It was usually believed that the partial dislocation and deformation twin were the results of permanent plasticity in materials. Here, in situ atomic-scale observations were made of reversible stacking faults and deformation twins during loading and unloading in nanocrystalline Ni under high-resolution transmission electron microscopy. The high propensity to reversibility of the stacking fault and deformation twin was due to the high stacking fault force and small grain size, and provided an understanding, at the atomistic scale, of the nature of the deformation in nanocrystalline materials.

Pseudoelastic Stacking Fault and Deformation Twinning in Nanocrystalline Ni. B.Q.Li, M.L.Sui, S.X.Mao: Applied Physics Letters, 2010, 97[24], 241912