Nano-scale oxide dispersoids by internal oxidation of Fe–Ti–Y intermetallics

The processing of high-temperature alloys containing nano-scale oxide dispersoids usually involves mechanical alloying, but dispersoid formation by internal oxidation is also an option. In this work, the internal oxidation of the intermetallics Fe17Y2 and Fe11YTi was studied. Internal oxidation resulted in small (∼20 nm) oxide particles in an iron solid solution matrix. Oxides such as Y2O3, YFeO3, Y2Ti2O7, and Fe2TiO4 were observed. Hardness values as high as those of the original intermetallics were observed. However, the oxide particles coarsened quickly during annealing at 1000 °C. In order to reduce the coarsening rates, oxides more similar to those in mechanically alloyed steels need to be synthesized.