Laser cladding as a flexible exploration tool for the design of cobalt-free hardfacing coatings made of high entropy materials

Significant research efforts have been undertaken over the past forty years to replace the StelliteTM cobalt-based alloys, which boast outstanding performances when used as hardfacing coatings, but proved problematic especially in radioactive environments. This work's purpose is to contribute to this effort by coming up with viable substitutes made of Complex Concentrated Alloys (CCAs). Previous work evidenced the (CrFeNi)90Mo5Ti5 alloy as a promising base that relies on the formation of intermetallic phases within a ductile matrix for an increase in hardness and an improved tribological behaviour. In this particular framework, the in situ alloying capabilities of the DED (Direct Energy Deposition) process were used for further explorations around this composition. Compositionally graded samples were successfully made despite the especially high brittleness of the alloys of interest. Coupled with an extensive use of the CALPHAD method, this combinatorial strategy dramatically speeds up material development compared to what the more conventional ways can achieve. The present paper emphasizes on the methodology and the high-throughput tools that were developed and used in this study, as such elements are growing in importance in the current context of intensive global research for new materials, especially in the CCAs field.