Phase peritectic systems

The use of an ideal-solution model meant that there were a number of instances where calculated and experimental results were quantitatively at variance. However, the approach very successfully predicted the general form of most of the phase diagrams, for example whether they were peritectic or eutectic, and accounted for the appearance of intermediate phases in systems such as Cr-Rh. That the approach could do this using such simple and internally self-consistent models is a demonstration of the inherent power of CALPHAD methods. The importance of this first step therefore cannot be overestimated, although its significance was not... 

Parts of the Th-N phase diagram were determined by X-ray, microscopic, chemical, and thermal analyses of phases equilibrated with nitrogen (up to 3 bar) at temperatures up to 3093 K. The Th-ThN portion of the phase diagram is a peritectoid-peritectic system wherein, npon heating, the face centred cubic Th phase with a N Th ratio (0.08 0.02) decomposes peritectoidally at (1878 + 20) K to body centred cnbic Th and ThN. The... 

Group III Peritectic systems Ill(a) Simple peritectic Ill(b) Partial miscibility in the a and 3 phases... 

Figure 5.12 gives the phase diagram for the almost ideal peritectic system, silver-platinum. As discussed by Uhlmann and Chadwick in the first detailed study of peritectic reactions, for virtually all compositions except those near the limits of the system, the microstructure after casting will consist of cored dendrites of one phase surrounded by the second phase. Thus with reference to Fig. 5.12 we would expect this structure for compositions from 30 to 90 wt % platinum. Furthermore, the peritectic reaction should seldom proceed to completion. When the primary phase has cooled to the peritectic... 

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 copper-zinc system shown in Fig. A1.38 has no fewer than five peritectic reactions. Locate them and ring the peritectic points. (Remember that when a single-phase field closes above at a point, the point is a peritectic point.)... 

J. Tiaden, B. Nestler, H. J. Diepers, I. Steinbach. Physica D 115 11, 1998 G. J. Schmitz, B. Nestler. Simulation of phase transitions in multiphase systems, peritectic solidification of YBaCuO-superconductors. Mater Sci Eng B 53 11, 1998. 

The Ca-Cu system has been reexamined using thermal analysis and x-ray diffraction methods an independent study of the CaCuj-Cu section has also been completed. The resultant phase diagram, although similar to that in ref. 3 at the Cu-rich end, differs markedly for Ca-rich alloys. Supporting evidence for the modifications has been obtained from the Ca-Mg-Cu ternaiy system. Three intermediate compounds are formed in the system CaCuj (950 C) melts congruently, whereas CajCu (488 C) and CaCu (567°C) are formed in peritectic reactions. Single-crystal x-ray diffraction studies verify the stoichiometry of CajCu and examine the polymorphism of CaCu. ... 

The Sr-Cu system has been critically assessed. The most recent phase diagram, determined by combining differential thermal analysis and x-ray diffraction techniques, contains two intermediate compounds, both of which form in peritectic reactions, SrCu (588°C) and SrCu, (845°C) SrCu has also been prepared for independent structural analysis-. ... 

The phase diagram for the Sr-Au system shows three congruently melting phases, /3-SrAu (970°C), SrAu2 (1085°C) and SrAu, (1040°C) four phases formed in peritectic reactions are also observed, Sr Au (640°C), SrjAu (590°C), y-Srj Au (750°C) and 5-Sr,Au2, which has a limited stability range from the eutectoid (725°C) to the peritectic reaction (770°C). Independent structural investigations confirm the forma-... 

The entire Ba-Cu system has been examined a partial study (0-50 at% Ba) has also been carried out. Where comparable the two sets of data are in agreement consequently, the recommended phase diagram is that in ref. 1. Two compounds exist in the system BaCu (570°C) melts congruently, whereas BaCujj (670°C) is formed in a peritectic reaction. Further evidence for BaCu has come from a structural study. ... 

Two versions of the Ba-Cd phase diagram are very similar and, but for some minor differences in the critical point parameters, differ only in the stoichiometry of the compound at 17 at% Ba-Ba2Cd9 or BaCd . Since ref. 5 includes a structural analysis of the intermediate compounds, this phase diagram is recommended. There are five intermediate compounds in the system. Four of these melt congruently, BaCd (SSS C), BaCdj (642°C), Ba2Cd, (620°C) and BaCd (672°C) the other, BajCd (409°C), is formed in a peritectic reaction. The existence of Ba2Cd BaCd, BaCdj, and BaCd], has been verified in separate crystallographic studies. 

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