Effect of Ag addition on the thermal stability and glass-forming ability of Zr35Ti30Cu7.5Be27.5 bulk metallic glass

The thermal stability and glass forming ability (GFA) of Zr_35−x Ti₃₀Cu_7.5Be_27.5Ag _x (x = 0–10) alloys were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and ultrasonic techniques. We found that the addition of 1 at.% Ag can considerably enhance the GFA as indicated by an increase in the critical glass dimension from 15 mm in the Zr₃₅Ti₃₀Cu_7.5Be_27.5 alloy to 20 mm in the Zr₃₄Ti₃₀Cu_7.5Be_27.5Ag₁ alloy. However, with the addition of more Ag the supercooled liquid region (ΔT _x) and γ parameter (defined as T _x/T _g+T _l)) drastically decreased from 155 K and 0.436 to 76 K and 0.363, respectively, resulting in a decrease in the GFA. Additionally, the elastic constant (the ratio of shear modulus to bulk modulus or Poisson’s ratio) was also used as a gauge to evaluate the GFA in Zr_35−x Ti₃₀Cu_7.5Be_27.5Ag _x alloys.