The superior elevated-temperature mechanical properties of Al-Cu-Mg-Si composites reinforced with in situ hybrid-sized TiCx-TiB2 particles.

The Al-Cu-Mg-Si matrix composites reinforced with in situ hybrid-sized TiC x -TiB 2 particles with sizes ranging from 20 nm to 1.3 µm were successfully synthesized using the Al-Ti-B 4 C reaction system via a method that combined the combustion synthesis and the hot press assisted with hot extrusion. The sizes of the fabricated TiC x and TiB 2 particles increased with increasing TiC x -TiB 2 content. The hybrid-sized TiC x -TiB 2 particles improved the elevated-temperature yield strength ( σ .2 ), the tensile strength ( σ UTS ), and the fracture ductility ( ε f ) of the composites at both 493 K and 573 K. The 40 wt% (TiC x -TiB 2 )/Al-Cu-Mg-Si composite exhibited superior σ .2 (141 MPa), σ UTS (164 MPa), and ε f (31.2%) at 573 K, with enhancements of 60.2%, 72.6%, and 22.4% compared to the Al-Cu-Mg-Si matrix alloy (88 MPa, 95 MPa, and 25.5%). The improvement of the elevated-temperature mechanical properties for the in situ (TiC x -TiB 2 )/Al-Cu-Mg-Si composites was attributed primarily to the strengthening effects induced by the hybrid-sized TiC x -TiB 2 particles and the θ′ precipitation strengthening. [ABSTRACT FROM AUTHOR]