Фазовая диаграмма системы B-Gd

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B-Gd (Boron-Gadolinium) P.K. Liao and K.E. Spear Detailed experimental work on the phase equilibria for the Gd-B system is not available, but the general nature of this system has been determined. The assessed phase diagram is based primarily on [72Spe] and [79Bla]. The equilibrium phases are (1) the liquid, L; (2) the terminal solid solutions based on the cubic (bGd) and cph (aGd); (3) the terminal solid solution based on rhombohedral (bB); and (4) five intermediate compounds, GdB2, Gd2B5, GdB4, GdB6, and GdB66. (bB) and (Gd) solid solutions have negligible composition ranges. The homogeneity ranges of Gd borides are small, except perhaps for GdB6. [ 76Spe] and [77Spe] discuss the rather wide homogeneity ranges for a number of REB6 phases. All available experimental data indicate that the hexaboride is stoichiometric at its metal-rich phase boundary and becomes B-rich by the formation of up to approximately 30% metal vacancies [76Spe, 79Bla]. 59Eic: H.A. Eick and P.W. Gilles, J. Am. Chem. Soc., 81, 5030-5032 (1959). 62Lap: S.J. LaPlaca, Brookhaven National Laboratory, private communication ( 1962); quoted in [64Pos]. 65Gie: R.F. Giese, Jr., J. Economy, and V.I. Matkovich, Z. Kristallogr., 122, 144-147 (1965). 66Man: R.M. Manelis, G.A. Meerson, N.N. Zhuravlev, T.M. Telyukova, A.A. Stepanova, and N.V. Gramm, Sov. Powder Metall., 11(47), 904-909 (1966). 70Car: J.-O. Carlsson and T. Lundstrom, J. Less-Common Met., 22, 317-320 (1970) . 71Yaj: S. Yajima and K. Niihara, Preprint of paper presented at 9th Rare Earth Research Conference, Blacksburg, VA, Oct 10-14 (1971). 72Sch: K. Schwetz, P. Ettmayer, R. Kieffer, and A. Lipp, J. Less-Common Met., 26, 99-104 (1972) in German. 72Spe: K.E. Spear and G.I. Solovyev, Solid State Chemistry, Proc. 5th Mat. Res. Symp., R.S. Roth and S.J. Schneider, Ed., NBS Spec. Pub. 364, Jul (1972). 76Spe: K.E. Spear, Phase Diagrams: Materials Science and Technology, Vol. IV, Academic Press, New York, 91-159 (1976). 77Cal: B. Callmer, Acta. Crystallogr., B33, 1951-1954 (1977). 77Spe: K.E. Spear, Boron and Refactory Borides, V.I. Matkovich, Ed., Springer- Verlag, New York, 439-456 (1977). 79Bla: J.H. Blanks, Phase Behavior in the Gadolinium-Boron System and Calculation of Metal Boride Equilibria, Ph.D. Thesis in Solid State Science, The Pennsylvania State University, University Park, PA 16802 (1979). Submitted to the APD Program. Complete evaluation contains 1 figure, 3 tables, and 21 references. Special Points of the Gd-B System