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

Abstract

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 Ecorr = 0.00 V, Icorr = 1.0 × 10− 6 A/cm2, Rp = 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.