However, researchers have just begun to harness high-speed X-ray diffraction to detail an experimental shock response in real-time 22, 23. Most common in situ techniques, such as laser interferometry, lack the spatial resolution necessary for detailing transient microstructures. Simulations have provided valuable insight into this process 21 but cannot replace in situ experimentation. Such deduction is particularly difficult when multiple mechanisms activate and deactivate over such small scales. However, post-mortem analysis can merely infer the complex mechanistic history. Finally, when shocking Cu along, stacking faults rather than twins or phase transformations dominate the deformation response 9, 14, 15, 16, 17.īecause these deformation modes operate at the picosecond time scale and the nanometer length scale, traditional shock characterization has been largely limited to post-mortem techniques, such as electron microscopy 18, 19, 20. In contrast, when shocking Fe along, the compressive wave induces an α (BCC) → ϵ (HCP) phase transformation, and then the release wave reverses this transformation and induces twins 10, 11, 12, 13. ![]() When shocking Ta along, twins form during the compressive wave and are annihilated by the release wave 1, 2, 3, 4, 5, 6, 7, 8, 9. In this manuscript, we examined three representative metallic systems in order to feature three of the most important deformation modes for shocked FCC and BCC microstructures: dislocation slip (stacking faults), deformation twining, and phase transformation. Moreover, the relative contributions and timings of these deformation modes can differ dramatically depending on the material. Over only a few tens of picoseconds, several deformation modes can activate and deactivate (even simultaneously) to significantly alter the material down to the nanoscale. Understanding and optimizing a shock response requires characterization not only of the final state but also of the transient microstructures that form during the propagation of the compression wave, the release wave, and their interactions leading to that final state. 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. 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. ![]() 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. High-speed diffraction offers a solution, but the interpretation of diffractograms suffers numerous debates and uncertainties. Neither post-mortem analysis on recovered samples nor continuum-based methods during shock testing meet both requirements. 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. During the various stages of shock loading, many transient modes of deformation can activate and deactivate to affect the final state of a material.
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