In this work, the influence of 0.5 at.% and 1 at.% Y additions on the high-temperature oxidation resistance of the equiatomic alloy NbMoCrTiAl at 1000 °C in air was investigated. Continuous isothermal and cyclic thermogravimetric experiments were conducted to characterize the oxidation kinetics of the alloys. Various analytical methods such as X-ray diffraction and electron microscopy with energy-dispersive X-ray spectroscopy were used to study the growth, morphology and composition of the oxide scales. It was found that the Y additions led to the formation of Al 2 Y phase along grain boundaries. The isothermal oxidation experiments of both Y-containing alloys showed lower oxidation rates after a short period of transient oxidation probably due to a reduction of fast-growing and voluminous Nb 2 O 5 oxides within the oxide layer. During the steady-state period, however, oxidation of Al 2 Y caused local stresses resulting in crack formation and subsequent breakaway oxidation, i.e. pronounce increase in the oxidation rates. The cyclic oxidation experiments revealed lower oxidation rates and thinner, more adherent oxide scales formed on the alloy NbMoCrTiAl1Y compared to NbMoCrTiAl. The increased scale adherence was attributed to the formation of pegs due to the oxidation of Al 2 Y phase at the oxide/metal interface.

中文翻译：

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Y添加量对新型耐火高熵合金NbMoCrTiAl在1000℃空气中氧化行为的影响

在这项工作中，研究了 0.5 at.% 和 1 at.% Y 添加量对等原子合金 NbMoCrTiAl 在 1000 °C 空气中的高温抗氧化性的影响。进行连续等温和循环热重实验以表征合金的氧化动力学。使用各种分析方法，例如 X 射线衍射和具有能量色散 X 射线光谱的电子显微镜，研究氧化皮的生长、形态和组成。发现Y添加导致沿晶界形成Al 2 Y相。两种含 Y 合金的等温氧化实验表明，在短暂的瞬态氧化后，氧化速率较低，这可能是由于氧化物层中快速生长的大量 Nb 2 O 5 氧化物的减少。然而，在稳态期间，Al 2 Y 的氧化引起局部应力，导致裂纹形成和随后的氧化断裂，即氧化速率显着增加。循环氧化实验表明，与 NbMoCrTiAl 相比，合金 NbMoCrTiAl1Y 上形成的氧化速率较低，并且形成的氧化皮更薄、附着力更强。由于Al 2 Y 相在氧化物/金属界面处的氧化而形成的桩子粘附力增加。