The Evolution Of Density And Distribution Of Shear Bands In Zr_61.7Al₈Ni₁₃Cu₁₇Sn_0.3 Bulk Metallic Glass After Compression Deformation

Metallic glasses are amorphous alloy which are mainly composed of metal elements. They have many excellent properties, such as high strength and hardness, high elastic limit, corrosion resistance, etc. However, the plasticity of metallic glasses is very poor at room temperature, and this also restricts the wide application to a great extent. At low temperature and high strain rate, metallic glasses occur inhomogeneous plastic deformation and the deformation is limited in a very narrow area, this area is called shear bands. It is studied that the density and distribution of shear bands has a great influence on the properties of metallic glasses, for example, Cu47.5Zr47.5Al5 metallic glass appeared the work hardening phenomenon, as well as improved plasticity were observed for Cu47.5Zr47.5Al5 metallic glass after inhomogeneous plastic deformation. The reason for the phenomenon is attributed to the formation of a large number of intersected shear bands. Therefore, it is very necessary to research the influence of inhomogeneous plastic deformation for metallic glass on the density and distribution of shear bands.In theory, the density and distribution of shear bands are affected by strain rate, strain and aspect ratio. So the influence of these factors on the distribution and density of shear bands in Zr61.7Al8Ni13Cu17Sn0.3 metallic glass which occurred unidirectional compression deformation is studied. In addition, the best condition of forming a higher density of shear bands is also studied.The results showed that when the aspect ratio increases from 0.25 to 2.25 in Zr61.7Al8Ni13Cu17Sn0.3 metallic glass, the average spacing of shear bands in the sample monotonically decrease, and the corresponding shear band density gradually increase. Especially, when the aspect ratio accesses 2.25, a minimal shear band spacing is 0.478μm, the corresponding shear band density is 2.092 μm-1. The spacing of shear bands below 100 nm accounted for 12.84% in the total shear bands of sample, and the spacing of shear bands below 50 nm accounted for 6.76%. In addition, with increasing strain, the average spacing of shear bands decreases in Zr61.7Al8Ni13Cu17Sn0.3 metallic glass, and the corresponding shear band density increases. On this bases, we continue to accumulate the sample with a strain of 87%, in order to continue to increase the strain of the sample. At the same time, the strain is 90%. The statistical result indicates that the average spacing of shear bands in the sample attain 0.299 μm, and the corresponding shear band density is 3.344 μm-1. In addition, the spacing of shear bands under 100 nm accounted for 31.65% and the spacing of shear bands under 50 nm accounted for 17.51%. It is also the best condition of forming the highest density of shear bands for Zr61.7AlsNi13Cu17Sno.3 metallic glass. When the strain rate is 1×10-2 s-1, the spacing of shear bands is relatively small, and the corresponding shear band density is relatively large, therefore, the strain rate of 1 × 10-2 s-1 is adopted in the whole experiment process.