Abstract
The α-phase transformation kinetics of as-cast U - 8 wt% Mo below the eutectoid temperature have been established by in situ neutron diffraction. α-phase weight fraction data acquired through Rietveld refinement at five different isothermal hold temperatures can be modeled accurately utilizing a simple Johnson-Mehl-Avrami-Kolmogorov impingement-based theory, and the results are validated by a corresponding evolution in the γ-phase lattice parameter during transformation that follows Vegard's law. Neutron diffraction data is used to produce a detailed Time-Temperature-Transformation diagram that improves upon inconsistencies in the current literature, exhibiting a minimum transformation start time of 40 min at temperatures between 500 °C and 510 °C. The transformation kinetics of U - 8 wt% Mo can vary significantly from as-cast conditions after extensive heat treatments, due to homogenization of the typical dendritic microstructure which possesses non-negligible solute segregation.
| Original language | English |
|---|---|
| Pages (from-to) | 149-156 |
| Number of pages | 8 |
| Journal | Journal of Nuclear Materials |
| Volume | 477 |
| DOIs | |
| State | Published - Aug 15 2016 |
| Externally published | Yes |
Funding
Funding for this research was provided by the Y-12 National Security Complex’s Plant Directed Research, Development, and Demonstration program . The Spallation Neutron Source (SNS) user facility, Oak Ridge National Laboratory, is supported by the Scientific User Facilities Division, the Office of Basic Energy Sciences, the U.S. Department of Energy . This work of authorship and those incorporated herein were prepared by Consolidated Nuclear Security, LLC (CNS) Pantex Plant/Y-12 National Security Complex as accounts of work sponsored by an agency of the United States Government under contract DE NA0001942 . Neither the United States Government nor any agency thereof, nor CNS, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility to any non‑governmental recipient hereof for the accuracy, completeness, use made, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency or contractor thereof, or by CNS. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency or contractor (other than the authors) thereof. This document has been authored by Consolidated Nuclear Security, LLC, under Contract DE‑NA‑0001942 with the U.S. Department of Energy/National Nuclear Security Administration, or a subcontractor thereof. The United States Government retains and the publisher, by accepting the document for publication, acknowledges that the United States Government retains a nonexclusive, paid‑up, irrevocable, world‑wide license to publish or reproduce the published form of this document, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, or allow others to do so, for U. S. Government purposes. The authors would like to thank Matt Frost of Oak Ridge National Laboratory for his logistical help throughout this experiment.
| Funders | Funder number |
|---|---|
| United States Government | DE NA0001942 |
| Y-12 National Security Complex’s Plant Directed Research | |
| U.S. Department of Energy | |
| Basic Energy Sciences |
Keywords
- Eutectoid decomposition
- Neutron diffraction
- Time-temperature-transformation diagram
- Transformation kinetics
- U-Mo alloys