ODS ferritic steels obtained from gas atomized powders through the STARS processing route: Reactive synthesis as an alternative to mechanical alloying

•Atomized powders contain required Y and mechanical alloying is not necessary.•Oxidation of powder particles develops a metastable oxide layer on their surface.•HIP at high temperature dissociates metastable Cr2O3 and Y2O3.•XAS and TEM confirm precipitation of very stable oxide nanoparticles.•TMTs are required to increase density of oxide nanoparticles.