Dresden 2006 – wissenschaftliches Programm
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MM: Metall- und Materialphysik
MM 4: Phase transitions I
MM 4.2: Vortrag
Montag, 27. März 2006, 10:30–10:45, IFW D
Coarsening dynamics in elastically anisotropic alloys — •Bastian Pfau1, Lorenz-Mathias Stadler1, Bogdan Sepiol1, Richard Weinkamer2, Federico Zontone3, and Gero Vogl1 — 1Fakultät für Physik der Universität Wien, Strudlhofgasse 4, A-1090 Wien, Austria — 2Max-Planck-Institut für Kolloid- und Grenzflächenforschung, D-14424 Potsdam, Germany — 3European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex, France
With the availability of coherent X-rays at third-generation synchrotrons it became possible to investigate the very slow dynamics of precipitate coarsening in phase separating alloys by utilising the emerging method of X-ray photon correlation spectroscopy [1]. Here, we present an in-situ study of coarsening dynamics in elastically anisotropic alloys [2]. Fluctuating speckle intensities in time series of coherent small-angle X-ray diffraction images are analysed for two different Ni–Al–Mo samples with different lattice misfit between precipitates and matrix. The detected long-term correlations depend not only on the norm but strongly on the direction of the scattering vector. The experimental findings are compared with results from Monte Carlo simulations. Our experiments together with the simulations indicate that in alloys with high elastic misfit, precipitate coarsening proceeds almost exclusively within {100 } planes. Furthermore, our data suggest that plate-like precipitates are formed by coalescence of smaller particles.
[1] L.-M. Stadler et al., Phys. Rev. B 68, 180101(R), (2003).
[2] B. Pfau et al., Europhys. Lett., to be submitted.