Synergistic effect of crystallographic orientation and porosity: Multi-mode corrosion mechanism of additive manufacturing Al-Fe-Mn-Sc-Zr alloy

This study elucidates the corrosion behavior of an Al-Fe-Mn-Sc-Zr alloy processed across a VED spectrum (38.9~138.9 J/mm³) through systematic electrochemical and accelerated corrosion testing. We identify a threshold VED of 55.6 J/mm³ that yields optimal corrosion resistance, as evidenced by the lowest corrosion current density (1.29 μA/cm²) and minimal exfoliation-induced roughness (0.837 μm).

In contrast, the sample processed at the lowest VED (38.9 J/mm³) exhibits severe intergranular attack, with a maximum depth of 104.62 μm and a corrosion current density of 21.38 μA/cm². Microstructural analysis reveals that intergranular corrosion susceptibility is governed by crystallographic orientation, with (111)-oriented grains showing the highest sensitivity, while exfoliation corrosion is primarily dictated by porosity.