The Isothermal Section of the Phase Diagram of Mg-Co-Ga Ternary System

Abstract

The isothermal section of the phase diagram of the Mg-Co-Ga ternary system at 200 °C for the full composition range was built. The formation of five ternary compounds was observed. The crystal structures of all ternary compounds: τ₁—MgCo₂Ga₅ (own structure type, Pnnm space group), τ₂—Mg₃Co₂Ga₇ (C2/c space group, own structure type), τ₃—MgCoGa₂ (P2₁/n space group, own structure type), τ₄—Mg_1−xCo_2−yGa_x+y (x = 0.06, y = 0.64) (Cmcm space group, own structure type), τ₅—Mg_1−xCo_2−yGa_x+y (x = 0.10, y = 0.16) (R-3 m space group, own structure type) were investigated by means of single crystal diffraction. In addition to ternary compounds, solid solutions based on binary phases are formed in the system. The solid solution MgCo_2−xGa_x (x = 0-1, P6₃/mmc space group, MgZn₂ structure type) represent the largest area of homogeneity. The phase content of alloys was determined by SEM/EDX analysis.