(1. 北京科技大學(xué) 材料科學(xué)與工程學(xué)院，北京 100083；
2. 廣東堅美鋁型材廠(集團(tuán))有限公司 技術(shù)中心，佛山 528231)
摘 要: 研究7050 鋁合金型材在固溶淬火與分級時效各階段亞晶界的演變，闡明亞晶界形成與晶粒內(nèi)取向梯度的關(guān)系。結(jié)果表明：固溶淬火后長軸為200 μm、短軸為80 μm 的紡錘狀粗晶組織經(jīng)過(121 ℃，360 min)+(177 ℃，60 min)雙級時效處理后，被分割碎化成20 μm 左右的等軸狀細(xì)小亞晶組織。電子背散射衍射技術(shù)(EBSD)證實(shí)碎化由小角度晶界分割造成，且固溶淬火后晶面的彎曲程度經(jīng)時效后降低了77.8%。透射電鏡(TEM)結(jié)果表明，時效過程使淬火散亂位錯逐步形成位錯列和小角度晶界。二級時效時MgZn2 相在亞晶界上析出，促進(jìn)了Graff 試劑的侵蝕效果，使得在光學(xué)顯微鏡(OM)下可觀察到亞晶界。
關(guān)鍵字: 7050 鋁合金；時效；晶粒細(xì)化；取向梯度；亞晶界
（1.School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China;
2. Technology Center,Guangdong Jianmei Aluminum Profiles Factory (Group) Co.,Ltd.,Foshan 528231,China）
Abstract:The evolution of sub-grain boundaries of 7050 Al alloy profiles during solution quenching and interrupted aging treatment was studied,and the relationship between formation of the sub-grain boundaries and the orientation gradient was clarified. The results show that the spindle-shaped grains with 200 μm in length and 80 μm in width after solution quenching break into fine equiaxed sub-grains with average diameter of about 20 μm after duplex aging at (121℃,360 min) and (177 ℃,60 min). EBSD analysis demonstrates that grain refinement results from the segmentation of coarse grains by low angle grain boundaries and the lattice curvature due to solution quenching decreases by 77.8% after aging treatment. The investigation of TEM shows that the scattered dislocations by quenching arrange into dislocation arrays and low angle grain boundaries with aging time. MgZn2 precipitates on the sub-grain boundary,which helps the etchant Graff to visualize the sub-grain boundary using OM in the secondary aging.
Key words: 7050 Al alloy; aging; grain refinement; orientation gradient; sub-grain boundary
