The effects of Hf, Y, and Zr additions on the growth of a thermally grown alumina scale formed on NiAlCr and NiAlPt alloys were investigated. Isothermal and thermal cycling oxidation experiments were carried out at 1150 °C, and cross sections of the oxidized samples were characterized using scanning electron microscopy. It was observed that single doping as well as co-doping of Hf, Y, and Zr reduces the rate of alumina scale growth on NiAlCr and NiAlPt alloys, with Hf showing a more significant effect than Y or Zr. The following possible contributing factors to these observations were assessed: (1) the ionic size of the minor alloying elements and (2) the bond strength between the doping elements and oxygen in the oxide grain boundaries in terms of formation and melting enthalpies of oxides. It was concluded that the bond strength between the doping elements and oxygen within the oxide grain boundaries plays an important role in retarding the alumina scale growth.

中文翻译：

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Hf、Y 和 Zr 对 NiAlCr 和 NiAlPt 合金氧化铝氧化皮生长的影响

研究了 Hf、Y 和 Zr 添加对在 NiAlCr 和 NiAlPt 合金上形成的热生长氧化铝氧化皮生长的影响。等温和热循环氧化实验在 1150 °C 下进行，氧化样品的横截面使用扫描电子显微镜进行表征。据观察，Hf、Y 和 Zr 的单掺杂和共掺杂降低了 NiAlCr 和 NiAlPt 合金上氧化铝氧化皮的生长速度，其中 Hf 显示出比 Y 或 Zr 更显着的影响。对这些观察结果的以下可能影响因素进行了评估：(1) 次要合金元素的离子大小和 (2) 掺杂元素与氧化物晶界中氧之间的结合强度，就氧化物的形成和熔化焓而言。