We begin by examining the 60 screw dislocation–GP
zone interaction. Upon the initial NPT relaxation from
the continuum screw dislocation displacement field, the
dislocation core dissociates into two partial dislocations
spaced 0.6 nm apart. During relaxation, the center of
the core remains stationary at 6.8 nm from the GP zone,
suggesting that the elastic forces acting on the dislocation
at this distance are below the Peierls stress (30 MPa). Figure
2a details the series of events that occur as applied
loading is increased at 0 K for a 4.4 nm diameter GP zone
that is intersected through its center by the (1 1 1) plane on
which the dislocation resides. As the load is increased the
dislocation begins moving towards the GP zone as the
force from the applied load overtakes the Peierls stress
and repulsion from GP zone. At
syz ¼ 36 MPa ð0:063sOrowanÞ, where sOrowan ¼ Gb
L ¼ 31:6 GPa2:86 ˚
A
158:7 ˚
A 570 MPa is the theoretical Orowan stress
[4]), the leading partial dislocation contacts the GP zone.
At syz ¼ 42 MPa ð0:074sOrowanÞthe dislocation cross-slips
onto the ð1 11Þ plane, where it remains pinned until
45 MPa ð0:079sOrowanÞ, at which point it glides away.