Point defect processes in neutron irradiated Ni, Fe–15Cr–16Ni and Ti-added modified SUS316SS

Abstract

The defect structures in Ni, Fe–15Cr–16Ni and Ti-added modified SUS316SS (modified SUS316) were examined after neutron irradiation below 0.3 dpa by the Japan Materials Testing Reactor and Belgian Reactor 2 to compare their defect structural evolution. The growth behaviour of interstitial-type dislocation loops (I-loops), stacking fault tetrahedra (SFTs) and voids was found to be quite different among these specimens. I-loops developed at lower temperatures in Ni than in Fe–15Cr–16Ni and modified SUS316, and more swelling occurred in Ni than in Fe–15Cr–16Ni. Finally, there were no voids in modified SUS316. These results were analysed in terms of the I-loop energy. A large discrepancy was found between the analytical results and experimental observations for Ni and modified SUS316, which suggests the formation of unfaulted I-loops directly from collision cascades. The growth of SFTs was detected in Fe–15Cr–16Ni and modified SUS316, and can be explained by a change in the dislocation bias of SFTs resulting from the absorption of alloying elements.

Keywords:

• Fe-Cr-Ni
• Ni
• austenitic stainless steels
• neutron irradiation
• irradiation damage

Acknowledgements

This study was performed under the sponsorship of a Grant-in-Aid for Science Research (B) by JSPS (Task No. 22360401). A part of this study was a result of “Clarification of material behaviors in accelerator driven systems by an FFAG accelerator” carried out under the Strategic Promotion Program for Basic Nuclear Research by the Ministry of Education, Culture, Sports, Science and Technology of Japan.