Preparation and characterization of As-cast and hot-rolled Mg–3Al–0.5Mn–0.5Zn–1MM alloy

Mg–3Al–0.5Mn–0.5Zn–1MM alloy was prepared by metal mould casting method. The as-cast ingot was homogenized and then hot-rolled at 673 K with total thickness reduction of 65%. Microstructure and mechanical properties of the as-cast and hot-rolled samples were investigated. The results showed that the as-cast sample mainly consisted of α-Mg, β-Mg17Al12, Al10Ce2Mn7, and Al11RE3 (RE = La and Ce) phases. The average grain size of the sample homogenized at 673 K was about 240 μm, and it was greatly refined to about 7 μm by dynamic recrystallization for the hot-rolled sample. The ultimate tensile strength and 0.2% yield strength of the hot-rolled sample were 300 MPa and 230 MPa, respectively. They were enhanced by 55% and 400% correspondingly compared with those of the as-cast sample. The improvement of the strengths was attributed to the refined grains, breakup of the precipitates and increase of the dislocation density.