Univ Lyon, INSA-Lyon, CNRS UMR5259, LaMCoS, Lyon, F-69621, France.
Department of Applied Mechanics, FEMTO-ST Institute, Univ Bourgogne Franche Comté, CNRS/UFC/ENSMM/UTBM, Besançon, F-25000, France.
Nat Commun. 2018 Apr 3;9(1):1298. doi: 10.1038/s41467-018-03642-w.
Single crystalline silicon fractures on low-energy cleavage planes such as (111) and (110). The crack propagation cannot accurately be predicted by linear elastic fracture mechanics since it does not account for small scale and inelastic phenomena such as atomic lattice trapping. Here we show that, under pure bending load, (110) cleavage in silicon single crystal rapidly accelerates to 3700 m/s without crack path deviation or crack branching, contrasting previous observations. We highlight that the crack front shape involves strong velocity dependence and presents a curvature jump during very high-speed crack growth. In addition, we observe special marks-a kind of periodic surface undulation-that exclusively arise on the rapid fracture surfaces, and we suggest that they are front wave traces resulting from an intrinsic local velocity fluctuation. This finding gives insight to the wavy nature of the crack front in the absence of material asperity.
单晶硅在低能量解理面上断裂，如（111）和（110）。线性弹性断裂力学不能准确预测裂纹扩展，因为它没有考虑原子晶格捕获等小尺度和非弹性现象。在这里，我们表明，在纯弯曲载荷下，（110）硅单晶的解理迅速加速至 3700 m/s，而不会发生裂纹路径偏离或裂纹分叉，这与以前的观察结果形成对比。我们强调，裂纹前沿形状具有强烈的速度依赖性，并在非常高速的裂纹扩展过程中呈现出曲率跳跃。此外，我们观察到特殊的标记——一种周期性的表面波动——仅出现在快速断裂表面上，我们认为它们是由于固有局部速度波动而产生的前缘波痕。这一发现揭示了在没有材料粗糙度的情况下，裂纹前沿的波动性质。
