Microstructural Evolution and Wear Behavior of AlCoCrCuFeNi High Entropy Alloy on Ti–6Al–4V Through Laser Surface Alloying

Abstract

AlCoCrCuFeNi high entropy alloy particles were laser surface alloyed on Ti–6Al–4V substrate to improve the tribological properties. The microstructure, phase formation and hardness improvement of the laser alloyed surface were examined. The wear resistance of the laser alloyed specimen were evaluated through pin-on-disc apparatus and compared with substrate specimen. The wear mechanism of the worn-out surface and roughness were studied. The laser alloyed specimen exhibits dual solid solution along with the BCC phase. The alloyed region shows dendrite and interdendrite structure with equiaxed grain formation. The hardness of laser alloyed region is 3 times higher than the substrate material due to dominant BCC phase formation. The laser alloyed specimen shows higher wear resistance compared to substrate due to solid solution strengthening and intermetallic formation. The wear resistance of the laser alloyed specimen was 2.62 times than the substrate at 50 N load and 0.9 m/s sliding velocity. Abrasive, adhesive wear and severe plastic deformation were observed in the substrate specimen, whereas in the laser alloyed specimen mild abrasive wear was observed. The laser alloyed specimen has 0.56 times the coefficient of friction of the Ti–6Al–4V substrate at 50 N load and 0.9 m/s sliding velocity due to self-lubrication property of HEA elements. Surface roughness of worn-out laser alloyed specimen was 0.44 times that of the Ti–6Al–4V substrate.