Study of the structural dynamics in metallic materials in the vitreous state

Candidate Yajuan Duan defended the thesis on March 13, 2024. The thesis, co-supervised by Drs. Jichao Qiao (Northwestern Polythecnic University, Xi'an) and Eloi Pineda (UPC), shows how the structural dynamics and atomic mobility of metallic materials with non-crystalline structure evolves during thermal and mechanical treatments. This study allows improving the pre-processing of these materials to modify and improve their mechanical properties.

Metallic glasses, especially high-entropy metallic glasses, characterized by their unique microstructure and mechanical properties, provide an effective way for investigating relaxation dynamics and related aspects in the field of glass science. This doctoral thesis focuses on the dynamic and structural heterogeneity of metallic glasses, with an emphasis on high-entropy

metallic glasses, unraveling the complex correlation between their microstructural characteristics, thermal behavior, and mechanical properties. The research aims not only to enhance the theoretical understanding of these materials but also to explore novel methods for their modulation and optimization.

An extensive characterization of dynamic and structural heterogeneity in metallic glasses is studied, The study reveals a critical temperature-dependent decrease in dynamic heterogeneity and enhances our comprehension of the fundamental properties of metallic glasses, especially in relation to their mechanical response. Furthermore, the modulation of dynamic heterogeneity in metallic glasses is unveiled. The studies through dynamic cyclic loading, creep testing, and stress relaxation measurements provide a more profound understanding of mechanical hysteresis loops and the mechanisms of inelastic deformation. Finally, the intrinsic correlation between dynamics and thermodynamics in high-entropy metallic glasses is investigated across both super-high and extremely low frequency domains.

Overall, this dissertation contributes substantially to the domain of non-equilibrium physics in glassy materials. The comprehensive analysis and findings of this research provide novel insights into the aging and relaxation dynamics of metallic glasses, enhancing our understanding of these complex materials. The comprehensive analysis and novel findings presented herein have far-reaching implications for the development, optimization, and application of metallic glasses, paving the way for future advancements in their application and functionality.