Фазовая диаграмма системы Be-Mo

К оглавлению: Другие диаграммы (Others phase diargams)

Be-Mo (Beryllium-Molybdenum) H. Okamoto and L.E. Tanner The assessed Be-Mo phase diagram is based on the diagram of [73Gol] and thermodynamic modeling by [Molybdenum], with review of the experimental data of [51Ham]. Four intermediate phases have been established in the Be-Mo system: (1) Be22Mo (Zn22Zr type); (2) Be12Mo (Mn12Th type); (3) Be2Mo (Zr2Mg type); and (4) BeMo3 (SiCr3 type). The melting points and homogeneity ranges have not been well established for any of the compounds. The melting point of bBe and the bBe = aBe allotropic transformation temperature are 1289 с 5 and 1270 с 6 C, respectively [Melt]. The reaction type between (bBe) and (aBe) and the solubility limits of Mo in these terminal solid solutions have been reported. The melting point of Mo is 2623 C [Melt]. [50Ham] estimated the solubility limit of Be in (Mo) as ~0.9 at.%. A eutectic structure composed of (Mo) plus Be2Mo was observed beyond the solid solubility [50Ham, 50Kau]. Diffusion studies suggested the existence of Be22Mo at temperatures between 1050 and 1200 C, but not at 950 C or at room temperature. Probably, the kinetics of Be22Mo formation was too slow to be noticed at the lower temperatures. The melting point of Be12Mo is approximately 1700 C [60Sto]. The melting point of Be2Mo was set at 1840 C by [59Pai]. The thermodynamic model of [Molydbenum] placed the melting point at a somewhat higher temperature (2027 с 200 C), in agreement with [73Gol], who had suggested a temperature higher than 1840 C for consistency with the observed L = Be2Mo + ( Mo) eutectic point. The superconducting transition temperature of Be2Mo is 1. 68 K [73Mat]. BeMo3 was reported by [59Pai] and believed to melt above 1650 C. However, this compound would have to decompose by a solid state reaction at a high temperature in order to be consistent with the presence of the established eutectic between (Mo) and Be2Mo. This high-temperature instability of BeMo3 is consistent with an abnormally low entropy usually found in a SiCr3-type structure. Because [64Mat] could not prepare BeMo3 in the temperature range between 900 to 1250 C (which confirms that the phase would not be stable to high temperatures), [Molybdenum] estimated that a peritectoid reaction occurs at 900 с 100 C. [80Tan] predicted the possible existence of a metastable phase, BeMo, with the CsCl-type crystal structure, from the study of a series of Be-transition metal systems. 36Mis: L. Misch, Metallwirtschaft, 15(6), 163-166 (1936) in German. 50Ham: J.L. Ham, Climax Molybdenum Company of Michigan, Annual Report, 31-331, 164 p (1950). 50Kau: A.R. Kaufmann, P. Gordon, and D.W. Lillie, Trans. ASM, 42, 785-844 ( 1950). 51Gor: S.G. Gordon, J.A. McGurty, G.E. Klein, and W.J. Koshuba, Trans. Metall. Soc. AIME, 191, 637-638 (1951). 51Ham: J.L. Ham, Climax Molybdenum Company of Michigan, Annual Report, 34-401 ( 1951). 55Rae: R.F. Raeuchle, and F.W. von Batchelder, Acta Crystallogr., 8, 691-694 ( 1955). 57Che: Ye.Ye. Cherkashin, Ye.I. Gladyshevskii, and P.I. Kripyakevich, Dop. Lvivsk. Derzh. Univ., 7(3), 180-183 (1957) in Russian. 57Gla: E.I. Gladyshevskii and P.I. Kripyakevich, Kristallografiya, 2, 742-745 ( 1957) in Russian; TR: Sov. Phys. Crystallogr., 2, 730-733 (1957). 58Che: Ye.Ye. Cherkashin, Ye.I. Gladyshevskiy, P.I. Kripyakevich, and Yu.B. Kuz'ma, Zh. Neorg. Khim., 3(3), 650-653 (1958) in Russian; TR: Russ. J. Inorg. Chem., 3(3), 135-141 (1958). 59Arz: P.M. Arzhanyi, Issled. Zharoproch. Splavam, Akad. Nauk SSSR, Inst. Met., 5, 199-202 (1959) in Russian. 59Pai: R.M. Paine, A.J. Stonehouse, and W.W. Beaver, WADC Tech. Rept. 59-29, 206 p (1959). 60Pai: R.M. Paine, J.A. Carrabine, Acta Crystallogr., 13, 680-681 (1960). 60Sto: A.J. Stonehouse, R.M. Paine, and W.W. Beaver, in Mechanical Properties of Intermetallic Compounds, J.H. Westbrook, Ed., John Wiley & Sons, New York, 297-319 (1960). 62Mat: N.N. Matyushenko, L.F. Verkhorobin, N.S. Pugachev, and N.V. Sivokon', Kristallografiya, 7, 862-864 (1962) in Russian; TR: Sov. Phys. Crystallogr., 7, 701-703 (1963). 63Kri: P.I. Kripykevich and E.I. Gladyshevskii, Kristallografiya, 8, 449-451 ( 1963) in Russian; TR: Sov. Phys. Crystallogr., 8, 349-351 (1963). 64Mat: N.N. Matyushenko, Izv. Akad. Nauk SSSR, Met., Gorn. Delo., (2), 167-171 (1964) in Russian. 73Mat: N.N. Matyushenko, A.A. Matsakova, and N.S. Pugachev, Ukr. Fiz. Zh., 18( 4), 672-675 (1973) in Russian. 73Gol: O. von Goldbeck, [Beryllium], 45-61 (1973). 75Stu: M. Stumke and G. Petzow, Z. Metallkd., 66(5), 292-297 (1975) in German. 80Tan: L.E. Tanner, Acta Metall., 28(12), 1805-1816 (1980). 84Col: D.M. Collins and M.C. Mahar, Acta Crystallogr. C, 40(6), 914-915 (1984). Published in Phase Diagrams of Binary Beryllium Alloys, 1987. Complete evaluation contains 1 figure, 4 tables, and 27 references. 1