Effect of laser remelting on high-temperature oxidation resistance of AlCoCrFeNi high-entropy alloy coating

To reveal the effect of laser remelting on the high-temperature oxidation resistance of high-entropy alloy (HEA) coating, an AlCoCrFeNi HEA coating was prepared on AISI 1045 steel by plasma spraying technology and then remelted by laser remelting process. The microstructure of the coatings before and after remelting was characterized, and oxidation experiment was carried out at 900 °C for 100 h. The results showed that, after laser remelting, the porosity of AlCoCrFeNi HEA coating decreased from 4.8 % to 0.3 %. Moreover, the phase compositions of the coating after remelting were the same as that before remelting, which were still dominated by a single BCC solid solution structure. After oxidation, the oxidation weight gain of the remelted coating was slightly greater than that of the as-sprayed coating. Nevertheless, uniform and dense multilayer oxide films were formed on the remelted coating surface, leading to the lower oxygen content in the remelted coating and at the interface of remelted coating/substrate. Therefore, laser remelting can effectively improve the ability of AlCoCrFeNi HEA coating to hinder oxygen at high temperature and prevent the substrate from oxidation.