Effect of Laser Remelting on Microstructure and Properties of AlCoCrFeNi High-Entropy Alloy Coating

A high-entropy alloy coating of AlCoCrFeNi was prepared by plasma spraying and then remelted via laser remelting. The effect of laser remelting on the microstructure, mechanical properties and wear resistance of the AlCoCrFeNi coating was investigated. Particularly, the effect of surface free energy on the wear resistance of the coatings before and after remelting was explored. The results showed that the remelted AlCoCrFeNi coating retained the same single BCC solid solution structure as the as-sprayed AlCoCrFeNi coating. Besides, the defects in the coating were basically eliminated by laser remelting, leading to the porosity of the coating decreased from 4.8 to only 0.3%. Consequently, the hardness, elastic modulus and fracture toughness of the coating were enhanced by 38%, and the wear loss of the remelted AlCoCrFeNi coating was only 22% of that of the as-sprayed one. Therefore, laser remelting is a feasible method to improve the microstructure and enhance the wear resistance of the AlCoCrFeNi high-entropy alloy coating.