Paramagnetic to ordered magnetic phase transition of He+ ions irradiated stainless steel studied by XMCD: a new perspective for early stage detection of defects in solids

Abstract

X-ray absorption and magnetic circular dichroism measurements have been carried out on stainless steel 316 samples, both before and after He+-ion irradiation. It was found that Fe and Cr were both oxidised in the surface layer due to exposure to ambient with the Cr oxidation layer running deeper into the sample. Irradiation with He+ ions apparently lead to a change in the chemical composition of the Fe oxide layer, from a more FeO-like to a more Fe2O3-like with the presence of some metallic Fe. Most importantly the irradiation process induced a paramagnetic to an ordered magnetic phase transition as revealed by the measurements done in magnetic remanent state. After irradiation no He bubbles were observed in the cross-sectional scanning electron microscopy images. © 2010 IOP Publishing Ltd