Microstructural analysis of network-like crack structure formed at Al–B4C interface

•In this study, the shape of the aluminium after penetration and the morphology of the cracks can be easily observed.•The molten aluminium fills the narrow cracks and forms a network.•Although Al reacts with B4C in the main junction, no aluminium compounds are found in the microcracks.•Capillarity and changes in chemical energy were taken into account simultaneously.