Abstract: Taking Ti-44Al-8Nb-xC(x=0, 0.3, 0.6) alloys as the research object, the effects of three different carbon contents and two aging temperatures on the microstructure, microhardness and high-temperature tensile properties were studied. The results show that when the carbon content increases to 0.6%, Ti₂AlC precipitates in the alloy. When the aging temperature increases from 800 ℃ to 900 ℃, Ti₃AlC precipitates in the alloy containing carbon. The increase in carbon content and aging temperature are all beneficial to improving the microhardness and tensile strength at 850 ℃ of the alloy, where the highest microhardness is (477.6±9.1) HV0.3, and the highest tensile strength at 850 ℃ is (605.07±5.01) MPa, which increases by 32.7% compored to the lowest tensile strength. The elongation is related to the number and size of carbides, and all the tensile fractures show brittle fracture. The alloy with 0.3% carbon has the best plasticity when aged at 900 ℃, the highest elongation is 5.41%±0.42%, which increases by 67.5% compared to the lowest elongation.

Key words: high Nb-TiAl alloy, carbon content, heat treatment, microstructure, mechanical properties