Electron Beam Surface Alloying of a Magnesium Alloy with Al

Magnesium alloy is an important engineering materials，but the wider application is restricted by poor corrosion and wear resistance. In the present study, an attempt was made to enhance corrosion resistance and microhardness of Mg alloy AZ91D by electron beam alloying. Flame spray method was used to prepare Al coating on the surface of AZ91D magnesium alloy, then remelted by high power electron beam. The microstructure and composition of the coating were analyzed in detail. Al-Mg diffusion was produced between the coating and the substrate to lead to the re-distribution of alloy elements in the melted layer. The coating was mainly composed of Al-Mg solid solution, Mg-Al intermetallic compounds and Mg-Al solid solution transition zone. Microhardness of the alloying layer was enhanced to 220 HV0.05 as compared to 70-80 HV0.05 of the substrate, due to the intermetallic phase formation, such as Mg2Al3 and Mg17Al12. These phases were good to improve anticorrosion property of AZ91D alloy．