Microstructure and tribological property of CoCrFeMoNi High entropy alloy treated by ion sulfurization

The microstructures and tribological properties of CoCrFeMoNi high entropy alloy (HEA) before and after sulfurization were compared and discussed in the present study. The results showed that the CoCrFeMoNi HEA was mainly composed of FCC solid solution. After being sulfurized at 260℃ for 2 h, the FeS/MoS2 multisulfides solid lubricant films with a thickness of approximately 5.0 μm were successfully fabricated and well combined with the HEA. The stable friction coefficients and weight losses of the sulfurized HEA (0.15 and 4.25 mg) were decreased obviously than the original HEA (0.47 and 15.1 mg). At the beginning of the friction, the friction coefficient of the sulfurized HEA was easier to reach into stable stage. Because of the synergistic work of FeS and MoS2 lubricant phases, the sulfides boundary lubricant films were formed in the later stage of friction under the wearing condition, which could help the friction system work for longer time under lower friction coefficient.