Effects of Rare Earth CeO₂ on Microstructure and Properties of AlCoCuFeMnNi High-entropy Alloys

Abstract

The AlCoCuFeMnNi high-entropy alloy cladding layer with CeO2 was prepared by plasma cladding technology on 45 steel. The microstructure and phase composition of the cladding layer were investigated by XRD, SEM and EDS, and its microhardness and wear property were also tested. The results show that the phase structure of the cladding layer is mainly composed of BCC dendrites and FCC interdendrites. Thermodynamic calculation shows a small amount of AlCoNi phase exists in the cladding layer without CeO2, and a large number of Fe-rich precipitated particles in the dendrites is observed, the hardness value exhibits gradient changes from 260HV0.2 to 420HV0.2, and their friction coefficient is between 0.16 and 0.57. After adding 1%(mass fraction) CeO2, the Fe diffusion decreases into cladding layer, and a 32μm Fe-rich peritectic transition layer is formed on the bottom of the cladding layer. The average hardness value is about 400HV0.2, and their friction coefficient is relatively stable (0.28-0.31). The mass loss of the layer with CeO2 is 74.4% of that without CeO2. The grain refinement strengthening is the main reason of the improvement of wear properties.

Keywords

• high-entropy alloy
• CeO₂
• microstructure
• wear property