Self-emitted surface corrugations in dynamic fracture of silicon single crystal

Meng Wang (1) , Marion Fourmeau (1) , Lv Zhao (2, 3, 4) , Franck Legrand (1) , Daniel Nélias (1)

1 LaMCoS - Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne]
2 HUST - Department of Mechanics [Wuhan]
3 Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment, Wuhan, 430074, China
4 HUST - Huazhong University of Science and Technology [Wuhan]

When a dynamic crack front travels through material heterogeneities, elastic waves are emitted, which perturb the crack and change the morphology of the fracture surface. For asperity-free crystalline materials, crack propagation along preferential cleavage planes is expected to present a smooth crack front and form a mirror-like fracture surface. Surprisingly, we show here that in single crystalline silicon without material asperities, the crack front presents a local kink during high-speed crack propagation. Meanwhile, local oscillations of the crack front, which can move along the crack front, emerge at the front kink position and generate periodic fracture surface corrugations. They grow from angstrom amplitude to a few hundred nanometers and propagate with a long lifetime at a frequency-dependent speed, while keeping a scale-independent shape. In particular, the local front oscillations collide in a particle-like manner rather than proceeding with a linear superposition upon interaction, which presents the characteristic of solitary waves. We propose that such a propagating mode of the crack front, which results from the fracture energy fluctuation at a critical crack speed in the silicon crystal, can be considered as nonlinear elastic waves that we call “corrugation waves.”

Mots clés: silicon single crystal; dynamic fracture; crack front kink; corrugation waves; solitary waves

Domaines: Mécanique des matériaux [physics.class-ph]

Meng Wang, Marion Fourmeau, Lv Zhao, Franck Legrand, Daniel Nélias. Self-emitted surface corrugations in dynamic fracture of silicon single crystal. Proceedings of the National Academy of Sciences of the United States of America, 2020, 117 (29), pp.16872-16879. ⟨10.1073/pnas.1916805117⟩. ⟨hal-03336878⟩