Synthesis, characterisation and erosion behaviour of AlCoCrMoNi high entropy alloy coating

Abstract

AlCoCrMoNi equiatomic high entropy alloy (HEA) powders were prepared by mechanical alloying. High energy planetary ball-mill was employed to mill the powders till single solid solution formation. X-Ray Diffraction (XRD) analysis of as prepared powder was done at 5, 10, 15 and 20 hours of milling. A single BCC phase was formed after 20 h. Field emission scanning electron microscopy (FESEM) was used to study the microstructure of the prepared powder. After 20 hours of milling, a homogenous mixture formed, which was further confirmed by EDAX mapping of as prepared powders. The alloy was coated onto a 316 steel substrate using High-velocity Oxy-fuel (HVOF) coating. Cross-section of the coating was analysed using scanning electron microscope (SEM). The slurry erosion resistance exhibited by the coating was tested using Water-jet Erosion tester with 20 m s−1, 25 m s−1 and 30 m s−1 jet velocity at 30°, 60° and 90° angular impingement. The coating exhibited high ductility along with superior erosion resistance compared to conventional wear resistant coatings.