Cold spray (CS) MCrAlY coatings have been widely explored as potential bond coats for thermal barrier coatings used on the hot-section components of modern gas turbines. In this study, NiCoCrAlTaY coatings were applied on CMSX-4 single-crystal Ni-base superalloy substrates using the CS technique. Nitrogen was used as process gas with low spray parameters to allow the production of in-situ nanocrystalline NiCoCrAlTaY coatings while using conventional powders of large grain size, as demonstrated in Part I of the study using scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). In this part of the study (Part II), the coated samples were examined under isothermal oxidation conditions at 1100 °C for 1 h to 500 h. The as-deposited NiCoCrAlTaY coatings, characterized by dense microstructure, low surface roughness, nanoscale grains, and a large number of crystallographic defects such as grain boundaries and dislocations, promoted the formation of a protective α-Al₂O₃ scale during short-term oxidation. Fast diffusion via these crystallographic defects facilitated Al diffusion in the coatings. This provides sufficient Al replenishment to the coating subsurface region, sustaining the growth of the α-Al₂O₃ scale during prolonged oxidation. The relatively low scale growth kinetics found in the study demonstrated enhanced oxidation performance of the CS nanocrystalline NiCoCrAlTaY coatings.

冷喷涂（CS）MCrAlY涂层已被广泛用作现代燃气轮机热截面部件上用作热障涂层的潜在粘结涂层。在这项研究中，使用CS技术将NiCoCrAlTaY涂层应用于CMSX-4单晶Ni基高温合金基底。氮气被用作具有低喷雾参数的工艺气体，以允许在使用大粒径的常规粉末的同时生产原位纳米晶NiCoCrAlTaY涂层，如在研究的第一部分中使用扫描电子显微镜（SEM）和扫描透射电子显微镜所证明的那样（干）。在研究的这一部分（第二部分）中，在1100°C等温氧化条件下1到500 h检查涂层样品。沉积后的NiCoCrAlTaY涂层，具有致密的微观结构，低的表面粗糙度，短期氧化过程中为₂ O ₃垢。通过这些晶体学缺陷的快速扩散促进了Al在涂层中的扩散。这提供了足够的Al补给到涂布地下区域，维持所述α-Al的生长₂ ö ₃延长氧化期间规模。在研究中发现的相对较低的尺度生长动力学证明了CS纳米晶NiCoCrAlTaY涂层的氧化性能增强。