Composition design and glass-forming ability of Ti-based bulk metallic glasses

Ti-based bulk metallic glasses (BMGs) have great potential for use as structural materials due to their excellent mechanical properties. How to fabricate Ti-based metallic glasses with sufficient large size has always been the key issue in both the theoretic and technology aspects since finding the BMG. In this paper, we try to fabricate Ti-based metallic glasses with high glass-forming ability (GFA) through composition design based on various empirical ideas. BMG alloy with composition of Ti_43.89Cu _43.60Zr_6.75Ni_5.76 was synthesized based on the deep eutectic idea, and the critical diameter of this glassy alloy reaches to 2 mm. The GFA of this alloy was further improved by small addition of Si (0.5-1 at %). BMG rods with diameters up to 3mm were synthesized for compositions of Ti_42.89Cu_43.60Zr_6.75Ni_5.76Si ₁, Ti_43.89Cu_43.60Zr_6.25Ni _5.76Si_0.5 and Ti_43.89Cu_43.60Zr _6.75Ni_4.76Si₁. The amorphous structure of all the samples was confirmed by X-ray diffraction (XRD) method. The thermal stability associated with glass transition, supercooled liquid region and crystallization was investigated by differential scanning calorimetry (DSC). Possible mechanisms for the improvement of GFA were discussed.