The Research of the Dynamic Displacements of Atoms at the Introduction of Interstitial Atoms in Ni3Al Intermetallide Containing Symmetric Tilt Grain Boundaries

Mikhail D. Starostenkov ,  Roman Y. Rakitin ,  Barchagul' D. Nurkenova 

Altai State Technical University (ASTU), Lenin st.46, Barnaul 656038, Russian Federation

Abstract

Grain boundaries are the integral part of the structure of polycrystals. Grain boundaries can be the source or flow of vacancies or interstitial atoms due to the presence of free volume. In this connection, absorption and emission of such defects take place. Such behaviour of grain boundaries can lead to the strengthening of the material. In the paper, structural reconstructions of atoms in Ni3Al alloy with symmetric grain boundaries of tilt were studied at different concentration of interstitial atoms Ni and Al. The experiment was made by the method of molecular dynamics using Morse pair potential. The calculated crystal represented parallelepiped and contained 25000-35000 atoms. The grain boundaries were located in the middle of the block. The inculcations were given randomly over the whole volume of the crystal so as stoichiometry of the crystal was not broken. The total amount of inculcated interstitial atoms was equal to 0.1 % - 1 % from the total amount of atoms of the crystal block. Then, low temperature relaxation was made. The displacements near inculcated atom were observed, the crystal energy decreased. Thereupon, dynamic relaxation during 50-100 ps at temperature 0.3 T melt took place. The research showed that inculcated atoms of Ni displaced for considerable big distances than inculcated atoms of Al. If inculcated atoms were located at the distances 5-10 Å between each other, they were able to form complexes of defects. The inculcated defects displaced in the direction of the grain boundary, if the distance between them and the boundary was 10-15 Å. But the grain boundary did not emit inculcated atoms. The following main mechanisms were observed at the displacement of atoms: a chain of the displacements of atoms, cyclic mechanisms, crowdion mechanisms. The dependences of the logarithm of diffusion coefficient on the inverse value of temperature were constructed for different concentrations of the inculcated atoms.

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Presentation: Poster at E-MRS Fall Meeting 2009, Symposium I, by Mikhail D. Starostenkov
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-08 08:21
Revised:   2009-06-07 00:48
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