Фазовая диаграмма системы Co-Hf

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Co-Hf (Cobalt-Hafnium) K. Ishida and T. Nishizawa The assessed phase diagram for the Co-Hf system is based on [69Sve] and [78Bus] with review of the data of [73Aok] and [81Spe]. The equilibrium phases are: ( 1) the liquid, L; (2) the Co-rich fcc terminal solid solution, (aCo), with small solid solubility of Hf; (3) the Co-rich cph terminal solid solution, ( eCo); (4) the tetragonal compound, Co7Hf, stable between 1050 and 1255 C; (5) the cubic intermediate phase, Co23Hf6, stable between 950 and 1275 C; (6) the orthorhombic compound, Co7Hf2, stable up to the peritectic temperature of 1350 C; (7) the cubic phase, Co2Hf, with a homogeneity range from 27 to 37 at.% Hf, stable up to the congruent melting temperature of 1670 C; (8) the cubic intermediate phase, CoHf, stable up to the congruent melting temperature of 1640 C; (9) the cubic phase, CoHf2, with a homogeneity range from ~67 to 74 at.% Hf, stable up to the peritectic temperature of 1315 C; (10) the Hf-rich bcc terminal solid solution, (bHf), stable between 1743 and 2231 C; and (11) the Hf-rich cph terminal solid solution, (aHf). [69Sve] estimated that the solid solubility of Hf in (aCo) is 0.8 at.% Hf at 1100 C and 1.4 at.% Hf at 1250 C. The solubility of Co in (aHf) was found to be small, not exceeding 0.5 at.% Co at 1100 C [69Sve]. Co2Hf is paramagnetic; the magnetic susceptibility of this phase was measured by [73Aok]. The magnetic moment per excess Co is estimated to be 0.61, 0.58, 0. 62, and 0.46 mB for the 29.1, 30.1, 31.5, and 32.2 at.% Hf alloys, respectively. The 27.1 and 28.1 at.% Hf alloys are a mixture of the paramagnetic compound Co2Hf and a ferromagnetic phase, which is probably Co7Hf2 with a Curie temperature of about 150 C [73Aok]. The Co atomic magnetic moment in Co6Hf was determined to be 1.35 mB, and the saturation magnetization was found to be 775 emu/cm3 [77Ore]. 59Dwi: A.E. Dwight, Trans. AIME, 215, 283-286(1959). 60Nev: M.V. Nevitt, J.W. Downey, and R.A. Morris, Trans. AIME, 218, 1019-1023 ( 1960). 61Dwi: A.E. Dwight, Trans. ASM, 53, 479-500 (1961). 61Ell: R.P. Elliott, Trans. ASM, 53, 321-329 (1961). 64Kri: P.I. Kripyakevich, M.A. Tylkina, and I.A. Tsyganova, Zh. Neorg. Khim., 9, 2599-2601 (1964) in Russian; TR: Russ. J. Inorg. Chem., 9, 1404-1405 (1964). 69Sin: A.K. Sinha, Trans. Metall. Soc. AIME, 245, 237-240 (1969). 69Sve: V.N. Svechnikov, A.K. Shurin, and G.P. Dmitriyeva, Izv. Akad. Nauk SSSR. Met., (1), 214-218 (1969) in Russian; TR: Russ. Metall., (1), 109-112 (1969). 73Aok: Y. Aoki, T. Nakamichi, and M. Yamamoto, Phys. Status Solidi (b), 56, K17-K20 (1973). 77Ore: J. Orehotsky and T. Wahl, J. Appl. Phys., 48, 2826-2827 (1977). 78Bus: K.H.J. Buschow, J.H. Wernick, and G.Y. Chin, J. Less-Common Met., 59, 61-67 (1978). 79Ess: R.M. Van Essen and K.H.J. Buschow, J. Less-Common Met., 64, 277-284 ( 1979). 81Spe: P.J. Spencer, O. von Goldbeck, R. Ferro, R. Marazza, K. Girgis, and O. Kubaschewski, Hafnium: Physico-Chemical Properties of Its Compounds and Alloys, K.L. Komarek, Ed., Atomic Energy Review Special Issue No. 8, International Atomic Energy Agency, Vienna (1981). 83Nis: T. Nishizawa and K. Ishida, Bull. Alloy Phase Diagrams, 4, 387-390 ( 1983). Submitted to the APD Program. Complete evaluation contains 1 figure, 3 tables, and 15 references. Special Points of the Co-Hf System