Phase-Field Model of Solution and Stoichiometric Phases with Molar Volume Difference

Phase-field models have proven indispensable for deciphering the microstructure complexities inherent in multicomponent systems. The confluence of varying phase molar volumes presents unique challenges. Understanding the impact of molar volume differences on multiphase systems is of crucial significance, as it directly influences the system's thermodynamic and kinetic behavior, as well as resulting phase morphologies and distributions. In this study, we developed a phase-field model of solution and stoichiometric phases that can account for the molar volume differences. With the phase molar volumes taken from existing CALPHAD thermodynamic databases, we quantitatively investigated how the different molar volume settings would influence the growth rate and morphologies of stoichiometric $\theta^\prime$-\ce{Al2Cu} and $\beta$-\ce{Al140Mg89} precipitates in Al-based alloys. We anticipate that this approach can be applied to various materials systems with phase- and composition-dependent molar volumes for more accurate phase-field predictions.