Lamellar-interpenetrated Al–Si–Mg/SiC composites fabricated by freeze casting and pressureless infiltration

Porous laminated SiC scaffolds with initial solid loadings of 20–40 vol% were prepared by freeze casting and then sintered at 1200 °C for 2 h in air to produce a SiO2 layer. Subsequently, the preforms were pressureless-infiltrated by an Al–12 wt% Si–10 wt% Mg alloy in a N2 atmosphere, forming a lamellar-interpenetrated structure in the composites. The resultant composites were investigated by compression tests and ultrasonic pulse echo measurements in the longitudinal and transverse directions, exhibiting weak orthotropic properties. The highest compressive strength (722±35 MPa) was achieved in the samples with 30 vol% SiC in a longitudinal direction and the largest elastic modulus (163 GPa) was exhibited in the 40 vol% SiC composites.