Effect of Dual Deformation Processes on the Microstructure and Mechanical Properties of Low-Alloyed Mg-Zn-Ca-Mn Alloy

To drive the advancement of cost-effective deformed magnesium alloys, a high-strength Mg-3Zn-1.2Ca-0.5Mn (wt%) alloy with moderate ductility is successfully manufactured by employing low-temperature extrusion and warm rolling techniques. The influence of extrusion-rolling (E+R) on the microstructure, texture and mechanical properties of Mg-3Zn-1.2Ca-0.5Mn alloy has been investigated through employing microstructure characterization techniques and mechanical property experiments. Experimental finding indicates that a tensile yield strength (TYS) of extruded Mg-3Zn-1.2Ca-0.5Mn alloy is 180 MPa. Subsequent warm-rolling further enhances the TYS of the extruded Mg-3Zn-1.2Ca-0.5Mn alloy, soaring it from 180 to 349 MPa. Through the rolling process, a substantial proportion of low angle grain boundaries (LAGBs) and twin boundaries are generated within the grain structure. With the obstruction of grain boundary migration by LABGs, the fragmentation of grains during rolling and twinning boundaries, the grain size is significantly reduced from 2.98 μm in extrusion to 1.53 μm in rolling. At the same time, the nanoparticles are identified as Ca₂Mg₆Zn₃, MgZn₂, Mg₄Zn₇, and α-Mn with the shape of rod and spherical, which hinder the migration of LAGBs and maintain the stability of LAGBs. Additionally, the rolled alloy also shows a typical strong basal texture, characterized by the alignment of the (0001) plane parallel to the rolling surface and the orientation of the <10-10> direction parallel to rolling direction (RD). The high strength in E+R Mg-3Zn-1.2Ca-0.5Mn alloy is mainly ascribed to the comprehensive effect resulting from a high fraction of LAGBs and a strong texture.

Graphical Abstract