Enhancing high-temperature mechanical property of Ti4822 alloy with in-situ Ti2AlC precipitates

Ti4822/xC composites with excellent high-temperature performance were prepared by spark plasma sintering technique. As the carbon content increased from 0.5 wt% to 1.5 wt%, the volume fraction of the Ti2AlC precipitates increased from 6.5% to 14.0%. The average size of the lamellar colony decreased from 305.5 ± 5 µm to 76.5 ± 5 µm. When the carbon content was 0.5 wt%, the lamellar size reached the minimum value of 75.5 ± 5 µm. Meanwhile, the equiaxed γ phase precipitated at the grain boundaries. With the carbon content of 0.5 wt%, the tensile properties reached the maximum value of 582 MPa, and the fracture elongation of 7.2% at 800 ℃. Compared with Ti4822 alloy, the ultimate strength and elongation of the composite increased by approximately 28% and 1.9% correspondingly. The dominant mechanism for high-temperature tensile properties of the composites was the combination of grain refinement strengthening, second phase strengthening, and γ phase weakening.