ATOMISTIC MODELLING OF SUPERSTRUCTURE REFINEMENT IN CRYSTALLINE MATERIALS
|Rafal Kozubski 3, Ewa Partyka 3, Mirosław Kozłowski 3, Véronique Pierron-Bohnes 1, Wolfgang Pfeiler 2|
1. Institut de Physique et Chimie des Materiaux de Strasbourg, UMR7504, CNRS - ULP, 23, rue du Loess, BP 43, Strasbourg CEDEX 2 67034, France
Chemical ordering in multicomponent crystalline systems is of fundamental technological importance and knowledge of its dynamics (kinetics) is crucial in materials engineering. The process, however, always competes with the general tendency for entropy maximization and hence, at any non-zero temperature T finite concentration of antisite defects is observed and increases with increasing T. Consequently, a change of system temperature is followed by generation/annihilation of antisite defects, so-called "order-order" relaxation, whose mechanism (atomic migration) is the same as that of diffusion. The kinetics of both phenomena are different due to non steady-state conditions during relaxation. "Order-order" relaxation may be successfully modeled by computer simulations, which involves the following tasks: (i) approximation of system energetics (Hamiltonian), (ii) energetics and thermodynamics of structural defects (vacancies, interphases, surfaces), (iii) implementation of particular atomic-jump mechanism, (iv) adaptation/elaboration of computer codes.
Presentation: oral at E-MRS Fall Meeting 2004, Symposium H, by Rafal Kozubski
See On-line Journal of E-MRS Fall Meeting 2004
Submitted: 2004-02-19 17:51 Revised: 2009-06-08 12:55