An analytical model, based upon classical dislocation theory, was used to explain the nucleation and growth of deformation twins in nanocrystalline Al. A 60° dislocation system consisting of a 90° leading partial and a 30° trailing partial was found to most readily nucleate and grow a deformation twin. The model suggested that the stress required for twin growth was much smaller than that required for its nucleation. It also predicted an optimum grain size for twin nucleation. The model successfully explains the deformation twins observed experimentally in nanocrystalline Al, and was applicable to other nanocrystalline metals.

Nucleation and Growth of Deformation Twins in Nanocrystalline Aluminum. Y.T.Zhu, X.Z.Liao, S.G.Srinivasan, Y.H.Zhao, M.I.Baskes, F.Zhou, E.J.Lavernia: Applied Physics Letters, 2004, 85[21], 5049-51