Phase equilibria at 500 °C of the Mg-Nd-Zn system in the region of 0–50 at%Nd

Abstract

The phase equilibria at 500 °C of the Mg–Nd–Zn system in the region of 0–50 at.% Nd were investigated by combining the electron probe microanalysis (EPMA) and X-ray diffraction (XRD) of the equilibrated alloys. The partial isothermal section was constructed. Eight ternary phases (τ1 to τ6, τ8 and T-NdMg12) were found at 500 °C. Among them, τ8 is the newly found ternary compound. T-NdMg12 is the Zn-stabilized Mnl2Th-type NdMg12 phase. Its composition range was measured to be Nd7.6-7.7Mg84.5-88.7 Zn3.7-7.8. The homogeneity ranges of the seven ternary compounds (τ1 to τ6 and τ8) were well determined. The solubilities of the third elements in the binary compounds of the three binary systems were also well measured. The lattice parameters of the τ1, τ2 and τ5 phases were determined to be a = 0.9709 (3) nm/b = 1.1253 (4) nm/c = 0.9545 (3) nm at Nd7.8Mg57.0 Zn35.2 (τ1), a = 1.46234 (1) nm/c = 0.8706 (1) nm at Nd7.1Mg28.5Zn64.4 (τ2) and a = 2.0883 (2) nm at Nd16.7Mg18.5Zn64.8 (τ5), respectively.