Isochronal and isothermal phase transformation of Cu45Zr45Ag7Al3 bulk metallic glass

Crystallization kinetics of Cu45Zr45Ag7Al3 bulk metallic glass in non-isothermal and isothermal modes were investigated by differential scanning calorimetry (DSC). Under continuous heating conditions, the activation energies of the glass transition and crystallization at the onset and first peak crystallization temperatures are determined by Kissinger plots and are found to be 376.8, 307.2 and 339.5 kJ/mol, respectively. However, under isothermal conditions the average activation energy for crystallization is about 413.7 kJ/mol obtained by using the Arrhenius equation, which is much larger than that deduced from Kissinger plots. The local Avrami exponent n is mostly in the range 1.82–3.51, implying that the crystallization is mainly governed by diffusion-controlled, three-dimensional growth with nearly constant nucleation rate.