Ordering fluctuation dynamics in AuAgZn 2

Frédéric Livet (1) , Mathieu Fèvre (2) , Guillaume Beutier (1) , Mark Sutton (3)

1 SIMaP - Science et Ingénierie des Matériaux et Procédés
2 LEM - ONERA - CNRS - Laboratoire d'étude des microstructures [Châtillon]
3 McGill University = Université McGill [Montréal, Canada]

The second-order ordering transition of the AuAgZn2 alloy has been studied by coherent x-ray scattering. Within a few degrees above the critical temperature Tc, equilibrium critical fluctuations are observed together with some pre-transitional local ordering connected to sample defects. The speckles observed correspond to heterodyne interference between local ordering and fluctuations and show a mixed static and dynamical behaviour in a narrow domain of a few tenths of degree above Tc. The dynamical behaviour is shown to correspond to the critical slowing down of the fluctuations in the vicinity of the transition (model " A " of Hohenberg and Halperin 1). A rough comparison can be carried out with the classical diffusion models. Some improvements of the method are discussed.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Frédéric Livet, Mathieu Fèvre, Guillaume Beutier, Mark Sutton. Ordering fluctuation dynamics in AuAgZn 2. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2015, ⟨10.1103/PhysRevB.92.094102⟩. ⟨hal-01203092⟩