High temperature tensile properties of as-cast Mg–Al–Ca alloys

In order to choose the appropriate process parameters for further thermo-mechanical processes, high temperature tensile tests of as-cast Mg–Al–Ca alloys containing 1, 4 and 7% of total amount of Al and Ca (denoted as AX1, AX4 and AX7, respectively), where Al:Ca = 29:26, were examined. During the tensile test, the Mg2Ca and (Mg, Al)2Ca compounds contribute to not only grain refining but also become crack initiation sites and lower the ductility, thus the AX4 alloy exhibits the best deformability. The area reduction above 50% is obtained at ε˙=1.4×10−2 s−1 and T = 623 K in AX series alloys and at which the dynamic recrystallization has also occurred. Therefore, extrusion deformation was performed at ε˙=4.2×10−2 s−1 and T = 623 K. The grain size of as-extruded specimen decreases with increasing total amount of Al and Ca contents and the average grain size of AX4 alloy specimen is refined to 1.4 μm.