Relaxation of a disclinated tricrystalline nanowire

Adjoining grains meeting at triple junctions generally suffer from misorientation mismatch, giving rise to disclinations in polycrystalline materials. This paper presents molecular dynamics simulations of the relaxation of a wedge disclination at the triple junction of a tricrystalline cobalt nanowire between 0 and 1200 K. The results show that complex relaxed structures can occur, including cracks and cavities, distorted grain boundaries, dislocations, twin bands, diffuse dislocation walls and amorphized zones, many of which have been observed in nanocrystalline metals. The realized structures depend on the nanowire size, temperature, disclination strength and grain boundary structures. Furthermore, there exists a critical disclination strength below which the disclination is stable and above which it relaxes via competing mechanisms. The critical disclination strength demonstrates a strong size effect at all temperatures. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.