Unlocking Strength-Ductility Synergy in Laser Additive Manufacturing of Ti-Cu Alloys via Core-Shell Feedstock Design

Solute segregation during conventional manufacturing restricts the development of Ti-Cu alloys despite their potential in biomedical applications. Here, we demonstrate that using core-shell Ti@Cu powders in laser powder bed fusion (PBF-LB/M) enables the fabrication of hypoeutectoid Ti-2.9Cu alloys with >98.4 % density, suppressed segregation, and enhanced chemical homogeneity. The resulting microstructure features equiaxed prior-β grains with ultra-fine α laths and well-distributed nano-sized Ti2Cu precipitates at lath boundaries, contributing to grain boundary and precipitation strengthening. Compared to blended elemental powders, the core-shell strategy improves ultimate tensile strength by 17 % (from 857 ± 15.9 MPa to 1004.5 ± 18.7 MPa) and ductility by 6.4 % (from 12.6 ± 0.01 % to 13.4 ± 1.0 %). Flow3D simulations indicate enhanced laser–powder energy coupling and a more stable, symmetric melt pool with reduced thermal gradients and uniform convection for the Ti@Cu feedstock, rationalizing the suppressed segregation. This study establishes feedstock architecture as a powerful lever to unlock strength–ductility synergy in laser additively manufactured Ti–Cu alloys for biomedical applications.