Fabrication of TiB2/6061Al composite with tailoring heterostructure and superior mechanical properties and investigation on deformation behaviors

Overcoming the trade-off between strength and ductility remains a critical challenge for Al matrix composites. Here, TiB2/6061Al composites with harmonic and lamellar heterostructures were fabricated via hot press sintering by altering the size of Al powders. The discontinuous dynamic recrystallization (DDRX) and DRX take place, with DDRX being particularly promoted by the presence of fine grains around coarse grains. The activated slip systems of the grains with similar orientations are nearly identical during tension, while those of the randomly orientated grains vary significantly. Geometrically necessary dislocations form in fine grains due to their limited deformation compatibility, and also in the boundaries between fine and coarse grains. The heterostructured composite exhibits a superior strength-ductility synergy compared to the homogeneous composite, attributed to the hetero-deformation induced strengthening and dislocation strengthening. Strain concentrates in fine-grain zones with TiB2 particles, while the strain concentration is alleviated in coarse-grain zones, contributing to a high elongation.