MICROSTRUCTURAL SELF-ORGANIZATION IN IRRADIATED SYSTEMS

Abstract

Irradiated metals and alloys are examples of open, dissipative systems far away from thermal equilibrium. In several cases they show self-organization of the microstructure resulting from non-linear reactions of the migrating point defects, i.e. vacancies and interstitials. In this review, the various published theoretical approaches to radiation-induced self-organization are discussed using a rate equation description. Two different mechanisms of defect interaction with the microstructure are possible origins for the occurrence of periodic fluctuations: (i) A diffusion-controlled reaction coupling involving biased constructive and destructive reactions and (ii) the coupling of atomic fluxes to interstitial and vacancy fluxes which are induced by the recombination reaction. Using an adiabatic approximation in a linear stability analysis, the conditions for the formation of radiation-induced periodic structures are obtained. The symmetry of the geometrical arrangements are deduced from an extension into the weakly non-linear regime. The results are compared with experimental observations. It is demonstrated that the radiation-induced defect wall structures and void lattice formation can well be explained as a self-organization process in an open, dissipative system.