Relaxation behavior of high-entropy bulk metallic glass: Influences of physical aging and cyclic loading

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<p indent="0mm">In this study, the correlation among the relaxation behavior, deformation mechanism, and structural heterogeneity of metallic glasses is examined using La₃₀Ce₃₀Ni₁₀Al₂₀Co₁₀ high-entropy bulk metallic glass as the model glass. Dynamic mechanical analysis (DMA) was used to investigate the influences of physical aging and cyclic loading on the dynamic relaxation and deformation mechanism of the model glass. The correlation between the deformation units and the structural heterogeneity was analyzed on the basis of the activation energy spectrum (AES). The results demonstrated that La₃₀Ce₃₀Ni₁₀Al₂₀Co₁₀ high-entropy bulk metallic glass displays an apparent β relaxation. A more stable state can be achieved during physical aging below the glass transition temperature and in cyclic loading because the atomic rearrangements are suppressed during these processes. This structural relaxation during the physical aging process enables the transition from liquid-like regions to an elastic matrix. Further, more time is required to activate the deformation units that are frozen during the transition. The applied stress results in a decrease in the number of liquid-like regions, which suppresses the activation of the deformation units during the cyclic loading process. As a result, the intensity of the β relaxation in the metallic glass decreases. Therefore, the origin of the β relaxation in La₃₀Ce₃₀Ni₁₀Al₂₀Co₁₀ high-entropy bulk metallic glass is ascribed to the liquid-like regions.