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MM: Metall- und Materialphysik

MM 9: Interfaces

MM 9.5: Vortrag

Montag, 27. März 2006, 15:45–16:00, IFW D

Paradoxical grain-growth kinetics observed in Al under compression — •Kejing Yang and Carl Krill — Materials Division, Albert-Einstein-Allee 47, University of Ulm, D-89081 Ulm, Germany

The mobility of grain boundaries in metals depends on stress in an intuitively reasonable manner: namely, compression slows the rate of boundary migration relative to that in the uncompressed state. Volkert and Lingk’s discovery of enhanced boundary mobility in compressed Al films therefore came as a great surprise [1]. These authors attributed the faster grain growth in compressed regions to planarization of the film surface, which would be expected to reduce the pinning forces associated with grain-boundary grooving. We have tested this hypothesis in microcrystalline Al foils prepared by melt spinning. Since our samples are much thicker than the initial average grain size, a clear distinction can be drawn between surface and volume-related effects. Characterization by EBSD confirms the mobility enhancement induced by compression, but cross-sectional analysis suggests that the greatest increase in growth rate occurs in the center of the sample rather than at the surface! We discuss possible explanations for this observation in terms of mechanisms for boundary migration.

[1] C. A. Volkert and C. Lingk, Appl. Phys. Lett. 73 (1998) 3677.