Microstructure and wear properties of the surface alloyed AZ31 magnesium alloy with aluminium

An attempt has been made to improve the surface properties of AZ31 magnesium alloy through surface melting and formation of alloyed layers with aluminium. Tungsten inert gas (TIG) process was used for supplying heat source to melt the surface layers. The microstructures of the surface treated layers were investigated using optical microscope and scanning electron microscope equipped with EDS analyser, and the phases were examined using XRD. The mechanical and tribological properties were evaluated using Vickers microhardness and wear testing machines. The alloyed surface layer which was made using aluminium powder contained alpha-Mg based substrate and Mg-Mg17Al12 eutectic. The microhardness test results showed that the hardness of AZ31 alloy was improved from 55 HV0.1 to 87 HV0.1 and 193 HV0.1 for melted layer and the alloyed layer with aluminium powder, respectively. The wear test showed that the wear rate of the surface alloyed layer with aluminium powder was reduced to about half of the as-received sample, due to the formation of the hard intermetallic compounds in the alloyed layer.