Abstract
An extensive experimental study characterizing the sequence of events that lead to the formation of a very high density of Y-Ti-O solute nanoclusters (NC) in mechanically alloyed, hot isostatically pressed ferritic stainless steels is reported. Yttria dissolves in the Fe-14Cr-3W(0.4Ti) powders during mechanical alloying. The dissolved Y and O, and when present Ti, subsequently precipitate during hot consolidation. The number densities and volume fractions of the NC decrease, and their radii increase, with increasing consolidation temperature. The NC form at 850 and 1000 °C in milled alloys containing Y, both with and without Ti additions. The presence of Ti refines the NC, and both Ti and high milling energy are necessary for the formation of NC at the highest consolidation temperatures of 1150 °C. However, the precise structure and composition of the NC are not well understood. Indeed, their character varies, depending on the alloy composition and processing variables.
| Original language | English |
|---|---|
| Pages (from-to) | 392-406 |
| Number of pages | 15 |
| Journal | Acta Materialia |
| Volume | 57 |
| Issue number | 2 |
| DOIs | |
| State | Published - Jan 2009 |
Funding
The research carried out was built on the pioneering contributions of J. Fisher (INCO), the inventor of MA NFA, as well as that of both Dr. M. Hamilton (PNNL) and her co-workers in the US Breeder Reactor Materials Program and Professor S. Ukai (currently at Hokkaido University) and his collaborators in Japan. The authors gratefully acknowledge Doug Klingensmith (UCSB) for his contributions to the SANS measurements, Professor Brian Wirth (UC Berkeley) for his help in analysis of the SANS data and both Dr. Mike Miller and Kaye Russell for their guidance the APT studies. We acknowledge the support of the National Institute of Standards and Technology, US Department of Commerce, Center for Neutron Research in providing the SANS facilities used in this work. Research at the Oak Ridge National Laboratory SHaRE User Center was sponsored by the Division of Materials Sciences, US Department of Energy (DOE), under contract DE-AC05-00OR22725 with UT-Battelle, LLC. The overall research effort at UCSB was supported by DOE Office of Fusion Energy Science (Grant DE-FG03-94ER54275) and the I-NERI DOE Office of Nuclear Energy through a subcontract with ORNL (Grant 400014112).
| Funders | Funder number |
|---|---|
| DOE Office of Fusion Energy Science | DE-FG03-94ER54275 |
| Division of Materials Sciences | |
| I-NERI DOE Office of Nuclear Energy | |
| U.S. Department of Energy | DE-AC05-00OR22725 |
| National Institute of Standards and Technology | |
| U.S. Department of Commerce | |
| Oak Ridge National Laboratory | 400014112 |
| NIST Center for Neutron Research |
Keywords
- Ferritic steel
- Fission and fusion reactor alloys
- Mechanical alloying
- Oxide dispersion strengthening
- Small angle neutron scattering
