Screw dislocation mobility in BCC Metals: a refined potential description for α-Fe

Abstract

In this work, we seek to develop a new interatomic potential for α-Fe that is able to rationalize experimental flow stress data. We generate a series of potentials with similar bulk and point defect properties, but exhibit different energetic landscapes for the Peierls potential. The family of potentials all possess a compact core structure, which we find necessitates a camel-hump shaped Peierls potential. Within this constraint, we analyze the relationships between the Peierls potential, the 3-D kink nucleation energetics, and the resulting shape of the kink structures for the screw dislocation. We find that one of our models, labeled MPG20, gives very good agreement with experimental flow stress data over the entire stress range considered.

Keywords:

• dislocation theory
• dislocation dynamics
• atomistic simulation
• plasticity
• plasticity of metals

Acknowledgements

A portion of this work was supported by the U.S. Department of Energy, Office of Basic Energy Science, Division of Materials Science and Engineering. Part of this research was performed at the Ames Laboratory. Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358. The authors gratefully thank Ju Li for helpful discussions and guidance throughout this work.