Solid-state phase equilibria in the Gd–Co–Al ternary system at 1173 K

Abstract

A portion of the isothermal section (1173 K) of the phase diagram of the Gd–Co–Al ternary system (up to 33.3 at.% Gd) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. Fourteen single-phase regions (including solid solution regions of the binary compounds), twenty-five two-phase regions and twelve three-phase regions were found to exist at this isothermal section. In the GdCo 2–GdAl 2 system, the existence of the GdCo 0.74Al 1.26 phase is identified and it has a composition range of 30–45 at.% Al, the maximum solid solubility of Al in GdCo 2 is about 15 at.%, and Co in GdAl 2 is about 16 at.%. Besides, the maximum solid solubility of Al in Co, Gd 2Co 17 and GdCo 5 is about 6, 17 and 25 at.% , respectively, the maximum solid solubility of Gd in Co, CoAl is below 2 at.% and the solid solubility range is from 47 to 61 at.% Al in CoAl phase. In this work, no new ternary compounds were observed.