Regensburg 2007 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 29: Intermetallic phases II

MM 29.5: Talk

Thursday, March 29, 2007, 12:45–13:00, H16

Mechanical milling of single phase beta-Al3Mg2 — •Mira Sakaliyska¹, Sergio Scudino¹, Kumar Babu Surreddi¹, Sebastian Sperling¹, Carsten Thomas², Michael Feuerbacher², and Jürgen Eckert¹ — ¹IFW Dresden, Institut für Komplexe Materialien, Postfach 27 01 16, D-01171 Dresden, Germany — ²Forschungzentrum Jülich GmbH, Institut für Festkörperforschung, D-52425 Jülich, Germany

In this work, the effect of mechanical milling on microstructure and thermal stability of the polycrystalline beta-Al3Mg2 phase, a complex metallic alloy (CMA) with a giant unit cell containing about 1168 atoms/u.c., has been investigated. With increasing milling time, the grain size of the beta-phase is reduced from micrometer to nanometer regime. At the same time, the mechanical treatment induces the formation of a nanoscale supersaturated Al(Mg) solid solution. Upon heating, the milled powders display a complex thermal behavior: at low temperatures, the phase evolution during heating is characterized by the rejection of an increasing amount of Mg from the solid solution with increasing temperature. At higher temperatures, a phase which resembles the starting beta-Al3Mg2 phase is formed and no traces of the solid solution can be detected, indicating that the solid solution is metastable and transforms into more stable phase(s). The subsequent exothermic events are characterized by the formation and growth of the beta-Al3Mg2 phase, thus indicating that the formation of the supersaturated solid solution during milling can be reversed by appropriately heat treating the mechanically milled powder.