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Effect of processing and Microalloying Elements on the Thermal Stability of Cr-Cr3Si and NiAl-Mo eutectic alloys

Published online by Cambridge University Press:  26 February 2011

A. Gali ,
H. Bei  and
E. P. George
A. Gali
Affiliation:
[email protected], University of Tennessee-Knoxville, Materials Science and Engineering, 210 North Purdue Avenue, Apt # 211, Oak Ridge, TN, 37830, United States, 865 574-4343
H. Bei
Affiliation:
[email protected], University of Tennessee-Knoxville, Materials Science and Engineering, Knoxville, TN, 37996, United States
E. P. George
Affiliation:
[email protected], University of Tennessee-Knoxville, Materials Science and Engineering, Knoxville, TN, 37996, United States
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Abstract

The thermal stability of multiphase intermetallics at temperatures to 1400°C was investigated by studying two model eutectic systems: Cr-Cr3Si having a lamellar microstructure and NiAl-Mo having a fibrous microstructure. In drop cast Cr-Cr3Si, coarsening was found to be interface controlled. The coarsening rate could be reduced by microalloying with Ce and Re, two elements which were chosen because they were expected to segregate to the Cr-Cr3Si interfaces and decrease their energies. Similarly, directional solidification, which is also expected to lower the Cr-Cr3Si interfacial energy, was found to dramatically decrease the coarsening rate. In the case of NiAl-Mo, coarsening was found to occur by fault migration and annihilation. Microalloying with B was found to significantly decrease the coarsening rate. The fiber density in the B-doped alloy was smaller than in the undoped alloy, suggesting that B affects the coarsening rate by lowering the fault density.

Keywords

microstructuredirectional solidificationfiber
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 980: Symposium II – Advanced Intermetallic-Based Alloys , 2006 , 0980-II05-36
Copyright
Copyright © Materials Research Society 2007

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References

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