Thermodynamic modeling and glass-forming ability of the Ti-Cu-Ni-B system

Developing Ti-based bulk metallic glasses containing neither toxic nor precious metal elements is of great significance for their applications as structural and biomedical materials. As a promising candidate, the Ti-Cu-Ni-B system was selected as the target system to explore the glass-forming ability by thermodynamic analysis and key experiments. Combining the thermodynamic parameters of the ternary sub-systems, the thermodynamic description of the Ti-Cu-Ni-B system was established. The eutectic rule and driving-force criterion were jointly employed to design the compositions of metallic glasses, which were then validated by experiments. It was found that, with the increase of Ti content, the envelope of the driving force curves dropped and the glass formation zone shifted to the Cu-rich side relative to the local minimum, indicating the intermetallic compounds are easier to suppress than the solid solution phase. Two high-Ti alloys were found to have the best glass-forming ability among the designed compositions. This study systematically reveals the glass-forming ability of the Ti-Cu-Ni-B system and provides a reference for the development of novel Ti-based bulk metallic glasses free of toxic and precious metal elements.