Normalized treatment for isothermally conducted phase transformation with variable kinetic parameters

On the basis of a general, flexible, analytical transformation model, normalized treatment is extended to isothermally conducted transformation with transformed fraction-dependent kinetic parameters. A characteristic time that corresponds to the extended transformed fraction reaching to unit is selected for the treatment to give a simple expression for the transformed fraction. It is found that the transformed fraction at the characteristic time is correlated with impingement mode. Accordingly, a straightforward method is proposed to determine the prevailing impingement mode from the data at half maximum of the transformation rate. Applying the newly proposed method to numerically calculated transformation, the result is in good agreement with the value for the assigned model parameter. Then, the method is applied to the isothermal crystallization of Cu-Zr-Al-Y bulk metallic glass at different annealing temperatures.