Kinetic evolution of unmixing in an AlLi alloy using x-ray intensity fluctuation spectroscopy

Abstract

Irreversible decomposition of an AlLi single crystal has been studied by x-ray photon correlation spectroscopy. The precipitate coarsening follows a universal behavior, as measured by the time-resolved average scattering. Using coherent scattering, two-time correlation functions have been measured. The time evolution of the speckle pattern gives new insight into the process of unmixing; at least two regimes govern this evaporation-condensation coarsening process. One is related to the overall arrangement of precipitates, and the characteristic time is linear with annealing time. The other is related to the motion of interfaces and is related to Porod's law.

Statics and kinetics of the ordering transition in theAuAgZn2alloy

“…Frames were summed after ''droplet'' analysis. 17 Critical scattering in the vicinity of the superstructure position is isotropic, as expected in a system dominated by Ising critical fluctuations.…”

X-Ray Intensity Fluctuation Spectroscopy Studies on Phase-Ordering Systems

“…However, there were many fewer attempts to extend XIFS and study nonequilibrium dynamics. The use of two-time correlation functions as proposed in [3,4], to study the dynamics of fluctuations, has proven to be useful in studies of phase separation experiments (model B) [5,6]. This Letter presents the first measurements of two-time correlation functions and their temperature dependence in systems undergoing first-order phase transition with nonconserved order parameter (model A).…”

X-Ray Photon Correlation Spectroscopy at the European X-Ray Free-Electron Laser (XFEL) facility

“…It was furthermore shown in the experiment that the correlation times actually obey a scaling law in agreement with the model expectations. Similar experiments were carried out in phase-separating AlLi alloys and analyzed successfully in terms of two-time correlation functions [18]. It is evident that the XFEL will allow the study of the early (short time) stages of these processes.…”

“…Information on the statistics of fluctuations about this average behaviour (which differs from classical fluctuation statistics) is, however, scarce because conventional methods are not easily applicable since (by the nature of the process) the absolute time matters. A time domain method, such as XPCS, can address such processes, as has been shown in recent prototype experiments [17,18]. Here fluctuations about the average intensity can be quantified by means of a two time (t 1 , t 2 ) intensity correlation function…”