Abstract
In this article, we present the creep characteristics of two reduced activation ferritic-martensitic steels of identical starting compositions formed by different fabrication routes: a nanostructured ferritic alloy commonly referred to as a castable nanostructured alloy (CNA) and a sintered nanostructured alloy (SNA) variant. Through a series of nanoindentation experiments spanning a temperature range of 25 °C to 650 °C, with a maximum load of 100 mN, we find creep behaviors in the cast and sintered materials to be remarkably similar. The creep stress exponent (n) for CNA and SNA were found to be in the range of 8–35 and the activation volume was ∼14–42b3, underscoring a dominance of dislocation-mediated mechanisms in both alloys. Notably, we observed a decline in the creep stress exponent with increasing temperature, attributable to the heightened influence of thermally activated dislocations. This phenomenon suggests a potential transition in the deformation mechanism towards a thermally activated dislocation climb process, significantly impacting the observed creep behavior.
| Original language | English |
|---|---|
| Article number | 155804 |
| Journal | Journal of Nuclear Materials |
| Volume | 611 |
| DOIs | |
| State | Published - Jun 2025 |
Funding
These experiments were supported by the U.S. Department of Energy Office of Fusion Energy Sciences under contract DE-SC0018322 with the Research Foundation for the State University of New York at Stony Brook. This research used resources from the Center for Functional Nanomaterials, which is a U.S. Department of Energy Office of Science Facility, at Brookhaven National Laboratory under contract no DE-SC0012704. The authors would also like to thank Kevin Schmalbach for the help rendered in running the glovebox nanoindenter used in this study. We wish to thank and acknowledge the two anonymous referees for their important and insightful comments that have helped strengthen this article. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-accessplan ). These experiments were supported by the U.S. Department of Energy Office of Fusion Energy Sciences under contract DE-SC0018322 with the Research Foundation for the State University of New York at Stony Brook. This research used resources from the Center for Functional Nanomaterials, which is a U.S. Department of Energy Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704. The authors would also like to thank Kevin Schmalbach for the help rendered in running the glovebox nanoindenter used in this study. We wish to thank and acknowledge the two anonymous referees for their important and insightful comments that have helped strengthen this article.
Keywords
- Creep
- Direct current sintering
- Nanoindentation
- Sintered nanostructured alloy
- Stress exponent