It was believed that the dynamics of dislocation processes during the deformation of nanocrystalline materials could only be visualized by computational simulations. Here it was demonstrated that observations of dislocation processes during the deformation of nanocrystalline Ni with grain sizes as small as 10nm could be achieved by using a combination of in situ tensile straining and high-resolution transmission electron microscopy. Trapped unit lattice dislocations were observed in strained grains as small as 5nm, but subsequent relaxation led to dislocation recombination.

Dislocation Dynamics in Nanocrystalline Nickel. Z.W.Shan, J.M.K.Wiezorek, E.A.Stach, D.M.Follstaedt, J.A.Knapp, S.X.Mao: Physical Review Letters, 2007, 98[9], 095502 (4pp)