Фазовая диаграмма системы Be-H

К оглавлению: Другие диаграммы (Others phase diargams)

Be-H (Beryllium-Hydrogen) H. Okamoto and L.E. Tanner No phase diagram is available for the Be-H system. Little information has been generated since [72Ald] gave a concise review of the principal works on the Be- H system. Two compounds, BeH and BeH2, are known in this system, but neither appears to be stable. BeH was found only in the gaseous state. Amorphous BeH2 has been prepared chemically and is metastable at ambient pressure. Crystalline BeH2 can be formed at high pressures and high temperatures. The melting point of bBe and the bBe = aBe allotropic transformation temperature are 1289 с 5 and 1270 с 6 C, respectively [Melt]. There appears to be negligible solubility of H in (aBe); Be did not react with H above 1000 C [59Vol], [Elliott]. In the temperature range 350 to 1050 C, the solubility of H in (Be) is less than 0.075 at.%, resulting from proton irradiation of Be and subsequent heat treatment [63Pem, 64Pem]. Little information is available for (H). The triple point of H2 is -259.34 C [ Melt]. The spectra of BeH and BeH+ were detected in an electric arc [28Pet, 28Wat1, 28Wat2, 29Wat, 31Wat, 35Koo, 37Wat]. BeH2 is stable with respect to atomic H, as suggested by a large negative enthalpy of formation. [33Pie] observed compound formation on the surface of Be in a current of atomic H, at 170 to 260 C. Two types of crystalline BeH2 were obtained by [78Bre]. A hexagonal structure was prepared by high-pressure compaction-fusion of amorphous BeH2 under pressures of at least 275 MPa at 200 C. A monoclinic or tetragonal structure was formed at still higher pressures and temperatures. The melting point of bBe and the bBe = aBe transformation temperature decrease with increasing H2 pressure from 1285 to 1245 C at 11.6 MPa and from 1056 to 1237 C at 11.6 MPa, respectively (values read from graph) [88Sha]. A partial Be-H2 phase diagram at H2 pressure of 5 MPa was also reported. 28Pet: M. Petersen, Phys. Rev., 31(6), 1130 (1928). 28Wat1: W.W. Watson, Phys. Rev., 31(6), 1130 (1928). 28Wat2: W.W. Watson, Phys. Rev., 32(4), 600-606 (1928). 29Wat: W.W. Watson, Phys. Rev., 34(2), 372-375 (1929). 31Wat: W.W. Watson and A.E. Parker, Phys. Rev., 37(1), 167-175 (1928). 33Pie: E. Pietsch, Z. Elektrochem., 39(7), 577-586 (1933) in German. 35Koo: P.G. Koontz, Phys. Rev., 48, 707-713 (1935). 37Wat: W.W. Watson and R.F. Humphreys, Phys. Rev., 52(4), 318-321 (1928). 53Lem: J.F. Lemons, W.B. Lewis, R.D. Fowler, E. Startzky, and C.E. Holley, Jr., U.S. At. Energy Comm. Rep. LA-1659 (1953). 57Hea: E.L. Head, C.E. Holley, Jr., and S.W. Rabideau, J. Am. Chem. Soc., 79( 14), 3687-3689 (1957). 59Vol: A.E. Vol, Constitution and Properties of Binary Metallic Systems, Vol. I, Gosudarst. Izdatel., Moscow, 579 (1959) in Russian. 63Pem: J.P. Pemsler, R.W. Anderson, and E.J. Rapperport, Tech. Rept. ASD-TDR- 61-1018 (AD 403370), 25 p (1963). 64Pem: J.P. Pemsler and E.J. Rapperport, Trans. Metall. Soc. AIME, 230, 90-94 ( 1964). 72Ald: F. Aldinger, Metall, 26(7), 711-718 (1972) in German. 78Bre: G.J. Brendel, E.M. Marlett, and L.M. Niebylski, Inorg. Chem. 17(12), 3589-3592 (1978). 88Sha: V.I. Shapovalov and Yu.M Du-kel'skii, Izv. Akad. Nauk. SSSR. Met., (5), 201-203 (1988) in Russian; TR; Russ. Metall., (5), 201-203 (1988). Published in Phase Diagrams of Binary Beryllium Alloys, 1987. Complete evaluation contains 3 tables and 47 references. 1