· Work hardening can be caused by the generation of dislocation loops around strong precipitate particles (second phases).
· The loops around the precipitates decreases the barrier spacing and increase the stress required to push another dislocation through the barrier.

· The local shear stress required to penetrate the array of precipitates is:
t_cr = 2Gb/(L - 2r),
where r is the radius of the outer dislocation loop around the precipitate.