Influence of Si Content on Microstructure and Properties of Mg-5Sn-1.5Al-1.2Zn Magnesium Alloy

The effects of silicon content on as-cast microstructure and mechanical properties of Mg-5Sn-1.5Al-1.2Zn magnesium alloywere studied when silicon element was added into melt in the form of magnesium-silicon interalloy with the range of 0-1.6%.The results indicate that Mg2Si is the strengthening phase made by combining alloying element silicon and magnesium matrix,and around Mg2Si phase Mg2(Si,Sn) composition is found,the emerging of Mg2(Si,Sn) advances the forming of τ-Mg32(Al,Zn)49 that is produced by Al and Zn elements.When Si element changes from 0 to 1.6%,tensile strength and elongation of the alloy display a trend which increase firstly and then decrease,its tensile strength and elongation match better when Si content is 1.0%,while hardness of the alloyis improved in the range of 0-1.6%Si,the increment of hardness becomes slow as Si content in the range of 1.2%-1.6%.