The evolution of the nanoscale dissipative structures in a distribution of defects within the isothermally irradiated f.c.c. crystal

Abstract

A kinetic model for the influence of external noises such as fluctuations of the vacancies’ generation rate and inhomogeneity of irradiated f.c.c. crystal on the formation of nanoscale modulated dissipative structure in a spatial distribution of vacancies is considered. The generation rate of vacancies all over the sites and a density of their dislocation-type sinks are modelled as independent random uniform stationary fields and with certain defined parameters of fluctuation correlations— spatial and temporal ones. Such stochastic fields can induce a spatial redistribution of vacancies that can lead to their density stationary uniform field or stochastic one. By the average value and correlation functions of these fluctuations, the conditions are determined for interacting fluctuations of the vacancies’ density, under which this homogeneous random field becomes unstable in relation to the stochastic field with a spatially periodic mean distribution of vacancies’ density. For instance, with f.c.c. nickel as a model of the irradiated functional material, the temperature dependence of spatial period d(T) of the modulated dissipative structure of vacancies’ subsystem in f.c.c. crystal is numerically forecasted and analysed, taking into account the total (‘electrochemical’ + ‘straininduced’) interaction between vacancies. Such d(T)-dependence is also determined by the kinetic characteristics of vacancies’ redistribution.