Effect of Processing and Microalloying Elements on the Thermal Stability of Cr-Cr3Si and NiAl-Mo Eutectic Alloys
- ORNL
The thermal stability of multiphase intermetallics at temperatures to 1400 C was investigated by studying two model eutectic systems: Cr-Cr{sub 3}Si having a lamellar microstructure and NiAl-Mo having a fibrous microstructure. In drop cast Cr-Cr{sub 3}Si, 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-Cr{sub 3}Si interfaces and decrease their energies. Similarly, directional solidification, which is also expected to lower the Cr-Cr{sub 3}Si 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.
- Research Organization:
- Oak Ridge National Laboratory (ORNL)
- Sponsoring Organization:
- SC USDOE - Office of Science (SC)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 931487
- Country of Publication:
- United States
- Language:
- English
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