A new strategy to modify grain size/basal texture in as-extruded Mg-Sn-Ca alloys via trace Sr addition

Abstract

In this study, a novel magnesium alloy with fine grain size and weakened basal texture was successfully developed through the addition of trace amounts of Sr followed by hot extrusion. Unlike the precipitates observed in the Mg-1Sn-0.25Ca (TX) alloy, the introduction of 0.5 wt% Sr not only facilitates the precipitation of the nano-scale CaMgSn phases within the matrix but also suppresses the formation of coarse (Ca, Sr)MgSn phases at grain boundaries. These alterations in precipitation behavior significantly modify the dynamic recrystallization (DRX) mechanism, shifting from discontinuous dynamic recrystallization (DDRX) in the TX alloy to continuous dynamic recrystallization (CDRX) in the TX-0.5Sr alloy. As a result, the average grain size is refined from 7.47 μm to 2.11 μm, and the maximum intensity of the basal texture is reduced from 12.14 MRD (multiples of random distribution) to 5.72 MRD. These microstructural enhancements contribute to a remarkable 122 % increase in yield strength and a 58 % improvement in elongation.