Surface modification of Ti-based alloy by selective laser melting of Ni-based superalloy powder

The present work investigates the possibility of modifying the surface of the Ti-based alloy Ti-6.5Al-1Mo-1V-2Zr by deposition of a coating by selective laser melting of Ni-based superalloy Ni-16Co-11Cr powder. Scanning electron microscopy, field emission transmission electron microscopy and X-ray structural analysis were applied to investigate the structural-phase state of the material. Nano-hardness and tribological tests were selected to study mechanical and wear properties. The thickness of the coating ranges from 70 to 130 μm. SLM coating deposition results in multiple titanium and nickel enrichment of the surface layer. The coating consists of several phases; the main ones contain titanium TiCo0.5Ni0.5, Ti0.25Al0.75, TiNi, TiCrAl. Nanohardness of the coating reaches its maximum of 10.5 GPa at the distance of 50 μm from the surface that is 2 times higher than that of the Ti-based substrate. Young's modulus of the coating varies similarly, reaching its maximum of 140 GPa at 50 μm from the surface and a minimum of 120 GPa in the substrate. The specific wear rate of the coating is 2.7 times lower than that of the substrate. To sum up, our work was the first to perform a detailed characterization of Ni-based coatings deposited on the Ti-based substrate via selective laser melting additive technology.