Effects of second-phase boron particles on impact response of aluminum

The influence of second-phase boron particles (up to 0.15 wt%) on impact response of aluminum is investigated under high strain rate gas gun loading. The Hugoniot elastic limit (∼0.11 GPa) shows a negligible dependence on boron particle content up to 0.15 wt%. The second-phase particles reduce considerably spall strength of aluminum, and such reduction is more pronounced at high boron content. Spall strength undergoes a slight decrease at high impact velocities. Scanning electron microscopy and synchrotron X-ray computed tomography analyses indicate a competition between microvoid nucleation and microvoid growth. The damage features and spall strength characteristics can be attributed to the weak particle–matrix interface.