Effect of Cavitation Water Jet Peening on Properties of AlCoCrFeNi High-Entropy Alloy Coating

High-entropy alloys have been widely used in engineering manufacturing due to their hardness, good wear resistance, excellent corrosion resistance, and high-temperature oxidation resistance. However, it is inevitable that metallurgical defects, such as micro cracks and micro pores, are produced when preparing the coating, which affects the overall performance of the alloy to a certain extent. In view of this situation, cavitation water jet peening (CWJP) was used to strengthen the AlCoCrFeNi high-entropy alloy coating. The effect of CWJP impact time on the microstructure and mechanical properties of CWJP were investigated. The results show that CWJP can form an effective hardening layer on the surface layer of the AlCoCrFeNi high-entropy alloy. When the CWJP impact time was 4 h, the microhardness of the surface layer of the specimen was harder than that of 2 h and 6 h, and the CWJP impact time had little effect on the thickness of the hardening layer. Observing the surface of the untreated and CWJP-treated specimens using the EBSD test, it was evident that the microstructure was significantly homogenized, the grains were refined, and the proportion of small-angle grain boundaries increased. The system reveals the grain refinement mechanism of the AlCoCrFeNi high-entropy alloy coating during plastic deformation. This study aims to provide a new surface strengthening method for obtaining high-performance AlCoCrFeNi high-entropy alloy coatings.