The oxidation behavior of Si- and/or Mn-Ni-25Cr alloys at 1050 °C in air was studied to provide new insights on the effect of minor additions on chromia-scale growth. Four nickel alloys with and without Si or Mn were prepared. Thermogravimetry and post-oxidation characterizations evidenced that manganese increased, whereas silicon addition decreased chromia growth rate. On the contrary, addition of both Si and Mn to the Ni-25Cr alloy led to an unchanged oxidation rate in comparison with the unalloyed Ni-25Cr material. Oxide scales were characterized by photoelectrochemistry (PEC) to evaluate the role of the additions on the point defects nature. The n and p contributions of chromia forming in air were not changed by Si. On the opposite, Mn modified the scale conducting properties since only n contributions were observed for both chromia and Mn 1+ x Cr 2− x O 4 spinel oxide with Mn-containing samples. In the latter case, the PEC contribution at ~ 3.2–3.4 eV was allocated to the signature of the Mn 1+ x Cr 2− x O 4 spinel oxide. These data suggested that manganese enhances and silicon limits grain boundary diffusion in chromia scale as reactive element does.

中文翻译：

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关于锰和硅对铬形成镍基模型合金在 1050 °C 氧化速率的协同影响

研究了 Si 和/或 Mn-Ni-25Cr 合金在 1050 °C 空气中的氧化行为，以提供关于少量添加对氧化铬鳞片生长影响的新见解。制备了含和不含 Si 或 Mn 的四种镍合金。热重分析和氧化后表征证明锰增加，而硅的添加降低了氧化铬的生长速率。相反，与非合金化的 Ni-25Cr 材料相比，在 Ni-25Cr 合金中同时添加 Si 和 Mn 导致氧化速率不变。氧化皮通过光电化学（PEC）表征，以评估添加物对点缺陷性质的作用。在空气中形成氧化铬的 n 和 p 贡献没有被 Si 改变。相反，Mn 改变了水垢导电性能，因为对于含Mn 的样品，仅观察到氧化铬和Mn 1+ x Cr 2- x O 4 尖晶石氧化物的n 贡献。在后一种情况下，约 3.2–3.4 eV 的 PEC 贡献被分配给 Mn 1+ x Cr 2- x O 4 尖晶石氧化物的特征。这些数据表明锰增强并且硅限制氧化铬尺度中的晶界扩散，正如反应性元素所做的那样。