Laser micro-engraving and heat treatment to enhance cell adhesion on DMLS-processed nickel alloy

Direct Metal Laser Sintering (DMLS) enables the fabrication of complex metallic components with excellent dimensional accuracy and tailored microstructures. This study investigates the effect of heat treatment and laser micro-engraving on the microstructure and biocompatibility of DMLS-processed Inconel 718 alloy. The fabricated specimens were subjected to solution treatment followed by double ageing to promote γ′ and γ″ precipitates. Optical microscopy and scanning electron microscopy revealed that heat treatment transformed the dendritic as-built microstructure into a homogeneous equiaxed structure. Laser micro-engraving produced well-defined surface textures, with the heat-treated alloy exhibiting higher surface roughness and enhanced surface activity. Biocompatibility was evaluated using an MTT assay with L929 fibroblast cells. After 72 h of exposure, the as-built alloy exhibited a cell viability of 79.9%, whereas the heat-treated alloy achieved 84.1%, corresponding to an improvement of approximately 5.3%. Microscopic observations further confirmed improved cell attachment and spreading on the heat-treated surface. The results indicate that heat treatment combined with laser micro-engraving enhances the biological performance of DMLS-processed Inconel 718 for potential biomedical applications.