Microstructural refinement and multi-property optimization of TiB₂-reinforced tial composites synthesized by spark plasma sintering

TiAl-xTiB₂ (0.5–3.0 wt%) composites were synthesized via spark plasma sintering (SPS) at 1200 °C and 50 MPa to enhance the microstructural integrity and multifunctional performance of TiAl intermetallic. Moderate TiB₂ additions (1.0–1.5 wt%) produced a refined, pore-free matrix through particle-matrix interactions and particle-assisted diffusion, achieving a maximum relative density of 99.2%. Hardness increased from 459 HV (0.5 wt% TiB₂) to 488 HV (3.0 wt% TiB₂), an improvement attributed to microstructural refinement and dislocation-particle interaction mechanisms. The wear rate decreased significantly from 52.5 × 10^{− 5} mm³/m (0.5 wt% TiB₂) to 11.0 × 10^{− 5} mm³/m (3.0 wt% TiB₂), owing to enhanced hardness, improved load-bearing capability, and the formation of protective mixed tribo-oxide films. Electrochemical tests in NaCl solution revealed the best corrosion resistance occurred at 1.0 wt% TiB₂ with E_corr = 0.00 V, I_corr = 1.0 × 10^{− 6} A/cm², R_p = 9.6 × 10³ Ω.cm², and a corrosion rate of 0.012 mm/yr. Excessive TiB₂ loading (> 2.0 wt%) promoted particle clustering, localized galvanic coupling, and reduced electrochemical stability. Overall, controlled TiB₂ reinforcement (1.0–2.0 wt%) optimally balanced densification, mechanical strength, wear resistance, and corrosion protection, underscoring the potential of SPS-processed TiAl-TiB₂ composites for high-temperature and aerospace structural applications.