Pronounced fl-relaxation in plastic FeNi-based bulk metallic glasses and its structural origin

Fe-based bulk metallic glasses (BMGs) usually exhibit brittle behavior and unconspicuous fl-relaxation in their dynamic mechanical spectroscopy. We report a distinct fl-relaxation behavior in FeNi-based BMGs with excellent plasticity. The origin of pronounced fl-relaxation and plastic behaviors for the FeNi-based BMGs were investigated by synchrotron X-ray diffraction and nanoindentation tests in detail. It is found that the structural heterogeneity plays a key role in the dynamic of the FeNi-based BMGs, leading to large amount of loosely packed regions. The pronounced fl-relaxation is also found to have a good correlation with the plasticity for the FeNibased BMGs. This study might provide guidance for us to develop plastic BMGs from an atomic structural and glass dynamic perspective.

Automated summary

This study reveals a distinct fl-relaxation behavior and excellent plasticity in FeNi-based BMGs, which is attributed to the structural heterogeneity playing a key role in their dynamics, leading to a large amount of loosely packed regions. The pronounced fl-relaxation is also found to have a good correlation with the plasticity for the FeNi-based BMGs, providing potential guidance for the development of plastic BMGs from an atomic structural and glass dynamic perspective.