Alternate Oxide Dispersion Strengthened Steels: Key Insights from Sintering Studies in Fe-ZrO₂ and Fe-Y₂O₃-Ti Model Systems

The model Oxide Dispersion Strengthened systems are evaluated with an objective to understand the thermal evolution of dispersoid and its interaction with the matrix. A relatively less-explored but promising Fe−15wt.%. ZrO₂ along with conventionally used Fe−15wt.%Y₂O₃-5wt.%Ti model ODS alloys were synthesized by mechanical milling followed by conventional sintering in vacuum. Scanning Electron Microscopy investigations of sintered Fe−15wt.% ZrO₂ system showed the coarsened ZrO₂ network on the grain boundary due to grain boundary dragging. No such Y-Ti-O network was observed in Fe−15wt.% Y₂O₃-5wt.% Ti under the same sintering conditions but large Fe grains were observed. Transmission Electron Microscopy showed retention of fine ZrO₂ and Y-Ti-O complex oxide inside the matrix as well. Despite the presence of Ti, dispersoids in Fe−15wt.% Y₂O₃-5wt.% Ti still grew and sizes of Y-Ti-O species and ZrO₂ were comparable. The quantity of ZrO₂ retained in the matrix was measured to be less compared to Y-Ti-O complex oxide.