Abstract: Traditional wave-absorbing materials often exhibit performance limitations at high temperatures, struggling to meet performance demands in extreme thermal environments. Fe₂AlB₂ has garnered significant attention in the field of high-temperature wave absorption due to its nano-layered structure and exceptional thermal stability. This study synthesized Fe₂AlB₂ powder through a wet ball milling process followed by sintering in an argon atmosphere. A systematic investigatigation was conducted to elucidate the oxidation mechanisms and to assess the evolution of its wave-absorbing properties at elevated temperatures. Additionally, CST software was utilized to model the radar cross-section(RCS) associated with its absorption process under 7 GHz microwave irradiation. The results indicate that the onset oxidation temperature of Fe₂AlB₂ is 671 ℃. As the oxidation temperature increases, a dense Al₂O₃ protective film forms on its surface, significantly enhancing its oxidation resistance. Beyond 1000 ℃, this Al₂O₃ film fractures, leading to the transformation of the primary phases into Fe₂O₃, Al₄B₂O₉, and amorphous B₂O₃. Within the oxidation temperature range of 300-800℃, the wave absorption performance of the sample progressively improves with increasing oxidation temperature, exhibiting particularly outstanding dielectric loss capabilities around 10 GHz. At an oxidation temperature of 900℃, the sample achieves a reflection loss (RL) of -42.6 dB at a frequency of 11.28 GHz, with a corresponding thickness of 2.8 mm. The Al₂O₃ film significantly enhances dielectric loss efficiency by inducing interfacial polarization loss at the "oxide film-matrix" interface. This study elucidates that the oxidation mechanisms of Fe₂AlB₂ at varying temperatures and examines the consequent impacts on its wave-absorbing properties, thereby providing a theoretical foundation for its application in high-temperature wave-absorbing environments.

Key words: Fe₂AlB₂, oxidation resistance, wave-absorbing properties, thermal stability