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Microstructural Investigations of the Unusual Deformation Behavior of Nb2Co7

Published online by Cambridge University Press:  01 February 2011

Frank Stein
Affiliation:
stein@mpie.de, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
Martin Palm
Affiliation:
palm@scholarone.com, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
Georg Frommeyer
Affiliation:
frommeyer@mpie.de, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
Padam Jain
Affiliation:
padam_jain@brown.edu, Brown University, Providence, Rhode Island, United States
Sharvan Kumar
Affiliation:
Sharvan_Kumar@brown.edu, Brown University, Division of Engineering, Providence, Rhode Island, United States
Lisa Siggelkow
Affiliation:
Lisa.Siggelkow@lrz.tu-muenchen.de, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
Daniel Grüner
Affiliation:
danielg@fos.su.se, Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany
Guido Kreiner
Affiliation:
Guido.Kreiner@cpfs.mpg.de, United States
Andreas Leineweber
Affiliation:
a.leineweber@mf.mpg.de, Max-Planck-Institut für Metallforschung, Stuttgart, Germany
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Abstract

Usually, single-phase intermetallics in bulk form can easily be crushed into powder by hammering. It was therefore quite a surprise when we found that a bulk sample of the monoclinic intermetallic compound Nb2Co7 could be extensively deformed at room temperature without shattering or fracturing. In a previous paper, results of microhardness, compression, tensile and bending tests were provided and discussed [1]. In order to understand the observed unusual deformation behavior of this intermetallic phase, its hitherto unknown crystal structure has been studied and the microstructure of undeformed and deformed samples has been analyzed in the present investigation by light-optical, scanning electron and transmission electron microscopy. Single-phase specimens deformed at very different strain rates (hammering and conventional compression testing) both show the occurrence of microcracks along grain boundaries which, in compression-deformed specimens, are strongly localized in extended shear bands oriented approximately 45° to the compression axis. The grains adjacent to the microcracks are heavily deformed whereas, away from the sheared regions, the samples remain free of any indication of plastic deformation.

Type
Research Article
Copyright
Copyright © Materials Research Society 2009

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References

REFERENCES

1. Siggelkow, L., Burkhardt, U., Kreiner, G., Palm, M., Stein, F., Mater.Sci. Eng. A 497, 174 (2008).Google Scholar
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