Atomic and magnetic ordering in bcc Cu?Al?Mn: computational study

ALEJANDRO ALÉS; FERNANDO LANZINI

MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING

IOP PUBLISHING LTD

Lugar: Londres; Año: 2014 vol. 22 p. 850071 - 8500716

0965-0393

The β phase of the ternary alloy Cu?Al?Mn, with bcc structure, displays aninteresting variety of long-range atomic ordering and magnetic transitions.In this work, we present a model that allows an accurate reproduction ofthe measured critical temperatures for alloys with compositions along thepseudobinary line Cu3 Al ↔ Cu2 AlMn. The method is based on the MonteCarlo technique, allowing simultaneous evolution of the atomic distributionand the magnetic state. The configurational part of the energy is representedwith a three-state Hamiltonian; the six interchange energies that govern thechemical interactions between nearest and next-nearest neighbours atoms havebeen determined. The magnetic counterpart is modelled by means of an Isingmodel. The predicted Curie temperatures agree well with the experimentalvalues when it is assumed that the crystal configuration remains fixed and withthe maximum possible degree of atomic ordering. The effects of configurationaldisorder on the magnetic transition have been evaluated.