Effects of minor Ti addition on as-cast microstructure and mechanical properties of Mg-3Sn-2Sr (wt.%) magnesium alloy

In this paper, the effects of minor Ti addition (0.1-0.3 wt.%) on the as-cast microstructure and mechanical properties of Mg-3Sn-2Sr (wt.%) magnesium alloy are investigated. The results indicate that the Mg-3Sn-2Sr alloy is mainly composed of α-Mg, primary and eutectic SrMgSn, and Mg2Sn (with small amount) phases. After the additions of 0.1-0.3 wt.% Ti to the Mg-3Sn-2Sr alloy, the formation of the primary and eutectic SrMgSn phases is suppressed and promoted, respectively. At the same time, the coarse needle-like primary SrMgSn phases are modified and/or refined, and the primary grains are also effectively refined. However, an increase in Ti amount from 0.1 wt.% to 0.3 wt.% does not have obvious effect on the primary grain size of the Ti-containing alloys. In addition, the additions of 0.1-0.3 wt.% Ti to the Mg-3Sn-2Sr alloy can simultaneously improve the tensile and creep properties of the alloy. However, an increase in Ti amount from 0.1 wt.% to 0.3 wt.% does not have obvious effects on the tensile and creep properties of the Ti-containing alloys.