MODELING OF VOID FORMATION UNDER REACTION DIFFUSION IN BINARY SYSTEM

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S. V. Kornienko

Abstract

The proposed model of void formation takes into account existence two types of sinks/sources of non-equilibrium vacancies, depending on their location: in the phase volume and at the interfacial boundaries. At the interdiffusion and reaction diffusion which happens on the vacancy atomic diffusion mechanism, the inequality of atoms fluxes is caused by their differential mobility, give rise to a directional flux of vacancies. This flux of vacancies cause an appearance of areas in a diffusion zone with supersaturation and deficiency in vacancies, where sinks/sources of non-equilibrium vacancies act. It is believed that the voids arise with a certain periodicity near the interfacial boundary, where there is a vacancy supersaturation due to the different mobility of the components. The voids move in volume of growing phase, their sizes change. The void radius increases as long as void is in the region of the diffusion zone where there is a vacancy supersaturation. The void radius begins to decrease if the void is in the area of the diffusion zone, where there is a negative vacancy supersaturation (the concentration of vacancies is less than the equilibrium) until it disappears. The study of the influence on the kinetics of void formation during reaction diffusion in the binary system of sinks/sources of vacancies was carried out by computer simulation. In the case of efficient operation of vacancies sinks/sources only at the borders (vacancies sinks/sources do not work in the phase volume) we get a significant saturation of vacancies in the diffusion zone, which leads to rapid voids growth and the existence of significant pore size differences. If the vacancies sinks/sources in the volume work well (the efficiency of their work at the interfacial boundaries does not affect the result in this case), then almost everywhere in the system an equilibrium concentration of vacancies is established, as a result of which the vast majority of pores have the same (maximum) size. The pore sizes are much smaller than with the previous case.

Article Details

Section
Materials Physics
Author Biography

S. V. Kornienko, The Bohdan Khmelnytsky National University of Cherkasy

Candidate of Physical and Mathematical Sciences, docent,

Educational and Scientific Institute of Information and Educational Technologies,

The Bohdan Khmelnytsky National University of Cherkasy, Cherkasy, Ukraine