Detrended fluctuation analysis in x-ray photon correlation spectroscopy for determining coarsening dynamics in alloys

作者：Stadler Lorenz M^*; Sepiol Bogdan; Pfau Bastian; Kantelhardt Jan W; Weinkamer Richard; Vogl Gero

来源：Physical Review E, 2006, 74(4): 041107.

DOI：10.1103/PhysRevE.74.041107

We study the dynamics of precipitate coarsening in phase-separating alloys at late stages of phase separation by x-ray photon correlation spectroscopy (XPCS). For analyzing time series of fluctuating speckle intensities from small-angle scattering of coherent x rays, the method of detrended fluctuation analysis (DFA), which is ideal for determining power-law correlations, is applied. We discuss the application of DFA with respect to XPCS data by means of simulated time series. In particular, the effects of different signal-to-noise ratios are examined. Results from measurements of the two model systems Al-6 at. % Ag at 140 degrees C and Al-9 at. % Zn at 0 degrees C are presented. Since the DFA effectively removes adulterating trends in the data, quantitative agreement with Monte Carlo simulations is obtained. It is verified that two different coarsening mechanisms are predominant in the two systems-coarsening either by diffusion of single atoms or by movement of whole precipitates.

• 出版日期2006-10