Microstructural characteristics and enhanced wear resistance of nanoscale Al2O3/13 wt%TiO2-reinforced CoCrFeMnNi high entropy coatings

High-entropy alloys (HEAs) are useful materials for surface engineering due to their superior properties. Nanoscale Al2O3/13 wt%TiO2 (AT13) reinforced CoCrFeMnNi HEA composite coatings were prepared by plasma spraying on Q235, and their detailed microstructure and relative mechanical properties were analyzed. XRD analysis indicated no interaction between the CoCrFeMnNi (FCC) and Al2O3/TiO2 phases. The HEA composite coatings featured typically layered structure, and the ceramic phase exhibited good bonding with the CoCrFeMnNi HEA matrix. The volume fraction of the ceramic phase in as-sprayed composite coatings increased with the AT13 proportion in feedstock powders. However, the porosity of the coating decreases firstly, and then increases. The maximum hardness and best elastic recovery property were obtained at an appropriate ceramic content (10 wt%). Wear rate results indicated that the Al2O3/TiO2 phase can dramatically improve the wear resistance of composite coatings. The composite coating with 10 wt% AT13 had the lowest wear rate and featured a relatively smooth surface following wear testing. Improved wear resistance was mainly reflected in resistance against deformation of the HEA matrix and reduced stress-induced crack propagation during wear testing. The appropriate content of AT13 ceramic can reduce the delamination wear of the HEA coating.