Gas-induced porosity is almost inevitable in additively manufactured aluminum alloys due to the evaporation of low-melting point elements (e.g., Al, Mg, and Zn) and the encapsulation of gases (e.g., hydrogen) during the multiple-phase reaction in the melt pool. These micropores are highly unstable during post-heat treatment at elevated temperatures and greatly affect mechanical properties and service reliability. In this study, the AlSi10Mg samples prepared by LPBF were subjected to solution heat treatment at 560 °C for 0.5 and 2 h, followed by artificial aging at 160 °C, 180 °C and 200 °C, respectively. The defect tolerance of gas porosity and associated damage mechanisms in the as-built and heat treated AlSi10Mg alloy were elucidated using optical, scanning electron microscopic analysis, X-ray micro computed tomography (XCT) and room temperature tensile testing. The results showed the defect tolerance of AlSi10Mg alloy prepared by LPBF was significantly reduced by the artificial aging treatment due to the precipitation of Mg-Si phases. Fracture analysis showed that the cooperation of fine precipitates and coarsened micropores assists nucleation and propagation of microcracks sites due to stress concentration upon tensile deformation and reduces the tensile elongation at break.

In this study, the influence of surface states (as-received versus polished state) on the antibacterial and anti-biofilm attachment properties of thermally sprayed Cu-bearing coatings was studied. Findings indicate that the Cu ion release rate remains the predominant factor influencing the short-period antimicrobial efficacy of these coatings in their as-received state. Additionally, the influence of surface states on the antibacterial efficacy varied with Cu distributions (Cu as a segregated phase within a composite versus Cu as a solute element within a single phase). During microbial corrosion testing with Desulfovibrio vulgaris over an extended exposure, Cu addition continues to exhibit a significant inhibitory effect on biofilm attachment in as-received state. In contrast to their polished counterparts, the rough surfaces of the as-received samples significantly enhanced biofilm attachment; however, this facilitating effect diminished over time. The mechanisms leading to reduced facilitation varied with Cu distribution, due to either the formation of Cu₂S in composite coatings or the preferential biofilm attachment in valley areas in coatings containing Cu as solute. Additionally, the results suggest that arc spray has greater advantages over HVOF in preparing antimicrobial corrosion coatings, as it produces more uniformly flattened splats that show inhibiting effect on biofilm attachment.