Background

Dislocation dynamic simulations are intended as a tool to understand and predict the mechanical behavior of metallic materials, but its prediction has never been directly verified by experiments due to differences in specimen strain rate and size.

Objective

In this work, a comprehensive experimental framework is proposed to attempt direct comparison between experiments and discrete dislocation dynamics (DDD) modelling.

Methods

By integrating high-throughput sample fabrication and a customized testing apparatus, the sample size and strain rate typically employed in DDD simulations are explored experimentally. Constitutive properties such as stress-strain response are measured, and microstructural information is obtained from transmission electron microscopy (TEM) imaging, electron backscatter diffraction (EBSD), and TEM-based orientation mapping.

Results

Magnesium and copper were selected, as case studies, to demonstrate the newly developed experimental procedure. Measured stress-strain responses for Mg are consistent with those obtained with a miniaturized Hopkison bar experiments. By exploiting the validated workflow, the effect of strain rate on micropillar heterogeneous deformation and associated dislocation plasticity were revealed.

Conclusion

The work establishes a methodology for the systematic study of not only metals but also other materials and structures at the microscale and high strain rates.

中文翻译：

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大直径微柱的原位SEM高应变率测试，然后进行TEM和EBSD事后分析

背景

位错动态模拟旨在作为一种工具来理解和预测金属材料的机械行为，但由于样品应变率和尺寸的差异，其预测尚未得到实验的直接验证。

客观的

在这项工作中，提出了一个全面的实验框架，以尝试在实验和离散位错动力学（DDD）建模之间进行直接比较。

方法

通过将高通量样品制造和定制的测试设备集成在一起，可以对DDD模拟中通常采用的样品大小和应变速率进行实验性探索。测量诸如应力-应变响应的本构特性，并从透射电子显微镜（TEM）成像，电子背散射衍射（EBSD）和基于TEM的方向映射中获取微结构信息。

结果

选择镁和铜作为案例研究，以证明新开发的实验程序。测得的Mg应力-应变响应与通过小型Hopkison条形实验获得的应力-应变响应一致。通过利用经过验证的工作流程，揭示了应变速率对微柱非均质变形和相关位错可塑性的影响。

结论

这项工作建立了一种方法，不仅可以对金属进行系统研究，而且还可以对微观和高应变率下的其他材料和结构进行系统研究。