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Characterizing Deformation Mechanisms in Ni3Ge-Fe3Ge Intermetallic Alloys

Published online by Cambridge University Press:  10 February 2011

T. J. Balk ,
Mukul Kumar ,
O. N. Mryasov ,
A. J. Freeman  and
K. J. Hemker
T. J. Balk
Affiliation:
Dept. of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218-2686
Mukul Kumar
Affiliation:
Univ. of California, Lawrence Livermore National Laboratory, L-370, Livermore, CA 94550
O. N. Mryasov
Affiliation:
Dept. of Physics and Astronomy, Northwestern University, Evanston, IL 60208-3112
A. J. Freeman
Affiliation:
Dept. of Physics and Astronomy, Northwestern University, Evanston, IL 60208-3112
K. J. Hemker
Affiliation:
Dept. of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218-2686
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Abstract

The Ni3Ge-Fe3Ge model system provides us with a unique opportunity to characterize the mechanisms of deformation in both anomalous and normal L12 intermetallic alloys. The elastic moduli of alloys in this system have been measured and used as benchmarks for first principles calculations. At 77K, increasing the Fe content has been found to result in a dramatic increase in flow stress. The Ni-rich alloys exhibit a yield strength anomaly, but as Ni is replaced by Fe, the anomalous temperature dependence gradually disappears, and no yield strength anomaly is observed for alloys with more than 25 at% Fe. At low temperatures and Fe contents, the deformation microstructure has been found to be dominated by Kear-Wilsdorf locking; but a transition from octahedral glide and Kear-Wilsdorf locking to cube glide is observed as either Fe content or temperature is increased. This transition is related to changes that occur in the core structures of dissociated superdislocations and planar fault energies measured through computer simulations of weak-beam TEM images.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 552: Symposium KK – High-Temperature Ordered Intermetallic Alloys VIII , 1998 , KK10.8.1
Copyright
Copyright © Materials Research Society 1999

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References

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