Ultra-high energy absorption high-entropy alloy syntactic foam

Abstract Metal matrix syntactic foams (MMSFs) are a class of fascinating particulate composites consisting of metal matrix and hollow spheres, which are promising in the light-weight structural and energy absorbing applications. However, the energy absorption capacity of most MMSFs is suffocated inevitably by relatively low strength of traditional metal matrix alloys, such as widely used aluminum and magnesium alloys. Here, we developed a novel MMSF with CoCrFeMnNi high entropy alloy matrix and alumina cenosphere fillers by pressure infiltration, which exhibits an ultra-high energy absorption capacity of 242.8 ± 20.6 MJ m−3, among the highest reported values of MMSFs. We show that this exceptional energy absorption capacity stems from excellent combination of high strength of alumina cenospheres and super-large ductility and fracture toughness of CoCrFeMnNi high entropy alloy. These results shed new light into design of advanced light-weight and energy absorbing materials.