激光熔覆制备高熵合金涂层的研究进展

Research Status of High-entropy Alloys Coating Prepared by Laser Cladding

激光熔覆技术具有高的冷却速度、低的稀释率、涂层与基体冶金结合等优点,采用激光熔覆技术制备耐磨性和耐腐蚀好的高熵合金涂层是近几年高熵合金领域的研究热点之一。首先概括了激光熔覆技术制备的高熵合金体系及组织结构特征,大多高熵合金涂层以固溶相为主,少数合金涂层形成了非晶相,与熔炼制备高熵合金块体材料相比,涂层组织具有均匀、细小致密等特点。然后介绍了涂层的性能特征,涂层具有较高的硬度、良好的耐磨性,同时指明高耐磨性涂层不仅具有高的硬度,同时还需要具有一定的塑韧性。涂层合金中大多包含有Al、Cr、Si和Co等形成稳定氧化膜的元素,呈现优异的抗腐蚀性能。随后重点概述了合金元素(Al、Mo、V、Ti、B、Ni、Nb和Cu等)、熔覆工艺参数(激光功率、扫描速度和预制层粉末厚度)和热处理工艺对涂层组织结构和性能的影响规律。其中,熔覆工艺参数对涂层组织结构和性能的影响研究相对较少,将是未来研究的重点内容之一。最后对激光熔覆技术制备高熵合金涂层存在的问题和未来的研究方向做了展望。

Laser cladding has the advantages of high cooling rate, low dilution rate, metallurgical combination between coating and substrate, etc. In recent years, high-entropy alloys coating with high wear resistance and corrosion resistance prepared by laser cladding has been one of research hotspots in high-entropy alloy field. Firstly, the high-entropy alloys prepared by laser cladding and corresponding microstructures were summarized. Most coatings were composed of solid solution phase, but some alloy coatings still formed amorphous phase. Compared with high-entropy alloys prepared by melting, the microstructure of this coating was more homogeneous, finer and denser. Then, the properties of the coating were introduced, including high hardness and good wear resistance and corrosion resistance. The coating with good wear resistance also had high hardness and certain plasticity. The coatings exhibited excellent corrosion resistance due to the existence of Al, Cr, Si and Co elements which formed the stable oxide film. Then, the effect of alloying elements (Al, Mo, V, Ti, B, Ni, Nb and Cu), cladding parameters (laser power, scanning rate and thickness of prepared layer) and heat treating parameters on the microstructure and properties was reviewed. The effect of cladding parameters on microstructure and properties is fewer and will be one of the key research contents. Lastly, the existing problems and the future research fields of high-entropy alloys coating prepared by laser cladding are prospected.