Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 14: Transport II: Atomic and ionic transport
MM 14.2: Vortrag
Montag, 7. März 2016, 16:00–16:15, H53
Effect of precipitation on grain boundary diffusion in an Al-based alloy — •Bengü Tas Kavakbasi1, Vladislav Kulitckii2, Sergiy V Divinski1, and Gerhard Wilde1 — 11Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Str. 10, 48341 Münster, Germany — 2Belgorod State University, Belgorod, 308015, Russia
Precipitation phenomena affect the kinetics of diffusion in the surrounding matrix. The present study is focused on the effect of Al3Sc precipitates on grain boundary diffusion in an Al-based AA5420 alloy (Al-4.6Mg-0.64Mn-0.2Sc-0.09Zr-0.2Ti-0.08Fe-0.02Si). Different states were prepared by combination of ECAP processing and heat treatments and the radioisotope 57Co was employed as a sensitive probe of a given grain boundary state. The results suggest that Co diffusion at room temperature is intimately coupled to the precipitation behavior of Al3Sc at elevated temperatures. In fact, the Co diffusion coefficients are first decreasing with increasing precipitate size and approach a minimum at their average size of about 20 nm, which is probably related to maximal elastic stresses around the precipitates. As the precipitates grow further, the diffusion coefficients begin to increase due to a loss of coherence accompanied by a change in the chemical composition and a reduction of stresses around the precipitates.
Financial support of DFG via SPP1713 is gratefully acknowledged.