Abstract High entropy alloys (HEAs) have drawn considerable attention owing to their unique properties such as high fracture toughness, good strength–ductility combination and enhanced corrosion resistance. In this study, the corrosion resistance dependence on the crystal structure and grain size of AlCoCrFeNi HEA is investigated. AlCoCrFeNi HEA with different mixture of body centered cubic (BCC) and face centered cubic (FCC) phases is produced using sequential alloying and tested for corrosion resistance in 3.5 wt.% NaCl solution. CoNi+Fe+Cr+Al (84% BCC), FeCr+Ni+Al+Co (62% BCC) and AlNi+Co+Cr+Fe (38% BCC) alloy sequences have corrosion potential of -454, -299 and -524 mV (vs. SCE), and corrosion current of 14, 0.4 and 12 µA, respectively. FCC is a tight binding lattice with higher packing fraction than BCC which made it better for corrosion resistance, but FCC is rich in elements like Co, Ni, and Fe which are easily corroded. These two competing effects lead to a nearly optimum corrosion resistance for FeCr+Ni+Al+Co alloy sequence with 62% BCC and 32% FCC. It is also observed that an increase in grain size improves corrosion resistance. The influence of different chemical elements, crystal structure and microstructure (coarse vs. nanocrystalline) on corrosion resistance is discussed.

中文翻译：

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晶体结构和晶粒尺寸对AlCoCrFeNi高熵合金腐蚀性能的影响

摘要 高熵合金（HEAs）由于其独特的性能，如高断裂韧性、良好的强度-延展性组合和增强的耐腐蚀性而引起了广泛的关注。在这项研究中，研究了耐腐蚀性对 AlCoCrFeNi HEA 的晶体结构和晶粒尺寸的依赖性。具有不同体心立方 (BCC) 和面心立方 (FCC) 相混合物的 AlCoCrFeNi HEA 是使用顺序合金化生产的，并在 3.5 wt.% NaCl 溶液中测试其耐腐蚀性。CoNi+Fe+Cr+Al (84% BCC)、FeCr+Ni+Al+Co (62% BCC) 和 AlNi+Co+Cr+Fe (38% BCC) 合金序列的腐蚀电位为 -454、-299 和-524 mV（相对于 SCE），腐蚀电流分别为 14、0.4 和 12 µA。FCC 是一种紧密结合的晶格，具有比 BCC 更高的堆积率，这使其具有更好的耐腐蚀性，但 FCC 富含 Co、Ni 和 Fe 等元素，这些元素很容易腐蚀。这两种相互竞争的效应导致了具有 62% BCC 和 32% FCC 的 FeCr+Ni+Al+Co 合金序列的近乎最佳的耐腐蚀性。还观察到晶粒尺寸的增加提高了耐腐蚀性。讨论了不同化学元素、晶体结构和微观结构（粗晶与纳米晶）对耐腐蚀性的影响。