Localization of crystallographic slip into shear bands during uniaxial compression of a copper single crystal is studied using very far-field high-energy diffraction microscopy (vff-HEDM). Diffracted intensity was collected in-situ as the crystal deformed using a unique mobile detector stage that provided access to multiple diffraction peaks with high-angular resolution. From the diffraction data, single crystal orientation pole figures (SCPFs) were generated and are used to track the evolution of the distribution of lattice orientation that develops as slip localizes. To aid the identification of ‘signatures’ of shear band formation and analyze the SCPF data, a model of slip-driven lattice reorientation within shear bands is introduced. Confidence is built in conclusions drawn from the SCPF data about the character of internal slip localization through comparisons with strain fields on the sample surface measured simultaneously using digital image correlation. From the diffraction data, we find that the active slip direction and slip plane are not directly aligned with the orientation of the shear bands that formed. In fact, by extracting the underlying slip system activity from the SCPF data, we show that intersecting shear bands measured on the surface of the sample arise from slip primarily on the same underlying single slip system. These new vff-HEDM results raise significant questions on the use of surface measurements for slip system activity estimation.

使用非常远场高能衍射显微镜（vff-HEDM）研究了铜单晶单轴压缩过程中晶体滑移在剪切带中的定位。原位收集衍射强度由于使用独特的移动检测器平台使晶体变形，因此可以访问具有高角度分辨率的多个衍射峰。根据衍射数据，生成了单晶取向极图（SCPFs），并用于跟踪随滑移局部而发展的晶格取向分布的演变。为了帮助识别剪切带形成的“特征”并分析SCPF数据，引入了剪切带内滑动驱动晶格重新定向的模型。通过与数字图像相关性同时测量的样品表面应变场的比较，从SCPF数据得出的有关内部滑动定位特征的结论中建立了信心。根据衍射数据，我们发现活动滑移方向和滑移平面与形成的剪切带的方向不直接对齐。实际上，通过从SCPF数据中提取基础滑移系统活动，我们表明，在样品表面上测量的相交剪切带主要来自同一基础滑移系统上的滑移。这些新的vff-HEDM结果对将表面测量值用于滑移系统活动估计提出了重大问题。