<p>This study presents a novel approach to enhance the processability and performance of In939 superalloy fabricated by selective laser melting (SLM) through the strategic incorporation of TiC particles. The work addresses a critical challenge in additive manufacturing of nickel-based superalloys—hot cracking and compositional segregation—by demonstrating that TiC acts as a potent grain refiner and heterogeneous nucleation agent. Notably, the addition of TiC not only increased the relative density of the composite to nearly fully dense levels, but also suppressed solidification defects, leading to a more homogeneous microstructure with controlled carbide evolution (from MC to M₂₃C₆). Mechanically, the composite achieved a significant improvement in room temperature tensile strength and yield strength, attributable to synergistic effects of grain refinement, dispersion strengthening, and precipitation hardening. These findings offer a scalable pathway for designing high-performance superalloy components with enhanced structural integrity and mechanical properties, aligning with emerging demands in additive manufacturing of advanced materials.</p> Graphical abstract <p></p>