Background

The internal strain distribution developing during plastic deformation is important for understanding the mechanical properties of polycrystalline materials. Such distributions may be determined by the microstructural feature tracking method. However, the strain accuracy and the sources of uncertainty of this method are not well quantified yet.

Objective

Evaluate the accuracy of local strain determination based on laboratory-based multimodal X-ray tomography measurements.

Methods

The plastic deformation behavior of a particle-contained fully recrystallized Al-4mass%Cu alloy was characterized during in-situ tensile testing using absorption contrast tomography to reveal marker particles and diffraction contrast tomography to reveal the grain structure.

Results

It was found that the accuracy in strain measurement is inversely proportional to the particle distance, whereas it is independent of the particle size, and the accuracy is not biased by grain boundaries. As an illustrative example, the preliminary analysis of the microstructure-strain relationships reveals significant strain differences both between and within individual grains.

Conclusions

The results document the validity and limitations of the microstructural feature tracking method for local strain measurements using a laboratory X-ray source, are of importance for local strain analysis in general and may be considered as an alternative to other methods, e.g. digital image correlation. The measurements allow evaluation of effects of the grain microstructure on the local strain development during plastic deformation. By a preliminary analysis of the strain difference between two selected grains, it is suggested that the grain shape and crystallographic relationships between neighboring grains are of importance for the development of local strains.

中文翻译：

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基于实验室的多峰X射线断层扫描技术研究晶粒结构与不均匀变形之间的关系：应变精度分析

背景

塑性变形过程中产生的内部应变分布对于理解多晶材料的机械性能很重要。这样的分布可以通过微结构特征跟踪方法来确定。但是，这种方法的应变精度和不确定性来源尚未得到很好的量化。

客观的

基于基于实验室的多模式X射线断层扫描测量，评估局部应变确定的准确性。

方法

在原位拉伸测试过程中，使用吸收对比层析成像技术来表征含颗粒的完全重结晶的Al-4mass％Cu合金的塑性变形行为，以显示标记颗粒，通过衍射对比层析技术来显示晶粒结构。

结果

发现应变测量的精度与颗粒距离成反比，而与颗粒尺寸无关，并且精度不受晶界的影响。作为一个说明性的例子，对微观结构-应变关系的初步分析表明，单个晶粒之间和内部都存在明显的应变差异。

结论

结果证明了使用实验室X射线源进行局部应变测量的微结构特征跟踪方法的有效性和局限性，通常对于局部应变分析非常重要，可以被视为其他方法（例如数字图像相关性）的替代方法。这些测量值可以评估塑性变形过程中晶粒微观结构对局部应变发展的影响。通过对两个选定晶粒之间的应变差异的初步分析，表明相邻晶粒之间的晶粒形状和晶体学关系对于局部应变的发展很重要。