38éme Colloque de Métallurgie de l'INSTN
Les intermétalliques : des superalliages aux quasicristaux

J. Phys. IV France 06 (1996) C2-15-C2-20
DOI: 10.1051/jp4:1996203

EXAFS Study of the Local Atomic Order in Ti₂AlX (X=Nb, Mo) B2 Intermetallic Compounds

T. Sikora¹, G. Hug¹, M. Jaouen² and A.-M. Flank<sup>3

1</sup>  Laboratoire d'Etudes des Microstructures, ONERA-CNRS, BP. 72, 92322 Châtillon, France
²  Laboratoire de Métallurgie Physique, URA 131 du CNRS, 40 avenue du Recteur Pineau, 86022 Poitiers cedex, France
³  Laboratoire d'Utilisation du Rayonnement Electromagnétique, CNRS-CEA-MEN, Centre Universitaire de Paris Sud, Bât. 209D, 91405 Orsay cedex, France

Abstract
Extended X-ray absorption fine-structure (EXAFS) has been used to study the local atomic order in Ti₂AlMo and Ti₂AlNb in the B2 phase. It is found that the Mo and Nb atoms have different behaviors. Whereas the Ti₂AlMo alloy is ordered as a pseudo-B2 structure in which the Mo and Al atoms are localized on one site and Ti atoms on the other, the Ti₂AlNb alloy exhibits a more disordered behavior since the Nb and the Ti atoms are distributed on both sites. EXAFS experiments allowed us to quantify the fraction of Nb on each site in Ti₂AlNb as well as the bond lengths in both alloys.

© EDP Sciences 1996