The role of Ga in the microstructure, corrosion behavior and mechanical properties of as-extruded Mg–5Sn–xGa alloys

The effect of Ga element on microstructure, corrosion behavior and tensile mechanical properties of as-extruded Mg–5Sn–xGa (x = 0, 1, 2, 3, all in wt%) alloys was investigated using immersion test, electrochemical test and tensile test. The results show that the Mg2Sn and Mg5Ga2 particles are dynamically precipitated during extrusion process, and the volume fraction of Mg5Ga2 precipitates increases with increasing Ga content. The corrosion resistance of Mg–5Sn alloy in the immersion test is increased approximately by four times after adding 2 wt% Ga, due to the fact that the Ga element weakens the cathodic reaction, and more stable corrosion products are formed in the Ga-containing alloys in the inner corrosion layer. The tensile strength of investigated alloys is improved monotonously with increasing Ga content. The maximum elongation to fracture reaches up to 21.7% for Mg–5Sn–1Ga alloy due to the modified basal grain texture. •Ga alleviates the effect of Mg2Sn precipitates as the cathode.•A protective corrosion layer was formed on the surface of the alloys with Ga additions.•The tensile strength of Mg-5Sn alloy is improved with Ga addition.