Фазовая диаграмма системы As-Co

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As-Co (Arsenic-Cobalt) K. Ishida and T. Nishizawa The assessed phase diagram for the Co-As system is based on [37Has] for the Co- rich region and on the transition temperatures for Co2As from [72Kje], CoAs from [73Sel], and CoAs2 from [77Kje]. The equilibrium phases are (1) the liquid, L; (2) the fcc solid solution, (aCo); (3) the cph solid solution, (eCo) ; and (4) six intermetallic compounds: Co5As2, Co2As, Co3As2, CoAs, CoAs2, and CoAs3. According to [57Hey], Co3As2 exists only above 940 C, which conflicts with the phase diagram of [Hansen]. Co5As2 also is a high-temperature phase which undergoes a eutectoid transformation into the (aCo) solid solution and Co2As at 867 C. The invariant temperature is in good agreement with the one reported by [37Has]. The solubility of As in (aCo) was estimated by [37Has] to be ~2 at.% As at 1063 C. The eutectic temperature of L = (aCo) + Co5As2 is 997 C. The solubility of As in (eCo) was estimated to be 2.2 at.% As at 624 C where the peritectoid reaction (aCo) + bCo2As = (eCo) occurs [37Has]. The Curie temperatures of (aCo) were determined by [37Has]. [72Kje] suggested that a paramagnetic = ferromagnetic transition in aCo2As occurs at -213 C. 37Has: U. Haschimoto, J. Jpn. Inst. Met., 1, 177-190 (1937) in Japanese. 57Hey: R.D. Heyding and L.D. Calvert, Can. J. Chem., 35, 449-457 (1957). 63Ros: E.H. Roseboom, Am. Min., 48, 271-299 (1963). 66Ben: S.L. Bennett and R.D. Heyding, Can. J. Chem., 44, 3017-3030 (1966). 66Dar: R. Darmon and M. Wintenberger, Bull. Soc. Fr. Mineral. Cristallogr., 89, 213-215 (1966) in French. 71Kje: A. Kjekshus, Acta Chem. Scand., 25, 411-422 (1971). 71Man: N. Mandel and J. Donohue, Acta Crystallogr. B, 27,2288-2289 (1971). 71Nyl: A. Nylund, A. Roger, J.P. Senateur, and R. Fruchart, Monatsh. Chem., 102, 1631-1642 (1971) in German. 71Sel: K. Selte and A. Kjekshus, Acta Chem. Scand., 25, 3277-3284 (1971). 72Kje: A. Kjekshus and K.E. Skaug, Acta Chem. Scand., 26, 2554-2556 (1972). 73Sel: K. Selte and A. Kjekshus, Acta Chem. Scand., 27, 3195-3206 (1973). 74Kje: A. Kjekshus and T. Rakke, Acta Chem. Scand., A28, 99-103 (1974). 77Ack: J. Ackermann and A. Wold, J. Phys. Chem. Solids, 38, 1013-1016 (1977). 77Kje: A. Kjekshus and T. Rakke, Acta Chem. Scand., A31, 517-529 (1977). 83Nis: T. Nishizawa and K. Ishida, Bull. Alloy Phase Diagrams, 4, 387-390 ( 1983). 84Lym: P.S. Lyman and C.T. Prewitt, Acta Crystallogr. B, 40, 14-20 (1984). 86Ell: M. Ellner, E. Lukacevic, and M. El-Boragy, J. Less-Common Met., 118, 327-333 (1986). Submitted to the APD Program. Complete evaluation contains 1 figure, 3 tables, and 21 references. 1