Residual microstructure associated with impact craters in TiB2/2024Al composite

Residual microstructures associated with hypervelocity impact craters in 55 vol.% TiB2/2024Al composite were investigated by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). TiB2–Al interface, TiB2 particles and Al matrix before and after hypervelocity impact were compared to discuss the effect of hypervelocity impact. A new AlxO1−x phase with the fcc structure and the crystal parameter of 0.69 nm was formed at TiB2–Al interface. Stacking fault with width of 10–20 nm was formed along the (0 0 1) plane of TiB2 particle. Formation of nanograins (∼100 nm) was observed within Al matrix, moreover, lamellar S′ phase was transformed into lenticular or spherical S phase after hypervelocity impact.

► A AlxO1−x phase with the face-center cubic structure forms around TiB2 particles in TiB2/Al composite after high speed impact.
► Stacking fault along the (0 0 1) plane of TiB2 appears around the interface of TiB2 particles and AlxO1−x phase after impact.
► S′ phase with lamellar shape changes to lenticular or spherical S phase within the 2024 aluminum matrix after impact.