A nanostructured pure Cu sample consisting of nano-scale twin bundles and nano-sized grains was produced by means of dynamic plastic deformation at cryogenic temperature. The apparent activation energy for recrystallization of the nanostructured Cu was determined, being about 57kJ/mol. Interfacial diffusion of Zn in the nanostructure was investigated using secondary ion mass spectrometry at 358 to 463K, in which the volume diffusion was negligible. The measured penetration profiles showed two distinct sections with different slopes, due to the direct and independent diffusion fluxes along twin boundaries and grain boundaries. The determined grain-boundary diffusivity was about 2 orders of magnitude higher than the twin-boundary diffusivity. Relative to the diffusivities and free energies of grain boundaries and incoherent twin boundaries in coarse-grained Cu, both values in the dynamic plastically deformed Cu sample were slightly higher at temperatures below 373K, and approach comparable values at higher temperatures.

Interfacial Diffusion in a Nanostructured Cu Produced by Means of Dynamic Plastic Deformation. H.L.Wang, Z.B.Wang, K.Lu: Acta Materialia, 2011, 59[4], 1818-28