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MM: Fachverband Metall- und Materialphysik
MM 23: Mechanical Properties II
MM 23.6: Vortrag
Dienstag, 8. März 2016, 13:00–13:15, H52
Correlation between elasticity and stability in refractory alloys — •Sandra Hoppe1, Sascha B. Maisel2, and Stefan Müller1 — 1Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany — 2Max-Planck Institut für Eisenforschung, Düsseldorf, Germany
Varying an alloy’s concentration or alloying constituents strongly influences its structural and mechanical properties. Modern simulation methods like density functional theory (DFT) in combination with the cluster expansion (CE) make the whole configuration space accessible. Recent results for several face-centered cubic (fcc) binary metal alloys [1] suggest a linear correlation between thermodynamic stability and elastic properties at a fixed stoichiometry. This study aims to investigate the generality of these findings by considering a similar correlation for the binary body-centered cubic (bcc) refractory alloy systems Ta-W and Mo-Nb. For this purpose, formation enthalpies as well as the symmetrically averaged elastic constants c11 and c44 are expanded via a CE fit with DFT input. Interestingly, the shear constant c44 shows an opposing trend to that observed for fcc alloys in certain concentration regimes. This phenomenon is discussed with regard to an anomalous behavior of c44 with varying alloy concentration, temperature or pressure [2,3].
[1] S. B. Maisel, M. Höfler, and S. Müller. Nature 491 (2012) 740.
[2] K. W. Katahara et al. J. Phys. F: Met. Phys. 9 (1979) 773.
[3] C. E. Anderson and F. R. Brotzen. J. Appl. Phys. 53 (1982) 292.