Improved mechanical properties of Mg-9Al-1Zn alloy by the combination of aging, cold-rolling and electropulsing treatment

The combination of carefully designed aging, cold-rolling and electropulsing treatment (EPT) was proposed to improve the strength and ductility of AZ91 alloy strip. Prior to cold-rolling, the extruded strip was aged in order to precipitate dispersed β-Mg17Al12 particles in the α-Mg matrix for improving the strength of the alloy. When EPT was applied to the cold-rolled strips, EPT rapidly completed the recrystallization of α-Mg matrix within several seconds at relatively low temperature of 508-553 K, and the pre-existed β-Mg17Al12 particles effectively impeded the α-Mg grain growth. The microstructure consisting of fine recrystallized grains and dispersed β-Mg17Al12 particles was obtained. The ultimate tensile strength, yield strength and elongation to failure of the EPT-samples were 362-370 MPa, 270 MPa and 27.6-28.4%, which were improved by 11-12%, 10% and 70-75%, respectively compared with those of the original extruded-strip. The mechanism of EPT improved the mechanical properties of the AZ91 alloy is discussed.