Berlin 2008 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 11: Nanostructured Materials III

MM 11.5: Talk

Monday, February 25, 2008, 15:45–16:00, H 0107

Grain boundary radiotracer diffusion of Ni in ultra-fine grained Cu--1wt.% Pb alloy produced by ECAP — •Jens Ribbe¹, Guido Schmitz¹, Juri Estrin², and Sergiy Divinski¹ — ¹Institut für Materialphysik, Universität Münster, Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany — ²Department of Materials Engineering, Monash University, Clayton, Australia

Severe plastic deformation is a promising technique for producing materials with a high hardness and sufficient ductility. Kinetic properties of internal interfaces in such materials with an ultra fine grained microstructure represent one of central issues. The radiotracer technique is applied for measuring Ni grain boundary diffusion in ultra fine grained pure copper materials with different nominal purities and in the Cu--1wt.%Pb alloy produced by equal channel angular pressing (ECAP). The stability of the structure of the nanostructured material was studied by focused ion beam.

The interface diffusion was investigated in the temperature interval from 300 to 520K under the Harrison C type kinetic conditions. Two distinct short-circuit diffusion paths were observed in all materials studied. The first (relatively slower) path corresponds unambiguously to general high-angle grain boundaries with diffusivities which are quite similar to those in their coarse-grained counterparts. The second path is characterized by even higher diffusivities. The measured data favour a one-dimensional but not planar nature of the second diffusion path in the Cu--1wt.%Pb alloy.