Study on the impact damage in a new AlN matrix composite

Si₃N₄/AlN-Al composite prepared by pressureless infiltration process is a new type of AlN matrix composite. The composite plates were penetrated by tungsten ball in a compressed air gun. Macro and micro-examinations of the fracture surface were conducted with digital camera and scanning electronic microscope (SEM), and the failure mechanisms of the composite were analyzed. The results show that the major failure mechanisms are three types: compressive frictionizing surface within crushed zone, shear predominated cone cracks and radial cracks resulting from dynamic tensile stress. The compressive frictionizing process between fragments within crushed zone, which is related to the fragmentation of AlN skeleton, the high strain rate localized deformation of aluminium alloy within the skeleton and the heat of friction, contributes to a special energy-consumption during the tungsten ball penetration process.