The formation of the complex oxide in Ni-based alloy powder during mechanical milling and heat treatment

•The Y2O3 particles detected by SEM were fragmented and dissolved in matrix during mechanical milling.•Y2Ti2O7 and YCrO3 particles were identified in powder after mechanical milling by HRTEM.•The fraction of complex oxides in powder was increased by the heat treatment corresponding to hot isostatic pressing (HIP).•Both two kinds of complex oxides in alloyed powder have coarsened after the heat treatment.