System peritectic

PERITECTIC TEMPERATURE. Temperature in a peritectic system at which there is equilibrium between the solid and the remaining melt, the composition of which conforms to the peritectic point, at which the temperature line meets the liquids curve. 

Consider the A-B binary peritectic system as shown in the following diagram ... 

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. 

Al—Cr. Although no commercial ahoys are based on this system, chromium [7440-47-3] Cr, is an ingredient of several complex and commercially significant ahoys (Fig. 16. The Cr is added for control of grain stmcture. The Al—Cr system has a peritectic portion at 661°C where soHd solubiHty is 0.7% Cr and Hquid solubiHty is 0.4% Cr. Free2ing of binary ahoys containing >0.4% Cr produces coarse primary crystals (metallic inclusions) of AlyCr [12005-37-7] which may adversely affect mechanical properties. In complex ahoys, the Hquid solubiHty can be reduced such that formation of primary AlyCr crystals may occur at significantly lower Cr contents. 

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. ... 

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