The 8th International Conference on Matter and Radiation at Extremes (ICMRE2025)

191 / 2025-03-21 23:09:52

Stress-dependent dynamic response and microstructural adaptation revealed by time-resolved diffraction

dynamic response,in-situ XRD

High-strain-rate deformation and structural phase transformations exhibit fundamentally distinct characteristics compared to quasi-static processes. Emerging experimental evidence reveals significant deviations from equilibrium phase transition pathways under dynamic compression, where shear stress involvement facilitates the formation of metastable structures absent from conventional phase diagrams. These observations underscore the complex interplay between equilibrium thermodynamics and nonequilibrium kinetics in governing the structural evolution of transition metals under extreme loading conditions, particularly when phase transformations become intricately coupled with plastic-deformation-induced microstructures. Through systematic investigation of two prototypical systems - textured copper and amorphous germanium - employing in situ X-ray free-electron laser (XFEL) diagnostics, we identify two dynamical processes: (i) texture-driven anomalous phase transition characteristics, and (ii) shock-induced crystallization kinetics and melting behavior in amorphous materials. The observed nonequilibrium pathways provide unprecedented insights into stress-mediated structural evolution mechanisms, establishing a quantitative framework for constructing dynamic phase diagrams.