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Titanium matrix composites reinforced with TiB whiskers were in situ synthesized by spark plasma sintering (SPS) at a temperature range of 11731473 K, using a mixture of 6.2 mass% TiB 2 , 4.1 mass% Ti, and 89.7 mass% Ti6Al4V powders. The in-situ synthesis mechanism and the effect of sintering temperature on the sintering microstructure were investigated. The results show that an increase of the sintering temperature causes the relative densities of the composites to increase and the reaction between Ti and TiB 2 to be more complete. Nano-sized TiB reinforcements with a diameter of around 80 nm and fine-grained matrix with an average grain size of 12 µm are obtained after SPSed at 1373 K. Clean and perfect TiB/matrix interfaces without debonding or cracks are obtained during SPS process. Low sintering temperature and short sintering time are believed to be the main reasons for the improved fine-grained microstructure.

The effects of Si addition on microstructures, high temperature compressive properties and creep properties of the ¢-stabilized Ti-45Al-3Fe-2Mo alloy have been studied in this work. The results show that the Si addition decreases the volume fraction of ¢ phase and precipitates particulate Ti 5 Si 3 phase. At the same time, the Si addition improves the high temperature strength of the Ti-45Al-3Fe-2Mo alloy for about 200 MPa at 800°C and decreases the creep strain for about 35% at 800°C under an applied stress of 150 MPa. The decrease in volume fraction of ¢ phase and precipitation of Ti 5 Si 3 particles are believed to be the dominant mechanisms for the improvement of the high temperature properties of the Si-doped TiAl alloy.

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