Achieving Superior Strength–Ductility–Conductivity Combination in TiB_2p/6201 Composites via Particle Rotation and Subgrain Refinement

The key factor in the material design of overhead power transmission lines is to obtain a desired balance among strength, ductility, and electrical conductivity. Herein, TiB₂ particulate‐reinforced aluminum matrix composites are prepared to find a way out of the intrinsic dilemma behind this balance by tailoring the subgrain refinement. The interaction in the form of inhomogeneous deformation induced by the flexibility discrepancy between the rigid particles and soft matrix is studied. On the one hand, the hexagonal plate‐like TiB₂ particles rotate with the inhomogeneous deformation, forcing the biggest exposed plane ((0001) basal plane) parallel to the plastic flow direction, which is beneficial for the dislocation multiplication and hindrance of dislocation slipping. On the other hand, inhomogeneous deformation generates plentiful geometry necessary dislocations and divides the microstructure into two types: in the particle‐rich region ultrafine grains are formed and in the particle‐free region significant subgrains refinement is observed. The subgrains with 3 wt% TiB₂ are refined from ≈897 to ≈248 nm. Thanks to these microstructural benefits, the composites achieve the following strength–ductility–conductivity combination: ultimate tensile strength is 370 MPa, elongation after fracture is 11.2%, and electrical conductivity is 51.79% IACS. Besides, the elastic modulus reaches 75.43 GPa.