Elastic moduli and mechanical properties of bulk metallic glasses after quasi-static compression

The effect of quasi-static compressive stress on the elastic moduli and mechanical properties of a Cu46Zr46Al8bulk metallic glass (BMG) was investigated. When the applied quasi-static stress is below 2 GPa (equivalent to 1.4 times the yield strength of the BMG), the elastic moduli of the deformed BMGs are found to decrease with the applied stress, revealing the softening or dilatation of the bulk metallic glass. The Poisson ratio is relatively stable when the stress is below 1000 MPa, but it decreases significantly afterwards. Both the plasticity and strength of the BMG are found to increase at low applied stress, and achieve a maximum value before decreasing at higher applied stress. The applied stress is shown to enhance the mechanical properties of the BMG and the properties can be controlled by quasi-static compressive stress. The results demonstrate that an applied stress far below the macroscopic yield strength can still result in microscopic yielding and microstructure change in metallic glass systems.