Surface characteristics of the Ni-based superalloy powders

This study investigated the surface state of the carbon and oxygen of the Ni-based superalloy powders. The findings elucidate that during the atomization process employed for alloy powder synthesis, carbides rich in Ti, Mo, and Nb, with an approximate size of 200 nm, selectively segregate to the powder surface. This phenomenon significantly influences the subsequent oxidation behavior of the powder. Specifically, the oxidation of these carbides leads to the formation of discrete TiO2 oxide particles directly above them, while the γ matrix devoid of carbides undergoes oxidation, resulting in the formation of a homogenous, amorphous film composed of oxides and hydroxides. Moreover, CALPHAD calculation analysis corroborates the observed carbide precipitation behavior on the surface of atomized powder during the atomization process. Thus, this investigation presents a novel insight into the surface state of light elements in original superalloy powders. © 2024 Elsevier Ltd