Degradation behavior of biomedical partially degradable Ti–Mg composite fabricated by 3D printing and pressureless infiltration

Abstract

Titanium-magnesium (Ti–Mg) composites have attracted increasing interest recently due to their partial degradability and excellent mechanical properties, which offers a new promise for medical bone implant and repair materials. Here we present a Ti–Mg composite fabricated by pressureless infiltration of pure Mg melt into the 3D-printed pure Ti scaffold. The spatially controllable distribution of phase structure and topology of Mg was achieved by 3D printing technology. The electrochemical corrosion and in vitro degradation behavior of Ti–Mg composite were investigated. The results exhibited that the composite's in vitro degradation rate in 0.9 wt% NaCl solution was faster in the first 48 h due to the influence of galvanic corrosion. After 14 days of immersion, the Mg inside the composite was completely degraded, and the porous Ti maintained its structural integrity throughout the in vitro degradation phase. Additionally, the electrochemical results show that the Ti–Mg composite is more susceptible to corrosion than pure Mg. The overall OCP of the composite tended to increase with increasing immersion time. During the first 24 h of immersion, the impedance value gradually increased due to the thickening of the corrosion product layer. Subsequently, the impedance started to decrease gradually after 3 days of immersion due to the thinning of the Mg(OH)2 film with the continuous degradation of Mg. This study may offer a theoretical reference for the feasibility of partially degradable Ti–Mg composites for long-term bone implants.

Keywords

• Ti-Mg composite
• 3D printing
• Pressureless infiltration
• Electrochemical
• Degradation
• Corrosion product