Regensburg 2007 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 5: Interfaces I

MM 5.3: Talk

Monday, March 26, 2007, 10:45–11:00, H6

Migration and Faceting of Low Angle Grain Boundaries in Aluminium-Bicrystals — •Bingbing Zhao, Dirk Kirch, Dmitri Molodov, and Günter Gottstein — Insitute of Physical Metallurgy and Metal Physics, RWTH-Aachen University, Kopernikusstr. 14, 52056 Aachen, Deutschland

Migration and faceting behaviour of low angle <100> tilt grain boundaries in Al-bicrystals was investigated experimentally by in-situ observations in a scanning electron microscope. The results reveal that for grain boundaries with misorientation angles in the range 10°<θ<15° there is a temperature TR, above which the boundary possess a curved shape and moves in a steady state under a capillary driving force. Below this temperature the grain boundary shows one singular facet corresponding to the minimum energy configuration with respect to the grain boundary inclination and does not move if the temperature remains constant. The transition temperature TR was found to depend on the misorientation angle θ. For boundaries with θ>15° no transformation faceted boundary-curved boundary was observed. At any temperature these boundaries moved in a steady state being curved. Also for boundaries with misorientations θ<10° no structural transition was observed. These boundaries keep their initial symmetrical straight configuration in the entire investigated temperature range up to the melting point of aluminium. The results are interpreted in terms of the grain boundary roughening transformation and the change of grain boundary properties in the transition range between low and high angle misorientations.