Abstract
Refractory alloys based on niobium, tantalum and molybdenum are potential candidate materials for structural applications in proposed space nuclear reactors. Long-term microstructural stability is a requirement of these materials for their use in this type of creep dominated application. Early work on refractory metal alloys has shown aging embrittlement occurring for some niobium and tantalum-base alloys at temperatures near 40% of their melting temperatures in either the base metal or in weldments. Other work has suggested microstructural instabilities during long-term creep testing, leading to decreased creep performance. This paper examines the effect of aging 1100 h at 1098, 1248 and 1398 K on the microstructural and mechanical properties of two niobium (Nb-1Zr and FS-85), tantalum (T-111 and ASTAR-811C) and molybdenum (Mo-41Re and Mo-47.5Re) base alloys. Changes in material properties are examined through mechanical tensile testing coupled with electrical resistivity changes and microstructural examination through optical and electron microscopy analysis.
| Original language | English |
|---|---|
| Pages (from-to) | 336-352 |
| Number of pages | 17 |
| Journal | Journal of Nuclear Materials |
| Volume | 366 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jul 1 2007 |
Funding
The authors thank J. Hack, R. Baranwal, T.M. Angeliu and Y. Ballout of the Naval Reactors Prime Contractor Team for many helpful technical discussions and guidance. The authors thank the following ORNL staff for their assistance on this Project: L.T. Gibson, D. Harper, R. Howell, J.W. Jones, J. Mayotte, J. McNabb, B. Sitterson, B. Sparks, K.A. Thomas and A.M. Williams in addition to C.E. Duty and F.W. Wiffen for their technical contributions. This work was performed under the sponsorship of NASA’s Project Prometheus and directed by DOE/NNSA Naval Reactors. Opinions and conclusions drawn by the authors are not endorsed by DOE/NNSA Naval Reactors. Work on the Nb–1Zr alloy was sponsored by the Office of Fusion Energy Sciences, US Department of Energy. Research at the Oak Ridge National Laboratory SHaRE User center was sponsored by the Division of Materials Sciences and Engineering, US Department of Energy. ORNL is managed for DOE by UT-Battelle, LLC, under Contract DE-AC-05-00OR22725.