Фазовая диаграмма системы B-Co

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B-Co (Boron-Cobalt) P.K. Liao and K.E. Spear The Co-B system consists of three intermetallic compounds-Co3B, Co2B, and CoB- and the terminal solid solutions-high-temperature fcc (aCo), low-temperature cph (eCo), and rhombohedral (bB). The mutual solid solubilities of the terminal elements are small, and the homogeneity ranges of the intermetallic compounds are very narrow. The assessed phase diagram is based primarily on the work of [66Sch] and incorporates the solubility data for B in Co by [73Ler]. The present diagram was obtained by thermodynamic optimization of the experimental data. Good agreement is evident between the calculated diagram and the experimental results. The maximum solubility of B in (aCo) is 0.163 at.% B. The incongruently melting phase Co3B, the congruently melting phase Co2B with a melting point of 1280 C, and CoB, which melts congruently at 1460 C, exist in this system. A metastable phase, Co23B6, was reported by [81Bas] when samples were cooled from the melt at high rates. 66Sch: J.-D. Schobel and H.H. Stadelmaier, Z. Metallkd., 57(4), 323-325 (1966) in German. 73Ler: C. Lerner and M.C. Cadeville, Scr. Metall., 7, 941-944 (1973) in French. 81Bas: V.F. Bashev, I.S. Miroshnickenko, and G.A. Sergeev, Izv. Akad. Nauk SSR, Neorg. Mater., 17(7), 1206-1211 (1981) in Russian. Published in Bull. Alloy Phase Diagrams, 9 (4), Aug 1988. Complete evaluation contains 3 figures, 3 tables, and 30 references. Special Points of the Co-B System