PROBING ON MICROSTRUCTURAL HETEROGENEITY OF La-BASED METALLIC GLASS: BASED ON THE STRESS RELAXATION

Metallic glass exhibits outstanding physical and mechanical properties owing to its unique microstructure. Many investigations demonstrated that the microstructural heterogeneity of metallic glasses is a challenging issue in the field of metallic glasses. The microstructural heterogeneity of metallic glasses is difficult to characterize with the help of the traditional techniques/methods. How to establish the intrinsic correlation between the macroscopic mechanical properties and microstructural heterogeneity of metallic glass is a crucial scientific challenging issue of solid mechanics. In the current work, La₆₂Cu₁₂Ni₁₂Al₁₄ metallic glass was selected as the model alloy. The stress relaxation behavior over a wide temperature window was investigated. One attempt to explore the evolutionary patterns of microstructural heterogeneity in metallic glasses under mechanical stimuli. With the help of stretched exponential equation and activation energy spectrum model, effect of thephysical aging below the glass transition temperature on the stress relaxation behavior was investigated. In parallel, in the framework of the free volume theory, the evolution of stress and defect in metallic glass during stress relaxation process was analyzed, thereby obtaining the effects of the aforementioned processes on the mechanical properties and structural state of metallic glasses. In addition, the competition between aging and deformation during the stress relaxation behavior was discussed, and a potential physical mechanism was clarified based on the flow units model. This current work employs stress relaxation as a mechanical excitation approach, on the basis of experimental investigations and theoretical analysis, one tries to reveal the evolution of the microstructural heterogeneity in metallic glasses during deformation from the perspective of mechanical response.