Deformation carrier kinetics and microstructural heterogeneity in bulk metallic glasses

The plastic deformation of bulk metallic glasses (BMGs) is dominated by the activation and cooperative motion of deformation carriers, with microstructural heterogeneity exerting a significant influence. Herein, we investigated the microstructural heterogeneity and deformation carrier kinetics of (Zr₅₀Cu₄₀Al₁₀)_100-xDy_x (x = 0 or 2) BMGs during nanoindentation. Based on shear transformation zone (STZ) theory, we calculated the size of deformation carriers and revealed a positive correlation between microstructural heterogeneity and carrier volume—stronger heterogeneity corresponds to larger carrier volumes. The Maxwell-Voigt model and Kohlrausch-Williams-Watts (KWW) equation were employed to analyze creep kinetics, uncovering the dynamic evolution of deformation carriers. Characteristic relaxation spectra indicate that both loading conditions and microstructural heterogeneity regulate the dynamic behavior of deformation carriers. Moreover, enhanced microstructural heterogeneity reduces hardness and modulates the kinetic behavior of deformation carriers. This study provides important experimental and theoretical insights into the correlation between microstructural heterogeneity and deformation carrier kinetics in BMGs.