Dynamics of metallic glasses explored by mechanical relaxation

This thesis explores the dynamics of metallic glasses (MGs) using dynamic mechanical analysis (DMA) to investigate the relaxation processes, particularly focusing on secondary relaxations termed as β-relaxation. These relaxations are characterized in DMA as excess wings or shoulders of primary relaxation peaks and are crucial for understanding the transition between the solid glass and supercooled liquid states. Although early studies suggested that β-relaxation arises from anelastic events within a metastable state, its origins remain unclear. This research employs quasi-static measurements such as creep and stress relaxation alongside DMA, reviewing current theoretical models and pertinent experimental data. Three distinct MG systems, Cu46Zr46Al8, Pd42.5Ni7.5Cu30P20, and Fe55Cr10Mo14C15B6, are analyzed to elucidate the varying behaviors of β-relaxations in DMA results and their different underlying mechanisms. The implications of these findings on the mechanical properties of MGs are discussed, highlighting their relevance to physical aging, mechanical deformation, and internal damping processes. Ultimately, this work aims to enhance our understanding of relaxation dynamics in metallic glasses to facilitate the development of new alloys with better mechanical performance.