激光熔覆高熵合金涂层组织结构及强化机理研究进展

激光熔覆作为一种绿色、高效的表面处理技术，能够快速制备组织致密、晶粒细小，与基体呈高强度冶金 结合的涂层，是近年来高熵合金领域的研究热点之一。概述了现有高熵合金涂层材料体系和制备方法，重点讨论 了激光熔覆CoCrFeNi-M 典型过渡族高熵合金涂层的组织结构，及其耐磨、耐蚀、抗高温氧化等性能，并归纳了 涂层的强化机制和方法。CoCrFeNi-M 系合金涂层主要呈现FCC 固溶体结构，综合力学性能普遍较好，通过合金 体系调控，在细晶强化、固溶强化、第二相强化等作用下，能够获得硬度、耐磨性、耐蚀性等性能的进一步提升。 同时，概述了激光熔覆难熔高熵合金涂层的组织结构，耐磨、耐蚀、抗高温氧化性能及性能强化机制，该体系合 金涂层主要呈现BCC 固溶体结构，硬度较高但室温韧性普遍不足，具有较好的高温强度，在高温领域具有较好 的应用前景，但抗高温氧化性能普遍不足，仍需通过合金体系优化进一步提升。此外，总结了基于激光熔覆技术 开展的高熵合金涂层制备及研究中存在的问题和不足，并展望了未来的发展方向。

Research Progress on the Microstructure and Strengthening Mechanism of High-entropy Alloy Coatings Deposited by Laser Cladding Technology

Laser cladding, a green and efficient surface treatment technology, could deposit coatings with dense structure, fine grain size and metallurgical bonding with the substrate, has become one of the research hotspots in the field of high entropy alloys (HEAs) in recent years. In this paper, the material system and preparation methods of the existing HEAs coatings were reviewed. The microstructural features, properties such as wear resistance, corrosion resistance, and high-temperature oxidation resistance, and the strengthening mechanisms of the laser cladded typical CoCrFeNi-M transition group HEA coatings were mainly discussed. The CoCrFeNi-M alloy system coatings mainly had FCC solid solution structure with excellent comprehensive mechanical properties. Through the regulation and optimization of alloy composition, the microhardness, wear resistance, corrosion resistance and other properties of the coating could get strengthened under the effect of fine grain strengthening, solid solution strengthening, or second phase strengthening mechanism. At the same time, the microstructural features, wear resistance, corrosion resistance, high-temperature oxidation resistance and performance strengthening mechanism of laser cladded refractory high entropy alloy (RHEA) coatings were discussed. The RHEA coatings mainly presented BCC solid solution structure with high hardness but limited room-temperature ductility in general. Despite the excellent high temperature strength and good application prospect in high temperature field, the high-temperature oxidation resistance of the RHEA coatings is insufficient, and still need to be enhanced through the optimization of the alloy composition. In addition, the current problems of laser cladded high-entropy alloy coatings were discussed, and the future development direction is prospected.