Effect of Ti addition on mechanical properties and corrosion resistance of Ni-free Zr-based bulk metallic glasses for potential biomedical applications

Toxic element free-Zr-based bulk metallic glasses (BMGs) have attracted considerable attentions for biomedical applications, in term of their excellent bio-corrosion and mechanical properties. In the present work, we fabricated a series of Zr_65-xTi_xCu₂₀Al₁₀Fe₅ (x = 0, 2, 4, 6 and 8) alloys using the injection copper-mold casting method, and reported the significant effect of Ti addition both on mechanical performance and corrosion behavior. It is found the glass forming ability (GFA) and plasticity are significantly improved by increasing Ti content up to 2 at.%, but deteriorated after excess Ti additions. The obtained Zr₆₃Ti₂Cu₂₀Al₁₀Fe₅ amorphous alloy provides the largest supercooled liquid region width of 73 K, compressive fracture strength of 1905 MPa and plasticity of 8.57%, which are much higher than 67 K, 1854 MPa and 5.43% of the pristine Zr₆₅Cu₂₀Fe₅Al₁₀ BMG. However, the electrochemical measurements show that as-prepared Zr₆₃Ti₂Cu₂₀Al₁₀Fe₅ alloy exhibits a terrible passivation ability and inferior corrosion resistance in phosphate-buffered saline (PBS) solution, which is mainly ascribed to the numerous defects in the passive films. On the contrary, further addition of Ti to 4–6 at.% promotes the intactness of passive film for Zr-based BMGs and enhances their resistance to pitting corrosion, in despite giving rise to unsatisfied mechanical performance.