The oxidation behaviour of four NiCoCrAl_x medium-entropy alloys (x = 0, 0.1, 0.3, or 0.5 mol.) was investigated in dry air at 600–900 °C. The oxidation kinetics of all the alloys followed the parabolic rate law at T> 700 °C, and the oxidation rates increased with an increase in temperature and a decrease in Al content. Discontinuous oxide granules were formed on all the alloys at 600 °C, while complex scales were detected, strongly depending on the Al content and temperature. Internal attack of AlN precipitates was also observed for Al-containing alloys at T> 700 °C.

中文翻译：

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NiCoCrAlx 中熵合金的高温空气氧化

在 600–900 °C 的干燥空气中研究了四种 NiCoCrAl _x中熵合金（x = 0、0.1、0.3或 0.5 mol.）的氧化行为。所有合金在 T >  700 °C 时的氧化动力学遵循抛物线速率规律，氧化速率随着温度的升高和 Al 含量的降低而增加。在 600 °C 下，所有合金上都形成了不连续的氧化物颗粒，同时检测到复杂的氧化皮，这在很大程度上取决于 Al 含量和温度。对于 T >  700 °C的含铝合金，也观察到 AlN 沉淀物的内部侵蚀。