Comparative Study on Microstructure and Mechanical Properties of Mg-3Nd-3Al and Mg-3Nd-0.5Zr Alloys Under Different Heat Treatment Conditions

Abstract

The effect of heat treatment conditions on the microstructure and mechanical properties of Mg-3Nd-3Al and Mg-3Nd-0.5Zr alloys has been comparatively investigated. The experimental results showed that the grain size of Mg-3Nd-3Al and Mg-3Nd-0.5Zr alloys was similar, which was 48 ± 4 μm and 46 ± 4 μm in as-cast condition and 50 ± 3 μm and 50 ± 4 μm in solid solution (T4) and solid solution + peak aging (T6) conditions, respectively. The intermetallic phases in the as-cast Mg-3Nd-3Al alloy were granular Al2Nd and acicular Al11Nd3. The intermetallic phase in the as-cast Mg-3Nd-0.5Zr alloy was Mg12Nd. The Al2Nd phase did not dissolve and the Al11Nd3 phase decomposed into the Al2Nd phase and the Mg12Nd phase completely dissolved into α-Mg during T4 treatment process. After T6 treatment, the amount of precipitation phase of the Mg-3Nd-3Al alloy was less than that of the Mg-3Nd-0.5Zr alloy. Compared with the Mg-3Nd-0.5Zr alloy, the Mg-3Nd-3Al alloy had higher strength and elongation in as-cast condition, lower strength in T6 condition and a weaker age-hardening effect.