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<p>This study employs an advanced phase-field model, integrated with molecular dynamics simulations, to investigate edge dislocation dynamics in Σ5 Ni bicrystals under different temperatures (100–600&#xa0;K) and applied shear (up to 18 GPa), focusing on their role in the crystalline-to-amorphous transition. While no direct MD simulations are performed, temperature-dependent parameters derived from prior MD studies are incorporated into the phase-field framework. The model, validated against existing theoretical and molecular dynamics data, accurately captures the dislocation parameters, such as slip system height and Burgers vector, using a stepwise crystalline energy barrier to prevent non-physical dislocation widening. The simulations reveal enhanced dislocation growth in the + 30° slip system due to favorable stress alignment at the grain boundary. Higher temperatures and shear stresses significantly increase dislocation density, with grain boundaries acting as dislocation sources, accelerating amorphization compared to single crystals, where dislocation motion delays structural disorder. Notably, bicrystals maintain stability up to 600&#xa0;K, beyond which rapid defect activity causes instability within 2&#xa0;ns. These findings underscore the crucial role of crystal structure, temperature, and stress in determining material stability, offering valuable insights for designing durable materials for high-stress applications in aerospace and energy systems. This work introduces a novel PF–MD coupling that implements a stepwise energy barrier at slip plane boundaries to prevent non-physical dislocation widening, enabling quantitative prediction of grain boundary-driven amorphization and revealing the + 30° slip system as a dominant dislocation growth pathway under shear. The focus remains on temperature-dependent dislocation slip behavior, with amorphization trends inferred from stress-induced disorder near grain boundaries rather than explicitly modeled.</p>

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Phase-Field Analysis of Edge Dislocation Dynamics in Σ5 Ni Bicrystals Under Different Thermal and Shear Loads

  • 期刊论文

  • 发表日期：

    2026年5月18日

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  • Armin Sabetghadam-Isfahani,
  • Mahdi Javanbakht,
  • Mohammad Silani,
  • Mohammad Mohammadi Aghdam

摘要

This study employs an advanced phase-field model, integrated with molecular dynamics simulations, to investigate edge dislocation dynamics in Σ5 Ni bicrystals under different temperatures (100–600 K) and applied shear (up to 18 GPa), focusing on their role in the crystalline-to-amorphous transition. While no direct MD simulations are performed, temperature-dependent parameters derived from prior MD studies are incorporated into the phase-field framework. The model, validated against existing theoretical and molecular dynamics data, accurately captures the dislocation parameters, such as slip system height and Burgers vector, using a stepwise crystalline energy barrier to prevent non-physical dislocation widening. The simulations reveal enhanced dislocation growth in the + 30° slip system due to favorable stress alignment at the grain boundary. Higher temperatures and shear stresses significantly increase dislocation density, with grain boundaries acting as dislocation sources, accelerating amorphization compared to single crystals, where dislocation motion delays structural disorder. Notably, bicrystals maintain stability up to 600 K, beyond which rapid defect activity causes instability within 2 ns. These findings underscore the crucial role of crystal structure, temperature, and stress in determining material stability, offering valuable insights for designing durable materials for high-stress applications in aerospace and energy systems. This work introduces a novel PF–MD coupling that implements a stepwise energy barrier at slip plane boundaries to prevent non-physical dislocation widening, enabling quantitative prediction of grain boundary-driven amorphization and revealing the + 30° slip system as a dominant dislocation growth pathway under shear. The focus remains on temperature-dependent dislocation slip behavior, with amorphization trends inferred from stress-induced disorder near grain boundaries rather than explicitly modeled.