(中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 通過(guò)力學(xué)性能測(cè)試和顯微組織觀察研究一種新型Al-Cu-Li合金在不同時(shí)效制度下組織和性能之間的關(guān)系。結(jié)果表明：該合金具有強(qiáng)度高、各向異性小、熱穩(wěn)定性好等特點(diǎn)；該合金在T6和T8狀態(tài)下強(qiáng)化相均為T1相和θ′相，其中T1相起主要作用；時(shí)效前的預(yù)變形促進(jìn)T1相析出，顯著提高合金強(qiáng)度，變形量控制在5%左右時(shí)，合金具有最好的強(qiáng)塑性匹配，抗拉強(qiáng)度達(dá)623.6 MPa，伸長(zhǎng)率為10.2%；固溶淬火后進(jìn)行先低溫后高溫的雙級(jí)時(shí)效制度并未提高合金強(qiáng)度，但稍微提高了合金塑性；合金在T6、T8狀態(tài)下強(qiáng)度各向異性均保持在5%以下；該合金在不高于150 ℃熱暴露時(shí)，表現(xiàn)出良好的熱穩(wěn)定性，但高于150 ℃熱暴露時(shí)，T1相粗化，熱穩(wěn)定性降低。
關(guān)鍵字: Al-Cu-Li合金；強(qiáng)度；各向異性；熱穩(wěn)定性；微觀組織
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The relationship between microstructures and properties of a new Al-Cu-Li alloy under different aging treatments was studied by tensile test and the microstructure observation. The results show that the alloy has high strength, little anisotropy and better thermal stability. The major strengthening phases are a large number of T1 phases and part of θ′ phases in both T6 and T8 temper. Pre-deformation before artificial aging promotes the precipitation of T1 phases and obviously improves the strength of alloy. The alloy shows excellent combination of strength (σb=623.6 MPa) and ductility (δ=10.2%) when the pre-deformation ratio is controlled at about 5%. The strength of the alloy does not improve after two-stage aging, namely low-temperature aging at 120 ℃ followed by high-temperature aging at 175 ℃, but slightly enhances the ductility of alloy. In T6 and T8 temper, the anisotropy indexes (IPA) of strength are both below 5%.The alloy has excellent thermal stability at temperature below 150 ℃, but its strength decreases greatly after higher temperature (＞150 ℃)exposure due to the coarsening of T1 phases.
Key words: Al-Cu-Li alloy; strength; anisotropy; thermal stability; microstructure
