Cramer T, Wanner A, Gumbsch P
Max-Planck-Institut fur Metallforschung, Seestrasse 92, 70174 Stuttgart, Germany.
Phys Rev Lett. 2000 Jul 24;85(4):788-91. doi: 10.1103/PhysRevLett.85.788.
Brittle fracture usually proceeds at crack driving forces which are larger than those needed to create the new fracture surfaces. This surplus can lead to faster crack propagation or to the onset of additional dissipation mechanisms. Dynamic fracture experiments on silicon single crystals reported here show several distinct transitions between different dissipation mechanisms. Cleavage fracture is followed by the propagation of a faceted crack front, which is finally followed by a path instability and the propagation of multiple cracks. The fracture surface qualitatively corresponds to the mirror, mist, and hackle morphology of amorphous materials. However, the corresponding fracture mechanisms, which remain largely unknown in the amorphous materials, can clearly be identified here.
脆性断裂通常在裂纹驱动力大于产生新断裂表面所需驱动力的情况下发生。这种过剩会导致裂纹扩展更快或引发额外的耗散机制。本文报道的硅单晶动态断裂实验显示了不同耗散机制之间的几个明显转变。解理断裂之后是多面裂纹前沿的扩展，最终是路径失稳和多裂纹扩展。断裂表面在定性上与非晶材料的镜面、雾状和毛状形态相对应。然而，在非晶材料中基本未知的相应断裂机制在此处能够清晰地识别出来。
