Cao Haobo, Hou Guoliang, Fu Zhiqiang, Ma Junkai, An Yulong, Zhou Huidi, Chen Jianmin
State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou730000, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing100049, China.
ACS Appl Mater Interfaces. 2023 Jan 18;15(2):3651-3663. doi: 10.1021/acsami.2c19210. Epub 2023 Jan 3.
The dispute over the effect of cavitation heat on material surface intensifies the fuzziness of cavitation erosion (CE) mechanism and limits the development of protective materials. Here, an anti-CE AlCrCoNi high-entropy alloy (HEA) coating with single face-centered cubic (FCC), prepared by high-velocity oxy-fuel (HVOF) spraying technologies, was designed by inducing mechanical and thermal energy-induced behaviors to transform or counteract each other. The results showed that, on the one hand, this coating underwent the refinement of the average grain size from 1.22 to 1.02 μm, the increase in dislocation density from 1.28 × 10 to 1.83 × 10 m, and the martensitic transformation from FCC to body-centered cubic (BCC) under the cavitation load; on the other hand, cavitation heat could indeed induce grain growth and realize structural relaxation, which confirmed that cavitation heat acting on the material surface at temperatures theoretically above 1206.28 K also played a significant role in the CE mechanism. That is, the surface microstructure of this coating was always in a dynamic cycle during the CE process. Therefore, the coating achieved the simultaneous absorption of mechanical impact energy and thermal energy released by the bubble collapse while effectively avoiding the overenrichment of crystal defects and finally exhibited a CE resistance 2 times better than that of the classical AlCrCoFeNi HEA coating. This design concept of inducing different energy restraints or neutralization through the special response behaviors of surface microstructure provides a completely new way for the development of CE-resistant materials.
空化热对材料表面影响的争议加剧了空蚀（CE）机制的模糊性，并限制了防护材料的发展。在此，通过高速氧燃料（HVOF）喷涂技术制备了一种具有单面心立方（FCC）结构的抗CE AlCrCoNi高熵合金（HEA）涂层，其设计思路是通过诱导机械能和热能诱导行为相互转化或抵消。结果表明，一方面，该涂层在空化载荷作用下，平均晶粒尺寸从1.22μm细化至1.02μm，位错密度从1.28×10增加到1.83×10 m，发生了从FCC到体心立方（BCC）的马氏体转变；另一方面，空化热确实能诱导晶粒生长并实现结构弛豫，这证实了理论温度高于1206.28 K时空化热作用于材料表面在CE机制中也发挥了重要作用。也就是说，该涂层的表面微观结构在CE过程中始终处于动态循环中。因此，该涂层在有效避免晶体缺陷过度富集的同时，实现了对机械冲击能量和气泡坍塌释放的热能的同步吸收，最终表现出比经典AlCrCoFeNi HEA涂层高2倍的抗CE性能。这种通过表面微观结构的特殊响应行为诱导不同能量约束或中和的设计理念，为抗CE材料的开发提供了全新的途径。
