Berlin 2008 – wissenschaftliches Programm

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SYMS: Symposium Modern developments in multiphysics materials simulations

SYMS 3: Modern developments in multiphysics materials simulations III

SYMS 3.9: Vortrag

Freitag, 29. Februar 2008, 12:15–12:30, A 053

Engineering materials-design parameters of the Mg-Li alloys from ab initio calculations — •William Art Counts, Martin Friák, Dierk Raabe, and Jörg Neugebauer — Max-Planck-Institute für Eisenforschung GmbH, Max-Planck Str. 1, D-40237, Düsseldorf, Germany

Ab initio calculations are becoming increasingly useful to engineers interested in designing new alloys because these calculations are able to accurately predict basic material properties only knowing the atomic composition of the material. In this paper, fundamental physical properties (like formation energy and elastic constants) of 11 bcc Mg-Li compounds are calculated using density-functional theory (DFT) and compared with available experimental data. These DFT-determined properties are in turn used to calculate engineering parameters like (i) specific Young’s modulus (E/ρ) or (ii) bulk over shear modulus ratio (B/G) differentiating between brittle and ductile behavior. These engineering parameters are then used to identify alloys that have optimal mechanical properties needed for a light weight structural material. It was found that the stiffest bcc magnesium-lithium alloys contain about 70 at.% Mg while the most ductile alloys have 0-20 at.% Mg. The specific modulus for alloys with 70 at.% Mg is equal to that of Al-Mg alloys and slightly lower than that of Al-Li alloys.