Research

Ab-initio calculations for structural properties of Zr–Nb alloys

Ab-initio calculations for the structural properties of Zr-Nb alloys at different values of the niobium concentration are done at zero temperature. Different cases for Zr-Nb alloys with unit cells having BCC and HCP structures are considered. Optimal values of the lattice constants are obtained. Critical value for the niobium concentration corresponding to the structural transformation HCP->BCC at zero temperature is defined. Electronic densities of states for two different structures with niobium concentrations 12.5% and 25% having HCP and BCC structures, accordingly, are studied.

V.O. Kharchenko, D.O. Kharchenko. Ab-initio calculations for structural properties of Zr–Nb alloys, Cond.Mat.Phys., 16, 13801(1-8) (2013).

Ab-initio modeling of Zr-alloys

Ab-initio calculations of the electronic structure for Zr - 12.5 % Nb and Zr - 25 % Nb alloys are done using density functional theory, method of linearized augmented plane-wave approximation and generalized gradient approximation. The structural and energetic properties, such as the electron densities, densities of states, energetically and X-ray spectra in the case of the hcp and bcc lattices are calculated. Optimal values for the lattice constants are found. The most favorable structure for each studied alloy is defined

V.O.Kharchenko, D.O.Kharchenko, A.V.Dvornichenko. Properties of Zr - 12.5% Nb and Zr - 25% Nb alloys with hcp and bcc lattices: ab-initio modeling, J. Nano- Electron. Phys., 4, N2, 02034 (2012).

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).

Our Team

Recent News

  • Seminar. 10.12.2015
    2015-12-09 11:24:00

    Науковий семінар зі статистичної фізики та мікроструктурних перетворень. Доповідач: Харченко Д.О. ...

  • Seminar. 03.12.2015
    2015-12-02 11:24:00

    Науковий семінар зі статистичної фізики та мікроструктурних перетворень. Доповідач: Харченко В.О. ...

  • Seminar. 12.11.2015
    2015-11-09 09:29:00

    Науковий семінар зі статистичної фізики та мікроструктурних перетворень. Доповідач: Бистрик Юрій...

  • Seminar. 17.09.2015
    2015-09-11 09:29:00

    Науковий семінар зі статистичної фізики та мікроструктурних перетворень. Доповідач: Заскока Антон...

  • Seminar. 21.05.2015
    2015-05-20 09:29:00

    Науковий семінар зі статистичної фізики та мікроструктурних перетворень. Доповідач: Латишев...