Dresden 2014 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 21: Topical Session: Thermodynamics at the nano scale I - Kinetics, nucleation, grain growth, segregation
MM 21.4: Vortrag
Dienstag, 1. April 2014, 11:15–11:30, BAR 205
Solid state amorphization of thin metal films embedded in bulk metallic glass — •Tobias Brink1, Daniel Şopu1,2, and Karsten Albe1 — 1Institut für Materialwissenschaft, Technische Universität Darmstadt, Germany — 2now at ICAMS, Ruhr-Universität Bochum, Germany
Metals commonly appear in crystalline phases. Even thin films of metal stay crystalline on a variety of substrates. In contrast, it was recently observed experimentally, that thin metal layers embedded in a bulk metallic glass matrix become amorphous if they are thin enough (Ghafari et al., Appl. Phys. Lett. 100 (2012), 203108). The resulting multilayer systems have possible applications in the realm of materials for magnetic tunnel junctions, among others. We reproduced this effect in a series of molecular dynamics simulations and investigated the driving force behind it. We show that thin amorphous metal nanolayers in our model system are thermodynamically stable. We present a model based on a competition between the excess energy of the amorphous phase and the interface energy. We show that the glass–glass interface has lower potential energy than the corresponding crystal–glass interface. Our model correctly predicts the critical thickness under which amorphization occurs. These results suggest that other technologically relevant systems with amorphization of metallic nanolayers may exist. The results are also of interest for the study of crystalline phases in bulk metallic glasses.