Grain refinement and mechanical enhancement of LPBF Inconel 718 via TiC particle addition

Laser powder bed fusion (LPBF) was employed to fabricate TiC-reinforced Inconel 718 composites using mechanically mixed Inconel 718 and TiC powders (1–5 wt.%). The powder characteristics, as-built microstructure, and mechanical performance were systematically investigated with an emphasis on process–structure–property correlations. SEM observations revealed a uniform satellite-type distribution of TiC particles on the Inconel 718 powder surface, ensuring stable powder spreading and laser processing. EBSD analysis demonstrated that TiC addition significantly refined the grain structure of LPBF Inconel 718, with the average grain size decreasing from ~65 μm at 1 wt.% TiC to ~25 μm at 5 wt.% TiC due to effective grain boundary pinning. Hardness and relative density exhibited a strong dependence on energy density and TiC content. An optimal balance between hardness and densification was achieved at intermediate TiC addition and energy density, highlighting a widened processing window. These results demonstrate that low-level TiC addition is an effective strategy to enhance the microstructure and mechanical performance of LPBF Inconel 718.