450 ℃ Isothermal Section of the Ni-Sb-Zn Ternary System at the Zn-Rich Corner

摘要

The 450 ℃ isothermal section of the Ni-Sb-Zn ternary system with an emphasis on the Zn-rich corner was experimentally determined by means of optical microscopy, SEM-EDS analysis and x-ray diffraction. The existence of two true ternary phase, the NiSbZn (τ_1) and Ni_2SbZn_2 (τ_2) phase, was confirmed in the system at 450 ℃. NiSbZn (τ_1) had an MgAgAs-type structure with a lattice parameter a = 0.58971 nm. Ni_2SbZn_2 (τ_2) is a ternary compound found in this system for the first time whose composition range spanned from 35.5-38.0 at.% Ni, 17.3-26.3 at.% Sb, 36.9-45.2 at.% Zn. It should be noted that the phase relationships at 450 ℃ are significantly different from the previous reported ones at 600 and 297 ℃. The solubilities of Ni in SbZn, Sb_2Zn_4 and Sb_2Zn_3 were limited. The maximum solubilities of Sb in δ-NiZn_8, γ-NiZn_3 and β_1-NiZn were 0.1, 4.0 and 1.5 at.%, respectively and the maximum solubilities of Zn in NiSb and NiSb_2 were 5.6 and 1.6 at.%, respectively.