X-ray photon correlation analysis of martensitic transformation

A German group led by Professor U. Klemradt (Aachen University) has recently performed an X-ray photon correlation spectroscopy (XPCS) experiment on martensitic transformation of a Au_50.5Cd_49.5 single crystal. XPCS experiments basically consist of the observation of a time-dependent speckle pattern caused by scattering of coherent X-ray photons, and give information on the dynamics of phase transformations in soft and hard condensed matter at atomic length scales. The measurement was done at ID 10A, European Synchrotron Radiation Facility (ESRF) in Grenoble, France. A standard Bragg scattering geometry was employed to see the fluctuations of the symmetric (0 0 1) Bragg reflection from the polished surface of the Au-Cd single crystal. The research team observed slow non-equilibrium-dynamics in a narrow temperature interval in the direct vicinity of the otherwise athermal phase transformation. For more information, see the paper, "Slow Aging Dynamics and Avalanches in a Gold-Cadmium Alloy Investigated by X-Ray Photon Correlation Spectroscopy", L. Muller et al., Phys. Rev. Lett. 107, 105701 (2011).