Shear bands at the fatigue crack tip of nanocrystalline nickel

Fatigue crack growth rates in electrodeposited nanocrystalline Ni and its coarse counterpart were experimentally investigated in this paper. The shear bands, called the epsilon plastic zone, were observed on the surface of nanocrystalline Ni samples. The length of the shear bands is close to the estimated size of the plastic zone at the crack tip. Atomic force microscopy measurements indicate that the shear strain in the shear bands and the width of shear bands increase with related crack length.