Processing, characterization, and in vitro/in vivo evaluations of powder metallurgy processed Ti-13Nb-13Zr alloys

This article presents details of processing, characterization and in vitro as well as in vivo evaluations of powder metallurgy processed Ti-13Nb-13Zr samples with different levels of porosity. Sintered samples were characterized for density, crystalline phases (XRD), and micro-structure (SEM and EDX). Samples sintered at 1000°C showed the highest porosity level (∼30%), featuring open and interconnected pores ranging from 50 to 100 uμm in diameter but incomplete densification. In contrast, samples sintered at 1300 and 1500°C demonstrated high densification with 10% porosity level distributed in a homogeneous microstructure. The different sintering conditions used in this study demonstrated a coherent trend that is increase in temperature lead to higher sample densification, even though densification represents a drawback for bone ingrowth. Cytotoxicity tests did not reveal any toxic effects of the starting and processed materials on surviving cell percentage. After an 8-week healing period in rabbit tibias, the implants were retrieved, processed for nondecalcified histological evaluation, and then assessed by backscattered electron images (BSEI-SEM) and EDX. Bone growth into the microstructure was observed only in samples sintered at 1000°C. Overall, a close relation between newly formed bone and all processed samples was observed.