Experimental Verification of the Decomposition of Y₂O₃ in Fe-Based ODS Alloys During Mechanical Alloying Process

In this study, we investigated the state of Y₂O₃, as a major additive element in Fe-based ODS alloys, during mechanical alloying (MA) processes by thermodynamic approaches and experimental verification. For this purpose, we introduced Ti₂O₃ that formed different reaction products depending on the state of Y₂O₃ into the Fe-based ODS alloys. In addition, the reaction products of Ti₂O₃, Y, and Y₂O₃ powders were predicted approximately based on their formation enthalpy. The experimental results relating to the formation of Y-based complex oxides revealed that YTiO₃ and Y₂Ti₂O₇ were formed when Ti₂O₃ reacted with Y; in contrast, only Y₂Ti₂O₇ was detected during the reaction between Ti₂O₃ and Y₂O₃. In the alloy of Fe–Cr–Y₂O₃ with Ti₂O₃, YTiO₃ (formed by the reaction of Ti₂O₃ with Y) was detected after the MA and heat treatment processes were complete, even though Y₂O₃ was present in the system. Using these results, it was proved that Y₂O₃ decomposed into monoatomic Y and O during the MA process.