the process of separating the components of a liquid mixture by cooling until crystallised solid is deposited from the liquid phase. Where the crystallisation process is used to separate, or partially separate, the components, the composition of the crystallised solid will differ from that of the liquid mixture from which it is deposited. The ease or difficulty of separating one component from a multi-component mixture by crystallisation may be represented by a phase diagram as shown in Figures 15.4 and 15.5, both of which depict binary systems — the former depicts a eutectic, and the latter a continuous series of solid solutions. These two systems behave quite differently on freezing since a eutectic system can deposit a pure component, whereas a solid solution can only deposit a mixture of components. 

Finally, the high-temperature peak at 452°C in Fig. 3.14 is due to the eutectic melting of the AljMg and Al(Mg) mixture according to the binary Mg-Al phase diagram [122]. 

Figure 2.5 Free energy of mixing for solid and liquid phases at various temperatures (a-e) and resulting temperature-composition phase diagram for a slightly soluble eutectic binary component system (f). From O. F. Devereux, Topics in Metallurgical Thermodynamics. Copyright 1983 by John Wiley Sons, Inc. This material is used by permission of John Wiley Sons, Inc.

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