Fabrication, Microstructure and Properties of the Mid-Fraction SiC Particles/6061Al Composites Using an Optimized Powder Metallurgy Technique

Abstract

Commercial F500 SiC powder and 6061Al powder were chosen to fabricate the mid-fraction SiC particles (SiCp)/6061Al composite of 30 vol % (volume fraction) SiC using a pressureless sintering technique. Decantation of the SiC powder and optimization of the sintering temperature were performed to improve the microstructure and properties of the composite. The results show that near full-densification of the 30 vol % SiCp/6061Al composite sintered at 680°C is achieved, and no SiCp/Al interfacial reaction occurs. The composite possess the following set of properties: relative density of 98.2%, bending strength of 425.6 MPa, thermal conductivity (TC) of 159 W/(m K) and coefficient of thermal expansion (CTE) of 12.5 × 10^–6/°C (20–100°C). The fracture of the composite occurs via cleavage of the SiC particles and ductile tearing of the Al alloy matrix, indicating a strong SiCp/Al interface bonding.