Linking high- and low-temperature plasticity in bulk metallic glasses II: use of a log-normal barrier energy distribution and a mean-field description of high-temperature plasticity

Abstract

A thermal activation model to describe the plasticity of bulk metallic glasses (Derlet and Maaß, Phil. Mag. 93 (2013) p.4232) which uses a distribution of barrier energies and some aspects of under-cooled liquid physics is developed further. In particular, a log-normal distribution is now employed to describe the statistics of barrier energies. A high-temperature mean-field description of homogeneous macroplasticity is then developed and is shown to be similar to a thermal activation picture employing a single characteristic activation energy and activation volume. In making this comparison, the activation volume is interpreted as being proportional to the average mean-square-value of the plastic shear strain magnitude within the material. Also, the kinetic fragility at the glass transition temperature is shown to represent the effective number of irreversible structural transformations available at that temperature.

Keywords:

• bulk metallic glasses
• plastic deformation
• theory

Acknowledgements

The authors wish to thank D. Rodney, K. Samwer and J.-P. Bouchaud for helpful discussions. R.M. thanks C.A. Volkert for institutional support.

Notes

1 If such a Eshelby construction were to be performed, the associated deformation and relaxation would clearly need to be atomically constrained in order to maintain the saddle-point configuration.