ABSTRACT

The corrosion behavior and mechanism of CoCrFeNi HEA under AC application were systematically studied in 3.5 wt.% NaCl solution containing different concentrations of NaHSO₃. The results showed that the existence of HSO₃⁻ increased the defect density within the passivation film on the surface of the HEA. With the increase of HSO₃⁻ concentration, the passivation zone became narrow, E_p shifted negatively, and i_p increased, which indicated that the corrosion resistance of the HEA was weakened. When the HSO₃⁻ concentration increased to 0.1 M, a clear transition zone appeared, indicating that the increase in concentration reduced the passivity of the HEA, and its corrosion behavior changed from the typical passivation characteristic to the activation state with increasing i_AC. The imposed AC promoted the nucleation of metastable pitting, which was indicated by a remarkable increase in the average pitting number density (N_avg) from 5 to 17 mm⁻² with the enhancement of i_AC.

摘要

_{在含不同浓度NaHSO 3}的3.5 wt.% NaCl溶液中，系统地研究了交流电作用下CoCrFeNi HEA的腐蚀行为和机理。_{结果表明，HSO 3} ^-的存在增加了HEA表面钝化膜内的缺陷密度。_{随着HSO 3} ^-浓度的增加，钝化区变窄，E _p负移，i _p增加，表明HEA的耐腐蚀性能减弱。当 HSO ₃ ^-浓度增加到0.1 M，出现明显的过渡区，表明浓度的增加降低了HEA的钝化，其腐蚀行为随着i AC 的增加从典型的钝化特征转变为活化_状态。施加的 AC 促进了亚稳态点蚀的成核，这表现为随着i _{AC的增强，平均点蚀数密度 (N avg} ) 从 5 显着增加到 17 mm ^-2。