Nonlinear dynamic instability in brittle fracture of GaAs

The process of brittle fracture in gallium arsenide was investigated to cla rify the relation between the dynamics of crack propagation and the observe d structure on the fracture surface with time-sensitive and structure-sensi tive methods. Within the full range of length scales, i.e., spanning eight orders of magnitude from angstrom units to centimeters, the fracture surfac e was characterized with a manifold of structure-sensitive methods comprisi ng optical microscopy, profilometry, atomic force microscopy, and scanning tunneling microscopy. We found that it is possible to predict the local ato mic-scale microstructure of a fracture surface from the knowledge of the gl obal macrostructure. The investigation of the fracture kinetics showed that the crack propagation process is characterized by three distinct velocity ranges. The present experimental results on structure and kinetics are cons istently interpreted within the framework of a nonlinear dynamic instabilit y in crack propagation. [S0163-1829(99)07131-3].