| Abstract Scope |
FeCrAl-based alloys are increasingly recognized as promising structural materials for advanced fission and fusion nuclear reactors due to their superior performance under extreme conditions, including high-temperature creep resistance, excellent oxidation behavior, and robust resistance to irradiation damage. To further enhance these properties, researchers have explored the incorporation of nano-scale precipitates—particularly nitrides and oxides—within the alloy matrix. This study investigates the impact of high-temperature heat treatment at 1200 °C for durations of 1 and 10 hours on the microstructural evolution and mechanical performance of Fe–12Cr–6Al–1Ti–0.25Y₂O₃ alloys produced via Laser Powder Bed Fusion (L-PBF), with a particular emphasis on the formation and transformation of in situ–synthesized nitride and oxide precipitates. Initially, the alloy exhibited an average grain size of 9 µm, which increased to 13 µm after 1 hour and to 16 µm after 10 hours of heat treatment, indicating progressive grain growth and recrystallization. After 1-hour, TiN precipitates were still present, accompanied by the appearance of Al₂O₃ and Y₂O₃ phases. Extended treatment for 10 hours led to the emergence of complex precipitates such as Al–Y–O and Y–O–N, while Al₂O₃ and Y₂O₃ phases diminished, and TiN remained stable. Notably, these precipitates also underwent gradual coarsening with prolonged exposure. Mechanically, the alloy exhibited reduced yield strength (YS) and ultimate tensile strength (UTS) after 1 hour of heat treatment, along with enhanced ductility. After 10 hours, the mechanical strength declined further, yet still outperformed the unreinforced Fe–12Cr–6Al alloy. |