Distribution of TiB2 particles and its effect on the mechanical properties of A390 alloy

The hypereutectic Al–Si (A390) matrix composite reinforced with TiB2 particles was successfully prepared by Al melt reaction method. In the composite, TiB2 particles have a size range from 0.5 to 1.5 μm and a block-like morphology. Some TiB2 particles are inside the primary Si, suggesting that they were engulfed during solidification. It is considered that TiB2 particles tend to be adsorbed into the primary Si, because of their high surface energy and strong adsorbability. Crystallographic analysis of TiB2 and Si was carried out with the edge-to-edge model. It is found that there exists good lattice matching coherence, which belongs to the matching planes and directions, 1   1   2 Si / 1   0   1 ¯   0 TiB 2 , { 1   1   1 } Si / { 0   0   0   1 } TiB 2 . Furthermore, with 3 wt% TiB2 particles addition, the mechanical properties of the base alloy, including the ultimate tensile strength at 300 °C, percentage elongation and wear resistance, have been obviously improved.