PRESSURELESS MELT INFILTRATION PROCESSING AND THE MICROSTRUCTURAL CHARACTERISTICS OF TiC/NiAl COMPOSITES

Pressureless melt infiltration was used for preparing high TiC content TiC/NiAl composites. Effects of the infiltration temperature and time on the microstructure, hardness and fracture toughness of the composites were studied. XRD and EDS/TEM were used to analyze the phase identification and the solubility of NiAl and TiC in each other. The results show that pressureless melt infiltration is an effective method to fabricate dense TiC/NiAl composites. The infiltration time can greatly decrease when the infiltration temperature suitably increases. No obvious effect of the infiltration temperature and time on the hardness and the fracture toughness of the composites was found. NiAl and TiC were well bonded, and they are the only two phases in the composites after infiltration. TiC partially dissolved into NiAl phase, and the solubility increased with increasing infiltration time. Little Al and a trace of Ni were detected at the outer layer of TiC.