Irradiation damage and powder quality impact on the strength of hot isostatically pressed ODS ferritic steel

Oxide dispersion strengthened (ODS) ferritic steels are being investigated for use in the nuclear industry for their high temperature strength and resistance to irradiation-induced defects. The structural properties especially creep resistance of these steels are predominantly dependent on an optimal distribution of yttrium-based nano-oxides which are typically incorporated into the matrix through powder metallurgy processes, such as mechanical alloying (MA) and powder atomisation. Gas atomisation reactive synthesis (GARS) has been developed as an alternative to MA, however its application to aluminium (Al) -containing alloys has not been comprehensively understood. The addition of Al has been found to form Y-Al-oxides, such as YAlO 3 (YAP), Y 3 Al 5 O 15 (YAG) and Y 4 Al 2 O 9 (YAM). PM2000 (Fe-20wt%Cr-5wt%Al-0.5wt%-0.5Y 2 O 3 ) ferritic stainless-steel powder was produced through typical MA and GARS production methods, and both powders were consolidated by the powder metallurgy hot isostatic pressing (PM HIP) process. The powders were characterised to determine physical and chemical properties. The mechanical properties of PM HIP ODS consolidated materials were determined to understand the effect of the particle strengthening through structural property modelling. The aim of this study is to develop the understanding of oxide formation in the powder, as-hot isostatically pressed (HIP’d) and as-proton irradiated conditions.