The passivation of Ni-22Cr, Ni-22Cr-6Mo, and Ni-22Cr-6Mo-3W (wt%) was characterized from 100 s to 10 days in 0.1 M NaCl in pH 4 at various potentials in the passive range. The influence of aqueous solution exposure time in NaCl (exposure aging), passivation potential, as well as Ni-Cr-X alloy composition (Mo or W) on passive film growth, composition, oxidation state, molecular identity, and inner versus outer film layering were investigated. Initial passive film formation was dominated by Ni(II). Cr(III) oxides and hydroxides tended to enrich upon formation and exposure aging. Corundum and rock salt are speculated to undergo a solid-state phase transformation to form NiCrO at long times under certain conditions. The concept of the time-potential-transformation diagrams to describe the evolution of passive film phases and protectiveness is introduced. Factors limiting Cr(III) enrichment were discussed. Aliovalent Mo and W ions were detected in passive films, particularly after aging. The roles of Cr enrichment, Ni depletion, and Mo and/or W aliovalent cations after oxide aging towards protectiveness to passive and localized corrosion in chloride (Cl) solutions were discussed.

中文翻译：

---

Ni-Cr 和 Ni-Cr-X (X = Mo, W) 合金在酸性氯化物溶液中氧化物的形成和长期暴露老化：对耐腐蚀性的影响


Ni-22Cr、Ni-22Cr-6Mo 和 Ni-22Cr-6Mo-3W (wt%) 在 pH 4 的 0.1 M 氯化钠中、在钝化范围内的不同电位下钝化 100 秒至 10 天。氯化钠水溶液暴露时间（暴露老化）、钝化电位以及 Ni-Cr-X 合金成分（Mo 或 W）对钝化膜生长、成分、氧化态、分子特性以及内膜与外膜的影响分层进行了研究。最初的钝化膜形成主要由 Ni(II) 组成。 Cr(III) 氧化物和氢氧化物在形成和暴露老化时趋于富集。据推测，刚玉和岩盐在一定条件下长时间经历固态相变形成 NiCrO。引入了时间-电势-变换图的概念来描述钝化膜相和保护性的演变。讨论了限制Cr(III)富集的因素。在钝化膜中检测到异价 Mo 和 W 离子，特别是在老化后。讨论了氧化物老化后 Cr 富集、Ni 消耗以及 Mo 和/或 W 异价阳离子对氯化物 (Cl) 溶液中被动和局部腐蚀的保护作用。