CO₂-assisted in-situ additive manufacturing of ODS-IN718

Nickel-based Oxide Dispersion Strengthened (ODS) alloys exhibit excellent performance but are challenging to manufacture. In this study, a high-oxygen IN718 alloy was manufactured using laser powder bed fusion (LPBF) with CO 2 atmosphere, introducing a large number of nano-sized oxides. An oxygen content of 720 ppm was successfully achieved, which is 7.5 times higher than that obtained using the conventional Ar–O₂ mixed gas. Monitoring of LPBF process revealed that the oxides were introduced via two sources: in-situ oxidation (CO 2 dissociation and O incorporation) and oxide-bearing spatters. A core-shell oxide@carbide architectures were formed, which not only enhanced carbide dispersion, but also improved the thermal stability of the oxides. The abundant dispersed core–shell oxides effectively suppressed recovery and recrystallization during heat treatment, contributing to a substantial enhancement in strength. This work provides new insights for introducing high-density nano-oxides in Nickel alloys.