Published online by Cambridge University Press: 22 June 2015
Through undulator sources at 3rd generation synchrotrons, highly coherent X-rays with sufficient flux are nowadays routinely available, which allow carrying over photon correlation spectroscopy (PCS) from visible light to the X-ray regime. X-ray photon correlation spectroscopy (XPCS) is based on the auto-correlation of X-ray speckle patterns during the temporal evolution of a material and provides access both to equilibrium and non-equilibrium properties of materials at the Angstrom scale. Owing to technical limitations (detector readout), XPCS has typically been used for the detection of slow dynamics on the scale of seconds. The variety of scattering geometries employed in conventional X-ray analysis can be combined with XPCS. In this work, we report on bulk diffraction (XRD) used to study the prototypical shape memory alloy Ni63Al37 undergoing a structural, diffusionless (martensitic) transformation. Two-time correlation functions reveal non-equilibrium dynamics superimposed with microstructural avalanches.