Magnetron Sputtered Non-Toxic and Precious Element-Free Ti-Zr-Ge Metallic Glass Nanofilms with Enhanced Biocorrosion Resistance

The chemical composition and structural state of advanced alloys are the decisive factors in optimum biomedical performance. This contribution presents unique Ti-Zr-Ge metallic glass thin-film compositions fabricated by magnetron sputter deposition targeted for nanocoatings for biofouling prevention. The amorphous nanofilms with nanoscale roughness exhibit a large relaxation and supercooled liquid regions as revealed by flash differential scanning calorimetry. Ti₆₈Zr₈Ge₂₄ shows the lowest corrosion (0.17 µA cm⁻²) and passivation (1.22 µA cm⁻²) current densities, with the lowest corrosion potential of −0.648 V and long-range stability against pitting, corroborating its excellent performance in phosphate buffer solution at 37 °C. The oxide layer is comprised of TiO₂, TiO_x and ZrO_x, as determined using X-ray photoelectron spectroscopy by short-term ion-etching of the surface layer. The two orders of magnitude increase in the oxide and interface resistance (from 14 to 1257 Ω cm²) along with an order of magnitude decrease in the capacitance parameter of the oxide interface (from 1.402 × 10⁻⁵ to 1.677 × 10⁻⁶ S sⁿ cm⁻²) of the same composition is linked to the formation of carbonyl groups and reduction of the native oxide layer during linear sweep voltammetry.