Synthesis and properties of high velocity oxy-fuel sprayed FeCoCrNi2Al high entropy alloy coating

The present study aims to develop dense FeCoCrNi2Al high entropy alloy (HEA) coating of thickness ≅ 200 μm by high velocity oxy-fuel (HVOF) process. Studies on the microstructure and mechanical properties like microhardness, erosion resistance of the HVOF coated FeCoCrNi2Al HEA has not been reported by any investigator. An adherent coating has been deposited displaying a lamellar microstructure. The X-ray diffractogram of the coating revealed the formation of a major FCC and a minor BCC phase with small amount of oxide. The oxide phase was confirmed to be Al2O3 using Raman spectroscopy. The microhardness of the coating is found to be 600 ± 30 VHN with no crack formation upto a load of 1 kgf. The erosion resistance of the HEA coated steel was evaluated upto a temperature of 800 °C. The coating displays good erosion resistance and the depth of penetration of the erodent was well within the coating thickness with no delamination of the coating, thereby making it suitable for high temperature applications.