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MM: Fachverband Metall- und Materialphysik

MM 12: Transport - High Entropy Alloys

MM 12.3: Vortrag

Montag, 16. März 2020, 16:15–16:30, IFW A

Radiotracer diffusion in single crystalline CoCrFeNi and CoCrFeMnNihigh entropy alloys — •Daniel Gaertner¹, Josua Kottke¹, Yury Chumlyakov², Gerhard Wilde¹, and Sergiy V. Divinski¹ — ¹Institute of Materials Physics, University of Münster,Münster, Germany — ²Department of Physics of Metals, Tomsk State University, Tomsk, Russia.

High entropy alloys are multicomponent alloys, which consist of five or more elements in equiatomic or nearly equiatomic concentrations. These materials are hypothesized to show significantly decreased self-diffusivities. For the first time, the temperature dependencies of the volume diffusion rates of all constituent elements in equiatomic CoCrFeNi and CoCrFeMnNi single crystals and additionally solute diffusion of Mn an Cu in the quaternary alloy and Zn in the quinary alloy are investigated using the radiotracer technique in an extended temperature range between 923 K and 1373 K. The components are characterized by significantly different diffusion rates with the activation enthalpies in a range between 200 and 300 kJ/mol. Cu is found to be a fast diffuser at moderate temperatures below 1273 K and its diffusion rate follows the Arrhenius law with an activation enthalpy of 149 kJ/mol. Furthermore, a distinct contribution of short-circuit pipe diffusion was observed and analyzed.