Effect of multi-pass equal channel angular pressing on microstructure and mechanical properties of Mg97.1Zn1Gd1.8Zr0.1 alloy

The microstructure and mechanical properties of as-cast Mg97.1Zn1Gd1.8Zr0.1 (at%) alloy processed by multi-pass equal channel angular pressing (ECAP) at 375 °C were investigated. The results show that besides the shattering process of β phases and dynamic recrystallization (DRX) phenomenon, the refining and re-distribution process of fine-lamellae LPSO phases is the other important feature of microstructure evolution with increasing ECAP passes. Both strength and ductility of the alloy are improved simultaneously with increasing ECAP passes. Notably, after 16 ECAP passes, the ultimate tensile strength, yield strength and elongation to failure of the alloy can reach 387 MPa, 324 MPa and 23.2%, respectively, which can be attributed to numerous units, mainly consisting of strip-distributed β phase particles, micro-sized and ultra-fined grains, high-density dislocations, and a large number of 14H LPSO microcells.