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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 8: Crystal Structure / Real Structure / Microstructure

KFM 8.3: Vortrag

Mittwoch, 29. September 2021, 11:15–11:30, H1

Mobility functions for [001] CSL grain boundaries in Nickel from Molecular Dynamics — •Etienne Ngenzi, Zakaria El Omari, Charlie Kalhoun, Brigitte Bacroix, and Sylvain Queyreau — LSPM UPR 3407 CNRS, Université Sorbonne Paris Nord, 93430, Villetaneuse, France

Multiscale simulations constitute a possible path to improve our understanding of the evolution of microstructures. In this work, we have systematically studied the migration of [001] CSL Grain Boundaries (GB) by Molecular Dynamics to provide input data for a mesoscale Phase Field model. We have systematically studied GB in nickel over a wide range of driving forces and temperature. To identify common features between very different GB and to sample different migration processes, we explored a large number of Σ 5, Σ 13, and Σ 25, covering symmetric pure tilt, pure twist, and mixed characters ranging from low to high misorientation angle GB. Since we systematically probed both driving force and temperature, the temperature dependence of migration was unambiguous. The response of grain boundary mobility to temperature is highly dependent on the structure of the grain boundary. Most of the studied GB show successive distinct behaviours, with an initially thermally activated regime at low driving force and temperature. When increasing the driving force, the GB velocity may transition to a linear regime. A correlation is made with the elementary migration mechanisms that are observed. A phenomenological velocity law covering the entire parameter space for each GB is proposed.