Effect of Ag addition on the thermal stability and glass-forming ability of Zr 35Ti 30Cu 7.5Be 27.5 bulk metallic glass

Abstract

The thermal stability and glass forming ability (GFA) of Zr 35-xTi 30Cu 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 Zr 35Ti 30Cu 7.5Be 27.5 alloy to 20 mm in the Zr 34Ti 30Cu 7.5Be 27.5Ag 1 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-xTi 30Cu 7.5Be 27.5Ag x alloys. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.