The synergistic effects of Al on Cr(III) passivation in a family of (FeCoNi)_100-x-y-Cr_x-Al_y (at.%) complex concentrated alloys (CCAs), where x = (0, 4, 10, 13, 16) and y = (0, 3, 6, 9, 13) were investigated. Homogenized solid solution alloys containing 10 at.% Cr intentionally selected below the stainless steel threshold of 12 at.% achieved excellent passivation by forming a Cr(III) rich film containing Al(III) when alloyed with small amounts of Al. For example, CCAs containing 10 at.% Cr and 6 at.% Al can attain comparable re-passivation properties as seen in 304L stainless steel in sulfuric acid. Potentiostatic re-passivation over 10 ks exposure revealed the benefit of Al addition leading to greater Cr(III) cation fractions in the film, better corrosion protection, and faster film formation. Two underlying mechanisms are proposed to explain the effect. The observed Al-Cr synergy can be understood as a type of third element effect due to Al where enrichment of Cr(III) in the passive films occurs due to the small but beneficial presence of Al (III). Al is also a secondary passivator detected in the passive film. Moreover, the potential effects of other alloying elements in CCAs were examined through the investigation of binary and ternary alloys containing Cr and Al. These studies also focus on the influence of Cr-Cr pairs by Al addition on their steady-state passivation, facilitated by chemical short-range ordering.

中文翻译：

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研究硫酸中 FeCoNi-Cr-Al CCA 钝化膜中 Al 对 Cr（III） 的协同作用


研究了 Al 对 （FeCoNi） _100-x-y -Cr _x -Al _y （at.%） 复合浓合金 （CCA） 家族中 Cr（III） 钝化的协同作用，其中 x = （0， 4， 10， 13， 16） 和 y = （0， 3， 6， 9， 13）。当与少量 Al 形成合金时，特意选择低于 12 at.% 不锈钢阈值的含 10 at.% Cr 的均质固溶体合金，通过形成含有 Al（III） 的富 Cr（III） 薄膜，实现了出色的钝化效果。例如，含有 10 at.% Cr 和 6 at.% Al 的 CCA 可以获得与 304L 不锈钢在硫酸中所见相当的再钝化性能。超过 10 ks 暴露的恒电位再钝化揭示了 Al 添加的好处，导致薄膜中更高的 Cr（III） 阳离子分数、更好的腐蚀保护和更快的成膜。提出了两种基本机制来解释这种影响。观察到的 Al-Cr 协同作用可以理解为一种由 Al 引起的第三元素效应，其中 Cr（III） 在钝化膜中的富集是由于 Al （III） 的存在很小但有益的。Al 也是在钝化薄膜中检测到的二次钝化剂。此外，通过研究含有 Cr 和 Al 的二元和三元合金，研究了 CCA 中其他合金元素的潜在影响。这些研究还关注 Al 添加的 Cr-Cr 对对其稳态钝化的影响，这得益于化学短程有序。