固溶和双级时效对反挤压2A12铝合金组织和性能的影响

采用光学显微镜(OM)、扫描电子显微镜(SEM)、能谱分析、X射线衍射(XRD)和常温万能拉伸试验机等观察检测手段,针对由反挤压工艺制备的2A12铝合金经过不同的固溶加双级时效(T6)处理,观察并分析在不同条件下处理前、后试样的微观组织和力学性能之间的联系。结果表明:在不同的固溶温度下,得到505℃×1 h的晶粒尺寸细小且弥散相沿晶界序列排布,残留共晶相溶解较充分,力学性能佳。继而分别研究双级时效温度和时间对合金组织和性能的影响,得到在100℃×2 h+200℃×5 h时合金的抗拉强度最高,达到450. 5 MPa,伸长率为14%,晶体中析出大量强化相θ(Al2Cu)和纳米级S相(Al2CuMg),并且弥散分布着难以随温度和时间溶解的T相(Al20Cu2Mn3)。

Influence of solid solution and two-stage aging on microstructure and properties for backward extrustion 2A12 aluminum alloy

For 2A12 aluminum alloy prepared by the backward extrusion process in different solid solution plus two-stage aging(T6)treatment,the relationship between microstructure and mechanical properties of samples before and after treatment under different conditions was observed and analyzed by optical microscopy(OM),scanning electron microscopy(SEM),energy spectrum analysis,X-ray diffraction(XRD) and universal tensile testing machines at normal temperature. The results show that at different solid solution temperatures,the grain size of 505 ℃ × 1 h is fine,the dispersed phase is arranged along the grain boundary sequence,the residual eutectic phase is well dissolved,and the mechanical properties are good. Then,the influences of two-stage aging temperature and time on the microstructure and properties of the alloy were studied. The tensile strength of 450. 5 MPa is the highest at 100 ℃ × 2 h + 200 ℃ × 5 h with the elongation of 14%. Furthermore,a large number of strengthening phase θ( Al2Cu) and nano-S phase( Al2CuMg) are precipitated in the crystal,and the T phase( Al20Cu2Mn3) which is difficult to dissolve with temperature and time is dispersedly distributed.