Multiple Shear Bands in Zr-Based Bulk Metallic Glass Processed by Severe Plastic Deformation

摘要

The Zr_(62)Cu_(22)Al_(10)Fe_5Dy_1 bulk metallic glass was subjected to high pressure torsion (HPT) processing at temperatures of 20 and 150℃. Structural studies were carried out by TEM on the lamella-sample prepared from the HPT-specimens in transversal direction to the specimen plane. TEM studies revealed formation of multiple shear bands with spacings in a 20-50 nm range for both HPT states. Shear bands could be divided in two types: primary and secondary bands. The morphology of shear bands strongly depends on the processing temperature. Shear bands are distributed homogeneously throughout the whole lamella-sample for state processed by HPT at temperature of 20℃. Regions with shear bands are divided by amorphous regions on lamella-sample cut from the sample processed by HPT at temperature of 150℃. Analysis of optical microscopy and SEM data showed that shear bands are distributed throughout the whole volume of HPT-specimens.