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MM: Metall- und Materialphysik

MM 18: Materials Design

MM 18.3: Vortrag

Dienstag, 28. März 2006, 15:15–15:30, IFW B

Beating the Miscibility Barrier Between Magnesium and Iron Group Metals (Fe, Ni, Co) by High-Pressure Alloying — •Leonid Dubrovinsky¹, Natalia Dubrovinskaia², Igor A. Abrikosov³, and Levente Vitos⁴ — ¹Bayerisches Geoinstitut, Universität Bayreuth, Germany — ²Physikalisches Institut, Universität Bayreuth, Germany — ³Department of Physics and Measurement Technology, Linköpings University, Sweden — ⁴Department of Materials Science and Engineering, Royal Institute of Technology, Sweden

It is now generally recognized that all metals and compounds show some solubility in the solid or liquid state, but the extend of solid solubility is different in different cases. Fe and Mg are almost immiscible at ambient pressure. Though two close chemical analogues of iron, namely nickel and cobalt, form intermetallic compounds with magnesium, solubility of Mg in these metals is also negligibly low. The low solubility of Mg in Fe is in complete agreement with well-known Hume-Rothery rule for metallic alloys. However, compressibility of Mg is much higher than that of Fe, and therefore the difference in atomic sizes between these two elements decreases dramatically with pressure. Based on the predictions of ab initio theoretical calculations, we demonstrate in series of experiments in a multianvil apparatus and in electrically- and laser-heated diamond anvil cells, that high pressure promotes solubility of magnesium in iron and at megabar pressure range more than 10 at% of Mg can dissolve in Fe, and then quenched to ambient conditions. Up to 4 at% of Mg could be dissolving in Ni or Co at 20 GPa and 2200 K.