Collaborative Research: Novel Atomistic-Continuum Simulation of Sequential Grain Boundary-Dislocation Slip Transfer Reactions

该奖项的研究目标是提出一种耦合原子连续模拟方法，以探索晶界滑移转移。缺乏这样的方法是目前发展本构关系，反映晶界的结构和行为，例如在多晶塑性进展的障碍。由于需要考虑位错场的长程相互作用，同时还要考虑界面的原子级结构细节，因此该问题变得复杂。 本研究将探索连续位错反应与双晶体界面的过程，通过保持全原子分辨率的界面反应和连续粗粒化的字段描述远离界面的距离，通常是无法完全解决的分子动力学。这样的能力将使参数研究的位错晶界滑移转移反应在整个范围内的晶界自由度，包括倾斜和扭曲的边界，以及不对称的边界，往往有多面结构，可以引起丰富的位错成核。也将考虑具有宽范围的孪晶间距的纳米孪晶结构。这项工作将使用国家的最先进的嵌入式原子方法的潜力，已被证明相当准确的面心立方金属，如铜在模拟位错成核，堆垛层错的形成，和位错相互作用的各个方面。这项研究将推进一个计算方法，耦合完全原子的描述纳米尺度的金属行为的介观和宏观本构行为。它将允许研究多晶金属中位错和晶界之间发生的复杂相互作用，这将导致基于物理的金属预测本构模型。这项研究将推进金属的多尺度建模，并导致改进的模拟和最终的材料设计。研究结果将纳入这两个机构的研究生课程。

The research objective of this award is to advance a coupled atomistic-continuum simulation method to explore slip transfer at grain boundaries. Lack of such a method is a current obstacle to progress towards developing constitutive relations that reflect the structure and behavior of grain boundaries, for example in polycrystal plasticity. The problem is complicated by the need to account for long range interactions of dislocation fields while also considering the atomic-level structural detail of the interface. This research will explore processes of sequential dislocation reactions with bicrystal interfaces by maintaining full atomistic resolution of the interface reactions and successively coarse graining the field description away from the interfaces at distances that are normally inaccessible to fully resolved molecular dynamics. Such a capability will enable parametric studies of dislocation-grain boundary slip transfer reactions over the full range of grain boundary degrees of freedom, including tilt and twist boundaries, as well as asymmetric boundaries that often have faceted structure and can give rise to profuse dislocation nucleation. Nanotwinned structures with a wide range of twin spacing will also be considered. This work will use state-of-the-art embedded atom method potentials which have proven quite accurate for fcc metals such as Cu in modeling various aspects of dislocation nucleation, formation of stacking faults, and dislocation interactions This research will advance a computational method that couples fully atomistic descriptions of nanoscale metallic behavior to mesoscale and macroscale constitutive behavior. It will permit study of the complex interactions that occur between dislocations and grain boundaries in polycrystalline metals which will lead to physics-based predictive constitutive models for metals. This research will advance the multiscale modeling of metals and lead to improved simulation and ultimately design of materials. Results of the research will be incorporated into graduate courses at both institutions.