Rejuvenation engineering in metallic glasses by complementary stress and structure modulation

Residual stress engineering is widely used in the design of new advanced lightweight materials. For metallic glasses, attention has been given to structural changes and rejuvenation processes. High-energy scanning X-ray diffraction strain mapping reveals large elastic fluctuations in notched metallic glasses after deformation under triaxial compression. Microindentation hardness mapping hints at a competing hardening-softening mechanism after compression and reveals the complementary effects of stress and structure modulation. Transmission electron microscopy proves that structure modulation and elastic heterogeneity distribution under room temperature deformation are related to shear band formation. Molecular dynamics simulations provide an atomistic understanding of the confined deformation mechanism in notched metallic glasses and the related fluctuations in the elastic and plastic strains. Thus, future focus should be given to stress modulation and elastic heterogeneity, which, together with structure modulation, may allow the design of metallic glasses with enhanced ductility and strain-hardening ability. In this work, by involving high-energy scanning X-ray diffraction strain mapping, we identify and distinguish between structural and elastic heterogeneity in the extremely rejuvenated metallic glasses under triaxial compression. Microindentation hardness hints at an unsymmetrical hardening/softening picture and further reveals the complementary effects of stress and structure modulation. Our results suggest that simultaneous stress and structural modulation can be used to enhance rejuvenation beyond the limits known to date, and may therefore aid in the design of MGs with enhanced ductility and strain-hardening capability.

Automated summary

Residual stress engineering is important for the design of advanced lightweight materials. In this study, the effects of stress and structure modulation on metallic glasses were investigated using various techniques, such as high-energy scanning X-ray diffraction and microindentation hardness mapping. The results show that simultaneous stress and structural modulation can enhance the ductility and strain-hardening ability of metallic glasses.