Effect of Laser Surface Processing on the Microstructure Evolution and Multiscale Properties of Atmospheric Plasma Sprayed High-Entropy Alloys Coating

Two types of high-entropy alloys (HEAs) AlCrCoFeNiTi and FeCrCoNiW_0.3 + 5 at.% C are fabricated using atmospheric plasma spray (APS) technique. Laser surface processing (LSP) is performed on the developed alloys using Nd:YAG pulsed laser. Post processing the surface roughness of the alloys are reduced by ~ 29%. The impact of laser surface processing reveals the presence of a single BCC phase and FCC phase with the evolution of more W-rich and Cr-rich carbides in AlCrCoFeNiTi and FeCoCrNiW_0.3 + 5 at.% C coatings, respectively. The microstructural study exhibits the formation of lamellar microstructure with minimum pores and interlaminar cracks. Post laser processing the microhardness of both the APS coated alloys are increased by 5%, nanoindentation results reveal an increase in the average elastic modulus (Er) by 12%, and average nanohardness by 18%. The FeCoCrNiW_0.3 + 5 at.% C coatings achieved maximum wear resistance of 39.71% among the two alloys, indicating the improvement achieved through laser processing. Also the observed improvements in surface morphology of both the alloys are reported.