Фазовая диаграмма системы B-Pm

К оглавлению: Другие диаграммы (Others phase diargams)


B-Pm (Boron-Promethium) P.K. Liao and K.E. Spear The phase equilibria in the Pm-B system have never been studied. The assessed phase diagram is a predicted equilibrium diagram of [76Spe] which was based on the assumption of similar behavior of the Pr-B, Nd-B, and Sm-B systems. The equilibrium phases are (1) the liquid, L; (2) the terminal solid solutions, bcc (bPm) and dcph (aPm); (3) the terminal solid solution, rhombohedral (bB); and (4) four intermediate compounds, Pm2B5, PmB4, PmB6, and PmB66. (bB) and both (Pm) solid solutions have negligible composition ranges. The homogeneity ranges of Pm borides are expected to be small except perhaps for PmB6. [76Spe, 77Spe] discussed 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, 77Spe] . Editor's note: Pm allotropes have been added to the phase diagram. 65Gie: R.F. Giese, Jr., J. Economy, and V.I. Matkovich, Z. Krist., 122, 144- 147 (1965). 70Car: J.-O. Carlsson and T. Lundstrom, J. Less-Common Met., 22, 317-320 (1970) . 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 8 references. Special Points of the Pm-B System