Фазовая диаграмма системы B-Ce

К оглавлению: Другие диаграммы (Others phase diargams)

B-Ce (Boron-Cerium) P.K. Liao and K.E. Spear Very little experimental work has been performed on the phase equilibria for the Ce-B system. The assessed phase diagram is based on [76Spe], which was modeled after the partial diagram given by [65Ste]. The adoption of a lower CeB6-B eutectic temperature at 2025 C by [76Spe] in order to make it consistent with a melting temperature of 2092 C for elemental B has been accepted in the assessed diagram. The only additional phase data available for the Ce-B system is the report of [60Sey] which states that the Ce content in the CeB6-B eutectic composition is less than 0.96 at.%. The equilibrium phases of the Ce-B system are (1) the liquid, L; (2) the terminal solid solutions based on (gCe) and fcc (dCe); (3) the terminal solid solution based on rhombohedral (bB); and (4) two intermediate compounds, CeB4 and CeB6. Both the (bB) and (Ce) solid solutions have negligible composition ranges. The homogeneity ranges of cerium borides are thought to be relatively small. CeB6 may have a measurable range [76Spe, 77Spe]. All available experimental data indicate that a hexaboride is stoichiometric at its metal-rich phase boundary and becomes B-rich by the formation of from a few percent up to approximately 30% metal vacancies [76Spe, 77Spe]. 51Bre: L. Brewer, D.L. Sawyer, D.H. Templeton, and C.H. Dauben, J. Am. Ceram. Soc., 34(6), 173-179 (1951). 53Zal: A. Zalkin and D.H. Templeton, Acta Crystallogr., 6, 269-272 (1953). 60Sey: A.U. Seybolt, Trans. ASM, 52, 971-989 (1960). 64Bli: G. Bliznakov and P. Peshev, J. Less-Common Met., 7, 441-446 (1964). 65Gie: R.F. Giese, Jr., J. Economy, and V.I. Matkovich, Z. Krist., 122, 144- 147 (1965). 65Ste: P. Stecher, F. Benesovsky, and H. Nowotny, Planseeber. Pulvermet., 13, 37-46 (1965) in German. 70Car: J.-O. Carlsson and T. Lundstrom, J. Less-Common Met., 22, 317-320 (1970) . 71Hac: H. Hacker, Jr., Y. Shimada, and K.S. Chung, Phys. Status Solidi (a), 4, 459-465 (1971). 71Yaj: S. Yajima and K. Niihara, The Nonstoichiometry of Rare Earth Hexaborides, preprint of paper presented at 9th Rare Earth Research Conference, Blacksburg, VA, 10-14 (1971). 72Fis: Z. Fisk, A.S. Cooper, P.H. Schmidt, and R.N. Castellano, Mater. Res. Bull., 7(4), 285-288 (1972). 76Spe: K.E. Spear, Phase Diagrams: Materials Science and Technology, Vol. 4, Academic Press, New York, 91-159 (1976). 77Cal: B. Callmer, Acta Crystallogr. B, 33, 1951-1954 (1977). 77Spe: K.E. Spear, Boron and Refractory Borides, V.I. Matkovich, Ed., Springer- Verlag, New York, 439-456 (1977). Submitted to the APD Program. Complete evaluation contains 1 figure, 3 tables, and 19 references. Special Points of the Ce-B System