Effects of the β phase size and shape on the oxidation behavior of NiCoCrAlY coating

•The MCrAlY coating with nano-dendritic β phase was prepared by LPD.•β phase with smaller size and higher aspect ratio benefits the formation of α-Al2O3.•Nano-dendritic β phase shows low TGO growth rate and residual stress.•LPD bond coat shows excellent oxidation resistance over HVAF and LPD-V bond coat.•Oxidation resistance is a result of the nano-dendritic β phase and dense structure. The effect of the β phase size and shape on the oxidation behavior of the NiCoCrAlY coating fabricated by laser powder deposition (LPD) was investigated. Thermal cycling experiment performed at 1150 °C indicates that β phase with smaller size and higher aspect ratio (dendritic or disc shape) benefits the exclusive formation of alumina, lower thermally grown oxides (TGO) growth rate and residual stress. The TGO lifetime of the LPD coating is almost a two-fold of that on the coating prepared by high velocity air fuel method, which is attributed to the nanoscale dendritic β phase and dense microstructure.