T. Kitamura et al., ATOMIC SIMULATION ON DEFORMATION AND FRACTURE OF NANO-SINGLE CRYSTAL OF NICKEL IN TENSION, JSME international journal. Series A, Solid mechanics and material engineering, 40(4), 1997, pp. 430-435
In order to elucidate the mechanism of deformation and fracture of mic
rocomponents, numerical simulations are conducted for a nanoscopic wir
e and film of nickel without lattice defects on the basis of a molecul
ar dynamics using the EAM (embedded atom method) potential. A bulk of
nickel is also treated by applying a periodic boundary condition for c
omparison. These materials are subjected to a tensile strain along the
[001] direction of the fee (face-centered cubic) lattice. Here, the t
ransverse stresses in the bulk material are kept at zero during tensio
n. The yielding is brought about by the crystallographic slips on the
(111) planes and there is little difference in the yield stress among
the wire, film and bulk. The slips continue to take place on multiple
(111) planes and the plastic deformation leads to ductile fracture. Ne
xt, the displacement in the transverse direction on the cell boundarie
s of the bulk is fixed in order to investigate the effect of constrain
t. It shows brittle fracture due to cleavage cracking. This implies th
at the constraint, which may be introduced by local inhomogeneity of t
he material, brings about early crack nucleation and reduces the ducti
lity of materials without lattice imperfection.