Plastic Deformation

· The diagram of a (111) plane shows the slip associated with the unit dislocation (BB) in red, and that of the two Shockley partial dislocations (BC) and (CB) in green.
· The total slip produced by the two partial dislocations is equivalent to that produced by the unit dislocation.

· Looking at the vectors and the square of their magnitudes: b₁= (b₂+b₃),
but : b₁² > (b₂² +b₃²) , so that the elastic strain energy of the two partials is lower than that of the single unit dislocation.
· The lower elastic strain energy favors the unit dislocation dissociation reaction.