Фазовая диаграмма системы Ta-Th

К оглавлению: Другие диаграммы (Others phase diargams)

Ta-Th (Tantalum-Thorium) R. Krishnan, S.P. Garg, and N. Krishnamurthy The assessed phase diagram for the Ta-Th system is based on the experimental work of [61Mcm], [72Ack1], [72Ack2], and [85Sar] and on earlier reviews in [ Tantalum] and [Thorium]. The eutectic and the liquidus data shown in the assessed diagram are taken mainly from [72Ack1] and [72Ack2]. The addition of Ta to Th decreases the aTh = bTh transformation temperature to 1338 C, with a eutectoid composition of about 99.88 at.% Th. The solid solubility of Th in (Ta) at 1350 C was found to be about 0.016 at.% [61Mcm]. The presence of an intermetallic compound, Ta2Th, has been suggested by [ 72Ack1] and [72Ack2], contrary to [61Mcm], who did not find evidence for any compound in the Ta-Th system. [72Ack1] and [72Ack2] made their conclusions primarily based on the shape of the liquidus curve (an apparent discontinuity in the liquidus curve was observed at 1892 C) and also because the atomic ratio of bcc Th and fcc Ta is 1.20, which is close to the ideal value of 1.225 for the Laves phases. However, [85Sar] indicated that intermetallic compounds are unlikely to exist in the Ta-Th system. Therefore, the assessed phase diagram has been drawn without showing any intermetallic compound. 61Mcm: O.D. McMasters and W.L. Larsen, J. Less-Common Met., 3, 312 (1961). 72Ack1: R.J. Ackermann and E.G. Rauh, High Temp. Sci., 4, 272-282 (1972). 72Ack2: R.J. Ackermann and E.G. Rauh, High Temp. Sci., 4, 496-505 (1972). 85Sar: A. Saroja, Y.J. Bhatt, and S.P. Garg, J. Less-Common Met., 114, 291-297 (1985). Published in J. Alloy Phase Diagrams, 5(1), Jan 1989. Complete evaluation contains 2 figures, 1 table, and 12 references. 1