Characterisation of Cr, Si and P distribution at dislocations and grain-boundaries in neutron irradiated Fe–Cr model alloys of low purity

Abstract

Segregations at some dislocations and grain boundaries in Fe–5%Cr, Fe–9%Cr and Fe–12%Cr model alloys of low purity after neutron irradiation at 300°C up to 0.6dpa have been analyzed with atom probe tomography. All dislocation lines and low- and high-angle grain boundaries (GBs) which have been observed were enriched with Cr, Si and P. The segregations reveal the different dislocation structures associated to different type of analysed GBs. Cr and Si atoms were found to be nonhomogenously distributed around the dislocation cores because of the non isotropic stress field induced by edge dislocation lines. Concerning GBs, precipitate free zones (PFZs) are exhibited around the planar defects which were analysed in Fe–9%Cr and Fe–12%Cr model alloys. These PFZ are size dependant with the nominal level of Cr.