Microstructures and properties of high-fraction Sip–6061Al composites fabricated by pressureless sintering

Pre-treated Si powder (Sip) and 6061Al powder were used to fabricate high-fraction Sip/6061Al composites via pressureless sintering, and the effects of the Sip content and the sintering temperature on the microstructures and properties of the composites were studied. The results show that in the composites, there exist MgAl 2 O 4 nanocrystalline particles, and the Si phase varied from a discontinuous particulate state to a semi-continuous skeleton state as the Si content increased from 30 to 50 wt-%. Densities, bending strengths, hardness, and thermal conductivities of the composites all increased initially and then decreased with the sintering temperature. The 680°C sintered 30 wt-% Sip/6061Al composites and the 700°C sintered 50 wt-% Sip/6061Al composites have the optimal mechanical and thermophysical properties.