First-principles study of atomic ordering in bcc Cu-Al

F. LANZINI; P. H. GRAGANO; P. R. ALONSO; G. H. RUBIOLO

MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING

IOP PUBLISHING LTD

Lugar: London; Año: 2011 vol. 19 p. 150081 - 1500815

0965-0393

The order-disorder transitions and phase stability in the body centered cubic structure of Cu-Al binary alloys are studied by means of theoretical methods. The total energy of different ordered compounds sharing a common bcc Bravais lattice was calculated within the framework of density functional theory. A set of effective cluster interactions was calculated through a cluster expansion (CE) of the total energies. The finite temperature phase diagram of bcc Cu-Al was obtained using the CE formalism coupled with the cluster variation method calculation of the configurational entropy. These results are confronted with a simpler semi-empirical approach based on effective pair interactions obtained from experiment. Both approaches predict a single first-order A2/DO3transition for compositions close to Cu3Al, in agreement with the most recent experimental results.