Preferential damage at symmetrical tilt grain boundaries in bcc iron

Abstract

The interaction of collision cascades with a (5 3 0) symmetrical tilt grain boundary in bcc iron has been studied using molecular dynamics simulations. Collision cascades were generated by a principle knock-on atom PKA of 1 keV at various distances from the boundary and with different velocity directions. Simulations reflect how the grain boundary acts as a barrier and also as a region where defects can be easily conducted along the boundary plane. Results show that there exist preferential sites in the periodic structure of the (5 3 0) symmetrical tilt boundary where defects are formed. These sites have been identified together with the atomic rearrangements produced in the grain boundary atomic structure have been analysed. The grain boundary energy increases after radiation. This increase in energy is proportional to the number of defects inside the grain boundary region.