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Cross Slip in an fcc crystal

Layer 1 (111) (111) b = 1 2 [110] Layer 2 Layer 1 (111) (111) b = 1 2 [110] Layer 2 Layer 1 (111) (111) b = 1 2 [110] Layer 2 Layer 1 (111) (111) b = 1 2 [110] Layer 2 Layer 3 Constriction

A screw dislocation with b = a/2[1 1 0] is moving on a (111) plane in an fcc crystal. By Frank's rule, it is energetically favorable for the screw dislocation to dissociate into two partial dislocations in the fcc crystal, forming a local constriction.

The screw dislocation, along with the local constriction, continues to glide in the (111) slip plane.

Layer 1 (111) (111) b = 1 2 [110] Layer 2 Layer 1 (111) (111) b = 1 2 [110] Layer 2 Layer 1 (111) (111) b = 1 2 [110] Layer 2 Layer 1 (111) (111) b = 1 2 [110] Layer 2 Layer 1 (111) (111) b = 1 2 [110] Layer 2 Layer 1 (111) (111) b = 1 2 [110] Layer 2 Layer 1 (111) (111) b = 1 2 [110] Layer 2

Layer 1 (111) (111) b = 1 2 [110] Layer 2 Layer 3 Screw dislocation dissociated into partials Partials constricted into perfect dislocations

In order to cross slip to the (111) plane, the partial dislocations have to recombine into a perfect screw dislocation.

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