Dongjiang Wu, Yepeng Yang, Jiangbo Cheng, Xiaoying Li
Current researcher adapted a “surface design strategy” for a high entropy alloy (HEA), with the combination of coating approach to effectively address the high-cost issue of HEAs and surface modification to enhance the surface properties of HEAs. This study systematically investigated the influence of direct current plasma nitriding (DCPN) treatment temperature (430–500 °C) on the microstructure and surface properties of plasma clad CoCrFeMnNi HEA coating through comprehensive microstructure characterization and property evaluation aiming to develop an advanced surface engineering approach for cost-effective and high-performance HEA coatings. The optimal performance was achieved for low-temperature (430 °C and 450 °C) plasma nitrided HEA coatings, where nitrogen-supersaturated S-phase formation resulted in the significant increase in surface hardness, mild abrasive wear and excellent corrosion resistance, demonstrating an ideal balance between mechanical, tribological and chemical properties. On the other hand, as the plasma nitriding temperature increased to 480–500 °C, although hardness was further enhanced through the formation of M 3 N and CrN precipitation, the combined effects of chromium depletion and brittle phase formation significantly deteriorated the corrosion performance. These findings establish 430 °C and 450 °C as the optimal DCPN treatment temperatures for applications requiring both high wear and corrosion resistance, while higher temperatures (>450 °C) should be avoided due to detrimental phase transformations that compromise surface integrity. The research provides fundamental insights into temperature-dependent microstructure evolution and its impact on surface performance, offering valuable guidance for the optimisation of industrial plasma nitriding processes and open doors to the wide industry application of surface engineered HEA coatings with affordable cost and high-performance.