The Effect of substitution Cu for Zn on the dominant active slip systems and deformation mechanism in Mg-Zn-Y Alloys

Microstructure evolution and Visco-Plastic Self-Consistent (VPSC) simulations are adopted to explore alloying elements Zn and Cu proportion effect on room mechanical characteristics of as-extruded Mg₉₅Y₃Zn₂, Mg₉₅Y₃Zn₁Cu₁, and Mg₉₅Y₃Cu₂ alloys (at%) at present. The findings indicate that the strength of the alloy gradually enhances as the Cu/Zn ratio increases, while compared with the alloy without Cu, the plasticity of the Cu-containing alloy slightly decreases. Mg₉₅Y₃Cu₂ alloy shows a better strength-plasticity matching relationship, with its yield strength, tensile strength and elongation being 284 MPa, 340 MPa and 16.2%, respectively. Combining EBSD-aided slip trace analysis and VPSC simulation, the mechanism of the slight decrease in plasticity of is Mg₉₅Y₃Cu₂ alloy resulted from the joint effect of deformation mode and grain characteristics. Furthermore, theoretical calculations indicate that compared with Mg₉₅Y₃Zn₂ and Mg₉₅Y₃Zn₁Cu₁ alloys, the higher strength of Mg₉₅Y₃Cu₂ alloy is mainly attributed to the effects of fine grain strengthening and LPSO phase strengthening.