Quasicontinuum simulation of crack propagation in nanocrystalline Ni 
Y. F. Shao and S. Q. Wang
Acta Physica Sinica, 59, 7258-7265 (2010).

ABSTRACT
The propagation process of crack in the nanocrystalline Ni is simulated via the
quasicontinuum method. The results show that the stress near the crack tip could
prompt the disassociation of grain boundaries, and the formation of stacking
faults and deformation twins. Farther front the crack tip, fewer deformation
twins can be found. There are more stacking faults than deformation twins in the
grains, which approximately have the same distance to the crack tip. The effect
on deformation twins front the variation of local stress and generalized planar
fault energies is manifested by these results. The distribution of hydrostatic
stress on atomic-level around the crack tip is also calculated. It is shown that
nanovoids can be easily created in grain boundaries in front of the crack tip.
There exists an intense tensile stress state in the grain boundary regions
around these nanovoids. As a result of the stress accumulation, the crack
propagates along the grain boundaries. Our simulated results qualitatively
uncover the propagation process of crack in nanocrystalline Ni, which agrees
well with the relevant experimental results.