Interfacial structure in TiB2/Al composite after high speed impact

Interfacial structure in 55%TiB2/Al composite before and after high speed impact was investigated in detail. It is found that there is no stacking fault in original TiB2 particle before fabrication or in TiB2 particle in composite. However, after the composite is impacted by 1.2 mm projectile with the velocity of 2.5 km/s, stacking fault forms along the (0 0 0 1) plane around the edge of TiB2 particle and grows with a step-like epitaxial way, resulting from the high pressure of shock wave. At the bottom of crater in the target, Al matrix around the TiB2 particle was molten and then oxidated, which results in the formation of AlxO1−x (x < 1) phase between TiB2 particle and Al matrix. It is found that TiB2 particle and AlxO1−x phase combine well and have no reacted layer at the interface and there exists an orientation between two phases: [0 1 1¯ 0]TiB2//[3 1 0]AlxO1−x, (2¯ 1 1 0)TiB2//(0 0 2)AlxO1−x.

► Microstructure of aluminum matrix composites after high speed impact was investigated.
► Stacking faults in TiB2 particle were found after impact in present paper.
► Models of stacking faults were presented.
► There exists an orientation between TiB2 particle and AlxO1−x phase: [1 2 0]TiB2//[3 1 0]AlxO1−x[1 2 0]TiB2//[3 1 0]AlxO1−x, (2¯ 1 0)TiB2//(0 0 2)AlxO1−x.
► Possibility of nucleation of AlxO1−x phase on the surface of TiB2 was discussed.