Superlubricity strategy for lubrication enhancement in boronized high-entropy alloys

Al_0.3CoCrFeNi high-entropy alloy (HEA) has broad application prospects in the aerospace field due to its excellent strength and ductility. However, its low surface hardness and wear resistance pose challenges to its engineering applications. Superlubricity materials and technologies with friction coefficient below 0.01 offer a promising solution to address the high friction and wear issues in Al_0.3CoCrFeNi HEAs. Here, we developed a synergistic superlubricity system on Al_0.3CoCrFeNi HEA by combining boride layer with glycerol lubricant optimization. The boride layer with multilayered structure, high hardness and ultrafine-grained characteristics was achieved after electrochemical boronizing treatment. The superlubricity system was realized on the boronized HEA under glycerol lubrication with near-zero friction (0.004) and near-zero wear (4 ×10⁻⁷ mm³/Nm) performance. The superlubricity mechanism was attributed to the anti-friction borate esters tribolayer on the interface and the load-bearing glycerol layer between friction pairs. This study developed a superlubricity system design strategy based on synergistic effect between the boronized HEAs and glycerol lubricant, which could promote the application of Al_0.3CoCrFeNi HEA under actual engineering conditions.