Crystallization behavior of ZrAlNiCu bulk metallic glass with wide supercooled liquid region

The crystallization processes of Zr55Al10Ni5Cu30 (at.%) bulk metallic glass from the amorphous state and supercooled liquid region during the continuous heating and isothermal annealing courses were investigated. The apparent activation energy derived from the Kissinger plots for glass transition E-g is higher than that for crystallization E-p and E-x calculated by the peak temperature T-p and onset crystallization temperature T-x during the continuous heating process. The isothermal activation energy obtained using Arrhenius equation shows that it increases accompanying the proceeding of the crystallization transformation. The incubation time of crystallization becomes longer and the crystallization process becomes slower as the annealing temperature is reducing during the isothermal process. The crystallization mechanism was studied using Kolmogorov-Johnson-Mehl-Avrami (KJMA) equation. The results indicate that the Avrami exponent n approximate to 2 at the initial crystallization stage, and it alters gradually following the increasing crystallization volume fraction. (C) 2002 Elsevier Science B.V. All rights reserved.