The effect of dislocation distributions, in the boundaries of an arrested twin, upon the nucleation of micro-cracks at its tip was investigated. The twin was simulated by a double-step pile-up (cluster) of twinning dislocations located in adjacent slip planes. The equilibrium equations for dislocations were solved numerically. Clusters with differing total numbers of dislocations, and with differing ratios of the numbers of dislocations at the upper and lower twin boundaries, were considered. The formation of micro-cracks as a result of the coalescence of head dislocations was analyzed. The equilibrium configurations of a single twin boundary and of the twin were calculated. It was found that the condition for micro-crack formation at the twin-tip depended upon the ratio of the numbers of dislocations in twin boundaries. In the limit, this condition coincided with the condition for crack formation at the tip of a single twin boundary having the same total number of dislocations. It was shown that thermally activated formation of a micro-crack corresponded to lower values of the critical stress.

Effect of Dislocation Distribution in Twin Boundaries on the Nucleation of Microcracks at the Twin Tip. V.A.Fedorov, V.A.Kuranova, Y.I.Tyalin, S.N.Pluzhnikov: Physics of the Solid State, 2002, 44[6], 1102-4