The Dependence of Creep Behavior on Elemental Partitioning in Mg-5AI-3Ca-xSn Alloys

摘要

Cast Mg-5Al-3Ca-xSn alloys have been examined to investigate the effect of Sn additions on elemental partitioning during solidification, microstructure development, and compressive creep behavior at 453 K (180 °C). Alloys containing 0.25 to 3.0 wt pct Sn were cast with a permanent mold technique. The addition of 0.75 to 1.0 wt pct Sn had a beneficial effect on Ca partitioning to the a-Mg phase. Additions beyond 1 wt pct Sn resulted in the formation of an orthorhombic Mg-Ca-Sn phase, with decreased Ca partitioning to the a-Mg. A lower minimum creep rate was observed for the Mg-5Al-3Ca-xSn alloy with increased Ca partitioning. Consistent with this finding, analyses that consider the influence of solute and precipitation strengthening on creep in Mg-5Al-3Ca-xSn alloys suggest that Ca in the a-Mg contributes to a greater degree than Al in solution to the creep resistance at 453 K (180 °C).