Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 9: Topical Session Bulk Nanostrucured Materials II - Processing

MM 9.2: Vortrag

Montag, 26. März 2012, 12:15–12:30, H 0107

Severe plastic deformation of NiAl by high pressure torsion — •David Geist, Christoph Gammer, Hans-Peter Karnthaler, and Christian Rentenberger — Universitys of Vienna, Physics of Nanostructured Materials, Boltzmanng. 5, 1090 Wien, Austria

Severe plastic deformation is an important process to render bulk materials nanostructured. In this work, the B2-ordered intermetallic compound NiAl is subjected to a high pressure torsion deformation at room temperature. The structure of NiAl after different amounts of shear deformation is studied using light microscopy, scanning and transmission electron microscopy. Plan view and cross-section samples are investigated for a local analysis of the occurring micro- and nanostructures. It is shown that high pressure torsion deformation of NiAl leads to different fragmented structures that are inhomogeneously distributed in the cross-section samples. In some regions, ultra-fine grained and nanocrystalline structures are observed. Contrary to B2 ordered FeAl [1], no indications of deformation-induced disordering were encountered. This difference in disordering behaviour is attributed to the dissociation modes of the glide dislocations with and without antiphase boundaries in FeAl and NiAl, respectively. It is shown that high pressure torsion can be used to severely refine the structure even in the case of a brittle compound like NiAl.

[1] C. Gammer et al. (2011) Scripta Materialia 65 (1) 57. The authors thank Dr. Sergiy Divinski, Institute for Materials Physics, University of Munster, for the kind provision of NiAl samples and acknowledge support by the Austrian Science Fund (FWF):[P22440, S10403]