Фазовая диаграмма системы Sn-Th

К оглавлению: Другие диаграммы (Others phase diargams)

Sn-Th (Tin-Thorium) D.E. Peterson and E.M. Foltyn The assessed Th-Sn phase diagram is based on the work of [83Cir], and the solubility data are taken from [48Hay]. According to [83Cir], Th5Sn3 was shown to melt congruently at 1800 с 30 C, and Th5Sn4 was estimated to decompose peritectically at approximately 1550 C. [83Cir] found that the addition of Th lowers the melting point of (bSn) to 220 C, where a eutectic reaction occurs at a composition estimated to be less than 1 at.% Th. This depression of the Sn melting point by 12ш must be too large considering the low solubility of Th in liquid Sn. Assuming a Th solubility of 0.026 at.% and Raoult's law, the melting point of Sn would be lowered by only a fraction of a degree. [83Cir] also estimated from metallographic studies that a Th-rich eutectic reaction occurs at about 20 at.% Sn at an estimated eutectic temperature of 1600 C. This result is in conflict with [61Bad], who observed a eutectic point at 15 at.% Sn and 1325 C. A small thermal effect they noted at about 1300 C using thermal analysis may have been the Th allotropic transformation at 1360 C. Examination by [83Cir] of the solution effects on lattice parameters suggested that Th solubility in (Sn) is negligible. [83Cir] identified the liquidus over the region 67.5 to 95 at.% Sn. [48Hay] reported Th solubility in liquid Sn to be less than 0.026 at.% at 600 C, 0.10 at.% at 700 C, 0.98 at.% at 800 C, and 2.25 at.% at 900 C. 48Hay: E.E. Hayes and P. Gordon, J. Metall. Ceram., 1, 130-141 (1948). 61Bad: T.A. Badaeva and R.I. Kuznetsova, The Structure of Alloys of Certain Systems Containing Uranium and Thorium, E.M. Potapova, Ed., Akademii Nauk, Moscow, 387-394 (1961) in Russian; TR: USAEC AEC-tr-5834, 367-375 (1963). 83Cir: S. Cirafici, A. Palenzona, and P. Manfrinetti, J. Less-Common Met., 90, 49-56 (1983). Published in Bull. Alloy Phase Diagrams 10(4a), Sep 1989. Complete evaluation contains 1 figure, 3 tables, and 8 references.