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.
Revised: January 7, 2009 |
Published: December 21, 2001
Citation
Bruemmer S.M., D.J. Edwards, V.Y. Guertsman, and E.P. Simonen. 2001.Grain Boundary Modification During Neutron Irradiation at Intermediate Temperatures. In Microstructural Processes in Irradiated Materials, 2000 MRS Proceedings, 650. Warrendale, Pennsylvania:Materials Research Society.PNNL-SA-33978.