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MM: Fachverband Metall- und Materialphysik

MM 50: Topical Session: Interface-dominated phenomena - Thermodynamics and Microstructure Evolution

MM 50.1: Topical Talk

Donnerstag, 19. März 2020, 10:15–10:45, IFW A

A Density-based Model for Grain Boundary Thermodynamics and Kinetics — •Reza Darvishi Kamachali, Lei Wang, and David Jacobson — Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, 40237 Düsseldorf, Germany

Despite their nonequilibrium nature, grain boundaries can have lasting effects on the alloys microstructure, especially when interacting with solute atoms. In fact, solute segregation to grain boundaries is identified as a tool for microstructure design. To make the most of its potentials, a quantitative understanding of grain boundary segregation is required. We propose here a model for studying phase stability and microstructure evolution at grain boundaries. A continuous density field and its corresponding gradients are considered to derive grain boundary thermodynamic functions based on available bulk thermodynamic data. Grain boundary equilibrium phase diagrams are obtained. Several results on segregation and phase separation in binary and ternary alloy systems will be discussed. Based on the current model, some new aspects of grain boundary kinetics and solute drag will be presented as well. The current density-based model for grain boundaries can be readily applied for studying and design of polycrystalline materials.

References: [1] Kamachali RD. A Model for Grain Boundary Thermodynamics. ArXiv: arXiv:1907.12231. 2019. [2] Kamachali RD, da Silva AK, McEniry E, Ponge D, Gault B, Neugebauer J, Raabe D. Segregation--Assisted Spinodal and Transient Spinodal Phase Separation at Grain Boundaries. arXiv:1905.07970. 2019.