The Effects of Al3(Sc, Zr) Precipitation Phase on Selective Laser Melting Al-Mg-Sc-Zr alloy: Microstructure, Mechanical properties and Fatigue resistance

Abstract In this study, an Al-Mg-Sc-Zr alloy fabricated through selective laser melting (SLM) was subjected to a single-stage heat-treatment process and a two-stage heat-treatment process to determine the effect of heat treatment on the tensile properties and fatigue properties of the alloy at room temperature and high temperatures. The results indicated that heat treatment caused the precipitation of Al3(Sc, Zr), thus increasing the tensile strength. The dynamic strain aging of the SLM Al-Mg-Sc-Zr alloy disappeared as the tensile temperature increased. The alloy exhibited the highest tensile strength after it was subjected to the single-stage heat treatment at both room temperature and high temperatures owing to the precipitated phase distribution at the melting pool boundaries. However, fatigue resistance and high-temperature necking of the as-printed SLM Al-Mg-Sc-Zr alloy were problems that could not be resolved with the single-stage heat treatment. In the two-stage heat treatment, the precipitated phases exhibited a uniform distribution in the matrix, thereby reducing the high-temperature necking phenomenon. The two-stage heat treatment helped reduce the melting pool interface effect and strengthen the matrix, restricting the propagation of fatigue cracks and increasing the fatigue life of materials.