热处理对Ti_2AlNb合金显微组织及力学性能的影响

Effect of Heat Treatment on Microstruture and Mechanical Properties of Ti_2AlNb Alloy

B2相区等温锻造的Ti-22Al-25Nb合金棒材940℃固溶后,在760~840℃时效处理,对其显微组织、拉伸及蠕变性能进行研究。结果表明：不同温度时效处理的显微组织均由初生粗板条状O相、二次析出的细板条状O相和B2基体组成,其中二次析出的O相可以通过时效温度来调节。随着时效温度的升高,Ti2Al Nb合金的室温及650℃高温拉伸强度降低而塑性提高;较低的时效温度（760℃）处理可以获得更好的抗蠕变性能。

Ti-22AI-25Nb（at. % ） alloy bars were isothermally forged at B2 phase region and solution treated at 940 ℃ , then aging treated at 760 ℃ to 840 ℃. Then the microstructure evolution and mechanical properties of the bars were studied. The results indicate that the microstructures at different aging temperatures contain primary lamellar O phase, secondary fine lamellar O phase and B2 matrix. The size and volume fraction of secondary fine lamellar O phase can be adjusted through aging treatment. The mechanical properties show that as aging temperature increasing, tile strength including room-temperature and 650 ℃ high-temperature tensile strength decrease, while the ductility increases. The lower aging-temperature （760 ℃ ） has better creep resistance.