Statistical analysis of the various LPSO phases in Mg₉₇Zn₁Y₂ and Mg_96.6Zn₁Y_2.2Zr_0.2 alloys regulated by different heat treatments

The morphologies and quantities of the LPSO phases in Mg₉₇Zn₁Y₂ and Mg_96.6Zn₁Y_2.2Zr_0.2 (at. %) alloys were regulated by different heat treatments. The two alloys show similar morphologies after the same heat treatments and are composed of three kinks of LPSO phases, namely, LPSO blocks, LPSO laths, and LPSO lamellae. Moreover, the volume fractions of the LPSO blocks and the thickness distributions of the LPSO lamellae are statistically analyzed. In addition, the strengthening effects of the LPSO phases with different morphologies on the alloy’s hardnesses were systematically measured and summarized. The results indicate that both the block-shaped LPSO phases and LPSO laths can significantly strengthen the grain interiors and intergranular regions of the Mg alloys, while the strengthening effect of LPSO lamellae is negligible. These results may shed light on the correspondence between microstructures and heat treatment processes and would be conductive to obtain Mg alloys with better mechanical properties.