Microstructure and properties of typical equiatomic CrMnFeCoNi high entropy alloy doped with different rare earth elements

The addition of rare earth elements (REEs) can effectively modify the microstructure of alloy and improve the properties. The effects of doping REEs in equiatomic CrMnFeCoNi high entropy alloys were investigated. Doping with REEs led to the formation of a few new phases enriched in the interdendritic regions and reduced the grain size. Doping REEs significantly improved the hardness and wear resistance of the alloy, and the Sm-doped alloy showed the most notable enhancement with the hardness value, the average friction coefficient and wear rate of HV 347.9, 0.28 and 0.91 × 10⁻⁶ mm³ N⁻¹ m⁻¹, respectively. The mechanical properties of the alloy were improved by the second phase strengthening and grain refinement and the wear mechanism was typical abrasive wear. However, the electrochemical properties indicated that doping with REEs weakened the corrosion resistance of the alloys; Pr- and La-doped alloys altered the corrosion behaviors on the alloy surfaces. The self-corrosion current density and potential of CrMnFeCoNiSm_0.2 alloy were 2.94 × 10⁻⁶ A cm⁻² and -0.46 V, respectively. This research plays a guiding role to study in REEs doping in HEA, meanwhile is of great significance in promoting the industrial application of HEA.