Mechanical properties of CoCrFeNi-X (X = Ti,Sn) high entropy alloy and tribological properties in simulated seawater environment

Five multimajor element CoCrFeNi-X(X = Ti,Sn) high entropy alloys (HEA) were prepared by vacuum hot press sintering. The phase composition, mechanical properties and tribological properties of CoCrFeNi-X(X = Ti,Sn) alloys in simulated seawater were investigated. The phase structure of CoCrFeNiTi high-entropy alloy is solid solution FCC phase, R phase, σ phase, and Laves phase. But after addition Sn elements, the phase structure become the FCC phase and Ni-Sn solid solution phase. CoCrFeNiTi alloy has lower density (7.17 g/cm³) and higher hardness (750 HV) than that of CoCrFeNiSn. The compressive yield strength of CoCrFeNiTi HEA is better than CoCrFeNiSn HEA. The CoCrFeNiSn high-entropy alloys showed lower wear rates. The main reason is that SnO₂ is generated on the wear scar surface, which has good wetting and corrosion inhibition effects, so CoCrFeNiSn HEA shows better wear resistance in simulated seawater. The main wear mechanism of the CoCrFeNiSn HEA is abrasive wear, oxidative wear, exfoliation wear and corrosive wear.