2297铝锂合金拉伸性能及强化机制

Tensile Property and Strengthening Mechanism of 2297 Al-Li alloy

通过金相显微镜、扫描电镜和透射电镜观察以及拉伸性能测试,研究了95 mm厚2297-T87铝锂合金热轧板材1/2厚度层不同方向的显微组织和拉伸性能。结果表明:2297-T87铝锂合金在同一厚度层不同方向的拉伸性能具有明显的各向异性。强度规律为LT方向>L方向>45°方向>ST方向;延伸率规律为L方向>45°方向>LT方向>ST方向。L方向、LT方向和45°方向断裂方式均是以塑性断裂为主的混合型断裂,而ST方向则以脆性断裂为主。晶内主要析出相为板条状T_1相和针状θ′相,T_1相数量明显多于θ′相,是2297合金的主要强化相。

The microstructure and tensile property of 2297-T87 Al-Li alloy in the 1/2 thickness layer were investigated by optical microscopy,scanning electron microscopy,transmission electron microscopy and tensile tests.The results show that the tensile property of 2297-T87 Al-Li alloy in different directions in the same thickness layer have obviously anisotropic.The tensile strength law is LT direction >L direction >45° direction >ST direction,the elongation law is L direction >45°direction >LT direction >ST direction.L direction,LT direction and 45° direction are mixed fracture dominated by plastic fracture,while brittle fracture is dominant in ST direction.The main precipitated phases in the crystal are lath T1 phase and acicular θ'phase.The number of T1 phase is significantly higher than θ'phase,which is the main strengthening phase of 2297 alloy.