High-temperature tensile strengths of in situ synthesized TiC/Ti-alloy composites

Ti-alloy matrix composites reinforced with 5, 10 and 15 vol.% TiC were prepared by in situ casting route. Ultimate tensile strengths of the composites in the temperature range from 700 °C to 900 °C have been researched. The results show that ultimate tensile strengths decrease linearly and degrade approximately 170 MPa per 100 °C increase in tensile temperature in all composites. Load-bearing effect of TiC with long strip shape is more evident than that with equiaxed morphology, resulting in the marginal discrepancy in the ultimate tensile strengths of the composites with 5 and 10 vol.% TiC. As TiC volume fraction increases to 10%, the ultimate tensile strength is enhanced, mainly due to high matrix strength, and the increment is approximately 50 MPa at the same test temperature. TiC fracture dominates the damage of all composites at 700 °C, while void nucleation, growth and coalescence are the main fracture mechanism above 800 °C.