Correlating the supercooled liquid region width with the fragility parameter in bulk metallic glasses

A linear correlation of fragility parameter D* with supercooled liquid region width ΔTx for Ca-based bulk metallic glasses (BMGs) was revealed. This relationship is found in La- and Zr-based BMGs as well and extended to several glass-forming systems. The origin of this phenomenon lies in the close relation between crystallization and temperature dependence of viscosity. This relationship can be formulated by ΔTx0.33=6.8×10-3×(D*)(Tg0.33)+2(K), indicating that the unique variation of the viscosity with the temperature correlates with the location and width of the supercooled liquid region. Moreover, an approximation of fragility parameter D* for BMGs can be evaluated by the formula.