Atomic dynamics in molten AlCu alloys of different compositions and at different temperatures by cold neutron scattering

TitleAtomic dynamics in molten AlCu alloys of different compositions and at different temperatures by cold neutron scattering
Publication TypeJournal Article
Year of Publication2013
AuthorsDahlborg U, Besser M, Kramer MJ, Morris JR, Calvo-Dahlborg M
Journal TitlePhysica B-Condensed Matter
Volume412
Pages50-60
Date Published03
Type of ArticleArticle
ISBN Number0921-4526
Accession NumberWOS:000314764900011
Keywordsab-initio, Chemical, diffusion, dynamics, excitations, initio molecular-dynamics, kinetic-theory, liquid binary-alloys, metals, microscopic, Molten alloys, neutron scattering, ni, ordering, simulations, structure
Abstract

The atomic motions in molten Al1-xCux (x=0.10, 0.171 and 0.25) around the eutectic composition (x=0.171) were studied by cold neutron inelastic scattering at three different temperatures (973 K, 1173 K and 1373 K). An alloy of eutectic composition containing the Cu-63 isotope was also studied. Self-diffusion coefficients for the Cu ions were determined from the width of quasielastic peaks and were found to decrease slightly with increasing Cu concentration. Longitudinal current correlation functions J(l)(Q,E) exhibit at all temperatures and at all compositions a shoulder at energies below 10 meV and one main maximum at higher energies. These features can be interpreted in terms of excitations of acoustic and optic nature. The shape of J(l)(Q,E) is sensitive to composition, being considerably more structured for larger Cu content. This can be coupled to the existence of a prepeak in the measured zeroth moment of dynamic scattering function indicating an increased chemical ordering with increasing Cu concentration for all temperatures. Indications for an existence of a liquid-liquid phase transition are presented. (C) 2012 Elsevier B.V. All rights reserved.

URL<Go to ISI>://WOS:000314764900011
DOI10.1016/j.physb.2012.12.019