On the corrosion of additively manufactured aluminium alloy AA2024 prepared by selective laser melting

The microstructure, and electrochemical properties of additively manufactured Al-alloy AA2024 (AM2024, Al-Cu-Mg) produced by selective laser melting are reported. In-depth microstructural characterisation was conducted to compare the resultant microstructure, including phase identification, size and distribution, against the wrought counterpart AA2024-T3. The prospect of producing net shape Al-alloys via additive manufacturing (AM) has the potential to provide cost effective and high specific strength components. It was revealed that the dominant second phase formed in AM2024 was Al ₂ Cu (θ–phase), in contrast to the typical Al ₂ CuMg (S-phase) observed in AA2024-T3. The AM2024 also revealed a refined microstructure, with an average constituent particle size < 1 μm. Thermodynamic calculations revealed that the preferential formation of θ-phase was influenced by the Si content of AM2024 (0.78 wt. %). Atomic emission spectroelectrochemistry (AESEC) measurements revealed a lower Al dissolution rate (5 times) in the case of AM2024. Anodic polarisation revealed that AM2024 was capable of forming an appreciable surface oxide relative to AA2024-T3. The findings herein demonstrate the possibilities of AM as applied to a high strength Al-alloy.