Optimization of the properties in Al/SiC composites by tailoring microstructure through gelatin freeze casting

The strength and toughness of a material are generally two mutually exclusive properties. Optimization of these properties can be realized by regulating microstructures based on a bio-inspired idea. Herein, we used gelatin as a pore-regulating agent to investigate the effect of microstructural transition from "nacre-like" lamellae to "honeycomb-like" reticulae on the mechanical properties of metal ceramic composites. By introducing different quantities of gelatin into SiC slurries during freeze casting and infiltrating the sintered SiC scaffolds with pure molten Al, we prepared the Al/SiC (88/12 in volume) composites with variable yet controllable microstructures and further demonstrated that the desired properties could be achieved by tailoring their microstructures. Specifically, the Al/SiC composites with a fully laminated structure exhibited optimal fracture toughness (K-Jc) of 51.9 +/- 2.9 MPa m(1/2) while those with a three-dimensional reticular structure displayed peak three-point flexural strength of 371 +/- 6 MPa. The relationship between the microstructures and mechanical properties of the composites was addressed based on material strengthening and toughening mechanisms.