AA7055鋁合金板材的微觀組織與力學(xué)性能

AA7055鋁合金板材的微觀組織與力學(xué)性能Microstructure and Mechanical Property of Aluminum Alloy Plate AA 7055

研究AA 7055-T7751板材不同厚度層的力學(xué)性能，并采用電子背散射衍射（EBSD）、透射電子顯微鏡（TEM）、小角度X射線散射（SAXS）等分析技術(shù)研究板材不同厚度層的微觀組織。結(jié)果表明：從板材表層到厚度中心，再結(jié)晶程度從69%下降到19.1%，亞晶粒尺寸從10 μm減小到2 μm；板材厚度中心主要為軋制型織構(gòu)，遠(yuǎn)離中心層其含量逐漸減少，板材表層主要為剪切型織構(gòu)；板材主要強(qiáng)化相為盤狀η'相，其盤面半徑為3.7 nm，厚度為1~3 nm，與基體的共格應(yīng)變約為0.0133；板材不同厚度層沿軋制方向的拉伸屈服強(qiáng)度近似呈線性變化：σy=-38.7S+604.8（0≤ S≤ 1）。

Through-thickness microstructure and mechanical property of AA 7055-T7751 aluminum alloy plate were investigated by using electron backscattered diffraction (EBSD), transmission electron microscope (TEM) and small angle X-ray scattering(SAXS). The results indicate an inhomogeneous distribution of microstructure through the thickness. The degree of recrystallization decreases gradually from 69% to 19.1%, as deepening from the surface to the center of the plate. The size of subgrains decreases from 10 μm at the surface to around 2 μm at the center. Strong texture of rolling type is observed near the center but the intensity decreases gradually as nearing the surface and the shear texture becomes the dominant. High density of plate-like η' phases are observed in the alloy, indicating the sufficient precipitation. η' precipitates of this condition are around 3.7 nm in radius, 1-3 nm in thickness and are found coherent with the Al matrix with a coherent strain of 0.0133, showing a strong strengthening effect. The heterogeneity in grain scale does not influence the distribution and the morphology of precipitates. The yield strength (L direction) varies linearly along the thickness direction of the plate, fitting an equation of σy=-38.7S+604.8 (0≤S≤1). The variation of yield strength is related to the heterogeneity of grain structure.

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