Thermodynamic and kinetic fragilities of Mg-based bulk metallic glass-forming liquids

The thermodynamic and kinetic fragilities of two near-eutectic Mg-based bulk metallic glass (BMG)-forming liquids, Mg₆₁Cu₂₈Gd₁₁ and Mg_59.5Cu_22.9Ag_6.6Gd₁₁, were investigated using high-precision differential scanning calorimeter (DSC). The thermodynamic fragility denoted as F_3/4 was determined by evaluating the temperature dependence of the excess entropy S_ex. The heating rate dependence of the relaxation time at the glass transition temperature was investigated to measure the kinetic fragility. A positive correlation between the thermodynamic and kinetic fragilities could be established in Mg-based BMG-forming liquids on the basis of Adam-Gibbs equation in contrast to a number of other BMGs.