Фазовая диаграмма системы Co-Sn

К оглавлению: Другие диаграммы (Others phase diargams)

Co-Sn (Cobalt-Tin) K. Ishida and T. Nishizawa The assessed phase diagram for the Co-Sn system is based on the work of [38Has] , [69Dar], and [85Com], with review of the data of [08Lew], [08Zem], and [ 68Mat]. The equilibrium phases are (1) the liquid, L; (2) the Co-rich fcc terminal solid solution, (aCo); (3) the Co-rich cph terminal solid solution, ( eCo), with small solid solubility of Sn; (4) Co3Sn2, with two modifications: high-temperature hexagonal b, stable up to the congruent melting temperature of 1170 C, and low-temperature orthorhombic a, stable below ~500 C; (5) the hexagonal phase, CoSn, stable up to the peritectic temperature of 936 C; (6) the tetragonal intermediate phase, CoSn2, stable up to the peritectic temperature of 525 C; and (7) the tetragonal solid solution, (bSn), with negligible solid solubility of Co. [38Has] estimated from the Curie temperature that the solid solubility of Sn in (aCo) is about 2 at.% Sn at 1033 C. [85Com] showed from activity measurements that the solubility of Sn in (aCo) is less than 1.25, 0.91, and 0. 42 at.% at 1000, 800, and 500 C, respectively. The solid solubility of Sn in ( eCo) was reported as 1.67 at.% Sn at 536 C [38Has], but this value seems too high. No data on the terminal solid solubility of Co in (bSn) are available, but it is estimated to be less than 0.5 at.%. The invariant reactions are L = (aCo) + bCo3Sn2 at 1112 C with a eutectic composition of 20.5 at.% Sn, bCo3Sn2 + L = CoSn at 936 C, CoSn + L = CoSn2 at 525 C, and L = CoSn2 + (bSn) at 229 C. Co3Sn2 forms congruently at 1170 C. From activity data, [85Com] estimated the compositions to be 39.2 to 41.2, 40.2 to 41.6, and 40.7 to 41.3 at.% Sn at 1000, 800, and 500 C, respectively. The stoichiometric compounds CoSn and CoSn2 form by peritectic reactions with liquid compositions of ~78 and 97 at.% Sn, respectively. Martensitic transformations of (aCo) = (eCo) have been studied by thermal dilatation [38Has, 70Kra], magnetic analysis [38Has], and X-ray diffraction [ 84Nik]. The transformation temperature on heating rises, whereas the Ms temperature decreases at the rate of 50 to 60 C/at.% Sn [38Has, 70Kra]. The crystal structure of martensite is cph below 1.5 at.% Sn; a seven-layer structure that contains a large number of random stacking faults is found in the compositional range of 1.5 to 8.1 at.% Sn [84Nik]. The data on the high content of Sn are questionable because the solubility of Sn is rather limited. [63Luo] reported that (aCo) solid solutions with up to 5 at.% Sn have been obtained by rapid quenching from the melt. The metastable stoichiometric compound Co3Sn has been obtained by splat quenching from the melt, which decomposes into (aCo) and bCo3Sn2 at about 577 C [80Sch]. [82Sin] also confirmed the metastable Co3Sn phase by rapid cooling from the melt. Amorphous films have been obtained by coevaporation of Sn and Co on liquid nitrogen-cooled substrates over the composition range 25 to 77 at.% Sn [ 82Gen]. [86Gaf] reported that an amorphous film was obtained by solid- state diffusion using an ultrafine Co powder covered with a deposit of Sn. The metastable compound Co3Sn formed by splat quenching from the melt is ferromagnetic, and the Curie temperature is estimated to be about 227 C [ 80Sch]. Other intermetallic compounds are paramagnetic [60Kan, 62Asa]. The hyperfine field at 119Sn in (aCo) and (eCo) was studied as a function of temperature, and anomalous temperature dependence was observed [67Jai, 69Cra]. 08Lew: K. Lewkonja, Z. Anorg. Allg. Chem., 59, 294-304 (1908) in German. 08Zem: S.F. Zemczuzny and S.W. Belynsky, Z. Anorg. Allg. Chem., 59, 364-370 ( 1908) in German. 38Has: U. Haschimoto, J. Jpn. Inst. Met., 2, 67-77 (1938) in Japanese. 60Kan: K. Kanematsu, K. Yasukoshi, and T. Ohyama, J. Phys. Soc. Jpn., 15, 2358 (1960). 62Asa: M. Asanuma, J. Phys. Soc. Jpn., 17, 300-306 (1962). 63Luo: H. Luo and P. Duwez, Can. J. Phys., 41, 758-761 (1963). 67Jai: A.P. Jain and T.E. Cranshaw, Phys. Lett. A, 25, 421-422 (1967). 68Mat: N.M. Matveyeva, S.V. Nikitina, and S.B. Zezin, Izv. Akad. Nauk SSSR Met. , 5, 194-197 (1968) in Russian; TR: Russ. Metall., 5, 132-134 (1968). 69Cra: T.E. Cranshaw, J. Appl. Phys., 40, 1481-1483 (1969). 69Dar: J.B. Darby, Jr. and D.B. Jugle, Trans. Met. Soc. AIME, 245, 2515-2518 ( 1969). 70Kra: W. Krajewski, J. Kruger, and H. Winterhager, Cobalt, 48, 120-128 (1970) in German. 72Hav: E.E. Havinga, H. Damsma, and P. Hokkeling, J. Less-Common Met., 27, 169- 186 (1972). 72Jai: K.C. Jain, M. Ellner, and K. Schubert, Z. Metallkd., 63, 258-260 (1972) in German. 76Ell: M. Ellner, J. Less-Common Met., 48, 21-52 (1976) in German. 80Sch: G. Schluckebier, E. Wachtel, and B. Predel, Z. Metallkd., 71, 456-460 ( 1980) in German. 82Gen: J.F. Geny, G. Marchal, Ph. Mangin, C. Janot, and M. Piecuch, Phys. Rev. B, 25, 7449-7466 (1982). 82Sin: V.K. Singh, M. Singh, and S. Bhan, Phys. Status Solidi (a), 74, K115- K117 (1982). 83Nis: T. Nishizawa and K. Ishida, Bull. Alloy Phase Diagrams, 4(4), 387-390 ( 1983). 84Nik: B.I. Nikolin and N.N. Shevchenko, Fiz. Met. Metalloved., 58(6), 1183- 1187 (1984) in Russian; TR: Phys. Met. Metallogr., 58(6), 129-133 (1984). 85Com: H. Comert and J.N. Pratt, Thermochim. Acta, 84, 273-286 (1985). 86Gaf: E. Gaffet, Mem. Etud. Sci. Rev. Metall., 83, 453 (1986) in French. Submitted to the APD Program. Complete evaluation contains 1 figure, 5 tables, and 28 references. 1