Optimization of heat treatment for an Al–Mg–Sc–Mn–Zr alloy with ultrafine grains manufactured by laser powder bed fusion

An ultrafine grained Al-Mg-Sc-Mn-Zr alloy fabricated by laser powder bed fusion (L-PBF) was prepared to investigate the effect of different annealing heat treatments on the mechanical properties and corrosion behaviors. The results show that the optimized heat treatment is determined to be annealing at 300 °C for 2 h, which achieves highest hardness (142 HV) and best corrosion resistance (6.2 μA/cm2) simultaneously. The improvement of the mechanical properties and the corrosion resistance is mainly attributed to the precipitation of the secondary Al3(Sc, Zr) precipitates with sub-nano size. Moreover, the size of the nanoscale Al3(Sc, Zr) precipitates and the micropores also play a role in the corrosion resistance of the L-PBF Al-Mg-Sc-Mn-Zr alloy