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M: Metallphysik

M 31: Nanokristalle II

M 31.4: Vortrag

Freitag, 27. März 1998, 11:10–11:30, H 39

Self-Diffusion in High Density Nanocrystalline Fe — •H. Tanimoto, P. Farber, R. Würschum, and H.-E. Schaefer — Universität Stuttgart, Institut für Theoretische und Angewandte Physik, Pfaffenwaldring 57, 70550 Stuttgart

For the understanding of the behavior of the nanocrystalline (n-) metals, the self-diffusion study is of great interest. We performed ⁵⁹Fe self-diffusion measurements on high density n-Fe specimens prepared by compaction of gas-condensed clusters at elevated temperatures and by severe plastic deformation. The penetration depth profiles observed are similar to those reported for ⁵⁹Fe in the high density cluster-compacted n-Pd specimens. The self-diffusion coefficient determined by assuming a type C diffusion process appears to possess a similar temperature dependence as that of Fe diffusion in n-Pd. The x-ray diffraction analysis reveals concurrent grain growth during diffusion annealing. A reduction of the self-diffusivity is observed after pre-annealing of severely deformed Fe specimens. This observation shows that the self-diffusivity in n-metals is reduced when a structural relaxation of the grain boundary occurs and that the self-diffusivity in high density n-metals with relaxed interfaces is similar to that in conventional grain boundaries.