Effect of Aging Treatment on the Microstructure and Tensile Properties of AZ61-xPd (x = 0, 1 and 2 wt%) Alloys

In this study, the effect of aging treatment on the microstructure and tensile properties of AZ61-xPd (x = 0, 1 and 2 wt%) alloys were investigated. The microstructure of as-cast AZ61-xPd alloys mainly consisted of α-Mg, Mg₁7Al₁2 and Al₄Pd phases. After solution treatment, most of the Mg₁7Al₁2 phases were dissolved into the Mg matrix. Thereafter, Mg₁7Al₁2 phases were finely formed and distributed near thermally stable Al₄Pd phases and inside the grains through aging treatment at 220°C during 88 hours. With the aging at 220°C, the peak aged AZ61-xPd alloys showed higher hardness than as-cast and solution treated AZ61-xPd alloys. In particular, the AZ61-1Pd alloy was optimized due to refined Mg₁7Al₁2 and Al₄Pd phases. Further, the peak aging time was reduced with increasing Pd addition (>1 wt%). Tensile strength was increased by Pd addition at 25°C, 150°C, both as-cast and peak aged AZ61-xPd alloys. After aging treatment, room and high temperature tensile strength were increased more than the as-cast specimens. The AZ61-1Pd alloy especially showed the largest strength increase range. Elongation was decreased with addition Pd at 25°C and 150°C.