Mishra Avanish, Kunka Cody, Echeverria Marco J, Dingreville Rémi, Dongare Avinash M
Department of Materials Science and Engineering, University of Connecticut, Storrs, CT, 06269, USA.
Institute of Materials Science, University of Connecticut, Storrs, CT, 06269, USA.
Sci Rep. 2021 May 10;11(1):9872. doi: 10.1038/s41598-021-88908-y.
During the various stages of shock loading, many transient modes of deformation can activate and deactivate to affect the final state of a material. In order to fundamentally understand and optimize a shock response, researchers seek the ability to probe these modes in real-time and measure the microstructural evolutions with nanoscale resolution. Neither post-mortem analysis on recovered samples nor continuum-based methods during shock testing meet both requirements. High-speed diffraction offers a solution, but the interpretation of diffractograms suffers numerous debates and uncertainties. By atomistically simulating the shock, X-ray diffraction, and electron diffraction of three representative BCC and FCC metallic systems, we systematically isolated the characteristic fingerprints of salient deformation modes, such as dislocation slip (stacking faults), deformation twinning, and phase transformation as observed in experimental diffractograms. This study demonstrates how to use simulated diffractograms to connect the contributions from concurrent deformation modes to the evolutions of both 1D line profiles and 2D patterns for diffractograms from single crystals. Harnessing these fingerprints alongside information on local pressures and plasticity contributions facilitate the interpretation of shock experiments with cutting-edge resolution in both space and time.
在冲击加载的各个阶段，许多瞬态变形模式会激活和失活，从而影响材料的最终状态。为了从根本上理解和优化冲击响应，研究人员寻求能够实时探测这些模式并以纳米级分辨率测量微观结构演变的能力。在冲击测试过程中，对回收样品的事后分析和基于连续介质的方法都无法满足这两个要求。高速衍射提供了一种解决方案，但衍射图谱的解释存在诸多争议和不确定性。通过对三种具有代表性的体心立方（BCC）和面心立方（FCC）金属系统进行冲击、X射线衍射和电子衍射的原子模拟，我们系统地分离出了显著变形模式的特征指纹，如实验衍射图谱中观察到的位错滑移（堆垛层错）、形变孪晶和相变。本研究展示了如何使用模拟衍射图谱将同时发生的变形模式的贡献与单晶衍射图谱的一维线形轮廓和二维图案的演变联系起来。利用这些指纹以及局部压力和塑性贡献的信息，有助于在空间和时间上以前沿分辨率解释冲击实验。
