On Evaluation of the Gibbs–Thomson Effect and Selection of Nucleus Size for the Kampmann–Wagner Numerical Model

For the Kampmann–Wagner numerical (KWN) model, to accurately describe the microstructure evolution in a solid-state precipitation reaction requires a good evaluation of the Gibbs–Thomson effect and an appropriate nucleus size to be used. In the present work, it is found that there exists a big discrepancy between the nucleation thermodynamics and growth thermodynamics when adopting the widely used Gibbs–Thomson equation to evaluate the Gibbs–Thomson effect. This discrepancy can reduce the computational accuracy of the KWN model. When adopting the numerical method, “the equivalence of nucleation thermodynamics and growth thermodynamics” can be achieved. But due to the relatively large value of the critical size, some waves can be formed in the PSD function if the nucleus size is not carefully selected. Based on the analysis of formation mechanism of waves in the PSD function, it is suggested that, when adopting the numerical method to evaluate the Gibbs–Thomson effect, the most appropriate nucleus size should be the one derived from Zeldovich’s theory.