Microstructure and Properties of Al2O3-13wt.%TiO2-Reinforced CoCrFeMnNi High-Entropy Alloy Composite Coatings Prepared by Plasma Spraying

摘要

This study deals with Al2O3-13wt.%TiO2-reinforced CoCrFeMnNi high-entropy alloy (HEA) composite coatings prepared by plasma spraying. The effect of the Al2O3-TiO2 ceramic phase on the microstructure, mechanical properties and high-temperature tribological performance of the as-sprayed composite coatings was investigated. The results showed that the composite coatings consisted of a HEA phase with a FCC (face-centered cubic) structure and an Al2O3-TiO2 ceramic phase with a three-dimensional network structure. The coatings presented a typical layered structure with less porosity than pure HEA coatings. The three-dimensional network structure was mainly due to partially melted Al2O3-13wt.%TiO2 particles during the spraying process. The composite coating with Al2O3-TiO2 ceramic phase had an improved plastic deformation resistance and a reduced elastic recovery resistance. Its wear rate was lower than that of the pure HEA coating. The main wear mechanisms included oxidation, wear and adhesive wear. The Al2O3-TiO2 ceramic phase reduced the adhesive wear and promoted the tribological behavior of the HEA composite coating at low temperature. The excellent wear resistance of the as-sprayed coating at high temperatures was mainly due to the formation of an oxide layer on the worn surface.