Deformation behaviour of ion-irradiated FeCr: a nanoindentation study

Illustration of FeCr load and displacement and stress and strain



Understanding the mechanism of plasticity in structural steels is essential for the operation of next-generation fusion reactors.  The study of ion-irradiated model FeCr binary alloys provides important insights into the effect of irradiation on the mechanical properties of steels.  

Kay Song, along with the members of the Hofmann Group and Oxford Micromechanics Group investigated the early stages of plasticity in ion-irradiated FeCr alloys using nanoindentation in this paper* published in the Journal of Materials Research.  

This study examined the indentation 'pop-in' phenomenon and the indentation stress-strain response as a function of irradiation dose and Cr content.  By using a range of indenter tip sizes, the authors were able to separate the effects of the nucleation of dislocations to initiate plasticity, from their propagation through the material.  It was found that the presence of Cr increases the retention of irradiation-induced defects, which in turn reduced the shear stress required for dislocation nucleation.  The indentation stress-strain response revealed an increase of yield strength and decrease of work hardening capacity with irradiation dose, which is similar to previous findings from uniaxial measurements of neutron-irradiated materials.

This study highlights the usefulness of nanoindentation for gaining mechanistic insights into the competing effects that control the initiation and evolution of plasticity in irradiated materials.  



*'Deformation behaviour of ion-irradiated FeCr: a nanoindentation study'.