M. Jo, J.H. Choi, I. Jo, S-K Lee, S. Lee
POSTECH,
Korea
Keywords: 7075 Al alloy, hybrid composite, SiC, B4C, liquid-pressing process, dynamic compression, ballistic impact test
Summary:
When ceramic-reinforced metal-alloy-matrix hybrid composites are fabricated by a liquid-pressing process, excellent protective capabilities against ballistic impacts can be achieved in armored structures and materials applications. In this study, a hybrid 7075-T6 Al matrix composite reinforced with SiC and B4C particulates (SiCp or B4Cp) was fabricated to increase the volume fraction of reinforcements and the resultant dynamic and ballistic properties, and was compared with monolithic composites reinforced with SiCp or B4Cp. Quasi-static and dynamic compressive properties were evaluated by operating a universal testing machine and a split Hopkinson pressure bar at strain rates of 10-3 s-1 and 2800 s-1, respectively. SiCps and B4Cps were homogeneously distributed in the Al matrix, while ceramic/matrix interfaces were well bonded without SiCp or B4Cp agglomerations, pores, or cracks, and the volume fraction of ceramic reinforcements reached 57 vol.%. In the hybrid composite, fine SiCp and finer B4Cp (size; 10 m and 5 m) worked for the synergic strengthening by increasing the total reinforcement fraction, and three fracture phenomena such as Al matrix deformation, cracking of ceramic reinforcements, and ceramic/matrix interfacial debonding were well homogenized, thereby leading to the excellent strength/ductility combination along with very high strain energy density and consequently to the great improvement of ballistic performance.