Unique yttria nanoparticle strengthening in an inconel 718 superalloy fabricated by additive manufacturing

Oxide dispersion strengthened (ODS) nickel (Ni)-based superalloys are advanced materials known for their outstanding tensile and creep performance at temperatures exceeding 1000 °C. Nevertheless, their conventional synthesis presents a longstanding challenge in cost-effectively producing intricate components for critical applications. In this work, electrostatic self-assembly (ESA) of powders with the laser powder bed fusion (LPBF) process have been successfully combined to produce yttria ODS Inconel 718 (IN718) alloy for the first time. The approach has demonstrated a significant contribution of yttria to the strength of IN718 after the solid solution heat treatment, as evidenced by ≈50% improvement in room temperature yield strength with a 0.5 wt.% yttria addition. The addition of yttria by this process leads to a heterogeneous microstructure. This heterogeneous microstructure comprises two distinct grain areas with varying amounts of yttria nanoparticles and dislocation storage. It has been shown that the yield strength increase can be predicted by the combination of both Y₂O₃ dispersion strengthening and dislocation strengthening mechanisms. These findings offer an effective approach to tailor heterogeneous microstructures, unlocking new opportunities for cost-effectively producing high-performance ODS Ni-based superalloy products with excellent mechanical properties.