SPS-processed alumina and reaction-bonded boron carbide ceramic composite (RBBC) were joined with Al10SiMg alloy by spark plasma sintering and tested in a series of planar impact experiments designed to measure dynamic tensile (spall) strength of the joints. The results of the impact testing, together with postmortem inspection of the fractured samples, confirmed the applicability of this approach for testing joint strength. The measurements show that in the case of an RBBC/metal joint, the dynamic tensile strength of the joint exceeds that of the ceramic part, and that fracture of the shock-loaded ceramic-metal pair occurred in the ceramic portion. The dynamic tensile strength of the interface between alumina and Al10SiMg alloy virtually coincides with that of the metal part, with the fracture occurring exactly at the interface. The coincidence may be explained based on the recently published results of atomistic calculations of the structure of an alumina-aluminum interface.