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

(CoCrFeMnNi)(85)Ti-15 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)(85)Ti-15 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 angstrom and is enriched with Co-Cr, the BCC solid solution has a lattice parameter of 2.998 angstrom 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)(85)Ti-15 HEA coating is 123.6 +/- 6.2, 150.1 +/- 7.4, and 910.5 +/- 26.6 HV, respectively. As the hardness of the (CoCrFeMnNi)(85)Ti-15 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 x 10(-6) mm(3) N(-1)m(-1), is obtained at 400 degrees C. The wear mechanisms of the (CoCrFeMnNi)(85)Ti-15 HEA coating are predominantly oxidation wear and contact fatigue, although there is evidence of oxidation wear and adhesive wear at 800 degrees C.