Revealing the disparate defect evolution paths with loading rates for ductile and brittle metallic glasses via nanoscale creep

Abstract

Ductile and brittle metallic glasses display significantly different mechanical behaviors. However, the microscopic deformation mechanisms and the defect dynamics in different metallic glasses remain unclear. In this work, an experimental strategy based on nanoscale creep was used to detect the defect evolution dynamics at different loading rates for six metallic glasses with varying plasticity. The plastic deformation ability and the strain rate sensitivity of these metallic glasses under different loading rates were systematically investigated. Furthermore, the evolution of defect volume and relaxation time spectrum under varying loading rates was analyzed utilizing the Cooperative Shearing model in conjunction with the Maxwell-Kelvin model. It was observed that ductile and brittle metallic glasses display markedly different defect dynamics at varying loading rates. Finally, a scheme was introduced to illustrate different defect evolution paths with various loading rates for ductile and brittle metallic glasses based on their heterogeneous viscoelastic structure. The study provides insights into the differences in microscopic deformation mechanism and their structural origins in various amorphous materials.