Kinetics analysis of the isothermal crystallization of Cu55Zr45 metallic glass by differential scanning calorimetry

The crystallization kinetics of Cu55Zr45 (at%) glassy alloy is studied under isothermal condition using differential scanning calorimetry (DSC). The plot of correlation between the crystallized volume fraction alpha and annealing time t shows a sigmoid-type curve, which is steeper with higher annealing temperature. Furthermore, in isothermal crystallization condition, local activation energy E-alpha values, determined using the Arrhenius equation, range from 181.1 to 187.8 kJ/mol, which is nearly a constant. The local Avrami exponent n(alpha) values, obtained by the Johnson-Mehl-Avrami equation, which range from 2.2 to 4.0 at different annealing temeperatures, which indicates that the crystallization mechanism is diffusion-controlled transformation. Moreover, n(alpha) becomes greater with increasing annealing temperature, which indicates that annealing temperature can affect nucleation rate and growth type.