Atomic image of indentation crack tip during stress corrosion cracking of mica in moist air

Delayed propagating, i.e. stress corrosion cracking, of a loaded indentation crack of mica in moist air has been investigated using atomic force microscopy. The results show that the indentation crack under constant deflection can propagate and then arrest. The depth near the tip of an arrested surface crack decreases gradually from 0.09 nm to zero. There is no evident demarcation line between the crack tip and the matrix. It is therefore possible to observe a regular lattice array of periodic structure in front of the crack tip.