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Grain Boundary Modification During Neutron Irradiation at Intermediate Temperatures

Conference ·
OSTI ID:946024
Grain boundary compositions and near-boundary microstructures have been measured in complex Fe-Cr-Ni alloys after neutron irradiation at critical intermediate temperatures. Radiation-induced segregation (RIS) and dislocation loop microstructures have been determined as a function of irradiation dose up to 13 dpa and at temperatures near 280?C. The most significant effect on RIS was the grain boundary structure (low-energy special boundaries versus high-energy random boundaries) and composition (enrichment of Cr and Mo) before irradiation. A similar grain boundary character distribution was seen after irradiation and only high-energy boundaries exhibited significant radiation-induced changes. The initial grain boundary composition in mill-annealed stainless steels was difficult to remove during subsequent irradiation and retarded the development of Cr- and Mo-depleted regions. The predominant microstructural feature produced at irradiation temperature below ~300?C is faulted dislocation loops. A distinct denuded zone was observed at high-energy boundaries in materials irradiated at low-to-intermediate doses that disappeared at higher doses. Denuded zone differences were detected in Mo-containing alloys that could not be directly related to composition, RIS or matrix microstructure. Radiation-induced grain boundary changes are evaluated in relation to the current understanding of irradiation-assisted SCC in stainless steel core components.
Research Organization:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC05-76RL01830
OSTI ID:
946024
Report Number(s):
PNNL-SA-33978; KC0201020
Country of Publication:
United States
Language:
English