Commercial-purity aluminum processed by equal channel angular pressing was used to investigate the deformation mechanism during further annealing of the severely plastic deformed materials. It was found that vacancy-type defects induced by severe plastic deformation were responsible for some unusual phenomena, such as hardening by annealing and softening by slight deformation in nanostructured metals. It was anticipated that the effective control of vacancy-type defects during severely plastic deformation and consequent annealing process will be combined to attain an optimum combination of strength and ductility in nanostructured metals.

Vacancy-Assisted Hardening in Nanostructured Metals. L.H.Su, C.Lu, A.K.Tieu, L.Z.He, Y.Zhang, D.Wexler: Materials Letters, 2011, 65[3], 514-6