Regensburg 2022 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 21: Transport in Materials: Thermal transport
MM 21.6: Talk
Wednesday, September 7, 2022, 11:45–12:00, H45
Appearance of non-equilibrium grain boundaries in additively manufactured high-entropy CoCrFeMnNi alloy — •Nuri Choi1, 2, Vladislav Kulitckii1, Josua Kottke1, Bengü Tas1, Jungho Choe3, Ji Hun Yu3, Sangsun Yang3, Joo Hyun Park2, Jai Sung Lee2, Gerhard Wilde1, and Sergiy Divinski1 — 1Institute of Material Physics, University of Münster, Germany — 2Dep. of Mat. Sci. & Chem. Eng., Hanyang University, South Korea — 3Center for 3D Printing Materials Research, KIMS, South Korea
Additive manufacturing process with laser melting includes the repetitive melting/solidification, which generates residual thermal stresses in the bulk material, alongside with creation of various defects, including point defects, dislocations and numerous grain boundaries. How far the kinetic properties of these interfaces are modified by the processing remains an open issue, that is of fundamental importance for such phenomena as creep, phase transformation and precipitation. In the present study, grain boundary diffusion in additively manufactured CoCrFeMnNi high-entropy alloys is measured using the radiotracer technique. Since the additive manufacturing results in a hierarchical microstructure, grain boundary diffusion is examined in different samples prepared via different scan/build strategies. A non-equilibrium state of a fraction of high-angle grain boundaries is discovered. The non-equilibrium state is shown to relax after annealing at low temperatures without measurable microstructural changes. The grain boundary diffusivities of the 3D printed alloys are discussed with respect to those for fully homogenized cast or severe plastically deformed alloys.