In-situ alloying and characterization of Ti-30Nb-5.5Sn alloy fabricated by powder bed fusion - laser beam for biomedical applications

This study reports the in-situ alloying of a Ti-30Nb-5.5Sn alloy processed by powder bed fusion - laser beam (PBF-LB) and the effect of solution heat treatment on its microstructure, and mechanical performance. As-built samples contained β + α″, while heat-treated conditions exhibited a mostly β microstructure with distinct grain morphologies depending on the processing conditions. EBSD analysis revealed that the grain morphology is governed by the processing regime defined by the combination of laser power and scanning speed. The condition with higher energy input (S1HT) retained partially columnar grains, whereas the lower energy input condition (S2HT), exhibited predominantly equiaxed grains with a near-random texture. S1HT exhibited a superior stiffness-strength-ductility balance, attributed to reduced Nb-particle residues, and retained directional grain morphology. These results demonstrate that optimized PBF-LB in situ alloying, combined with appropriate heat treatment, can effectively control the microstructure of Ti-Nb-Sn alloys, enabling precise tailoring of their mechanical performance for biomedical applications. • Powder Bed Fusion - Laser Beam enabled in-situ Ti-30Nb-5.5Sn alloy with β + α '′. • Heat-treatment (HT) promotes mostly β phase in the specimens. • The combination of laser power and scanning speed + HT controlled grain morphology. • Scan speed of 100 mm/s + HT showed columnar grains, and 300 mm/s + HT showed equiaxed β. • Scan speed of 100 mm/s + HT showed best strength-ductility and fewer Nb residues.