Characterization of plastic responses and sink strengths of reduced-activation ferritic/martensitic steel focused on low-angle grain boundaries

Abstract

Structural materials for fusion reactors and Gen-IV reactors are required to have stable mechanical behaviors under high irradiation dose. To improve radiation tolerance of materials, grain boundaries have been studied as important microstructural features that can absorb point defects induced by irradiation. However, in case of general high-angle grain boundaries, they hinder the dislocation motions in lattices and make materials brittle. In this study, it was experimentally confirmed that low-angle grain boundaries in reduced-activation ferritic/martensitic steels do not effectively block the dislocation motions and the mobility of dislocation networks on lath boundary planes mediates the plastic deformation using micro-pillar compression tests. In addition, the sink abilities of low-angle grain boundaries in RAFM steels were characterized by observing the distribution of defect-free zone near the boundaries.