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Nanostructured NiCrAlY starting powders were produced using a high-energy milling process, and subsequently a nanostructured NiCrAlY coating was deposited on IN738 superalloy by cold spraying. The results showed that the nanostructure of the milled NiCrAlY feedstock was completely retained in the coating after cold spraying. The surface roughness parameter was reduced from Rz = 26 microns in the as-sprayed state to Rz = 14 microns after shot peening. During the early oxidation stage at 900 degC, alpha-Al2O3 grew on the surface of the coating in a spherical morphology. Lateral growth led to the formation of a uniform oxide layer. At 1,000 deg C, alpha-Al2O3 oxide grew rapidly in the early oxidation stage. The oxide growth rate decreased significantly after 10 hours of oxidation. This slow growth feature is possibly attributed to the nanostructure of the coating. Moreover, it was clearly found that the surface morphology of the nanostructured coating has a significant impact on the morphology of the oxide evolved on the coating surface. The rapid growth of the oxide on the as-sprayed nanostructure in large, granular morphology could not contribute to the formation of a uniform oxide. As a result, it is clear that the surface geometry of the cold-sprayed MCrAlY coating must be modified through post-treatment such as by shot peening to promote the formation of a uniform oxide layer.