本团队博士生于凯昌等在Surface and Coatings Technology发表研究论文。

摘要：Simultaneously enhancing the wear resistance and interfacial reliability of hot-work die steels under extreme thermo-mechanical loading conditions remains a significant challenge in the field of surface engineering. Inspired by the multi-level armored structure of the scaly-foot snail (Chrysomallon squamiferum), this study proposes a biomimetic functionally graded high-entropy alloy (BFG-HEA) strategy. A metallurgically bonded “H13–CoCrFeNi–CoCrFeNiMo” gradient system was successfully fabricated on the surface of H13 die steel using laser cladding technology. Specifically, the CoCrFeNi layer with good plasticity serves as a ductile transition layer and establishes a continuous compositional gradient, which helps enhance interfacial bonding stability. Concurrently, the rapid solidification during the laser cladding process drives the preferential segregation of Mo in the top layer, promoting the coupled growth of alternating σ-phase and FCC-matrix lamellae. This process constructs a robust σ/FCC eutectic reinforcing skeleton, resulting in an average surface hardness of 678.6 HV (approximately 3.6 times that of the H13 substrate). Furthermore, the BFG-HEA coating exhibits a significantly reduced coefficient of friction (COF) and an approximately 83% reduction in wear volume compared to the substrate. During high-temperature wear testing at 500 °C, the coating also maintains superior tribological stability, with the average COF reduced from 0.52 for H13 to 0.42 and the wear-track width decreased from 1.10 mm to 0.54 mm. As revealed by microstructural characterizations, interfacial nano-indentation tests, and XPS analysis, this exceptional tribological performance originates from the hierarchical synergistic effect among the dense Cr/Mo composite oxide glaze layer formed in situ on the surface, the subsurface σ/FCC eutectic reinforcing skeleton, and the underlying transition layer. This study provides new insights into the structural tailoring and performance optimization of gradient HEA coatings, providing valuable theoretical insights for achieving the synergistic enhancement of high wear resistance and interfacial reliability on die steel surfaces.