Preparation, Characterization, and Properties of Novel Ti-Zr-Be-Co Bulk Metallic Glasses

We developed novel Ti-Zr-Be-Co bulk metallic glasses through Co addition based on a ternary Ti₄₅Zr₂₀Be₃₅ alloy. By altering the alloying routes and alloying contents, the influence of Co alloying on glass-forming ability, thermal stability, thermoplastic formability, crystallization behavior, and corrosion resistance has been investigated systematically. It was found that the best alloying route for enhancing the glass-forming ability, thermoplastic formability, compressive plasticity, and corrosion resistance is to replace Be by Co. Ti₄₅Zr₂₀Be₂₃Co₁₂ possesses the largest critical diameter of 15 mm for glass formation. Ti₄₅Zr₂₀Be₂₇Co₈ possesses the highest thermoplastic formability which is comparable to that of Vitreloy alloys. Ti₄₅Zr₂₀Be₂₅Co₁₀ exhibits the largest room temperature plasticity of 15.7% together with a high specific strength of 3.90 × 10⁵ Nm/kg. The addition of Co also strongly affects the crystallization behavior of the base alloy, resulting in a more complex crystallization process. The corrosion resistance of Ti-Zr-Be alloy in 1 mol/L HCl solution can also be enhanced by Co alloying. The related mechanisms have been explained in detail, which provide guidance for the composition design of Ti-based metallic glasses with improved properties.