Structure-dependent diffusion at bonded Al/Al interfaces

Diffusion behavior at a bonding Al/Al interface formed through the jump-to-contact process is investigated using molecular dynamics simulations. The analysis introduces a new methodology for quantifying interface and grain boundary diffusion by extracting diffusivity from its spatial variation across the interface, thereby eliminating the need to define interface area or width. Results reveal a strong dependence of interface diffusion on misorientation axis and twist angle, establishing a clear structure–diffusion relationship. At the atomic scale, diffusion is governed by structural distortions created by the interfacial dislocation network, which generate and preserve regions of excess atomic volume that promote atomic motion. Even modest variations in free volume leads to pronounced diffusion enhancement along connected fast-diffusion pathways.