Unraveling the complexities of metal deformation requires a deep understanding of dislocation dynamics and their intermittent behavior. Here, high-resolution acoustic emission (AE) measurements during in situ microcompression of Ni single-crystal micropillars are used to reveal new insights into the rapid deformation dynamics of dislocation avalanches. Spectral analysis of the AE signals uncovers multiple short waves during individual strain bursts, exposing a rich landscape of intermittent plasticity that was previously hidden. Our analysis identifies distinct acoustic signatures that correlate with various stages of deformation: early-stage large avalanches generate strong AE bursts, while later stages characterized by denser dislocation networks emit AE signals of lower amplitude. Notably, given the used sensor, a consistent AE frequency band ranging from 30 to 50 kHz is observed across all recorded avalanches, directly linking this spectral feature to the kinematics of dislocations moving through the crystal lattice. These findings provide a non-destructive characterization approach of dislocation dynamics during the deformation of bulk metals and establish quantitative connections between defect dynamics and macroscopic deformation behavior. More broadly, this work highlights the potential for AE-based techniques to provide insights into the fundamental mechanisms of plasticity in crystalline materials.

中文翻译：

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间歇性塑性的声学分析


要揭示金属变形的复杂性，需要对位错动力学及其间歇性行为有深入的了解。本文利用 Ni 单晶微柱原位微压缩过程中的高分辨率声发射 （AE） 测量，揭示了对位错雪崩快速变形动力学的新见解。AE 信号的频谱分析揭示了单个应变爆发期间的多个短波，暴露了以前隐藏的丰富的间歇性可塑性景观。我们的分析确定了与变形的各个阶段相关的不同声学特征：早期大型雪崩会产生强烈的 AE 爆发，而以更密集的位错网络为特征的后期阶段会发出较低振幅的 AE 信号。值得注意的是，鉴于使用了传感器，在所有记录的雪崩中都观察到了 30 到 50 kHz 的一致 AE 频带，将该光谱特征与通过晶格移动的位错的运动学直接联系起来。这些发现提供了一种对块体金属变形过程中的位错动力学进行无损表征的方法，并在缺陷动力学和宏观变形行为之间建立了定量联系。更广泛地说，这项工作强调了基于 AE 的技术在深入了解晶体材料中塑性的基本机制方面的潜力。