晶界相变实现位错的无扩散攀移
Grain Boundary Phase Transitions Enable Diffusionless Climb of Disconnections
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中文总结 AI 辅助
该研究通过双晶几何学与分子动力学模拟，发现铝中晶界相变可实现位错的无扩散保守攀移，建立了晶格位错与晶界演化的直接耦合，揭示了新型位错攀移机制。
中文摘要 AI 辅助
位错-晶界（GB）相互作用通过控制位错吸收、位错透射及界面塑性，决定多晶材料的力学响应。传统认知中，位错攀移需要吸收或发射通过长程体扩散提供的点缺陷，而晶界具有与其原子结构（或微态）相关的本征构型自由度，或可提供替代机制。本研究采用双晶几何学与分子动力学模拟，探究剪切位错环与铝中[1 1 0](-5 5 14)对称倾斜晶界的相互作用，结果显示位错吸收会生成具有非零攀移分量的可动外在位错，该位错沿界面保守传播，无需长程体点缺陷传输；其运动伴随由晶界核心内协同原子重排介导的局域晶界相变，产生连续的亚稳晶界微态。这些发现确立了晶格位错与晶界相变演化间的直接耦合关系，揭示了一种与传统空位介导攀移根本不同的位错攀移保守机制。
英文摘要
Dislocation-grain boundary (GB) interactions govern the mechanical response of polycrystalline materials by controlling dislocation absorption, transmission, and interfacial plasticity. While disconnection climb is conventionally understood to require the absorption or emission of point defects supplied through long range bulk diffusion, GBs possess intrinsic configurational degrees of freedom associated with their atomic structure, or microstate, that may provide an alternative mechanism. Here, using bicrystallography and molecular dynamics simulations, we investigate the interaction of shear dislocation loops with the [1 1 0](-5 5 14) symmetric tilt grain boundary in Al. We show that dislocation absorption generates a mobile extrinsic disconnection with a nonzero climb component that propagates conservatively along the interface without long-range bulk point-defect transport. Its motion is accompanied by a localized GB phase transformation mediated by cooperative atomic rearrangements within the GB core, producing successive metastable GB microstates. These findings establish a direct coupling between lattice dislocations and GB phase evolution and reveal a conservative mechanism for disconnection climb fundamentally distinct from conventional vacancy-mediated climb.
