Electron microscopy of severely deformed L12 intermetallics

Autor(en)

David Geist, Christoph Gammer, Clemens Mangler, Christian Rentenberger, Hans-Peter Karnthaler

Abstrakt

Severe plastic deformation (SPD) can be used to make bulk, nanostructured materials. Three L12 long-range ordered (LRO) intermetallic compounds were studied by TEM methods. The superlattice glide dislocations can dissociate according to two schemes: antiphase boundary (APB) coupled unit dislocations or superlattice intrinsic stacking fault (SISF) coupled super Shockley partials; both of them are analysed by weak-beam TEM methods. The nanostructures resulting from SPD carried out by high pressure torsion (HPT) are strongly affected by the different dissociation schemes of the dislocations. APB-dissociated superlattice dislocations and especially the APB tubes they form lead to the destruction of the LRO by HPT deformation as observed in Cu3Au and Ni3Al, whereas in Zr3Al heavily deformed (100,000% shear strain) at low temperatures the order is not destroyed since the deformation occurs by SISF-dissociated dislocations. In addition to the effects on the LRO the different dissociation schemes of the dislocations have a strong impact on the refinement and destruction of the crystalline structure by SPD. They seem to be decisive for the dynamic recovery considered as the limiting factor for the final grain sizes and the possibility of reaching amorphisation. Finally, the correlation between the reduction of the LRO and the structural refinement occurring during SPD is different in the three different alloys: In Cu3Au, the LRO is already strongly reduced before the structural refinement reaches saturation, in Ni3Al both are occurring simultaneously, whereas in Zr3Al, the formation of the nanograins does not seem to be connected with disordering.

Document Type: Article

Organisation(en)

Physik Nanostrukturierter Materialien

Journal

Philosophical Magazine

Band

90

Seiten

4635-4645

Anzahl der Seiten

11

ISSN

1478-6435

DOI

https://doi.org/10.1080/14786435.2010.482178

Publikationsdatum

2010

Peer-reviewed

Ja

ÖFOS 2012

103023 Polymerphysik, 210006 Nanotechnologie, 103018 Materialphysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/fd3ba34a-1065-4f80-b9df-e435186422f1