Henning Friis Poulsen
ABSTRACT:Crystalline materials such as most metals, ceramics, rocks and bone tend to self-organize in hierarchically structures comprising e.g. defects, domains and grains. This organization governs the mechanical properties and influence others, such as the electrical properties of multiferroics. Despite of this broad impact, we are far from understanding the underlying processes. As an example, the best models for plastic deformation of metals can hardly even predict that patterning taking place. In the first part of this talk I will present synchrotron based diffraction tomography and diffraction microscopy techniques that allows for 3D movies to be acquired locally within representative (bulk) samples. By zooming in and out the local phase, orientation and strain may be monitored on length scales from 1 mm to 20 nm. I discuss how such movies can be used as input to guide and validate multiscale materials modelling. In the second part I demonstrate the use of the methodologies in an attempt to provide a physics based description of the patterning processes taking place when deforming metals. The talk will conclude with some future research directions based on collaboration with Stanford.
BIO: Henning Friis Poulsen is a professor at the Physics Department of the Technical University of Denmark. His research interest is at the crossroad between x-ray and neutron physics, crystallography and multiscale materials science (metals, energy materials). Specifically, he has developed hard X-ray microscopy as an in situ approach for filming the evolution of the internal structure of hierarchical materials and applied this for studies of plasticity, coarsening and flow. He is the recipient of two ERC Advanced Grants, the head of the 3D Imaging Center in Denmark, and involved with instrumentation at ESRF, ESS and MAX IV. Moreover, he is co-founder of three companies.