Regensburg 2019 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MM: Fachverband Metall- und Materialphysik

MM 16: Methods in Computational Materials Modelling (methodological aspects, numerics)

MM 16.1: Vortrag

Dienstag, 2. April 2019, 10:15–10:30, H45

Atomistic mechanism of nucleation in Ni: the role of pre-structuring and seeding in polymorph selection — •Grisell Díaz Leines and Jutta Rogal — Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany

Understanding the fundamental principles of polymorph selection during crystal nucleation is essential in the control and prediction of materials properties. However, to obtain a precise knowledge of the crystallization mechanism is often challenging as most physical systems exhibit polymorphic transitions and are often heterogeneously seeded by the presence of impurities. Here we employ transition path sampling together with maximum likelihood estimation to analyze the atomistic mechanism of crystal nucleation in Ni. We further investigate the effect of small pre-structured seeds on the crystallization process. The analysis of the transition path ensemble reveals that the pre-structured liquid region that surrounds the nucleus plays a crucial role in the description of the nucleation process together with the amount of fcc particles in the core of the crystal cluster. Consistent with our interpretation of the nucleation mechanism, we demonstrate that seeds with structures compatible with those observed in the growing nucleus (fcc and pre-structured liquid) facilitate the nucleation and determine the polymorph selected, while seeds with hcp and icosahedral structures have neither an effect on the nucleation rate nor on the mechanism. Our results shed light on the atomistic processes of polymorph selection during crystallization in Ni.