Microstructural and thermal evolution of hBN reinforced Fe3Al intermetallic synthesized via SHS

Abstract

In this study, Fe₃Al-based intermetallic composites reinforced with hexagonal boron nitride (hBN) nanoparticles were synthesized using Self-Propagating High-Temperature Synthesis (SHS), followed by controlled heat treatment and sintering. During SHS, FeAl formed as a transient phase and transformed into stable Fe₃Al after heating at 1000 °C. The addition of hBN significantly affected both the microstructure and thermal behavior, facilitating the in-situ formation of secondary phases such as AlN and Al₂O₃. Despite challenges in achieving uniform dispersion, SEM–EDX analysis confirmed the retention of hBN's lamellar morphology and its interfacial interaction with the matrix. While moderate hBN content enhanced thermal stability, excessive amounts reduced densification and increased brittleness. Short-term heat treatment after SHS was found to be critical for microstructural refinement. The results highlight the multifunctional role of hBN as both a structural reinforcement and a thermal modifier, supporting the potential of Fe–Al/hBN composites for high-temperature applications in aerospace, energy, and metallurgical industries.