Microstructure and thermal conductivity of submicron Si3N4 reinforced 2024Al composite

An 2024Al matrix composite reinforced with 36%(volume fraction) β-Si3N4 particles was fabricated by pressure infiltration method, and its microstructure and the effect of annealing treatment on thermo-conductivity were discussed. Si3N4 particles distribute uniformly without any particle clustering and no apparent particle porosity or significant casting defects are observed in the composites. The combination of particles and matrix is well. The raw Si3N4 particles are regular cylindrical polyhedron with flat surface and change to serrated surface in composite due to reactions during fabrication. Thermal conductivity of as-cast Si3N4p/2024 composite is 90.125 W/(m·K) at room temperature, and increases to 94.997 W/(m·K) after annealing treatment. The calculated results of thermal conductivity of the Si3N4p/Al composite by Maxwell model, H-S model and PG model are lower than experimental results while that by ROM model is higher.