Comparison of residual microstructures associated with impact craters in Al–Sc and Al–Ti alloys

Al–Sc and Al–Ti semi-infinite targets were impacted by high-speed projectiles with velocities of 0.8, 2 and 4 km s−1, respectively. The results show that deep columned craters with hemispherical bottoms were formed in the Al–Ti target, while near-hemispheroidal or relatively shallower craters formed in the Al–Sc alloy. It is concluded that different microstructures of Al–Sc and Al–Ti alloys, including different grain sizes and secondary particles precipitated in the matrix, result in their having greatly different capabilities of resisting impact. Residual microstructures of different samples are further discussed. It is possible that, due to the very large amount of energy imported into the target by high-speed impact, secondary Al3Sc lost its coherency and consequently recrystallization occurred.