Фазовая диаграмма системы Al-Th

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Al-Th (Aluminum-Thorium) M.E. Kassner and D.E. Peterson The assessed Th-Al phase diagram is based primarily on the data of [58Mur], with review of the work of [27Leb], [42Gru], [64Ban], and [73Poy]. With the exception of a few modifications, it is similar to the diagrams of [Smith] and [Chiotti], which are based on the diagram of [58Mur] with important modifications according to [61Vuc], [64Ban], and [68Fru]. [58Mur] found that the solubility of Al in (aTh) falls with decreasing temperature, being 0.85 and 0.4 at.% at 1300 and 1000 C, respectively. Solubility measurements of Al in (bTh), the higher temperature phase, do not appear to be available, although [58Mur] and [55Sal] indicated that the solubility is limited (less than 1 at.%). [64Ban] suggested a metatectic at 1382, с 10 C and that the solubility of Al in (bTh) is, therefore, greater than in (aTh) at that temperature. Other reviews ([Chiotti] and [Thorium]), however, suggest approximately 1360 C at the aTh = bTh transformation temperature and retain the 1382 C invariant reaction as a peritectic where Al solubility in (aTh) is higher than in (bTh). [Smith] suggested that the invariant temperature and the transformation temperature are nearly coincidental at 1382 C and that there is higher solubility in (bTh) at this temperature. It is difficult to construct this portion of the phase diagram so as to be consistent with the pure aTh = pure bTh transformation temperature of 1360 C and the observations of decreasing allotropic transformation temperatures with Al additions, as well as the invariant temperature separating (aTh) + L and (bTh) + L phase fields at about 1382 C [58Mur, 64Ban] and 1378 C [55Sal], where the purity was between 99.5 and 99.9%. In agreement with [Chiotti] and [ Thorium], the 1360 C allotropic transformation and a 1382 C peritectic transformation are retained in the assessed diagram. [68Fru] reported data on Th2Al7. This new phase was found by dissolving Th in an Al melt at 1000 C. The peritectic reaction ThAl3 + L = Th2Al7 was presumed to be below 1000 C. [69Hav] reported that the Th3Al2 becomes superconductive at 2.6 K, whereas [ 72Hav] noted Th2Al is a superconductor at 0.09 K. 27Leb: I.A. Leber, Z. Anorg. Chem., 166, 16-26 (1927) in German. 38Bra: G. Brauer, Naturwissenschaften, 26, 710 (1938) in German. 42Gru: G. Grube and L. Botzenhardt, Z. Elektrochem., 48, 418-425 (1942) in German. 55And: A.F. Andresen and J.A. Goedkoop, Acta Crystallogr., 8, 118 (1955). 55Bra1: P.B. Braun and J.H.N. van Vucht, Acta Crystallogr., 8, 117 (1955). 55Bra2: P.B. Braun and J.H.N. van Vucht, Acta Crystallogr., 8, 246 (1955). 55Mur: J.R. Murray, J. Inst. Met., 84, 91-96 (1955-56). 55Sal: H.A. Saller, and F.A. Rough, "Compilation of U.S. and U.K. Uranium and Thorium Constitutional Diagrams," USAEC Rept. BMI-1000 (1955). 58Mur: J.R. Murray, J. Inst. Met., 87, 349-352 (1958-59). 61Bro: A. Brown, Acta Crystallogr., 14, 860-865 (1961). 61Vuc: J.H.N. van Vucht, Philips Res. Rept., 16, 1-40 (1961). 64Ban: G.H. Bannister and J.R. Thomson, J. Nucl. Mater., 12, 16-23 (1964). 68Fru: A.J. Frueh and J. Sygusch, Z. Kristallogr., 127, 139-144 (1968). 69Hav: E.E. Havinga, M.H. Van Maaren, and H. Damsma, Phys. Lett., 29A, 109-110 (1969). 72Hav: E.E. Havinga, H. Damsma, and J.M. Kanis, J. Less-Common Met., 27, 281- 291 (1972). 73Poy: A.M. Poyarkov, V.A. Lebedev, I.F. Nichkov, and S.P. Raspopin, Atom. Ehnerg., 35, 434-435 (1973) in Russian; TR: Sov. Atomic Energy, 35, 1138-1140 ( 1973). 86God: B.K. Godwal, V. Vijayakumar, S.K. Sikka, and R. Chidambaram, Physica B, 144, 44-47 (1986); TR: J. Phys. F, Met. Phys., 16, 1415-1418 (1986). Published in Bull. Alloy Phase Diagrams, 10(4a), Sep 1989. Complete evaluation contains 1 figure, 3 tables, and 26 references. Special Points of the Th-Al System