Predicting shear coupling behaviors in disconnection-mediated migration of asymmetrical tilt grain boundaries

RQ Dang and YW Zhang and HJ Gao, INTERNATIONAL JOURNAL OF PLASTICITY, 193, 104441 (2025).

DOI: 10.1016/j.ijplas.2025.104441

Grain boundaries (GBs) play a critical role in determining the mechanical properties of polycrystalline materials. Due to their inherent structural complexity and atomic variability, characterizing the loading response of GBs can be highly challenging. Disconnections, a type of line defects at GBs, have been widely used to model the migration of GBs under shear and has been extensively validated through experiments. While this approach has proven effective for symmetrical tilt grain boundaries (STGBs), it has encountered challenges when modeling asymmetrical tilt grain boundaries (ATGBs). Here, we combine molecular dynamics (MD) simulations with a disconnection-based theoretical model to investigate disconnection-mediated migration of ATGBs in Cu. Our model, which treats an ATGB under shear as a combination of two STGBs, yields predictions in excellent agreement with results from MD simulations for cases undergoing solely disconnection- mediated migration. We further discuss the adaptability of our model across various GB types and temperatures, covering more complex migration mechanisms. This study enhances our understanding of shear- coupled migration of ATGBs and offers potentially useful insights for GB engineering.

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