Correlating the atomisitic nature of grain boundary phase transformations to their macroscopic kinetic properties

• Applicants: Professor Dr. Sergiy Divinski; Professor Dr. Christian Liebscher; Professor Dr.-Ing. Gerhard Wilde
• Subject Area: Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 467491887

The present proposal aims to correlate the atomistic origins of structural transformations at metallic grain boundaries with their impact on the transport properties. The goal is to establish a fundamental understanding of temperature-induced grain boundary phase transformations in pure metallic grain boundaries, as well as those induced by impurity segregation, and their direct impact on interfacial properties. The structure and transitions of grain boundaries will be explored at the atomic scale by aberration-corrected transmission electron microscopy (TEM) and their macroscopic transport properties will be probed by tracer diffusion experiments. The experimental results will systematically be supported by atomistic simulations of structure and diffusion of selected interfaces. Segregation-induced grain boundary transitions and their effect on the kinetic properties will be explored in the systems Cu-Ag, Cu-Co and Cu-Zr. Defined [001] tilt grain boundaries will be obtained by bulk bi-crystal growth, allowing to tailor grain misorientation and grain boundary inclination on demand. This also enables the scale bridging characterization from the atomic level to µm length-scales. The obtained Cu grain boundaries will be doped under controlled conditions with Ag, Co and Zr and advanced TEM resolves their temperature dependent structure, segregation and transitions. The same grain boundaries are probed by tracer diffusion experiments to determine their kinetic properties parallel and perpendicular to the tilt axis. Furthermore, the impact of deviations in grain boundary inclination on grain boundary transitions and their transport properties will also be explored to establish a holistic understanding of the impact of grain boundary transformations on interfacial properties.

• DFG Programme: Research Grants
• International Connection: USA
• Cooperation Partner: Dr. Timofey Frolov