Yu. N. Gornostyrev

Ternary site preference energies, size misfits and solid solution hardening in NiAl and FeAl

The electronic structure of NiAl and FeAl doped with Ti, V, Cr, Mn, Fe, Co, Y, La and Zr additions in both sublattices has been investigated with the local density linear muffin-tin orbital (LMTO) method. The peculiarities of chemical bonding for both undoped and with some ternary additions in NiAl and FeAl were analyzed using the LMTO-Green function method. The preferred sites for ternary additions were found and the sensitivity of site preference energies to crystal relaxation effects was investigated. It was shown that the relaxation has an elastic nature and the values of size misfit parameters for substitutional impurities were estimated. The experimental data concerning solid solution hardening were reanalyzed and the additional contributions to hardening besides the conventional size misfit mechanism were shown to be of importance for Ti ternary additions.

Superdislocation core structure in L12 Ni3Al, Ni3Ge and Fe3Ge: Peierls–Nabarro analysis starting from ab-initio GSF energetics calculations

Superdislocation core structures in L1 2 Ni3Ge, Fe3Ge and Ni3Al were determined on the basis of ab-initio generalized stacking fault (GSF) energetics calculations. Superdislocation dissociation schemes, partials separation and core widths were calculated within the modified Peierls–Nabarro (PN) model with ab-initio GSF parameterization. Calculated superdislocation core structure parameters were found to be in agreement with available experimental data. The superdislocation core with type I (fourfold) dissociation was found to be unstable in Fe 3Ge but stable and energetically preferred in Ni3Ge and Ni3Al. These results allows us to suggest a mechanism for the octahedral glide being inactive in Fe 3Ge which is found to be different in several aspects with those discussed so far in the literature.  2002 Acta Materialia Inc. Published by Elsevier Science Ltd.

Magnetism and local distortions near carbon impurity in gamma-iron.

Local perturbations of the crystal and magnetic structure of gamma-iron near carbon interstitial impurity is investigated by ab initio electronic structure calculations. It is shown that the carbon impurity creates locally a region of ferromagnetic ordering with substantial tetragonal distortions. Exchange integrals and solution enthalpy are calculated, the latter being in very good agreement with experimental data. The effect of the local distortions on the carbon-carbon interactions in gamma-iron is discussed.

Dangling bonds and magnetism of grain boundaries in graphene

Grain boundaries with dangling bonds (DBGB) in graphene are studied by atomistic Monte Carlo and molecular dynamics simulations in combination with density functional (SIESTA) calculations. The most stable configurations are selected and their structure is analyzed in terms of grain boundary dislocations. It is shown that the grain boundary dislocation with the core consisting of pentagon, octagon and heptagon (5-8-7 defect) is a typical structural element of DBGB with relatively low energies. Electron energy spectrum and magnetic properties of the obtained DBGB are studied by density functional calculations. It is shown that the 5-8-7 defect is magnetic and that its magnetic moment survives after hydrogenation. The effects of hydrogenation and of out of plane deformations on the magnetic properties of DBGB are studied.

Effect of magnetic state on the gamma-alpha transition in iron: First-principles calculations of the Bain transformation path

Energetics of the fcc (

Role of magnetism in the formation of a short-range order in iron-silicon alloys

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Effect of magnetism on the solubility of 3d elements in BCC iron: Results of first-principle investigations

) - bcc (

Composition of cementite in the dependence on the temperature. In situ neutron diffraction study and Ab initio calculations

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Complex evolution of dislocation core structure in a process of motion: model analysis with ab-initio parameterization

) lattice transformation by the Bain tetragonal deformation is calculated for both magnetically ordered and paramagnetic (disordered local moment) states of iron. The first-principle computational results manifest a relevance of the magnetic order in a scenario of the

Structural transformations in Fe-Ni-alloy nanoclusters: Results of molecular-dynamic-simulation

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