Enhancing High-Temperature Mechanical Property of Ti4822 Alloy with In-Situ Ti2alc Precipitates

Abstract

Ti4822/xC composites with excellent high-temperature performance were produced using spark plasma sintering technique. As the carbon content increased from 0.5 to 1.5 wt.%, the volume fraction of the Ti2AlC precipitates increased from 6.5% to 14.0%, and the average size of the lamellar colony decreased from 305.5±5 to 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.

Keywords: Ti2AlC precipitate, Microstructure, Metal-matrix composite, TiAl alloy, High-temperature tensile property