Фазовая диаграмма системы Ba-Cu

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Ba-Cu (Barium-Copper) D.J. Chakrabarti and D.E. Laughlin The assessed Cu-Ba phase diagram has been derived from [59Bra] and [71Bru], with review of the work of [80For]. Cu and Ba are virtually insoluble in one another in the solid state, but are soluble in all proportions in the liquid. Two intermediate phases, of stoichiometry Cu13Ba and CuBa, are formed in this system. CuBa undergoes congruent melting. The crystal structure of Cu13Ba is isotypic with Zn13Na, and CuBa is the prototype of a new structure. The equilibrium phases in the Cu-Ba system are (1) the liquid, miscible in all proportions and stable down to 458 C at 79.4 at.% Ba; (2) the fcc solid solution, (Cu), with negligible solubility of Ba; (3) the bcc solid solution, ( Ba), with negligible solubility of Cu; (4) Cu13Ba, the fcc intermediate phase that decomposes incongruently via a peritectic reaction at 670 C; and (5) CuBa, the hexagonal intermediate phase that undergoes congruent melting at ~570 C. The lower temperature limits of stability of Cu13Ba and CuBa have not been determined experimentally. Ba is extremely reactive in air, as are Ba-Cu alloys. Thus, contamination is always a problem with these alloys, particularly in the liquid. Because the Cu-Ba phase diagram is reasonably well established, the equilibrium boundaries between the coexisting phases can be used to derive expressions for the thermodynamic variables of the different phases. The variables, in turn, can be used to reproduce the phase boundaries as a check for self-consistency and also to calculate the critical points in the system for which no experimental data may be available. Both of these aspects have been attempted in the present evaluation. Analytic representations as polynomials of composition of the liquidus (temperature) have been obtained by least-squares analysis over the different composition ranges. The fit between the assessed and calculated liquidus is within с2 C in most of the ranges. 59Bra: P.B. Braun and J.L. Meijering, Recueil Trav. Chim., 78(1), 71-74 (1959). 71Bru: G. Bruzzone, J. Less-Common Met., 25(4), 361-366 (1971). 80For: M.L. Fornasini and F. Merlo, Acta Crystallogr. B, 36, 1288-1291 (1980). Published in Bull. Alloy Phase Diagrams, 5(6), Dec 1984. Complete evaluation contains 2 figures, 5 tables, and 9 references. Special Points of the Cu-Ba System