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<p>This study examines the mechanical behaviour, high-temperature oxidation, and corrosion performance of TiAl-based composites containing varying amounts (0–7 wt%) of silicon nitride (Si<sub>3</sub>N<sub>4</sub>) fabricated via spark plasma sintering (SPS). Microstructural analysis revealed the in-situ formation of Ti<sub>5</sub>Si<sub>3</sub> and Ti<sub>2</sub>AlN phases, particularly pronounced at intermediate Si<sub>3</sub>N<sub>4</sub> contents, with optimal phase dispersion observed at 1.5 wt% Si<sub>3</sub>N<sub>4</sub>. 1.5Si<sub>3</sub>N<sub>4</sub>/TiAl composite displayed a peak compressive strength of 2208 ± 25&#xa0;MPa and enhanced fracture resistance, attributed to synergistic toughening mechanisms including Orowan strengthening, crack deflection, and particle-stimulated nucleation. Thermogravimetric analysis and surface oxidation morphologies showed that 1.5Si<sub>3</sub>N<sub>4</sub>/TiAl composite also provides a superior oxidation resistance with the least weight gain of 1.68% compared to 2.77% obtained for the pure TiAl, due to the formation of stable, adherent oxide layers consisting of Al<sub>2</sub>O<sub>3</sub>, SiO<sub>2</sub>, and complex silicates. The developed Si<sub>3</sub>N<sub>4</sub>/TiAl composites exhibited significant corrosion resistance enhancement in 0.5 M H<sub>2</sub>SO<sub>4</sub>, with the lowest corrosion current observed in the composite containing 7 wt% Si<sub>3</sub>N<sub>4</sub>. However, SEM analysis of the corroded surfaces suggests that only the 1.5Si<sub>3</sub>N<sub>4</sub>/TiAl composite maintains structural reliability over prolonged exposure due to its uniform microstructure and stable passive film formation.</p>

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Investigation of mechanical, oxidation and corrosion performance of Si3N4 reinforced TiAl-based composites fabricated via spark plasma sintering technique

  • 期刊论文

  • 发表日期：

    2025年12月5日

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  • Azeez Lawan Rominiyi,
  • Peter Madindwa Mashinini

摘要

This study examines the mechanical behaviour, high-temperature oxidation, and corrosion performance of TiAl-based composites containing varying amounts (0–7 wt%) of silicon nitride (Si3N4) fabricated via spark plasma sintering (SPS). Microstructural analysis revealed the in-situ formation of Ti5Si3 and Ti2AlN phases, particularly pronounced at intermediate Si3N4 contents, with optimal phase dispersion observed at 1.5 wt% Si3N4. 1.5Si3N4/TiAl composite displayed a peak compressive strength of 2208 ± 25 MPa and enhanced fracture resistance, attributed to synergistic toughening mechanisms including Orowan strengthening, crack deflection, and particle-stimulated nucleation. Thermogravimetric analysis and surface oxidation morphologies showed that 1.5Si3N4/TiAl composite also provides a superior oxidation resistance with the least weight gain of 1.68% compared to 2.77% obtained for the pure TiAl, due to the formation of stable, adherent oxide layers consisting of Al2O3, SiO2, and complex silicates. The developed Si3N4/TiAl composites exhibited significant corrosion resistance enhancement in 0.5 M H2SO4, with the lowest corrosion current observed in the composite containing 7 wt% Si3N4. However, SEM analysis of the corroded surfaces suggests that only the 1.5Si3N4/TiAl composite maintains structural reliability over prolonged exposure due to its uniform microstructure and stable passive film formation.