Lobmeyer Dana M, Biswal Sibani Lisa
Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005 USA.
Sci Adv. 2022 Jun 3;8(22):eabn5715. doi: 10.1126/sciadv.abn5715.
The complexity of shear-induced grain boundary dynamics has been historically difficult to view at the atomic scale. Meanwhile, two-dimensional (2D) colloidal crystals have gained prominence as model systems to easily explore grain boundary dynamics at single-particle resolution but have fallen short at exploring these dynamics under shear. Here, we demonstrate how an inherent interfacial shear in 2D colloidal crystals drives microstructural evolution. By assembling paramagnetic particles into polycrystalline sheets using a rotating magnetic field, we generate a particle circulation at the interface of particle-free voids. This circulation shears the crystalline bulk, operating as both a source and sink for grain boundaries. Furthermore, we show that the Read-Shockley theory for hard-condensed matter predicts the misorientation angle and energy of shear-induced low-angle grain boundaries based on their regular defect spacing. Model systems containing shear provide an ideal platform to elucidate shear-induced grain boundary dynamics for use in engineering improved/advanced materials.
剪切诱导的晶界动力学的复杂性在历史上一直难以在原子尺度上观察到。与此同时，二维（2D）胶体晶体作为模型系统已崭露头角，能够在单粒子分辨率下轻松探索晶界动力学，但在探索剪切作用下的这些动力学方面却有所欠缺。在此，我们展示了二维胶体晶体中固有的界面剪切如何驱动微观结构演化。通过使用旋转磁场将顺磁性粒子组装成多晶薄片，我们在无粒子空隙的界面处产生了粒子循环。这种循环剪切了晶体本体，充当晶界的源和汇。此外，我们表明，针对硬凝聚态物质的里德 - 肖克利理论基于其规则的缺陷间距预测了剪切诱导的低角度晶界的取向差角和能量。包含剪切的模型系统为阐明用于工程改进/先进材料的剪切诱导晶界动力学提供了理想平台。
