title: Complex precipitation pathways in multicomponent alloys.
abstract: One usual way to strengthen a metal is to add alloying elements and to control the size and the density of the precipitates obtained. However, precipitation in multicomponent alloys can take complex pathways depending on the relative diffusivity of solute atoms and on the relative driving forces involved. In Al-Zr-Sc alloys, atomic simulations based on first-principle calculations combined with various complementary experimental approaches working at different scales reveal a strongly inhomogeneous structure of the precipitates: owing to the much faster diffusivity of Sc compared with Zr in the solid solution, and to the absence of Zr and Sc diffusion inside the precipitates, the precipitate core is mostly Sc-rich, whereas the external shell is Zr-rich. This explains previous observations of an enhanced nucleation rate in Al-Zr-Sc alloys compared with binary Al-Sc alloys, along with much higher resistance to Ostwald ripening, two features of the utmost importance in the field of light high-strength materials.
authors.affiliation: Service de Recherches de Métallurgie Physique, CEA/Saclay, 91191 Gif-sur-Yvette, France. emmanuel.clouet@cea.fr
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Clouet
authors.forename: Ludovic
authors.initials: L
authors.lastname: Laé
authors.forename: Thierry
authors.initials: T
authors.lastname: Epicier
authors.forename: Williams
authors.initials: W
authors.lastname: Lefebvre
authors.forename: Maylise
authors.initials: M
authors.lastname: Nastar
authors.forename: Alexis
authors.initials: A
authors.lastname: Deschamps