Brittle-ductile behavior of a nanocrack in nanocrystalline Ni: A quasicontinuum study 
Y. F. Shao, X. Yang, X. Zhao and S. Q. Wang
Chinese Physics B, 21, 093104 (2012).

ABSTRACT
The effects of stacking fault energy, unstable stacking fault energy, and
unstable twinning fault energy on the fracture behavior of nanocrystalline Ni
are studied via quasicontinuum simulations. Two semi-empirical potentials for Ni
are used to vary the values of these generalized planar fault energies. When the
above three energies are reduced, a brittle-to-ductile transition of the
fracture behavior is observed. In the model with higher generalized planar fault
energies, a nanocrack proceeds along a grain boundary, while in the model with
lower energies, the tip of the nanocrack becomes blunt. A greater twinning
tendency is also observed in the more ductile model. These results indicate that
the fracture toughness of nanocrystalline face-centered-cubic metals and alloys
might be efficiently improved by controlling the generalized planar fault
energies.