Regensburg 2022 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 3: Microstructures and Phase Transformations: Metals & Alloys
MM 3.6: Vortrag
Montag, 5. September 2022, 11:45–12:00, H45
Grain boundary phase transitions and patterning in a copper tilt grain boundary — •Tobias Brink1, Lena Frommeyer1, Rodrigo Freitas2, Timofey Frolov3, Christian H. Liebscher1, and Gerhard Dehm1 — 1Max-Planck-Institut für Eisenforschung GmbH, Germany — 2MIT, USA — 3LLNL, USA
The atomic structure of grain boundaries (GBs) can exhibit different “phases” (also called complexions), which undergo thermodynamic phase transitions, but which have been observed in just a few simulation studies. Experimental confirmation often remains indirect. Here, we report on such a transition investigated by molecular dynamics computer simulations and supported by direct evidence from STEM imaging [1]. Two distinct atomistic structures could be found in a Σ37c [111] tilt GB by a search with an evolutionary algorithm. Free energy calculations using the quasi-harmonic approximation predict a GB phase transition at 460 K. In the experiment, both phases also occur, but exhibit a pattern at room temperature in which the two phases alternate. We present a hypothesis to explain this thermodynamically unexpected phenomenon by elastic interactions of the phase junctions, which are line defects with partial dislocation character.
Acknowledgment: This result is part of a project that has received funding from the ERC under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 787446).
[1] Frommeyer, Brink et al., “Dual phase patterning during a congruent grain boundary phase transition in elemental copper” Nat. Commun. (accepted, 2022)