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

Abstract

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°C for 4 h possesses highest mechanical properties, but is more susceptible to corrosion. When heat treatment temperature reaches 400°C, the loss of coherency for Al3(Sc, Zr) precipitates decreased the strength, but the Al6Mn phase is corroded as cathode instead of the α-Al matrix, thereby inhibiting the occurrence of pitting corrosion. The specimen heat treated at 300°C for 4 h exhibited high strength and high elongation as well as superior corrosion resistance.