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Strength, Thermal Defects, and Solid Solution Hardening in Nickel-Containing B2 Iron Aluminides

Published online by Cambridge University Press:  15 February 2011

J. H. Schneibel ,
P. R. Munroe  and
L. M. PIKE
J. H. Schneibel
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831–6115
P. R. Munroe
Affiliation:
School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, Australia
L. M. PIKE
Affiliation:
Dept. of MS&E, University of Wisconsin-Madison, Madison, WI 53706–1595
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Abstract

Nickel-containing ternary iron aluminides with an aluminum concentration of 45 at. % were investigated with respect to room temperature strength, equilibrium vacancy concentration, and the kinetics of vacancy removal. As compared to binary iron aluminides with the same Al concentration, nickel additions reduce the thermal equilibrium vacancy concentration at 1273 K, whereas they increase this concentration at 973 K. Furthermore, at low temperatures such as 673 K, nickel additions increase dramatically the time needed to reach vacancy equilibrium. During prolonged annealing at 673 K, the density of <001> dislocations in Fe-45Al-3Ni (at. %) increased by an order of magnitude. This suggests that dislocations act as sinks for vacancies. At the same time, the number density of small (20–50 nm) voids decreased, indicating that they were not stable in the absence of substantial vacancy supersaturations. Our findings show also that the solid solution strengthening of iron aluminides due to Ni is much weaker than previously thought.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 460: Symposium Z – High-Temperature Ordered Intermetallic Alloys VII , 1996 , 379
Copyright
Copyright © Materials Research Society 1997

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References

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