3D simulation of the stress fields associated with disordered finite dislocation walls in face centred cubic crystals

Abstract

Simulations of the 3-dimensional elastic stress fields of finite dislocation walls with spatial disorder were carried out. Each wall consisted of 40 dislocations with an average spacing of L = 40 nm. The dislocation lines involved were decomposed into piecewise straight segments representing translatoric vectors of a face centred cubic lattice. Spatial disorder of the walls was achieved by incorporating curved dislocations. The results substantiate that the disorder of the dislocation lines involved alters the stress fields associated with the walls. In the direct vicinity of the walls (distance ≤ 2πL) the shear stress is only weakly dependent on the degree of order and decays as predicted analytically for an infinite low angle tilt boundary. Within the intermediate range (2πL < distance ≤ 60πL) a maximum of the shear stress occurs which decreases with increasing degree of disorder. The long range stress fields (distance > 60πL) are only weakly affected by the type of disorder imposed in the present approach. The profile of the shear stress of the dislocation walls showing a maximum in the intermediate range is attributed to the fact that finite rather than infinite walls are considered. The decrease of the maximum occurring shear stress in the intermediate range with decreasing order is interpreted in terms of self screening effects.