Microstructures and mechanical properties of a two-layer B4C/Al-B4C/TiB2 composite

A two-layer structure composite, in which one layer was B4C/Al compound and the other layer was B4C/TiB2 compound, was prepared using a two-step method for both hot pressing and infiltration of aluminum in vacuum. The experimental results showed that the two-layer B4C/Al-B4C/TiB2 composite having good interfacial bonding was prepared. Before aluminum infiltration process, the B4C porous layer of the two-layer preform looked like a three-dimensional network of interconnected capillaries that could promote the infiltration of liquid aluminum. For the B4C/TiB2 layer the TiB2 dispersed homogeneously in B4C matrix and the microstructure showed no apparent change before and/or after aluminum infiltrating process. The fracture toughness of this material was improved to about twice that of pure B4C material. A number of twins were observed in the B4C matrix of the two-layer material.