Electron Diffraction Study on Ordered Alloys of the Copper-Gold-Palladium System I. Ordered Alloys of Cu₂AuPd and CuAu₂Pd

抄録

An electron diffraction study on ternary alloys of the copper-gold-palladium system was carried out by using evaporated single crystal films and the following results were obtained: The superlattice structure of Cu₂AuPd is not of the CuAuI type, as proposed by Raub and Wörwag but of a modified CuAuI type belonging to the space group D_4h¹-4⁄mmm. Furthermore, it was found that an ordered alloy CuAu₂ Pd exists and its superlattice structure is also of the modified CuAuI type, identical with that of Cu₂AuPd. The temperatures of the order-disorder transformation were estimated at about 550°C and 430°C for both alloys of nearly stoichiometric compositions, Cu₂AuPd and CuAu₂Pd. The tetragonality, c⁄a, varies from 0.92 at 500°C to 0.87 at 300°C for Cu₂AuPd, and from 0.98 at 400°C to 0.93 at 200°C for CuAu₂Pd.