THEORY OF RADIATION-INDUCED SELF-ORGANIZATION OF DEFECT STRUCTURES .1. STACKING-FAULT-TETRAHEDRON LATTICES

During high-dose electron irradiation of thin foil of face-centred cub ic metals and dilute alloys in a high-voltage electron microscope at t emperatures above recovery stage III, planar ordering of Stacking-Faul t Tetrahedra (SFT) in square lattices with the same orientations as th e crystalline host lattices has been observed. In the present paper, a theory is presented that relates the formation of such SFT lattices t o 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 pheno menon, expressions for the interactions between the SFT are derived. A s shown by linear stability analysis, there is a regime of control-par ameter values in which these interactions induce a phase transition fr om a disordered SFT arrangement to a SFT lattice. The properties of th is lattice and their dependences on parameters that can be controlled by experiment are investigated and compared to observations.