Nanostructured multi-phase titanium-based particulate composites consolidated by severe plastic deformation

Fully dense (pore-free) nanostructured TiN-reinforced titanium matrix composites have been synthesized by consolidating ball-milled mixtures of pure titanium and TiN particles using back-pressure assisted equal channel angular pressing (ECAP). Prior to consolidation, ball milling was conducted on powder mixtures of titanium and TiN to achieve breakdown of TiN particles to the nanoscale level and to generate a homogeneous distribution of TiN in the titanium matrix. Severe shear deformation, induced during subsequent ECAP, led to disruption of surface oxide layers and allowed direct contact between freshly exposed clean and reactive titanium surfaces, thus achieving bonding integrity between particles. Since consolidation did not rely on diffusion, full density (pore-free) can be attained at much lower temperatures compared with conventional sintering.