Effect of SPS Consolidation and Heat Treatment on Microstructure and Mechanical Behavior of Fe–Cr–Al–Y2O3 ODS Alloys with Different Ti and V Contents

Oxide dispersion strengthened (ODS) alloys, due to their high irradiation resistance and good mechanical properties at high temperatures, are promising for applications in Generation IV reactors, especially GFR, and fusion installations. However, the biggest challenge in applying ODS materials is related to fabrication techniques. This paper aims to evaluate powder metallurgy processing and the effect of small additions of oxide- and carbide-forming elements on the microstructure and mechanical properties of Fe–Cr–Al-based ODS alloys. The series of ODS alloys with Y2O3 and different additions of Ti and V was prepared by mechanical alloying (MA) and consolidated by spark plasma sintering (SPS), which is less often employed to fabricate ODS alloys than hot extrusion or hot isostatic pressing. The investigations were performed on MAed powders, bulk-sintered samples, and samples after homogenization annealing. The MAed powders reveal two body-centered cubic (bcc) alloyed phases with close lattice parameters. The sintered samples show a single bcc phase (a = 2.88–2.89 Å) matrix and a high-volume fraction of homogenously distributed nanometric oxide precipitates. The addition of vanadium and titanium leads to the formation of vanadium- and titanium-rich nanometric oxides and carbides. The bulk samples show fine grain and stable microstructure with an average grain size slightly below 1 µm. Moreover, after homogenization annealing and air cooling, the relative density slightly increases. Hardness after heat treatment is relatively stable, which was confirmed by nanoindentation and Vickers microhardness results. These experimental findings promise to develop Fe–Cr–Al-based ODS materials tailored for operation under harsh conditions in nuclear reactors.