Dresden 2020 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 20: Topical Session: Interface-dominated phenomena - Diffusion
MM 20.1: Topical Talk
Tuesday, March 17, 2020, 10:15–10:45, IFW A
The early stage of reactive interdiffusion in the Cu-Al system investigated by in-situ TEM — •Xavier Sauvage1, Florent Moisy2, and Eric Hug2 — 1Groupe de Physique des Matériaux, UMR CNRS 6634, University Rouen Normandy, France — 2CRISMAT, University Caen Normandy, France
The early stage of the reactive interdiffusion in the Al/Cu system was investigated by in-situ TEM at 350°C and 300°C. Original Al/Cu interfaces were created by a purely mechanical process using co-deformation at room temperature by drawing. During the reactive interdiffusion three IMCs were detected: Al2Cu and AlCu grew in the Al side and the Al4Cu9 in the Cu side. Systematic comparisons with ex-situ annealed samples and with regions out of the electron beam proved that there was no significant artefact (thin foil or beam effect). Although GBs may act as fast diffusion path, no preferential growth of IMC along these defects could be observed. The mean growth rates of all IMCs follow a classical parabolic law indicating that the kinetic of the transformation is controlled by diffusion mechanisms. A strong deviation was observed however in the early stage of the reaction. Nanoscaled Mg2Si particles located in the Al phase strongly interact with the transformation front. It leads to large fluctuations of the velocity of interphase boundaries at the nanoscale. The pinning effect in connection with change in local concentration gradients and driving forces will be discussed.