Abstract Conventional phase-field models often drive solid-solid interfaces to merge when in close proximity. This limits their use for processes like diffusion bonding, where interfaces might need to remain distinct under certain conditions. We propose a phase-field model to address this. Our model modifies the kinetic evolution equation using a physically-motivated geometric criterion to control interface merging. This criterion, based on nonlocal higher-derivative curvature invariants of the phase field, can be temperature-dependent. It acts as a potential barrier, allowing a range of behaviors from complete fusion to the preservation of distinct boundaries. Our approach is thermodynamically consistent and can be linked to sharp-interface limits through asymptotic analysis. Simulations show controlled bonding kinetics, demonstrating capabilities not available with existing methods for modeling interfaces that must remain distinct below specific thermodynamic thresholds.
Khodadad et al. (Wed,) studied this question.