Berlin 2015 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 19: Methods in Computational Materials Modelling I: Materials Design
MM 19.1: Talk
Tuesday, March 17, 2015, 10:15–10:30, H 0106
Theory-guided design of high-strength superlattices containing metastable phases: example of nano-scale CrN/AlN — •Martin Friák1,2, Darius Tytko1, David Holec3, Pyuck-Pa Choi1, Philip Eisenlohr1, Dierk Raabe1, and Jörg Neugebauer1 — 1Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany — 2Institute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., Brno, Czech Republic — 3Montanuniversität Leoben, Leoben, Austria
A theory-guided materials design of nano-scaled superlattices containing metastable phases is critically important for future development of advanced lamellar composites. Our study combining theoretical and experimental methods exemplifies this approach in the case of elastic properties of AlN/CrN superlattices with a bilayer period of 4 nm in which CrN stabilizes AlN in a metastable B1 cubic phase. As B1-AlN crystals do not exist as bulk material at ambient pressure, experimental data for this phase are not available. Therefore, quantum-mechanical calculations have been applied to simulate an AlN/CrN superlattice. The ab initio predicted Young’s modulus (428 GPa) in a direction perpendicular to (001) oriented interfaces is in excellent agreement with measured nano-indentation value (408 +/- 24 GPa). Aiming at a future rapid high-throughput design of superlattices, we have also tested predictions obtained within linear-elasticity continuum modeling that employs elastic properties of B1-CrN and B1-AlN phases as input. Using single-crystal elastic constants from ab initio calculations for both phases, we discuss the accuracy of this approach, too.