Atomic-Ordering Kinetics and Diffusivities in Ni–Fe Permalloy
Using the static concentration waves’ method and self-consistent-field approximation, the Onsager-type kinetics equation is solved to describe the L12-type long-range order (LRO) relaxation. To calculate the diffusivities for Permalloy, the experimental diffraction data in respect to LRO-parameter evolution for Ni3Fe are used. Theoretical curves of a time-dependent LRO for Ni– Fe are plotted. Dilution of alloying element (with a deviation from stoichiometry) results in deceleration of the LRO-parameter history (at the initial evolution stage) and in an increase of its relaxation time. Both statistical-thermodynamics and kinetics results show: at high temperatures, equilibrium LRO parameter for non-stoichiometric Permalloys can be higher than for stoichiometric one.
Andreas Öchsner and Graeme E. Murch
T. M. Radchenko and V. A. Tatarenko, "Atomic-Ordering Kinetics and Diffusivities in Ni–Fe Permalloy", Defect and Diffusion Forum, Vols. 273-276, pp. 525-530, 2008