In this work, a fully dense CoCrFeNi high entropy alloys (HEAs) coating with homogeneous microstructure was successfully prepared on AZ91 alloy by cold spray. It is innovative to cross-integrate HEAs with Mg alloys using cold spray to break through the “bottleneck” of Mg alloys. The average microhardness of the coating was 5 times higher than Mg alloys. The weight loss of the coating in wear test was 2 orders of magnitude lower than Mg alloys. The E_corr of the coating was noticeably improved to be ~ − 290 mV_SCE and the i_coor of the coating was significantly decreased by 4–5 orders of magnitude. The coating exhibited significantly spontaneous passivation due to the multi-layer passive film composed of FeO, Cr₂O₃ and NiO. The weight loss of CoCrFeNi coated AZ91 plates was below 1% after 28 days immersion. Lots of tiny micro-pits in size less than 1 µm were distributed on the corroded coating surface because the formation of large pitting pits was restricted. Unique corrosion mechanisms of the coatings were found: the repeatedly repassivation effect and the competing effect triggered by the rapid initiations of new pittings. The stable passive film and uniform microstructure of the coating resulted in the significant decrease of corrosion rate. The shielding effect of the coating can bring outstanding surface protection for Mg alloys.

在这项工作中，通过冷喷涂成功地在 AZ91 合金上制备了具有均匀微观结构的全致密 CoCrFeNi 高熵合金 (HEA) 涂层。使用冷喷涂技术将 HEA 与镁合金交叉集成以突破镁合金的“瓶颈”是一种创新。涂层的平均显微硬度是镁合金的 5 倍。磨损试验中涂层的重量损失比镁合金低2个数量级。涂层的 E _corr显着提高到 ~ - 290 mV _SCE，涂层的 i _coor显着降低了 4-5 个数量级。_{由于由FeO、Cr 2} O ₃组成的多层钝化膜，涂层表现出显着的自发钝化和 NiO。CoCrFeNi 涂层 AZ91 板在浸泡 28 天后重量损失低于 1%。由于大点蚀坑的形成受到限制，腐蚀的涂层表面分布着许多尺寸小于1 µm的微小微坑。发现了涂层的独特腐蚀机制：反复再钝化效应和新点蚀的快速引发引发的竞争效应。涂层稳定的钝化膜和均匀的微观结构导致腐蚀速率显着降低。涂层的屏蔽作用可为镁合金带来出色的表面保护。