Microstructure and mechanical properties of in situ synthesized (TiB2 + Al2O3)/Al–Cu composites

Microstructures and mechanical properties of Al–Cu matrix composites reinforced by in situ TiB2 and Al2O3 particulates have been investigated in this paper. Result of XRD analysis indicates that the (Al2O3 + TiB2)/Al–Cu composites can be fabricated with the direct melt reaction method. Analysis in SEM shows that TiB2 particles distribute along the grain boundaries and interweave with CuAl2 phase; while Al2O3 particles have a tendency to agglomeration. The interfaces between reinforcements and matrix in as-cast composites are clean. From the investigations on mechanical properties of composites, we deduce that the UTS and hardness of as-cast or T6-treated (TiB2 + Al2O3)/Al–Cu composites are obviously higher than those of composites reinforced with the same percentage reinforcements of TiB2 or Al2O3 particles.