Mechanical behavior and phase transformation of β-type Ti-35Nb-2Ta-3Zr alloy fabricated by 3D-Printing

Additive manufacturing (AM) has a substantial capability to produce superior and divergent properties of titanium alloys for biomedical implants, unlike the existing conventional technologies. This work investigated the mechanical properties and microstructure evolution of a β-type Ti-35Nb-2Ta-3Zr alloy prepared by selective laser sintering (SLS) process. The superelastic properties of the resultant specimen were characterized by cyclic loading-unloading tensile testing to evaluate the effect of SLS-process on the β-type Ti alloy specimen. The zigzag and V-shaped formation of {112} β twins, coexisting with stress-induced ω-formation, were observed by the transmission electron microscopy (TEM). The formation of Type I twin martensite along with β-structure is attributed to superelastic recovery and elastic recovery of SLS-produced specimen. High resolution TEM (HRTEM) observation was used to investigate the transition between β and ω phases. Thin layers of ω-formation in weak interfacial stress regions along with the longitudinal twin boundaries were also analyzed. The orientation relationship between ω-structure and parent β-phase involves an overlapping of ω-phase, observed along with longitudinal β-matrix and β-twins. Moreover, dislocation tangles and dislocation pile-ups form along with twin martensite, stress-induced ω-phase, and β-phase. •β-type Ti-35Nb-2Ta-3Zr alloy specimen was prepared by a selective laser sintering.•The zigzag and V-shaped formation of {112} β twins, coexisting with stress-induced ω-formation were observed.•Thin layers of ω-formation in weak interfacial stress regions along with the longitudinal twin boundaries were analyzed.