Microstructure and oxidation resistance of a Ti-Mo-Nb-Al-Si titanium matrix composite reinforced with in situ TiC prepared by powder metallurgy

The mixture of the Ti-Mo-Nb-Al-Si matrix powder and Carbon nanotubes (CNTs) particles was used as the starting powder to produce the in-situ TiC reinforced TMCs using reaction synthesis method. The effect of the adding various CNTs content on the microstructure, phase composition, hardness, and oxidation behavior of the composites was investigated. The results show that the phases of the composites were composed of mainly alpha-Ti, beta-Ti and TiC. With the increase of adding CNTs content, the porosity increased gradually, and the hardness initially increased and then decreased. The hardness of the composites with adding 1.0 wt% CNTs content was 496.1 HV, which was about 13.89% higher than that of the matrix alloy. With the increase of adding CNTs content, the oxidation mass gain first decreased and then increased. The oxidation mass gain of composites with adding 1.0 wt% CNTs content was 2.212 mg cm(-2), which was about 63.33% less than that of the matrix alloy, and the parabolic rate constant (k(p)) was the minimum, which was 1.67 x 10(-3) mg(2) cm(-4) h(-1). The oxidation resistance of the composites was better than the matrix alloy.