Effect of Ti Doping on the Microstructure and Properties of SiCp/Al Composites by Pressureless Infiltration

The effects of Ti doping on the microstructure and properties of SiCp/Al composites fabricated by pressureless infiltration were comprehensively investigated using first-principles calculations and experimental analyses. First-principles calculations revealed that the interface wetting and bonding strength in an Al/SiC system could be significantly enhanced by Ti doping. Subsequently, the Ti element was incorporated into SiC preforms in the form of TiO2 and TiC to verify the influence of Ti doping on the pressureless infiltration performance of SiCp/Al composites. The experimental results demonstrated that the pressureless infiltration of molten Al into SiC preforms was promoted by adding TiC or TiO2 due to the improved wettability. However, incorporating TiO2 leads to the growth of AlN whiskers under a N-2 atmosphere, thereby hindering the complete densification of the composites. On the other hand, TiC doping can improve wettability and interface strength without deleterious reactions. As a consequence, the TiC-doped SiCp/Al composites exhibited excellent properties, including a high relative density of 99.4%, a bending strength of 287 +/- 18 MPa, and a thermal conductivity of 142 W<middle dot>m(-1)<middle dot>K-1.