Фазовая диаграмма системы Be-Pd

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Be-Pd (Beryllium-Palladium) H. Okamoto and L.E. Tanner The equilibrium phases of the Be-Pd system are (1) the liquid, L; (2) the bcc and cph terminal solid solutions, (bBe) and (aBe), based on the two allotropic forms of Be; (3) Be12Pd (Mn12Th type); (4) Be5Pd (AuBe5 type); (5) BePd (CsCl type); (6) Be3Pd4, stable between 1055 and 1200 C; (7) Be2Pd3; (8) BePd2; (9) BePd3; and (10) the fcc terminal solid solution, (Pd). Homogeneity ranges for all of the intermediate phases have not been established. The assessed phase diagram is based on the thermal analysis data of [38Win] for the composition range 50 to 100 at.% Pd and has been approximated between 0 and 50 at.% Pd by consideration of thermodynamic requirements. The present diagram is not much different from that of [38Win]. Modifications were due to the smoothing of data points through thermodynamic analysis and the omission of an unusual phase (BePd1.08 [38Win] or Be12Pd13 [Hansen]). Because the (bBe) = (aBe) allotropic temperature is lowered by Pd [60Gel], the reaction involving these phases with increasing Pd must be catatectic. The solubility limit of Pd in (Be) was roughly estimated by [50Kau] from metallographic and lattice parameter data. Hence, the (aBe) phase boundary in the assessed diagram must be regarded only as a schematic approximation. The solubility of Be in (Pd) was estimated by [38Win] to be about 0.7 at.% at the eutectic temperature of 830 C [Hansen]. Melt quenching a Be-72 at.% Pd alloy produces an amorphous structure [84Coc]. Crystallization of this metallic glass at 367 C produced a complex X-ray diffraction pattern that is likely to be due to the coexistence of the two stable phases in this region, plus the possibility of the presence of metastable phases. 38Win: O. Winkler, Z. Metallkd., 30(5),162-173 (1938). 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. At. Energy Comm. NMI-1218, 44 (1960). 84Coc: G. Cocco, S. Enzo, C. Antonine, L. Battezzati, and G. Riontino, Phys. Status Solidi (a), 82(2), 371-377 (1984). Published in Phase Diagrams of Binary Beryllium Alloys, 1987, and Bull. Alloy Phase Diagrams, 8(4), Aug 1987. Complete evaluation contains 1 figure, 4 tables, and 13 references. Special Points of the Be-Pd System