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.
