Microstructure and tensile properties of friction stir processed Mg-Sn-Zn alloy

Abstract

this study, as-cast Mg-6Sn-2Zn (wt.%) alloy was subjected to friction stir processing (FSP) and the microstructure and tensile properties of FSP Mg-6Sn-2Zn samples were investigated. It was found that, in the stir zone (SZ) of FSP Mg-6Sn-2Zn samples, α-Mg grains were significantly refined via dynamic recrystallization (DRX) and the Mg2Sn phase was broken and partially dissolved. The microstructure in SZ was nonuniform and DRXed grains in the SZ-up regions were coarser than those in the SZ-down regions. Coarse broken Mg2Sn particles were observed in the SZ-up regions, while only fine Mg2Sn particles were observed in the SZ-down regions. Strong (0001) basal texture developed in the SZ regions of Mg-6Sn-2Zn samples after FSP. The increase of travel speed had little effect on the texture of different SZ regions. The ductility of FSP Mg-6Sn-2Zn samples was obviously improved, while the improvement in strength was negligible when compared to the as-cast sample. The tensile properties of FSP Mg-6Sn-2Zn samples were influenced by grain refinement, texture modification, and the breaking up and dissolution of the Mg2Sn phase.