Atomic-migration-controlled processes in intermetallics

Author(s)

Rafal Kozubski, A. Biborski, Miroslaw Kozlowski, Christine Goyhenex, Veronique Pierron-Bohnes, Mebarek Alouani, Marcus Rennhofer, S. Malinov

Abstract

Chemical ordering kinetics in Ll(0)- and B2-ordered AB binary intermetallics was simulated by means of Monte Carlo (MC) technique implemented with vacancy mechanism of atomic migration. While vacancy concentration is usually much lower than the antisite defect concentration in Ll(0)-ordered systems, triple defects are generated in particular B2-ordered systems. The latter definitely affects the chemical ordering process and requires that full thermal vacancy thermodynamics is involved in B2-ordering simulations. The study on Ll(0)-ordered binaries was dedicated to FePt thin layers considered as a material for ultra-high-density magnetic storage media. Metastability of the Ll(0) c-variant with monoatomic planes parallel to the layer surface and off-plane easy magnetization was revealed. Thermal vacancy formation in B2-ordered binaries was modelled by implementing a mean-field Hamiltonian with a specific formalism of phase equilibria in a lattice-gas composed of atoms and vacancies. It was demonstrated that for particular pair-interaction energetics, equilibrium concentrations of vacancies and antisites result mutually proportional in well-defined temperature ranges. The MC simulations of B2-ordering kinetics involved the modelled equilibrium vacancy concentration and reproduced the experimentally observed low rate of the process.

Organisation(s)

Dynamics of Condensed Systems

External organisation(s)

Jagiellonian University in Krakow, Université de Strasbourg, University College Dublin

Pages

113-118

No. of pages

6

DOI

https://doi.org/10.4028/www.scientific.net/DDF.277.113

Publication date

2008

Austrian Fields of Science 2012

103015 Condensed matter

Portal url

https://ucris.univie.ac.at/portal/en/publications/atomicmigrationcontrolled-processes-in-intermetallics(cf4cbe50-0920-4613-8333-27566ce43441).html