Effect of Ti Doping on the Microstructure and Properties of SiC[sub.p]/Al Composites by Pressureless Infiltration

The effects of Ti doping on the microstructure and properties of SiC[sub.p]/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 TiO[sub.2] and TiC to verify the influence of Ti doping on the pressureless infiltration performance of SiC[sub.p]/Al composites. The experimental results demonstrated that the pressureless infiltration of molten Al into SiC preforms was promoted by adding TiC or TiO[sub.2] due to the improved wettability. However, incorporating TiO[sub.2] leads to the growth of AlN whiskers under a N[sub.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 SiC[sub.p]/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·m[sup.−1]·K[sup.−1].