EFFECT OF Zr, Zn AND Cu ADDITIONS ON ELEVATED-TEMPERATURE MECHANICAL PROPERTIES OF AS-EXTRUDED Mg-3Sn-1Ca ALLOY

In this study, the effects of Zr, Zn and Cu additions on the microstructure, room-temperature and high-temperature mechanical properties of an Mg-3Sn-1Ca alloy (from 25 °C to 250 °C) were studied. The results reveal that additions of Zr and Zn do not change the phase composition of the alloy, composed of CaMgSn and Mg2Sn phases. After the addition of Zn, the grains are significantly refined, the volume fraction of the second phase is increased and dispersed, and the Mg2Ca phase is precipitated. The grain refinement of Zr is better than that of Zn. After adding the Cu element, the Mg2Cu phase precipitates besides the CaMgSn phase. A comparison of mechanical properties shows that the alloy with Zr (TXK311) has the best mechanical properties at room temperature and high temperature, and the elongation of the TXK311 alloy can reach 68.3 % at 250 °C. The TXK311 alloy was comprehensively considered to find its optimum mechanical properties. The analysis shows that fine grains, a uniform phase distribution and texture play important roles in the deformation of the alloy.