  The microscopic model of atomic diffusion is considered to describe the
short-range order relaxation kinetics within the f.c.c.-Ni-Fe Permalloys. The
model takes into account both the discrete and anisotropic characters of atomic
jumps within the long-range field of concentration heterogeneities of the
interacting atoms. The diffusion coefficients and activation energies for the
disordered Ni-Fe permalloy are estimated with the evaluated probabilities of
atomic jumps. As shown, the increasing of a temperature with a fixed
composition influences on the 'potential' field of interatomic interaction
ambiguously: the field 'potential' increases for defined coordination shells
and decreases for some of other ones. Although the temperature increasing
promotes the increasing of any atomic-probabilities jumps generally, but
decreasing of the action of 'potential' field generated by the atoms of defined
element and caused by its concentration heterogeneities onto the distant sites
results in increasing of the atomic-jumps' probabilities of just this element,
first of all, into the sites, which are more distant from the 'source' of
heterogeneity. Within the framework of the static concentration waves' method
along with the self-consistent field approximation, the Onsager-type kinetics
equation is obtained to describe the long-range order relaxation by the
L12-type superstructure. To calculate diffusivities for the ordered Ni3Fe
permalloy, the independent, diffraction experimental data of the long-range
order parameter relaxation are used. Theoretical curves of the long-range order
time evolution for the non-stoichiometric f.c.c.-Ni-Fe permalloys are plotted.
Decreasing of the concentration of alloying element results in decelerating of
the long-range order parameter change and in increasing of its relaxation time.
