Understanding the structural origins of embrittlement in amorphous alloys

Objective

From the glass in windows to plastics and gels, amorphous materials are everywhere in our daily lives. A particular class of amorphous materials are metallic glasses (MGs), which possess a disordered glassy microstructure that is exploited in high-tech applications, including biomedical micro- and nano-electromechanical systems and energy-efficient soft magnetic devices. Whilst exceptional in many regards, MGs suffer from unpredictable property changes that are driven by aging of the glass structure. Indeed, a long-standing question in MG-research is to uncover the structural origin of annealing-induced embrittlement in the glassy solid domain. This is what UN-STRUCT will answer. Building on novel insights from atomistic simulations of glassy microstructural evolution, the project proposes a unique cross-scale experimental approach. This approach combines macro- and nanoscale probing of mechanical performance in the evolving glassy microstructure and its structural correlation lengths, integrated with synchrotron-based extended X-ray absorption fine structure analysis. In concert, the proposed approach will quantify the annealing-induced structural origins of abrupt toughness losses that MGs suffer from. Atomic-scale structural and nano-scale mechanical probing along annealing isotherms will be pursued by the applicant in the hosting group, whereas the link to macroscale mechanical performance will be conducted during a two-months secondment abroad. If successful, UN-STRUCT will solve a long-standing fundamental challenge in glass science, enabling the reliable and safe use of MGs in engineering applications operating at practical, application-relevant time scales. The applicant, experienced in nanomechanical testing, will significantly expand her technical knowledge, methodology skills, and professional network, all of which are relevant for her future employability as principal investigator in the materials engineering field.