Effects of Zn Addition on the Microstructure and Mechanical Properties of Mg-8Al-2Sn Alloy

Abstract:

The effect of adding 0-2.0 wt.% Zn to the Mg-8Al-2Sn alloy was investigated by analyzing the microstructures and tensile properties. The results revealed that the phase compositions of Mg-8Al-2Sn-xZn alloys are α-Mg, Mg₁₇Al₁₂ and Mg₂Sn phases. The morphology of eutectic phases of the as-cast alloys was changed from normal eutectic to divorced eutectic with Zn addition. Grain sizes of the alloys were uniform after hot extrusion with Zn addition. Dynamic precipitation of the second phases was promoted by the addition of Zn during hot extrusion. The second phases coarsened in Mg-8Al-2Sn-2Zn alloy. Precipitates formed during the aging treatment and the amount of which increased with the addition of Zn content. Besides, the ultimate tensile and yield strength of the extruded and aged alloys gradually increased with the addition of Zn content. The results showed that Mg-8Al-2Sn-2Zn alloy has the best mechanical property that the ultimate tensile strength, yield strength and elongation of the as-aged alloy were 385 MPa, 291 MPa and 6.44%, respectively.