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M: Metallphysik

M 30: Nanoskalige Materialien IV

M 30.4: Vortrag

Mittwoch, 26. März 2003, 17:15–17:30, IFW A

Atomic mechanisms of ion-irradiation induced grain growth in Ni — •Wolfgang Voegeli, Karsten Albe, and Horst Hahn — Technische Universität Darmstadt, Institut für Materialwissenschaft, Petersenstrasse 23, 64287 Darmstadt, Germany

It is experimentally well known that ion irradiation of nanocrystalline metals can lead to significant grain growth if the average grain size is below 20nm [1]. In this study we have investigated the atomic mechanisms responsible for the grain growth by means of molecular dynamics simulations. Collision cascades of 5keV were calculated in bulk nc-Ni samples generated by a Voronoi tesselation method. We find that the cascade position relative to the GB areas is decisive for stimulating ion-beam induced grain growth. Using bicrystal geometries we have therefore investigated the role of the GB orientation on grain growth in more detail. For certain symmetric grain boundaries we find growth that can be explained by means of a simple geometrical model. In the case of the asymmetrical boundaries we observe a strong dependence on the atomic density in the crystalline layers adjacent to the GB area. The influence of triple lines is also discussed.

[1] M. Rose, Strahleninduzierte Defektbildung in nanocrystallinen Materialen, No. 503 in Fortschrittberichte VDI, Reihe 5 (VDI Verlag, Düsseldorf, 1997)