In situ atomic-scale observation of continuous and reversible lattice deformation beyond the elastic limit

Abstract

The elastic strain sustainable in crystal lattices is usually limited by the onset of inelastic yielding mediated by discrete dislocation activity, displacive deformation twinning and stress-induced phase transformations, or fracture associated with flaws. Here we report a continuous and gradual lattice deformation in bending nickel nanowires to a reversible shear strain as high as 34.6%, which is approximately four times that of the theoretical elastic strain limit for unconstrained loading. The functioning deformation mechanism was revealed on the atomic scale by an in situ nanowire bending experiments inside a transmission electron microscope. The complete continuous lattice straining process of crystals has been witnessed in its entirety for the straining path, which starts from the face-centred cubic lattice, transitions through the orthogonal path to reach a body-centred tetragonal structure and finally to a re-oriented face-centred cubic structure.

Dynamic and atomic-scale understanding of the twin thickness effect on dislocation nucleation and propagation activities by in situ bending of Ni nanowires

“…For twin-structured nanocrystalline (NC) metals, the inverse Hall-Petch effect is suggested to occur with decreasing twin thickness, which limits the increase in the strength of these metals [2,3]. Twin-structured nanowires (NWs) are a new family of nanomaterials [6][7][8][9][10][11][12], which are expected to exhibit unusual mechanical properties relative to those of twin-free NWs. It has been demonstrated that twin-structured metallic NWs exhibit strong HallPetch effects with a decrease in twin thickness (TT) [6,8,[13][14][15], with a nearly ideal strength achieved by decreasing the TT [6,[13][14][15].…”

Elastic strain engineering for unprecedented materials properties

“…12 As inelastic strains are localized in microstructures such as dislocation-swept areas, new grains, or domain variants (or new martensitic phases), ISE is philosophically direct kin of "microstructure control properties," probably the best known mantra in materials science. In certain applications, where the property of interest is phase Figure 1.…”

Nanotwinned and hierarchical nanotwinned metals: a review of experimental, computational and theoretical efforts

“…177,178 The development of in situ atomic scale experimental techniques promotes the investigation of dynamic dislocation-TB interaction modes. 176,[179][180][181][182][183][184] Actually, the detailed interactions between dislocations and TBs are also widely investigated by means of MD simulations. Owing to the significant merit of MD simulation that the microstructure evolution can be tracked perfectly, the simulation studies on dislocation-TB interaction in NT metals have been comprehensively discussed in recent years.…”