Collective motion of atoms in grain boundary migration of a bcc metal

Abstract

Molecular dynamics simulations of grain boundary (GB) migration of a bcc metal, tungsten, have been carried out. The GB is of asymmetrical ⟨ 110⟩ tilt type. Detailed examinations of atomic processes in the migration, show that the GB migration consists mainly of GB dislocation glides. Furthermore, each motion of a GB dislocation involves a cooperative motion of about three atoms on each of the atomic planes perpendicular to the tilt axis, leading to their realignment from the receding grain to the advancing grain. This collective motion is not synchronized in all of the atomic planes, but appears to be in two or three adjacent planes, suggesting a kink mechanism for glides of the GB dislocations.

Acknowledgements

The authors wish to thank Dr. Hanchen Huang for helpful discussions and revision of the draft manuscript. Support from the Natural Science Foundation of China under a grant numbered 10262002 for completion of the present work is gratefully acknowledged.