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 Zr35−x Ti30Cu7.5Be27.5Ag 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 Zr35Ti30Cu7.5Be27.5 alloy to 20 mm in the Zr34Ti30Cu7.5Be27.5Ag1 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 Zr35−x Ti30Cu7.5Be27.5Ag x alloys.