(中南大學 材料科學與工程學院，長沙 410083)
摘 要: 采用力學性能測試和透射電鏡觀察的方法，研究2099鋁鋰合金不同時效狀態(tài)下的拉伸性能、應力腐蝕性能以及微觀組織。結果表明：在欠時效條件下，合金抗拉強度、屈服強度和伸長率分別為453 MPa、382 MPa和12.5%，基體中形成大量的δ′相；峰時效條件下，大量的T1相以及少量的θ′相在基體中析出，晶界上生成一定數(shù)量的第二相，并形成無沉淀析出區(qū)，合金相應的抗拉強度、屈服強度和伸長率分別為613 MPa、581 MPa和7.9%；過時效條件下，合金抗拉強度、屈服強度和伸長率分別為610 MPa、570 MPa和7.8%，其微觀組織與峰時效合金的相似。在欠時效合金中，由于晶界上殘余AlCuFeMn相的存在，從而導致合金具有較高的應力腐蝕敏感性；在峰時效合金中，由于大量的T1相在基體中析出，促使合金獲得理想的抗應力腐蝕性能，強度損失率為0.8%；過時效合金具有與峰時效合金相近的抗應力腐蝕性能。
關鍵字: 2099鋁鋰合金；拉伸性能；應力腐蝕
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:Tensile properties, stress corrosion properties and microstructures of 2099 Al-Li alloy under different aging conditions were investigated by mechanical tests and TEM. The results show that, under the under-aged condition, the tensile strength, yield strength and elongation of alloy are 453 MPa, 382 MPa and 12.5%, respectively, and many δ′ phases form in the alloy. Under the peak-aged condition, a great number of T1 phases as well as a few of θ′ phases precipitate in the matrix, some secondary phases precipitate along the grain boundaries and the precipitation free zone form, the corresponding tensile strength, yield strength and elongation of alloy are 613 MPa, 581 MPa and 7.9%, respectively. Under the over-aged condition, the tensile strength, yield strength and elongation of alloy are 610 MPa, 570 MPa and 7.8%, respectively, and the microstructures are similar to that of peak-aged alloy. Remained AlCuFeMn phases at grain boundaries result in high SCC susceptibility of under-aged alloy. Peak-aged alloy obtains desirable stress corrosion resistance because many T1 phases precipitate in the matrix, and the strength loss rate is 0.8%. Over-aged alloy obtains similar stress corrosion resistance as peak-aged alloy.
Key words: 2099 Al-Li alloy; tensile properties; stress corrosion
