Preparation and the thermal stability of CuCr nanostructured materials

Bulk nanostructured materials show extremely high strength compared to bulk materials, and have received unprecedented attention in material research also due to its potential applications in industry. Severe plastic deformation is an emerging and quite efficient route to generate nanocrystalline materials out of normally immiscible systems.

However, the main issue on nanostructured materials is its thermal stability. In this presentation, the thermal stability of nanostructured Cr-Cu materials will be explored at the high spatial resolution using modern spherical transmission electron microscopy (TEM) via simultaneous in-situ imaging and spectroscopy analysis. The evolution of the structural and chemical composition in the nanostructured materials with temperature was tracked in real-time. It demonstrates that the nanostructured materials are not only subjected to a structural change but also to an obvious chemical composition fluctuation upon annealing. The destabilization process in the nanostructured materials starts at a quite low temperature. Real-time imaging and composition determination reveal the concentration changes with temperature, and allows further analyzing the dynamic behavior in nanocrystalline materials in details, i.e. deducing the instantaneous diffusion coefficients and excess vacancy concentration generated by deformation.