Achieving synergistic printability and mechanical property enhancement in Ni superalloys via tailored primary precipitate interfaces

Optimizing primary interfaces is key to suppressing hot cracking in additively manufactured Ni superalloys. This study demonstrates the dual role of primary NbC/γ interface: optimal NbC density reduces B enrichment in interdendritic region and suppress low melting point boride formation, reducing cracking. Conversely, excessive NbC promotes detrimental eutectics that disrupt dendrite solidification and impede terminal liquid feeding, inducing cracks. Statistical analysis reveals these mechanisms, enabling quantitative optimization. The alloy with tailored interfaces achieves excellent printability and strength–ductility synergy. These findings provide a pathway for crack suppression and compositional design in AM Ni superalloys.