Effect of accumulated shear on the microstructure and morphology of severely deformed Cu60Zr30Ti10 metallic glass

Cu60Zr30Ti10 metallic glass sample was subjected to different amount of continuous rotational straining by high pressure torsion. Deformation dependent morphology, microstructural and thermal properties were characterized by scanning electron microscopy, synchrotron radiation, X-ray diffraction, and calorimetry, respectively. In order to estimate the temperature rise in the metallic glass during high pressure torsion, quasi three-dimensional heat conduction equation with a source term was considered. Solutions indicate that the final temperature strongly depends on the total amount of plastic deformation while details of the microstructure are mainly determined by the balance between the local shear rate and temperature.

• Microstructural characterization of severely deformed Cu60Zr30Ti10 metallic glass has shown that initially elongated crystalline blocks appear in the amorphous matrix and at a later stage these blocks transform into robust, eutectic-like regions.
• Temperature evolution profiles obtained from numerical calculations indicate that the devitrification process in high pressure torsion can be divided into distinct stages.
• For small plastic deformation the temperature remains below the glass transition temperature in the entire disk.
• For larger deformation the glass transition temperature is exceeded in the disks and the remarkable microstructural differences can be explained by the competition of local strain rate and thermal mobility.