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Designing Precipitation-Strengthened Iron-Aluminides for High-Temperature Applications

Published online by Cambridge University Press:  28 February 2011

P.J. Maziasz ,
C.G. Mckamey  and
C.R. Hubbard
P.J. Maziasz
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831
C.G. Mckamey
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831
C.R. Hubbard
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831
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Abstract

A combination of minor solutes was added to an Fe3AI-type base alloy (Fe-28%AI6%Cr-0.05%B) to produce carbide precipitates. These solutes reacted to produce coarse Ti-rich MC and Cr- and Mo-rich M6C precipitates during fabrication at 650–1000°C. X-ray diffraction of hot-worked material revealed a significant amount of the higher temperature B2 phase is retained at room temperature, indicating that the D0s.↔,B2 phase transformation was retarded. During subsequent heat-treatments, the coarse carbides partially dissolved during annealing at 1100–1200°C, and no grain coarsening was observed at temperatures up to 1200°C. Specimens annealed for lh at 1250°C and quenched exhibited fine carbide precipitates both along some of the dislocations and at grain boundaries. The annealed and quenched specimens also contained many fine dislocation loops which coarsened and evolved into networks during further aging at 750°C for 1-10h. Tensile testing at 600°C showed improvements in strength and ductility of annealed and aged material relative to the hot-worked condition. Correlation of microstructural behavior with tensile properties changes supports the idea that microstructural control can be used to develop better high-temperature strength in the B2 phase. However, more data is needed on the combinations of alloying and heattreating which produce fine, stable matrix carbide dispersions in iron-aluminides.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 186: Symposium I – Alloy Phase Stability and Design , 1990 , 349
Copyright
Copyright © Materials Research Society 1991

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