Theory of radiation-induced self-organization of defect structures

Abstract

During high-dose electron irradiation of thin foils of face-centred cubic metals and dilute alloys in a high-voltage electron microscope at temperatures above recovery stage III, planar ordering of Stacking-Fault Tetrahedra (SFT) in square lattices with the same orientations as the crystalline host lattices has been observed. In the present paper, a theory is presented that relates the formation of such SFT lattices to dynamic SFT interactions mediated by the anisotropic drift-diffusion of radiation-induced point defects in the SFT strain fields. Treating the SFT dynamics on the mesoscopic length scale of the ordering phenomenon, expressions for the interactions between the SFT are derived. As shown by linear stability analysis, there is a regime of control-parameter values in which these interactions induce a phase transition from a disordered SFT arrangement to a SFT lattice. The properties of this lattice and their dependences on parameters that can be controlled by experiment are investigated and compared to observations.