Effect of cooling rate on microstructure and mechanical properties of Mg-9Gd-4Y-1Zn-1Al alloy

In this paper, the effect of cooling rate on solidification behaviour, microstructure evolution and mechanical properties of Al-refined Mg-9Gd-4Y-1Zn was studied. As cooling rate decreased, grain size increased and when cooling rate was 32.5°C/s, grain size was the smallest (30.57 µm). The second phases included lamellar LPSO, block-like Mg 3 (Zn, RE), granular Al 2 RE and acicular Al 2 RE. As cooling rate decreased, the content of granular Al 2 RE increased, while that of other phases decreased. As cooling rate decreased, ultimate tensile strength (UTS), yield strength (YS) and elongation all decreased. When cooling rate was 32.5°C/s, the mechanical properties were the best, and UTS, YS and elongation were 228.2 MPa, 158.2 MPa and 8.8%, respectively.