Effects of glissile interstitial clusters on microstructure self-organization in irradiated materials

We analyze the formation and selection of self-organized defect microstructure in irradiated materials within the framework of a kinetic model for point and clustered defects. We take explicitly into account the influence of glissile interstitial clusters on the stability and morphology of ordered microstructure. Under void growth conditions, we find that the anisotropic motion of interstitial clusters provides a key element for microstructure morphology selection. In particular, it results in the formation of the void lattice in parallel orientation with the underlying crystal structure, in agreement with experimental observations. We also find that bcc and fcc void lattices develop in bcc and fcc crystals, respectively, while in hcp crystals, voids form ordered arrays parallel to basal planes. It is also predicted that a fcc void lattice is unstable, explaining the experimental difficulty for void lattice formation in fcc crystals.