Фазовая диаграмма системы Be-Si

К оглавлению: Другие диаграммы (Others phase diargams)

Be-Si (Beryllium-Silicon) H. Okamoto and L.E. Tanner The assessed Be-Si phase diagram is based on the experimental work of [29Mas]. The observed liquidus data show a degree of uncertainty (see [Hansen]). The assessed Be-rich liquidus is based on the present calculation. Further improvement of the modeling may be attained when the liquidus boundaries are better established through the use of purer materials and modern techniques. The absence of intermediate phases has been confirmed by several investigators. The solubility ranges of the terminal phases appear to be quite narrow. The melting point of bBe and the bBe = aBe allotropic transformation temperature are 1289 с 5 and 1270 с 6 C, respectively [Melt]. No solubility range has been determined for the (aBe) phase [32Slo], [50Kau], [62Jor]. [ 61Hin] observed that an alloy of 0.31 at.% Si was two phase. Therefore, the solubility limit must be less than this value. Thermal analysis was not successful in defining the solubility limit of (bBe) [60Gel, 61Gel]. The melting point of Si is 1414 с 2 C [Melt]. Solubility of Be in (Si) was not detected by [62Jor]. [82Tom] estimated the solid solubility of electrically active Be in (Si) from the resistivity profile of a diffusion couple. Solubility was expressed as 2.2 x 1020 exp (-1.97 x 104/T) atoms/cm3 for the temperature range 800 to 1000 C, or 0.402 exp (-1.97 x 104/T) at.%, assuming that the density of Si is 2.55 g/cm3. The lattice parameter changes in various alloys suggested the existence of some sizable solubility of Be in (Si) [61Jor1] or Si in (aBe) [61Jor2]. However, further detailed studies on rapidly quenched alloys did not reveal any solubility [62Jor]. The assessed eutectic temperature is tentatively placed at 1090 C (the highest observed value). There may be about с10 C uncertainty in this value. The eutectic composition was proposed as 33 at.% Si from the trend of arrest time with Si concentration at the eutectic temperature [29Mas]. 29Mas: G. Masing and O. Dahl, Wiss. Veroffentl. Siemens-Konzern, 8(1), 248-256 (1929) in German. 32Slo: H.A. Sloman, J. Inst. Met., 49, 365-388 (1932). 50Kau: A.R. Kaufmann, P. Gordon, and D.W. Lillie, Trans. ASM, 42, 785-844 ( 1950). 60Gel: S.H. Gelles and J.J. Pickett, U.S. Atomic Energy Comm., NMI-1218, 44 p ( 1960). 61Gel: S.H. Gelles, J.J. Pickett, E.D. Levine, and W.B. Nowak, Institute of Metals Conference on Metallurgy on Beryllium, London, Preprint No. 33, 11 p ( 1961); The Metallurgy of Beryllium, Inst. Metals, Monograph Rept. Ser. No. 28, Institute of Metals, London, 588-600 (1963). 61Jor1: C.B. Jordan, Monthly Prog. Rep. AD 270977, 3 p (Aug 1961). 61Jor2: C.B. Jordan, Monthly Prog. Rept. AD 268088 4 p (Nov 1961). 62Jor: C.B. Jordan, Tech. Rept. ASD-TDR-62-181 AD 284409, 33 p (1962). 82Tom: H. Tomokage, M. Hagiwara, and K. Hashimoto, Mem. Fac. Eng., Kyushu Univ. , 42(2), 89-94 (1982). Published in Phase Diagrams of Binary Beryllium Alloys, 1987. Complete evaluation contains 2 figures, 3 tables, and 15 references. 1