Abstract Nickel aluminide coatings - produced using atmospheric plasma spraying method - attracted considerable attention due to their high melting temperature and oxidation resistance. What is more, an addition of CrB2 allows to significantly increase their wear resistance. Such coatings are typically used up to 500 °C, what requires thermal stability of their microstructure. Therefore, in this paper, the in-situ TEM heating of APS-deposited NiAl coating with addition of 15 wt% of CrB2 up to 800 °C was performed in order to follow the microstructure changes and eventual phase transformations. The TEM observations backed with phase analysis showed that the amorphous veins present in the NiAl matrix of as-deposited coating transform into Ni6AlB3 phase at approaching 500 °C. On the other hand, the CrB2/NiAl interface preserved its shape and remains free from any precipitates even up to 800 °C. The ex-situ TEM microstructure observations of NiAl + CrB2 coating, carried out after high-temperature wear test (500 °C, ~15 min), showed that after it amorphous channels indeed turns crystalline. In addition, the NiAl matrix presents significantly higher dislocation density, being a result of repeated loading received during the wear test.

中文翻译：

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通过原位 TEM 加热实验研究等离子喷涂 NiAl/CrB2 复合涂层的热稳定性

摘要 使用常压等离子喷涂法生产的铝化镍涂层因其高熔点和抗氧化性而引起了广泛关注。此外，添加 CrB2 可以显着提高其耐磨性。此类涂层通常在高达 500 °C 的温度下使用，这要求其微观结构具有热稳定性。因此，在本文中，对添加 15 wt% CrB2 的 APS 沉积的 NiAl 涂层进行原位 TEM 加热至 800°C，以跟踪微观结构变化和最终的相变。以相分析为支撑的 TEM 观察表明，在接近 500 °C 时，沉积涂层的 NiAl 基体中存在的非晶脉转变为 Ni6AlB3 相。另一方面，CrB2/NiAl 界面保持其形状，即使在高达 800 °C 的温度下也没有任何沉淀物。NiAl + CrB2 涂层的异位 TEM 微观结构观察，在高温磨损试验（500 °C，~15 分钟）后进行，表明在它之后非晶通道确实变成了结晶。此外，NiAl 基体表现出明显更高的位错密度，这是磨损试验期间反复加载的结果。