Design of a low Young’s modulus Ti-Zr-Nb-Sn biocompatible alloy by in situ laser powder bed fusion additive manufacturing process

Abstract

A new metastable β Ti-22Zr-11 Nb-2Sn (at%) biomedical titanium alloy was elaborated from elemental powders by in situ laser powder bed fusion technique (L-PBF). Iterative design of experiments was used to identify optimized manufacturing parameters to obtain dense and homogeneous parts (>99.3%) with low unmolten niobium fraction (<0.05%). The microstructural and mechanical properties of this alloy were investigated in its as-fabricated state and after two heat-treatments at 400 °C and 700 °C, respectively. The alloy, showing a β-type microstructure, possesses a very low Young’s modulus (∼50 GPa) combined with a high tensile strength reaching about 1100 MPa after heat-treatment. These properties are very suitable for medical devices in osseous site such as hip prostheses or dental implants and the results were compared to the Ti-6Al-4 V ELI (wt%) medical grade fabricated from pre-alloyed powders. Thus, the present work demonstrates the significant potential of the in situ L-PBF technique to elaborate highly biocompatible titanium alloys with tailored chemical compositions.