In the microscopic observation of deforming metals, it is well known that crystallite defects that accommodate strain can occasionally become visible, namely, they introduce image contrast to their locality. For microscopic digital image correlation (DIC) applications, this is typically known as a disturbance. Here, we explore a potential upside of these image-intensity offsets, to present a new mode of differential imaging that exclusively displays the underlying plasticity agents. For this, the intensity-offset signal is isolated with residual intensity, essentially the differential between reference- and deformed-configuration intensity of each material point. The premise is showcased over an autocatalytic twin band in Magnesium AZ31, with an advanced DIC instrument that utilizes bright-field optical microscopy. With robust area-scanning that utilizes in-situ corrective measures, a material field of around 5000 grains (13 μm average size) is sampled with a maximal intragranular resolution (~250 data points per grain) for this technique. For added robustness against the intensity alterations, a DIC algorithm (Augmented Lagrangian DIC) that enforces global kinematic compatibility constraints is utilized. The calculated residual intensity map yields a detailed image of the twin networks that show a strong positional alignment with the strain localizations. At the band boundary, the twins (and their accompanying strain localization) protrude into the dormant material in a comb-like pattern. With a combination of high-resolution optics and defects that alter the surface topography, residual intensity presents a new in-situ microscopy mode that is tied to the DIC analysis. This principle also offers potential micro-deformation imaging capabilities for various other material-microscopy combinations.

中文翻译：

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残余强度作为显微图像相关中孪晶场的形态学标识符

在变形金属的显微观察中，众所周知，适应应变的微晶缺陷偶尔会变得可见，即它们会为其局部引入图像对比度。对于显微数字图像相关 (DIC) 应用，这通常称为干扰。在这里，我们探索了这些图像强度偏移的潜在优势，以呈现一种新的差分成像模式，该模式专门显示潜在的可塑性剂。为此，强度偏移信号与残余强度隔离，基本上是每个材料点的参考和变形配置强度之间的差异。前提是在镁 AZ31 中的自催化双带上展示了该前提，以及利用明场光学显微镜的先进 DIC 仪器。通过利用原位校正措施的强大区域扫描，该技术以最大颗粒内分辨率（每粒约 250 个数据点）对约 5000 个晶粒（平均尺寸为 13 μm）的材料场进行采样。为了增加对强度变化的鲁棒性，使用了强制全局运动兼容性约束的 DIC 算法（增强拉格朗日 DIC）。计算出的残余强度图产生了双网络的详细图像，显示出与应变定位的强位置对齐。在带边界处，孪晶（及其伴随的应变定位）以梳状图案突出到休眠材料中。结合高分辨率光学元件和改变表面形貌的缺陷，残余强度提出了一种新的原位显微镜模式，该模式与 DIC 分析相关。该原理还为各种其他材料显微镜组合提供了潜在的微变形成像能力。