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Influence of copper precipitates on clustering behavior of alloying elements observed in Japanese reactor pressure vessel surveillance materials using atom probe tomography.
- Source :
-
Journal of Nuclear Materials . Dec2020, Vol. 542, pN.PAG-N.PAG. 1p. - Publication Year :
- 2020
-
Abstract
- • Chemical compositions of solute atom clusters in surveillance materials from four nuclear power plants were compared. • The balance of Mn-Ni-Si in solute clusters in a BWR material is similar to that of the Γ 2 phase. • Relative Si concentrations in solute clusters in PWR materials are higher than the Si concentration in the G phase. This suggests the contribution of radiation-induced segregation of Si. • The "catalyst effect" of Cu precipitates on the gathering of Mn and Ni may assist in Mn-Ni-Si cluster formation. In a highly irradiated reactor pressure vessel (RPV), solute Mn, Ni, and Si (MNS) atoms gather to form nanometer-sized microstructures, generally called MNS clusters. MNS often gather with Cu-rich precipitates, which can form in RPVs following lower dose irradiation. In this study, surveillance specimens provided from four nuclear power plants in Japan were analyzed using three-dimensional atom probe tomography (APT), and the nature of the solute enrichment was carefully compared. When analyzing the chemical composition of each cluster, a clear negative correlation was found between Si and Cu in all materials, but conversely, Mn was likely present in clusters with a high Cu concentration. Moreover, in a boiling water reactor material with high Cu, the ratio of MNS was shown to be similar to that of the Γ 2 phase [Mn (Ni, Si) 2 ]. In pressurized water reactor materials with medium and low Cu, however, Ni and Si enrichment was demonstrated to be higher than the ratio of the expected intermetallic compounds; such as a Γ 2 phase and a G phase [Mn 6 Ni 16 Si 7 ]. Ni and Mn atoms, once enriched in a copper-rich region, may elute out, and form an intermetallic compound with Si atoms within the vicinity. Particularly in highly irradiated RPV materials, such a structure may tend to be decorated by irradiation-induced lattice defects with Si segregation. Image, graphical abstract [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00223115
- Volume :
- 542
- Database :
- Academic Search Index
- Journal :
- Journal of Nuclear Materials
- Publication Type :
- Academic Journal
- Accession number :
- 146681808
- Full Text :
- https://doi.org/10.1016/j.jnucmat.2020.152508