Limitation of the Johnson-Mehl-Avrami equation for the kinetic analysis of crystallization in a Ti-based amorphous alloy

摘要

The primary crystallization of the Ti40Zr25Ni8Cu9Be18 amorphous alloy was studied by isochronal differential scanning calorimetry(DSC).The activation energy was determined by the Kissinger-Akahira-Sunose method.Trying to analyze the crystallization kinetics of the Ti40Zr25Ni8Cu9Be18 amorphous alloy by two different methods,it was found that the crystallization kinetics did not obey the Johnson-Mehl-Avrami equation.A modified method in consideration of the impingement effect was proposed to perform kinetic analysis of the isochronal crystallization of this alloy.The kinetic parameters were then obtained by the linear fitting method based on the modified kinetic equation.The results show that the isochronal crystallization kinetics of the amorphous Ti40Zr25Ni8Cu9Be18 alloy is heating rate dependent,and the discrepancy between the Johnson-Mehl-Avrami method and the modified method increases with the increase of heating rate.