Unraveling the dynamical and structural origin of embrittlement of metallic glasses

• Applicants: Professor Dr. Robert Maaß; Dr. Birte Riechers
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 573692340

Metallic glasses (MGs) are high-performance alloys with a bright future. However, a central challenge of these structural solids is their metastability and therefore potential property deterioration with time, related to physical aging. Accompanied by an enthalpy relaxation, aging may for example cause a complete loss of toughness. Irrespective of the type of property degradation, the underlying atomic scale origin continue to remain unknown. Latest insights from our earlier work on microsecond-long molecular dynamics simulation nurture a microstructural view of MGs, in which a low-energy motif network is growing during isothermal annealing of the structural glass. This novel microstructural view has the potential to explain macroscopic observations of embrittlement and enthalpy relaxation. However, a direct assessment of this picture and evolving heterogeneity is still to be made. Leveraging fore-front coherent scattering at the now available upgraded 4th generation synchrotrons, the assessment of structural dynamics over an extended realm of wave-vectors, and therefore length scales is possible. The aim of this project is thus to directly identify a structural and dynamical origin of embrittlement in MGs by validating this microstructural model based on micro-second MD simulations. In concert, the inherent metastability of MGs will be addressed by i) mapping out the evolution of toughness and enthalpy under annealing in the solid regime, ii) investigation of wave-vector dependent dynamics from coherent x-ray experiments, iii) analysis of dynamic and static speckle pattern contributions also by new analysis approaches, and iv) finally linking the evolution of the amorphous microstructure to enthalpy relaxation and embrittlement. If successful, this research project may provide a fundamental mitigation strategy for property degradation in MGs.

• DFG Programme: Research Grants