Tuning the mechanical and corrosion properties of Al-Mg-Sc-Zr alloy processed by laser powder bed fusion through heat treatment

The current interest in Al-Mg-Sc-Zr alloy fabricated by powder bed fusion-laser beam (PBF-LB) is centered around excellent mechanical property without taking into account its corrosion behavior. In this work, gas-atomized Al-Mg-Sc-Zr alloy powder was manufactured by PBF-LB. The influence of heat treatment on microstructure, phase evolution, mechanical properties, and electrochemical corrosion behaviors were investigated and microstructure-property relationship was established to obtain high-performance alloy. The result suggests that the sample heat treated at 350 degrees C for 4 h possesses highest mechanical properties, but is more susceptible to corrosion. When heat treatment temperature reaches 400 degrees C, the loss of coherency for Al3(Sc, Zr) precipitates decreased the strength, but the Al6Mn phase is corroded as cathode instead of the alpha-Al matrix, thereby inhibiting the occurrence of pitting corrosion. The specimen heat treated at 300 degrees C for 4 h exhibited high strength and high elongation as well as superior corrosion resistance.