On the thermodynamics and kinetics of crystallization of a Zr-Al-Ni-Cu-based bulk amorphous alloy

Three Zr-based amorphous bulk samples with different compositions were prepared by liquid undercooling. The stability of the amorphous alloy samples and the thermodynamics and kinetics of crystallization have been investigated by differential scanning calorimetry (DSC). The results showed that the crystallization activation energy, determined from anisothermal annealing using the Kissinger equation, could not truly reflect the influence of the elements on the stability of amorphous alloy. The kinetic analysis based on the Johnson-Mehl-Avrami (JMA) equation shows that the Avrami exponents in several Zr-Cu-based alloys are nearly the same. However, the incubation time (t(i)) and the position of the JMA kinetic curve (ln[ - ln(1 - X-v)] vs. In t) are very different from one alloy to another. When taking the incubation time (t) during isothermal annealing as a characteristic parameter, the crystallization activation energy estimated by the Arrhenius is more reasonable, indicating that the influence of different elements on the stability of amorphous alloys mainly occurs in the early stage of nucleation. (C) 2001 Elsevier Science Inc, All rights reserved.