Effect of Particulate Ti–Al–TiC Reinforcements on the Mechanical Properties of Epoxy Polymer Composites

The influence of particulate reinforcements produced from an 85 wt.% Ti + 15 wt.% Al powder mixture, processed through high-voltage electric discharges (HVED) in kerosene, on the key mechanical properties of a polymer composite with an ED-20 epoxy oligomer matrix was studied. Following HVED processing, the powder showed the following phase composition: 74 wt.% Ti, 15 wt.% Al, and 11 wt.% TiC, with an average particle size of 10–12 μm. The reinforcement content of the composite varied from 0.25 to 2.0 wt.%. The optimal reinforcement content that substantially improved the strength and impact toughness of the composite (by 1.7–1.8 times compared to the starting matrix) was found to be 0.5 wt.%. When the particulate reinforcement content in the composite was raised to 1.25–2.0%, the fracture strength reduced significantly, nearly reaching the level of the starting epoxy matrix. A model was proposed to account for the extremum observed in the dependences of the mechanical properties on the reinforcement content of the composite. The model relied on the hypothesis that mechanical and structural factors independently influenced the properties of the composite. The mechanical effect was determined by the redistribution of strain-induced stresses between the matrix and reinforcement and by the adhesion between the composite components. The structural effect resulted from changes in the properties of the polymer matrix induced by surface interactions with the reinforcement particles.