Nb-base FS-85 Alloy as a Candidate Structural Material for Space Reactor Applications: Effects of Thermal Aging

Journal Article · Thu Jan 01 04:00:00 EST 2009 · Metallurgical and Materials Transactions A

DOI:https://doi.org/10.1007/s11661-008-9771-3· OSTI ID:948533

Leonard, Keith J ^[1]; Busby, Jeremy T ^[1]; Hoelzer, David T ^[1]; Zinkle, Steven J ^[1]

---

1. ORNL

The proposed use of fission reactors for manned or deep space missions have typically relied on the potential use of refractory metal alloys as structural materials. Throughout the history of these programs, the lead candidate has been Nb-1Zr due to its good fabrication and welding characteristics. However, the less than optimal creep resistance of this alloy has encouraged interest in the more complex FS-85 (Nb-28Ta-10W-1Zr) alloy. Despite this interest, a relatively small database exists for the properties of FS-85. These gaps include potential microstructural instabilities that can lead to mechanical property degradation. In this work, changes in microstructure and mechanical properties of FS-85 were investigated following 1100 h of thermal aging at 1098, 1248 and 1398 K. The changes in electrical resistivity, hardness and tensile properties between the as-annealed and aged materials are compared. Evaluation of the microstructural changes was performed through optical, scanning and transmission electron microscopy. The development of intragranular and grain boundary precipitation of Zr-rich compounds as a function of aging temperature was followed. Brittle tensile behavior was measured in the 1248 K aged material, while ductile behavior occurred in material aged above and below this temperature. The effect of temperature on the under and overaging of the grain boundary particles are believed to have contributed to the mechanical property behavior of the aged material.

• Research Organization: Oak Ridge National Laboratory (ORNL); Shared Research Equipment Collaborative Research Center
• Sponsoring Organization: ORNL work for others
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 948533
• Journal Information: Metallurgical and Materials Transactions A, Journal Name: Metallurgical and Materials Transactions A Journal Issue: 4 Vol. 40A
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
36 MATERIALS SCIENCE
AGING
ELECTRIC CONDUCTIVITY
GRAIN BOUNDARIES
HARDNESS
MICROSTRUCTURE
MORPHOLOGICAL CHANGES
NESDPS Office of Nuclear Energy Space and Defense Power Systems
NIOBIUM BASE ALLOYS
SPACE POWER REACTORS
TANTALUM ALLOYS
TENSILE PROPERTIES
TUNGSTEN ALLOYS
ZIRCONIUM ADDITIONS