Фазовая диаграмма системы Sn-Zr

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Sn-Zr (Tin-Zirconium) J.P. Abriata, J.C. Bolcich, and D. Arias The assessed Zr-Sn phase diagram is based primarily on the micrographic analysis of [53Mcp], with review of the work of [53Spe] and [ 82Ari]. In general, the diagram is considered to be rather uncertain regarding most of the liquidus, as well as the entire region between about 30 and 50 at.% Sn. Using optical and electron microscopy, hardness measurements, and X-ray diffraction, [81Car] studied the aging response of Zr-Sn alloys below the peritectoid reaction temperature and up to 7 at.% Sn. Under most conditions of aging (including up to 1000 h at temperatures in the range 500 to 600 C), following solution treatment in the (aZr) or (bZr) phases, minimal precipitation of second-phase particles occurred. The volume fraction of this second phase was always more than an order of magnitude less than predicted from the phase diagrams given by [53Mcp] and [ 53Spe]. Accordingly, [81Car] concluded that the solubility of Sn in (aZr) may be significantly higher than previously suggested. The reasons for this apparent discrepancy between the results of [81Car] and those of [53Mcp] and [53Spe] are not clear. It may be that the volume fractions observed by [81Car] really correspond to metastable equilibrated samples between (aZr) and a Sn-rich intermediate phase other than Zr4Sn. Zr4Sn is only weakly stable against the decomposition Zr4Sn <259> (aZr) + Zr5Sn3, because rather low levels of Fe impurities make the Zr4Sn phase unstable [ 60Tan]. In the Zr-Sn-Fe ternary, Zr4Sn exists only in the Zr-Sn binary; even a small amount of Fe makes this phase unstable. When some metallic solutes such as Be, Cu, and Fe dissolve in solid Zr, they exhibit an interstitial-like (fast-diffusing) behavior. However, this is not the situation for Sn, which has a well-defined substitutional character when highly diluted in Zr. 53Mcp: D.J. McPherson and M. Hanson, Trans. ASM, 45, 915 (1953). 53Spe: G.R. Speich and S.A. Kulin, Zirconium and Zirconium Alloys, American Society for Metals, Cleveland, Oh, 197 (1953). 60Tan: L.E. Tanner and D.W. Levinson, Trans. ASM, 52, 1115 (1960). 81Car: G.J.C. Carpenter, E.F. Ibrahim, and J.F. Watters, J. Nucl. Mater., 102, 280 (1981). 82Ari: D. Arias, unpublished work, ASM repository No. APD-R-83-003 (1982). ( Copies are available from ASM). Published in Bull. Alloy Phase Diagrams, 4(2), Sep 1983. Complete evaluation contains 4 figures, 1 table, and 38 references. Special Points of the Zr-Sn System