Pattern formation of point defects

Abnormal grain growth in nonequilibrium systems: Effects of point defect patterning

We present a mean-field model for abnormal grain growth processes described by competition of both deterministic and stochastic mechanisms with the grain mobility depending on the grain size. The derived approach is applied to study delayed dynamics of grain growth in system of point defects subjected to irradiation according to the swelling rate theory for irradiated materials. We have shown that with the irradiation dose increase, the corresponding grain growth dynamics is slowed down and growth processes with power-law time asymptotics are realized. We discuss behavior of grain size distributions with competing regular and fluctuation mechanisms. © 2014 American Physical Society.

V.O.Kharchenko, D.O.Kharchenko. Abnormal grain growth in nonequilibrium systems: Effects of point defect patterning, Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 89(4), art. no. 042133 (2014)

Properties of spatial arrangement of V-type defects in irradiated materials: 3D-modelling

We consider dynamics of pattern formation in system of point defects under sustained irradiation within the framework of the rate theory. In our study we generalize the standard approach taking into account a defects production by elastic fields and a stochastic production, representing internal multiplicative noise. Using 3D-modeling we have shown that with the damage rate growth a morphology of clusters composed by vacancies is changed. The same effect is observed with variation in the multiplicative noise intensity. Stationary patterns are studied by means of correlation analysis.

V.O. Kharchenko, D.O. Kharchenko. Properties of spatial arrangement of V-type defects in irradiated materials: 3D-modelling, Cond.Mat.Phys., 16,  33001(1-12) (2013).

Pattern formation of point defects in systems subjected to irradiation

We consider spatial organization of point defects in the generalized model of defects formation in elastic medium by taking into account defects production by irradiation influence and stochastic contribution for defects dynamics satisfying the fluctuation dissipation relation. We have found that depending on initial conditions and control parameters reduced to defects generation rate caused by irradiation, temperature and the stochastic source intensity different stationary structures of defects can be organized during the system evolution. Studying phase transitions between phases characterized by low- and high defect densities in stochastic system we have shown that such phenomena are described by mechanisms inherent in entropy-driven phase transitions. Stationary patterns are studied by amplitude analysis of unstable
slow modes.

V.O.Kharchenko, D.O.Kharchenko. Noise-induced pattern formation in system of point defects subjected to irradiation, Eur. Phys. J. B, 85, 383 (2012).

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