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MM: Fachverband Metall- und Materialphysik

MM 37: Nanomaterials II

MM 37.8: Talk

Thursday, March 17, 2011, 15:45–16:00, IFW B

High-temperature thermal stability of nanocrystalline iron — •Jules M. Dake and Carl E. Krill III — Institute of Micro and Nanomaterials, Ulm University, Ulm, Germany

Nanocrystalline materials promise enhanced properties, but the realization and application of such materials is limited by their thermal stability. The large specific grain-boundary area leads to a strong driving force for grain growth, which can, in some cases, occur at or even below room temperature [1]. When atoms of a second species with an appreciable segregation enthalpy are introduced, they should, in theory, reduce the grain-boundary energy and thus the driving force. Exactly this has been reported for numerous binary systems, as summarized in [2]. Our investigations of binary Fe alloys show similar results up to a temperature of ∼ 900^∘C. Above this limit, however, stability is suddenly lost. In situ XRD results appear to incriminate the α-to-γ transformation. Direct observation of the microstructure by FIB microscopy reveals a growth morphology similar to that of recrystallization or abnormal grain growth.
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