Enhancement in bio-corrosion resistance of metallic glass by severe surface deformation

Abstract

Amorphous metals, also known as bulk metallic glasses, are promising materials for advanced healthcare applications. This is attributed to their exceptional properties, unseen in crystalline materials. Their unique ability to undergo relaxation during low temperature annealing provides opportunity to develop tailored properties. Here, we show a new pathway to significantly accelerate the relaxation kinetics in a zirconium based metallic glass through severe surface deformation using thermo-mechanical processing. The combined strain and thermal field during thermo-mechanical processing significantly reduced the relaxation time compared to vacuum annealing concurrent with remarkable enhancement in its bio-corrosion resistance. The corrosion resistance was found to have a direct correlation with the wetting behavior and oxide layer composition. The surface of relaxed glass was found to be rich in zirconium oxide compared to its as-cast state with higher fraction of aluminum oxide. The difference in oxide layer composition was attributed to annihilation of free volume in relaxed glass resulting in limited atomic transport. Relaxed metallic glass exhibited more hydrophobic nature likely due to its lower surface energy state as a consequence of structural densification. In addition, the relaxed glass showed better cell proliferation, thereby, enhancing its appeal as a next-generation biomaterial.