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MM: Fachverband Metall- und Materialphysik

MM 28: Transport I - atomic transport

MM 28.5: Vortrag

Dienstag, 21. März 2017, 11:15–11:30, IFW D

Grain boundary diffusion and segregation of ⁵⁷Co in high-purity copper: Radiotracer measurements in B- and C-type diffusion regimes — •Daniel Gaertner, Gerhard Wilde, and Sergiy Divinski — Institute of Materials Physics, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster

Grain boundary diffusion of ⁵⁷Co in high-purity polycrystalline copper is investigated using the radiotracer technique in Harrison’s B- (850−1150 K) and C-type (550−950 K) kinetic regimes. The triple product P=s·δ· D_gb (s is the segregation factor and δ the grain boundary width) and the grain boundary diffusion coefficient D_gb of Co in Cu are determined to obey the Arrhenius laws with the activation enthalpies of Q_gb=66.2 kJ/mol and H_gb=100.9 kJ/mol, respectively. Using the experimental estimate of δ, δ ≅ 0.5 nm, Co is found to segregate strongly at Cu grain boundaries and the corresponding segregation factor follows an Arrhenius dependence with the segregation enthalpy of H_s=−34.7 kJ/mol . Co-diffusion experiments with the ⁵⁷Co and ^110mAg isotopes support a ’sub-interface’-type of grain boundary segregation of Co in Cu.