High-temperature isothermal oxidation behavior of the mechanically alloyed Nb–Ti–Si refractory alloy in air and N2 atmosphere

In this study, an NbSi alloy was synthesized by mechanical alloying and subsequently consolidated via spark plasma sintering (SPS) at 1400 °C to investigate its high-temperature oxidation behavior. The alloy was subjected to thermogravimetric–differential thermal analysis (TG–DTA) at 1300 °C for 100 h under a nitrogen atmosphere to assess its long-term thermal stability and oxidation resistance. Post-oxidation characterization was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) to examine surface morphology and cross-sectional features. A stable oxide scale with a compact and uniform microstructure was observed, indicating controlled oxidation kinetics. Cross-sectional analysis revealed limited inward diffusion and a well-adhered oxide layer, confirming excellent oxidation resistance at elevated temperatures. These results demonstrate that the SPS-processed NbSi alloy demonstrates favorable high-temperature stability under inert conditions, highlighting its potential for structural applications in extreme environments.