Combinatorial development and assessment of a Zr-based metallic glass for prospective biomedical applications

In the quest of corrosion-resistant biomaterials, the emergence of metallic glasses is a welcome stimulus, however, their progress is potentially impeded by the complex fabrication routes. This paper explores a Zr₄₀Ti₃₅Ni₁₄Nb₁₁ metallic glass, developed through combinatorial magnetron co-sputtering. Structural characterization of the system via Grazing-Incidence X-Ray Diffraction and Transmission Electron Microscopy coupled with Fourier Transformation demonstrate single phase homogeneous amorphous structure. The metallic glass, upon comparative electrochemical examination in physiological solution, displays relatively better corrosion resistance properties than conventional biomaterials, i.e. stainless steel 316L and commercially pure titanium, by an order of magnitude lower corrosion current density, (17 nA/cm²), lower passive current density (3.1 μA/cm²), invulnerability to pitting corrosion and one-order higher charge transfer resistance (6.9 MΩ·cm²). The superior corrosion resistance properties are ascribed to the synergistic effect of chemically and structurally homogeneous amorphous structure and protective passive film, enriched with chemically stable oxides of Zr and Ti. Mechanical characterization of the metallic glass via nanoindentation studies reveal high hardness (7.1 GPa) and fairly low elastic modulus (121.7 GPa), making it a candidate material for bioimplants.