Improvement of mechanical, thermal, and corrosion properties of Ni- and Al-free Cu-Zr-Ti metallic glass with yttrium addition

The development of biocompatible metallic glasses with enhanced ductility that are free of potentially toxic elements such as aluminium and nickel remains a challenge. Although Cu is associated with cytotoxicity levels above a safe threshold, the mechanical properties of Cu-rich metallic glasses are particularly attractive. Herein, the effect of minor additions of yttrium to the Cu-Zr-Ti system is studied. Rods of composition (Cu60Zr30Ti10)((100-x))Y-x (with x = 0, 1, 2) were prepared, and the critical diameter was improved from 2 to 3.5 mm with the addition of 1 at% Y. The compressive fracture strength was greater than 2000 MPa for all of the compositions, and the plastic strain increased from 0.9% to 2% with the addition of 1 at% Y. Transmission electron microscopy analysis revealed the presence of yttria precipitates surrounded by nanocrystallized areas, suggesting that the precipitates improved the plasticity. The addition of yttrium also led to the formation of a protective layer, which enhanced both the thermal stability and corrosion resistance of the metallic glass. Finally, the biocompatibility improved with minor additions of yttrium. Our findings demonstrate the wide range of beneficial properties of Cu-based metallic glasses, which may open the door for their potential application as biomaterials.