Deformation Localisation in Ion-Irradiated FeCr

TL;DR

This study investigates how ion irradiation affects deformation localization in FeCr steels, revealing that irradiation causes significant plasticity confinement and that chromium content has limited influence on these effects, informing nuclear reactor material design.

Contribution

The paper provides the first detailed non-destructive analysis of deformation localization and plasticity confinement in irradiated FeCr steels using advanced microscopy and diffraction techniques.

Findings

Irradiation causes increased pile-up height and slip step formation.

Over 85% of plasticity is confined near the indent site in irradiated materials.

Cr content has limited impact on irradiation-induced deformation characteristics.

Abstract

Irradiation-induced ductility loss is a major concern facing structural steels in next-generation nuclear reactors. Currently, the mechanisms for this are unclear but crucial to address for the design of reactor components. Here, the deformation characteristics around nanoindents in Fe and Fe10Cr irradiated with Fe ions to $\sim$1 displacement-per-atom at 313 K are non-destructively studied. Deformation localisation in the irradiated materials is evident from the increased pile-up height and slip step formation, measured by atomic force microscopy. From 3D X-ray Laue diffraction, measurements of lattice rotation and strain fields near the indent site show a large confinement, over 85%, of plasticity in the irradiated material. We find that despite causing increased irradiation hardening, Cr content has little effect on the irradiation-induced changes in pile-up topography and deformation fields. The results demonstrate that varying Cr content in steels has limited impact on retaining strain hardening capacity and reducing irradiation-induced embrittlement.