Determination of activation energy for crystallization in amorphous alloys

Applying an analytical model, a recipe has been deduced for the determination of the effective activation energy from the experimental transformation-rate data, without recourse to any specific kinetic model. The recipe was applied for isochronal crystallization of amorphous Pd₄₀Cu₃₀P₂₀Ni₁₀ alloy subjected to isothermal pre-annealing (T_pre) using differential scanning calorimetry. According to the analytical model, the isochronal crystallization subjected to the minimal (620 K) and the maximal (629 K) T_pre, is controlled by continuous nucleation and site saturation, respectively. Thus the recipe reduces to the Kissinger's method and average effective activation energy can be deduced. For intermediate cases where 620 K < T_pre < 629 K, the subsequent isochronal crystallization is according to the analytical model dominated by mixed nucleation, then the Kissinger method is not applicable, and the effective activation energy was deduced to be a function of the transformed fraction.