Microstructure and selected mechanical properties of aged Ti-15Zr-based alloys for biomedical applications

Highlights: • α″ → α and β → α phase decomposition taking place in the alloys • Aging promoted nucleation and the growth of globular and lath-shaped α phase along the β phase grains. • Vickers microhardness and Young's modulus values were dependent on aging times as a result of α phase precipitation. - Abstract: In this study, Ti-15Zr-xMo (5, 10, 15, and 20 wt%) alloys were submitted to solution and aging treatments and their effects evaluated in terms of phase composition and selected mechanical properties (Vickers microhardness and Young's modulus) for use as biomedical implants. The solution treatment was performed at 1123 K for 2 h, while aging treatments were carried out at 698 K for 4, 8, and 12 h, followed by water quenching. Phase composition and microstructure were dependent of the heat treatments, with Ti-15Zr-5Mo (α + β type) and Ti-15Zr-10Mo (metastable β type) alloys exhibiting intense α phase precipitation. The α-phase precipitates were related to α″ → α and β → α phase decompositions. The Ti-15Zr-10Mo alloy exhibited an intermediary isothermal ω-phase precipitation after aging for 4 h. Vickers microhardness and Young's modulus values changed gradually with the amount of α phase. Aged Ti-15Zr-15Mo and Ti-15Zr-20Mo alloys presented better combinations of hardness and Young's modulus than CP-Ti and Ti-64 ELI for biomedical applications.