Dual effect of oxide inclusions in additively manufactured nickel superalloys

Powder oxidation is a key issue in additive manufacturing, yet the form and role of oxygen in additively manufactured Inconel 718 remain unclear. This study shows that oxygen mainly exists as core–shell oxide inclusions, which exert a dual effect on mechanical properties. Strength degradation arises from stress concentration-induced cracking caused by deformation incompatibility between oxide inclusions within the Laves phase and the matrix, while strengthening results from dislocation pinning by oxide inclusions. These findings provide new insight into the role of oxygen in additively manufactured Inconel 718 and establish a basis for assessing powder usability.