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The research of thermoactivated changes of the structure of antiphase boundaries in Cu3Au and Ni3Al alloys

Mikhail D. Starostenkov ,  Evgenia A. Dudnik 

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

Abstract

It is known that physical and physics-mechanical properties of ordered alloys and intermetallides are connected with the peculiarities of a thin structure of antiphase boundaries (APB). The changes of atomic order near APB <110>{100} and ½<110>{111} in L12 superstructure on the examples of Cu3Au and Ni3Al alloys were studied in the paper. The definite type of APB were introduced in the calculated block of three-dimensional crystal containing 2×105 atoms. Periodical boundary conditions were applied outside the block. Interactions between different pairs of atoms were given by Morse potential. The definite configuration of vacancies was introduced in the system accidentally. Their distribution over the sites was regulated by the condition of keeping of stoichiometric composition A3B. Then the atoms were allowed to occupy vacant sites. Activation of atomic jumps in the dependence on temperature was simulated on the basis of the Monte-Carlo method. The change of the energy of APB formation and local distribution of energy over the planes related to the boundary were observed upon reaching the definite dynamical equilibrium by the crystal. Observed was the distribution of atoms of alloy component, the change of long and short order over the planes which were parallel to a boundary. The extent of the area with transition order with respect to a boundary plane increased with the growth of temperature. Faceting of APB relief took place at the expense of the precipitation of point displacement defects. Main contribution in deformation strengthening is made at the expense of structural reconstruction and changing of order near antiphase boundaries at relatively high temperatures. In this connection, the energy of APB formation decreases with the growth of temperature and washing of a crystal structure near APB is accelerated with the growth of vacancy concentration.

 

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Related papers

Presentation: Poster at E-MRS Fall Meeting 2006, Symposium H, by Mikhail D. Starostenkov
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-20 07:26
Revised:   2009-06-07 00:44