Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 23: Topical Session Bulk Nanostrucured Materials V - Microstructure and Characterization III
MM 23.6: Vortrag
Dienstag, 27. März 2012, 12:45–13:00, H 0107
Chemical disordering in intermetallic FeAl induced by cold rolling and folding — •Anna Findeisen1,2, C. Gammer1, C. Rentenberger1, J. Eckert2, and H.P. Karnthaler1 — 1University of Vienna, Physics of Nanostructured Materials, Wien, Austria — 2Inst. of Complex Materials, IWF Dresden, Germany
Cold rolling and folding is used for the severe plastic deformation of the B2 ordered intermetallic compound FeAl. The structural changes induced by this deformation are studied by transmission electron microscopy (TEM) methods in combination with differential scanning calorimetry (DSC) and magnetic measurements. The TEM study reveals the formation of a nanocrystalline structure that is accompanied by a reduction of the long range order. The process of chemical disordering causes a transition from the initial paramagnetic state to a ferromagnetic one. DSC and magnetic measurements show that the reduction of order increases with increasing deformation. This leads to a state of saturation of strongly reduced chemical order that is formed by homogeneously distributed chemically ordered domains with a size of about 2 nm as revealed by TEM images. This structure containing a high density of defects is rather unstable as it starts to relax even at room temperature. The results of the transitions occurring upon heating of both the magnetic state and the process of re-ordering are compared with those of FeAl severely deformed by high pressure torsion [1,2,3]. [1] C. Mangler et al. Acta Mater. 58, 5631 (2010). [2] C. Mangler et al. J. Alloys and Comp. 509, Suppl. 1, 389 (2011) [3] C. Gammer et al. Scripta Mater. 65, 57 (2011).