Effect of TiO 2 –Si 3 N 4 hybrid interphase composition on the tensile performance of Ti6Al4V/carbon-fibre metal laminates

This study examines composition-dependent interfacial modification of Ti6Al4V/carbon-fibre metal laminates using TiO2–Si3N4 nanofilled epoxy adhesives. A fixed 3/2 Ti/C/Ti/C/Ti architecture was fabricated with neat epoxy, single-filler TiO2 and Si3N4 systems, and three hybrid filler ratios. Tensile behaviour was evaluated according to ASTM D3039/D3039M-17. An interface-sensitive peel test was also performed to determine the peak peel load and peak peel strength of each adhesive composition. SEM–EDS examination was used for qualitative assessment of the as-fabricated interfaces and tensile-fracture morphologies. The balanced TC-H50 laminate achieved the highest ultimate tensile strength of 684 ± 13 MPa. The TiO2-dominant TC-H60T system produced the highest tensile modulus and proportional-limit strength of 79.1 ± 1.4 GPa and 488 ± 10 MPa, respectively. In contrast, the Si3N4-dominant TC-H60S laminate showed the highest elongation and tensile toughness of 2.95 ± 0.19% and 14.1 ± 0.8 MJ/m3. TC-H60S also showed the highest peak peel load and peak peel strength of 260.0 ± 22.3 N and 10.40 ± 0.89 N/mm, respectively. The combined results indicated composition-dependent differences in laminate stiffness, tensile deformation, and resistance to peel initiation. TiO2-rich systems showed a predominantly stiffness-oriented tensile response, whereas the Si3N4-dominant TC-H60S system showed the highest tensile toughness and peak peel strength.