Interfacial microstructure evolution and mechanical properties of carbon fiber reinforced Al-matrix composites fabricated by a pressureless infiltration process

In this study, unidirectional carbon fiber reinforced aluminum-matrix (CF/Al) composites were successfully fabricated by using a pressureless infiltration process to infiltrate Ni-coated CFs with Al. The evolution of the interfacial microstructure was investigated. The results showed that the Al-Ni reaction provided the main driving force for infiltration of Al melt into CF bundles by the significantly improving wettability. As the infiltration time increased from 0 min to 8 min, the infiltration behavior gradually improved with fewer defects and better fiber dispersion. Furthermore, the Al-Ni intermetallic compounds (IMCs) transformed from the large-sized primary Al3Ni phase to fine Al3Ni phase with eutectic structure, and were uniformly distributed around the CFs, which was beneficial for transferring the load and preventing the crack propagation. However, the harmful Al4C3 phase grew up at the interface. The ultimate tensile strength (UTS) of the CF/Al composites with the optimal infiltration time of 6 min was 135 +/- 4 MPa, which was 121.3 % higher than that of the Al matrix.