Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 14: Topical Session Bulk Nanostrucured Materials III - Microstructure and Characterization I

MM 14.2: Vortrag

Montag, 26. März 2012, 16:00–16:15, H 0107

Re-ordering of FeAl made nanocrystalline by high pressure torsion — •Christoph Gammer, Clemens Mangler, Hans-Peter Karnthaler, and Christian Rentenberger — University of Vienna, Physics of Nanostructured Materials, 1090 Wien, Austria

In this work bulk intermetallic FeAl is made nanocrystalline by high pressure torsion deformation of a B2 ordered Fe-45at.%Al alloy. In the literature it was reported that in FeAl the long-range order is lost during deformation as indicated from X-ray measurements. In contrast, the present work shows that the disorder is not complete since it is revealed by TEM methods that chemically ordered nanodomains of about 2nm are observed after deformation [1]. Upon heating the long-range order is recurring by coarsening of the ordered nanodomains until they reach the grain size. Based on the coarsening of the chemically ordered nanodomains a model for the reordering process is developed and fitted to the results yielded from differential scanning calorimetry. This model allows to determine the vacancy concentration, the vacancy migration enthalpy and the vacancy migration volume. Finally, by annealing of specimens deformed by high pressure torsion without unloading, i.e. maintaining the hydrostatic pressure, their vacancy concentration is determined and compared to that after unloading. This leads to the result that vacancy relaxation occurs during unloading.

[1] C. Gammer, C. Mangler, H. P. Karnthaler, C. Rentenberger. Scripta Mater. 65, 57 (2011).

This work was supported by the Austrian Science Fund (FWF):[S10403,P22440].