Characterisation and property evaluation of High Entropy Alloy coating on 316L steel via thermal spray synthesis

Abstract

The advancement in the alloys led the development of High Entropy Alloys (HEA) that possess improved performance and characteristics. In the current study, AlCoCrFeNi HEA powder was synthesised using gas atomisation and coated onto SS316L stainless steel substrate using the atmospheric plasma spraying process. The microstructural characterisation of the synthesised HEA powder exhibited spherical morphology with a mean particle size of 20 µm. The crystal structure is observed to be BCC phase. The coated samples displayed uniform coating with homogenous distribution of HEA over the coating thickness of 150 µm. The microhardness of the coated samples had an increment of 2.46 times against the uncoated samples due to the excellent bonding and fine dispersion of HEA. The subsequent wear test performed by varying the process parameters revealed improved wear resistance on the coated samples than the uncoated samples. The lower range of load, sliding velocity and sliding distance of coated samples offered 83.92 %, 76.56 % and 74.59 % increments in wear resistance respectively and the characterisation of the worn surface revealed the mechanism to be plastic delamination and adhesive wear. The corrosion test conducted in 3.5 wt% NaCl electrolytic solution also exhibited better corrosion resistance for the coated samples due to the formation of an oxide layer along the coating acting as a protective layer for the enhanced resistance to corrosion.