Microstructure and mechanical properties of selective laser melted Mg-9 wt%Al powder mixture

Selective laser melting (SLM) of Mg-Al powder mixture is a promising method to additively manufacture Mg-Al alloy components without using pre-alloyed powder as feedstock. However, the microstructure and consequent tensile properties of SLMed Mg-9 wt%Al powder mixture have not been systematically investigated. In this work, spherical Mg and Al powder with a weight ratio of 91:9 were mixed using ball milling and the mixture was SLMed at different processing parameters. Mg-Al alloy was successfully fabricated and the highest relative density achieved was 95.7%. The results of scanning electron microscopy showed that the microstructure and volume of defects could be controlled by tuning the processing parameters. The highest ultimate tensile strength achieved was 274 MPa, which was comparable to the strength of SLMed pre-alloyed Mg-9 wt%Al as reported in literature. Based on this study, SLM of different Mg powder mixture can be investigated in future.