Effects of WC–10Co4Cr and TiC additions on microstructure and tribological properties of laser cladded FeMnCoCr HEA coatings

Abstract

FeMnCoCr high–entropy alloy (HEA), FeMnCoCr HEA–10%(WC–10Co4Cr) and −10%TiC coatings were fabricated by laser cladding. The effects of WC–10Co4Cr and TiC on the microstructure, phases and hardness of obtained coatings were analyzed via a super depth field microscope, X–ray diffraction, and microhardness tester, respectively. The tribological properties of obtained coatings at 500 °C were investigated using a ball–on–disc wear tester, and the wear mechanism was discussed in detail. The results show that the hardness of FeMnCoCr HEA coating is increased by the WC–10Co4Cr and TiC additions, which is attributed to the solid solution strengthening effects of WC and TiC. The wear rates of FeMnCoCr HEA–10%(WC–10Co4Cr) and −10%TiC coatings are decreased compared with the FeMnCoCr HEA coating by 65.47 % and 75.58 %, respectively, showing that the TiC has better strengthening effect than the WC. After the friction test, the worn track of FeMnCoCr HEA–10%TiC coating is composed of CoSiO4, MnFeO4 and FeCr2O4 phases, which forms the oxide film to prevent the wear loss of coating. The wear mechanism of FeMnCoCr HEA coating is adhesive wear and oxidative wear, accompanied with abrasive wear; while those of FeMnCoCr HEA–10%(WC–10Co4Cr) and −10%TiC coatings are abrasive wear, adhesive wear and oxidative wear.