Grain boundary migration in bcc metals

March 25, 2007

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

Authors: L Zhou, N Zhou, and G Song

Bibliographic details: Philosophical Magazine, Volume 86, Number 36, 21 December 2006, pp. 5885-5895(11)


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.

Notes: In this paper, the authors try to answer two specific questions regarding grain boundary migration in bcc metals using molecular dynamics simulations:

  1. The number of atoms involved in each collective motion (and what determines the number); and,
  2. The relationship between the collective mechanism and grain boundary dislocation mechanism.

There also seems to be indications of grain rotations at around 1.7 nm or so (which is not pursued in this paper). Finally, to answer the questions above–the grain boundary migration is via dislocation glide; each glide is associated with a collective motion of three atoms; further, the glide might also be associated with a kink motion.


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