  Carbon nanofibers (NFs) have been envisioned with broad promising
applications, such as nanoscale actuators and energy storage medium. This work
reports for the first-time super-elastic tensile characteristics of NFs
constructed from a screw dislocation of carbon nanocones (NF-S). The NF-S
exhibits three distinct elastic deformation stages under tensile, including an
initial homogeneous deformation, delamination, and further stretch of covalent
bonds. The delamination process endows the NF-S extraordinary tensile
deformation capability, which is not accessible from its counterpart with a
normal cup-stacked geometry. The failure of NF-S is governed by the inner edges
of the nanocone due to the strain concentration, leading to a common failure
force for NF-S with varying geometrical parameters. Strikingly, the
delamination process is dominated by the inner radius and the apex angle of the
nanocone. For a fixed apex angle, the yielding strain increases remarkably when
the inner radius increases, which can exceed 1000%. It is also found that the
screw dislocation allows the nanocones flattening and sliding during
compression. This study provides a comprehensive understanding on the
mechanical properties of NFs as constructed from carbon nanocones, which opens
new avenues for novel applications, such as nanoscale actuators.
