Crack Interaction With Tilt Grain Boundaries in Brittle Fracture of Aluminum

Abstract

This paper presents a molecular dynamics study of crack propagation in aluminum bicrystals with tilt grain boundaries under uniaxial tension. The simulations showed that crack propagation is always preceded by an abrupt increase in the atomic volume at the crack tip as a result of nanopore formation. The beginning of crack growth or crack initiation after arrest is always accompanied by a rapid decrease in the atomic volume at the crack tip. The results obtained in this study show that the crack can cause significant grain boundary migration. The amount of grain boundary migration increases with decreasing grain misorientation angle. Tilt grain boundaries with misorientation angles above 20° fully prevent crack propagation into a neighboring grain. At smaller tilt angles, the crack is temporarily arrested by the grain boundary, and the arrest time increases with increasing tilt angle.