Local microstructure evolution at shear bands in metallic glasses with nanoscale phase separation

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Plastic flow in metallic glasses (MGs) localizes in shear bands.
• Shear band formation, evolution, and multiplication mechanisms remain debated.
• Understanding these phenomena is crucial for designing MGs with enhanced plasticity.

Purpose of the Study:

• Investigate local conditions at shear bands in phase-separated bulk MGs.
• Examine the behavior of glassy nanospheres within and around shear bands.
• Clarify the role of affected zones in the matrix on material properties.

Main Methods:

• Compression testing of phase-separated bulk metallic glasses.
• Microstructural analysis of shear bands and surrounding matrix.
• Observation of nanosphere dissolution and Ostwald ripening.

Main Results:

• Glassy nanospheres within shear bands dissolve via mechanical mixing.
• Nanospheres in the matrix coarsen through Ostwald ripening due to increased atomic mobility.
• An affected zone with low-strain plastic deformation is identified around shear bands.

Conclusions:

• Deformation-induced atomic mobility changes around shear bands influence material properties.
• Both shear bands and adjacent affected zones contribute to property changes in MGs.
• Direct visualization of deformation effects, including atomic mobility, around shear bands is achieved.