Pattern formation in self-assembly metallic composite structures under non-isothermal growth conditions

In situ studies of microstructure evolution or changes in materials in response to external fields can be extended to resolutions beyond the current limits by the new hard X-ray transmission microscopy being developed at the ESRF. Using compound refractive X-ray optics, the microscope can be operated both in monochromatic and non-monochromatic modes, the latter by applying a special illumination scheme that effectively reduces chromatic aberrations. The non-monochromatic mode provides two orders of magnitude increase of the brilliance in the sample position, which opens for X-ray tomography acquisition on the scale of 1?2 s, with spatial resolutions below 200 nm, while radiography with similar spatial resolution can be acquired at millisecond frame rates. Potential application areas of fast 2D and 3D microscopy have been demonstrated with a few selected science cases, comprising regular and irregular eutectic solidification microstructure formation in different Al-based alloys, and self-assembly of colloidal crystal systems composed of different polymer particles with diameters in the micrometer range. Operation of the microscope in Zernike phase contrast extends the range of possible applications to samples that other- wise would produce only faint contrast.

The project aims to further develop the recent high-resolution transmission X-ray microscopy (HRTXM) setup at beam line ID6 for time-resolved studies in 3D of evolving mesoscopic structures. To commission the setup in situ studies will be carried out on s elf-assembly patterns that form during growth of metallic composites in ternary eutectic systems. The in situ studies will focus on pattern formation physics outside the near-isothermal planar interface stability limits, and should if successful bring abo ut truly novel and unique information on self-organised eutectic structure formation in multicomponent systems. The patterns, composite interface morphologies and propagation dynamics constitute contrast objects that evolve in spatio-temporal ranges whi ch are very well studied to the performance of the HRTXM.