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Wetting behaviors of carbon, TiC, SiC or ZrC by molten NiAl intermetallic compound at 1800℃ were investigated by the sessile drop technique under vacuum. Active element and addition quantity were optimized by spreading and infiltrating experiment in the NiAl-modified C/C composite. NiAl-modified C/C composites were prepared by the vacuum molten infiltration. The microstructures and infiltration mechanism were analysed by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The results show that NiAl has lower wettability on carbon or SiC, while has higher wettability on TiC or ZrC. It is indicated that adding Ti can improve the wettability between C/C composites and NiAl intermetallic. NiAl with about 15%Ti (mass fraction) possesses good wettability on the surface of C/C composites. The death of NiAl permeable layer on C/C composite is about 0.8~0.9 mm. The molten NiAl intermetallic compound containing titanium infiltrates into the C/C composites preform, and TiC phase forms in the NiAl-modified C/C composites. The improvement of adding titanium for molten NiAl infiltration into the C/C composites preform results from the improvement of the chemical and physical adsorption characteristic of NiAl on the composites. The liquid NiAl infiltrates into the preform under the capillary pressure.