Dissimilar friction stir welding of 7075 aluminum alloy to AZ31 magnesium alloy using SiC nanoparticles

In this study, a new approach for dissimilar friction stir welding of aluminum alloy and magnesium alloy was developed. In order to make metal matrix composite in the weld stir zone, silicon carbide nanoparticles were embedded into the weldment. The admixture pattern of the stir zone, weld microstructures, intermetallic phases, powder distribution, and mechanical properties of the welds were investigated in this paper. Due to using silicon carbide nanoparticles as reinforcement in friction stir welding, the weld microstructure was affected by pinning mechanism. Meanwhile, it was observed that the formation of brittle and hard intermetallic phases also affected the welded joint microstructure. The effects of friction stir welding process parameter such as tool rotational and traverse speeds were also examined. It was observed that increasing the tool rotational speed and decreasing the tool traverse speed improved the mixing of two alloys at the stir zone. By controlling the process parameters, a fine microstructure with an average grain size of 4.3 mu m at the stir zone was obtained.