Microstructure and Properties of TiC/Ni3Al Composites Prepared by Pressureless Melt Infiltration with Porous TiC/Ni3Al Preforms

In this article, porous TiC/Ni3Al preforms were fabricated by self-propagating high-temperature combustion synthesis (SHCS). Then, the porous TiC/Ni3Al preforms were densified with infiltrated Ni3Al melt via the conventional pressureless infiltration, and TiC/Ni3Al composites were prepared. The composites were characterized by microstructure observation and mechanical property measurements. The results demonstrate that the wetting ability of liquid Ni3Al to porous TiC/Ni3Al preforms is better than that of liquid Ni3Al to TiC preforms. The porous TiC/Ni3Al preforms can be completely infiltrated by Ni3Al melt via pressureless infiltration technique, and then densified TiC/Ni3Al composites without defects can be obtained. During the infiltration process, both Ni3Al and TiC/Ni3Al preforms were thermally and chemically stable, and the infiltration resulted in no new phases. Comparing the similar composites prepared with TiC preforms infiltrated by melt Ni3Al via pressureless infiltration, bending strength of the TiC/Ni3Al composites of this work was much improved with higher reliability. The interfaces between TiC particles and the intermetallic compound Ni3Al were the main points of failure in the composites. Strengthening mechanism of the TiC/Ni3Al composites consisted of mainly pullout of TiC particles from the matrix and crack deflection surrounding Ni3Al particles.