Enhancing the surface properties of Ti-6Al-4V with high entropy alloy coating prepared by electron beam cladding

A high entropy alloy (HEA) coating was applied on Ti-6Al-4 V by electron beam cladding Al₇(CoFeNi)₈₆Ti₇ HEA powder. The optimal electron beam cladding parameters, determined through orthogonal experimental analysis, were: 64 kV accelerating voltage, 12 mA welding beam current, and 3 s scanning time. Microstructure, phase composition, nano-hardness and wear resistance of the coating prepared using optimal parameters were investigated. The primary phases in the top, middle, and bottom regions of the coating were identified as body-centered cubic (BCC) solid solution with Ti-rich compounds (NiTi, Ti₂Ni, and Ti₂Co), BCC + Ti_0.85Al_0.15, and Ti_0.85Al_0.15, respectively. The coating had an average grain size of 3.9 μm, and the dislocation density of the BCC phase was 1.51 × 10¹⁴/m². Due to the presence of compounds, fine grains, and high dislocation density, the coating achieved an average nano-hardness of 8.39 ± 0.29 GPa, approximately 1.8 times higher than that of Ti-6Al-4 V. Additionally, the wear rate of the cladded coating was 22.28 ± 4.56 × 10^− 6 mm³/(N·m), representing a 65.5% reduction compared to Ti-6Al-4 V.