Aging-Assisted Grain Boundary Engineering and Its Impact on the Deformation Behavior in Precipitation Hardenable Multicomponent Mg-10Sn-3Al-1Si Alloy

The influence of Si addition on the artificial aging (AA) response of multicomponent Mg-10Sn-3Al-1Si (wt.%) alloy has been systematically investigated. Scanning electron microscopy investigation reveals that variation in aging duration for 100 h and 500 h at 200 °C alters the morphology and distribution of nanoscale rod- or lath-like Mg₁₇Al₁₂ precipitates, without any alternation in the size of micro-meter size intermetallic β-Mg₂Sn precipitates. Besides, no gradual drop in the hardness value even after aging for 500 h at 200 °C predicting its superior thermal stability, which is attributed due to the precipitates of β-Mg₂Sn along the grain boundaries (GBs). In addition, alteration of the nanoscale Mg₁₇Al₁₂ precipitates distribution at the GB regions induces moderate age hardening and recovers its tensile properties. Comprehensive characterization suggests that during tensile loading in 100-h AA alloy, DP-type Mg₁₇Al₁₂ precipitates near GBs, resulting strain localization near GBs which leads to premature GB failure. However, prolonged aging for 500 h suppresses the formation of CP-type Mg₁₇Al₁₂ precipitates at the GBs and leads to precipitate inside the grain, thereby reduces strain localization during tensile loading and somewhat recovers ductility. These results can come up with new hints for controlling the deleterious effect of AA at high temperature and provide new guidelines for designing multicomponent high-performance Mg- alloys.