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Environmental Effects in B2 FeAl Alloys

Published online by Cambridge University Press:  01 January 1992

O. Klein
Affiliation:
Thayer School of Engineering,Dartmouth College, Hanover, NH 03755
P. Nagpal
Affiliation:
Thayer School of Engineering,Dartmouth College, Hanover, NH 03755
I. Baker
Affiliation:
Thayer School of Engineering,Dartmouth College, Hanover, NH 03755
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Abstract

The low room-temperature ductility of iron-rich B2-structured FeAl has been attributed to atomic hydrogen arising from a reaction between water vapor and aluminum atoms at crack tips [C.T. Liu and C.G. McKamey, in “High Temperature Aluminides and Intermetallics”, eds. S.H. Whang et al (TMS, Warrendale, PA, 1990), p. 133]. Since hydrogen diffusion is time-dependent, the ductility might be expected to improve with increasing strain rate. Such behavior has been confirmed by tensile tests on Fe-45A1 and Fe-40Al-5Cr in air at strain rates ranging from 1 × 10−6 s−1 to 1 s−1. A brittle-to-ductile transition was observed at a strain rate of ∼10−2 s−1. The material with Cr appeared to be slightly less susceptible to environmental embrittlement, as reflected by the shift of the brittle-to-ductile transition to a lower strain rate. Fracture toughness tests on Fe-45A1 in air demonstrated a similar strain rate effect.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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References

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