Ameliorating mechanical properties and reducing anisotropy of as-extruded Mg-1.0Sn-0.5Ca alloy via Al addition

Effects of Al addition to a Mg-Sn-Ca ternary alloy on its microstructure and tensile properties after extrusion were studied via extrusion of Mg-1.0Sn-0.5Ca-xAl (x = 0, 0.8, 2.4 wt%) sheets and analysis of the extruded materials. The results showed that Al addition not only refined the grain size (from 9.8 +/- 0.7 mu m to 8.3 +/- 0.4 mu m and 7.6 +/- 0.5 mu m) but also accelerated the generation of more second phase (from 0.98 to 1.72 and 4.32%). Except for the CaMgSn and Mg2Ca in Mg-1.0Sn-0.5Ca alloy, new phase (Mg, Al)(2)Ca appeared after Al addition. The addition of Al into Mg-Sn-Ca alloy induced the textural variation from an initially ED-split double-peaked texture to a weakened texture, i.e., divergent elliptical texture, due to the effect of particle stimulated nucleation. This eventually contributed to the improvement of mechanical anisotropy as well as the higher Hc value and n-value. For the strain hardening behavior when tension along the TD, the prolonged stage II of Al-modified alloys was closely connected with the additional TD textural components, accelerating the activation of more basal slip. The decreased theta III0 in stage III of Al-modified alloys is beneficial to the grain refinement and the emergence of more second phase.