<i>In situ</i> heavy ion irradiation in ferritic/martensitic ODS steels at 500°C

Abstract

Three different ferritic/martensitic oxide dispersion-strengthened steels (9Cr, 12Cr and 16Cr) were irradiated using dual beam ions (Kr + and He + ), with in situ transmission electron microscope observation. Helium was found to be essential in cavity nucleation and growth. The 9Cr alloy presented the lowest formation of cavities among the three irradiated steels, which is attributed to the presence of significant amounts of martensite. During the irradiation of 16Cr alloy with dual beam ions, cavity segregation to grain boundaries was observed at a relatively low dose ∼1 dpa, whereas it occurred at ∼2 dpa in 9Cr and 12Cr alloys. Nano-sized Y–Ti–O particles were stable during the entire irradiation to ∼8 dpa. The lattice defects were characterised and mainly consist of [Formula: see text] interstitial loops.