Microstructure and Mechanical Properties of In Situ TiB2/2024 Composites Fabricated by Powder Metallurgy

In the present study, a uniform distribution of nanosized TiB2 particles in the metal matrix was achieved by powder metallurgy using the composite powders with pre-embedded particles. The composite powders were consolidated into compacts via spark plasma sintering without additional treatment such as mechanical milling or mixing. The concentrated shear stress around the uniformly distributed TiB2 particles with size similar to the width of the elongated grains during hot extrusion leads into grain fragmentation and refinement. The T4-treated TiB2/2024 composites had a better combination of yield strength of 385 MPa, ultimate tensile strength of 568 MPa and uniform elongation of 14.6% compared to the Al-Cu-Mg alloys and Al-Cu-Mg based composites in the published work. The longer uniform elongation of the composites in the present work was analyzed in respects of dislocation accumulation rate k(1) and dislocation recovery rate k(2).