Study of high temperature friction and wear performance of (CoCrFeMnNi)85Ti15 high-entropy alloy coating prepared by plasma cladding

(CoCrFeMnNi)85Ti15 high-entropy alloy (HEA) coating prepared on Q235 steel substrate via plasma cladding was investigated for its microstructure, hardness, and high temperature tribological performance. The microstructure of (CoCrFeMnNi)85Ti15 HEA consists of FCC and BCC solid solutions as well as an intermetallic sigma phase. The FCC solid solution is characterized by a lattice parameter of 3.669 Å and is enriched with Co-Cr, the BCC solid solution has a lattice parameter of 2.998 Å and is enriched with Fe-Mn, and the intermetallic sigma phase is enriched with Ni-Ti. The micro-hardness of the Q235 steel substrate, the CoCrFeMnNi HEA coating, and the (CoCrFeMnNi)85Ti15 HEA coating is 123.6 ± 6.2, 150.1 ± 7.4, and 910.5 ± 26.6 HV, respectively. As the hardness of the (CoCrFeMnNi)85Ti15 HEA coating is enhanced six times more than that of the CoCrFeMnNi HEA coating, it exhibits a lower wear rate and a better wear resistance at high temperatures. The best wear resistance, which corresponds to a wear rate of 4.08 × 10−6 mm3·N−1·m−1, is obtained at 400 °C. The wear mechanisms of the (CoCrFeMnNi)85Ti15 HEA coating are predominantly oxidation wear and contact fatigue, although there is evidence of oxidation wear and adhesive wear at 800 °C.