In Situ Synchrotron X-Ray Diffraction Characterization of Corrosion Products of a Ti-Based Metallic Glass for Implant Applications

Abstract

Ti-based bulk metallic glasses are under consideration for implants due to their high yield strength and biocompatibility. In this work, in situ synchrotron X-ray diffraction (XRD) is used to investigate the corrosion products formed from corrosion of Ti₄₀ Zr₁₀ Cu₃₄ Pd₁₄ Sn₂ bulk metallic glass in artificial corrosion pits in physiological saline (NaCl). It is found that Pd nanoparticles form in the interior of the pits during electrochemical dissolution. At a low pit growth potential, the change in lattice parameter of the Pd nanoparticles is consistent with the formation of palladium hydride. In addition, a salt layer very close to the dissolving interface is found to contain CuCl, PdCl₂ , ZrOCl₂ ∙8H₂ O, Cu, Cu₂ O, and several unidentified phases. The formation of Pd nanoparticles (16 ± 10 nm at 0.7 V vs Ag/AgCl) containing small amounts of the other alloying elements is confirmed by transmission electron microscopy. The addition of albumin and/or H₂ O₂ does not significantly influence the nature of the corrosion products. When considering the biological compatibility of the alloy, the biological reactivity of the corrosion products identified should be explored.

Keywords: artificial pits; bulk metallic glasses; corrosion; in situ synchrotron X-ray diffraction; metallic biomaterials.