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FORCE Seminar 2025.09.26 Klaus-Dieter Liss
Title: Metals under extremes: Characterization, physical behavior and structural design under high pressure and after high-pressure torsion processing Abstract: The development of advanced technologies requires metals and materials that can withstand extreme environments, including ultra-high temperatures, pressures, and radiation damage. Conversely, such extreme conditions can also be exploited to design new materials with unprecedented properties. Central to both aspects is the characterization of materials — particularly their defect structures — under in-situ conditions at high temperature. This talk will present advanced neutron and synchrotron diffraction techniques for probing structural states, their evolution, anisotropy, and inhomogeneity at room temperature and during heating. Following a brief introduction to modern diffraction methods and their complementarity in studying thermo-mechanical processes, an example of in-situ high-pressure and high-temperature experiments on titanium aluminides will be given. The focus will then shift to materials processed by high-pressure torsion, where the mapping reveals inhomogeneities, residual stresses, and textures. Heating experiments further elucidate microstructural evolution, stress relaxation, dislocation density, grain size changes, recovery, recrystallization, and grain growth. Some systems additionally undergo phase transformations, such as the precipitation of secondary phases, which may be accelerated by the high stored energy in the material. Finally, an outlook will be provided on future applications using FORCE equipment — especially the Twister — for the design of next-generation structural and functional materials.
