Characterization of AlCrN films deposited onto Selective Laser Melted Ti6Al4V substrates

The mechanical performance and the microstructure of thin-film coatings deposited on selective laser melted (SLMed) Ti-6Al-4V were investigated. Specifically, the focus was on how properties like mechanical strength and surface roughness of the substrate affected the performance of films deposited by physical or plasma-enhanced chemical vapour deposition (PVD, PE-CVD). The substrate was a SLMed Ti-6Al-4V alloy, heat-treated either below or above the  -transus, finished by different grit sizes to get smooth and rough surfaces, and coated with PVD AlCrN. Scratch adhesion on harder surfaces treated below the -transus was higher, whilst the substrate finishing had a negligible effect. Conversely, in ball-on-disc sliding wear tests, substrate roughness had a dominant effect: rough surfaces always resulted in earlier cracking and delamination of the coatings. Microstructure was investigated by scanning electron microscopy and light microscopy to study the cross-sectional area and topography of the coating.