(1. 石家庄铁道大学 材料科学与工程学院，石家庄 050043；
2. 河北省交通工程材料重点实验室，石家庄 050043；
3. 河北科技大学 材料科学与工程学院，石家庄 050018)
摘 要: 采用搅拌摩擦焊(FSW)对厚度为6mm的7075铝合金进行不同工艺下的平板对接试验，使用光学显微镜、显微硬度仪、X射线衍射仪(XRD)及透射电镜(TEM)对接头微观组织、显微硬度及沉淀相种类与形貌进行分析。结果表明：接头中沉淀相主要有棒状MgZn2、椭圆状AlCuMg以及胶囊状Al2CuMg三种，AlCuMg和Al2CuMg强化效果好于MgZn2的。焊核区(WNZ)中沉淀相主要是AlCuMg与Al2CuMg，显微硬度较高；相比WNZ，热机影响区(TMAZ)中沉淀相AlCuMg和Al2CuMg相对较少，MgZn2相对较多，显微硬度降低；热影响区(HAZ)中的MgZn2相对更多，显微硬度进一步降低。随着转速(ω)的增加，WNZ和TMAZ中沉淀相尺寸增大，显微硬度先升高后降低；HAZ中沉淀相尺寸和数量变化不大。随着焊速(v)的增加，WNZ、TMAZ和HAZ中沉淀相数量增多、尺寸变小，显微硬度有所上升。
关键字: 7075铝合金；搅拌摩擦焊工艺；沉淀相
（1. School of Materials Science and Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China;
2. Hebei Provincial Key Laboratory of Traffic Engineering Materials, Shijiazhuang 050043, China;
3. School of Materials Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China）
Abstract:The flat butt welding was carried out on 7075 aluminum alloy with the thickness of 6 mm using friction stir welding under different processes. The microstructure, microhardness and the kinds, morphology of precipitated phase among the joints were analyzed by optical microscope, microvickers hardness tester, X-ray diffractometer (XRD) and the transmission electron microscopy (TEM). The results show that the precipitated phases are MgZn2 with rod shape, AlCuMg with elliptical shape and Al2CuMg with capsule shape. The strengthen effect of the AlCuMg and Al2CuMg is better than that of the MgZn2. The precipitated phases in WNZ mainly include AlCuMg and Al2CuMg. The microhardness in this zone is pretty high. The numbers of the AlCuMg and Al2CuMg in TMAZ is lesser and the number of the MgZn2 is more compared with the WNZ, which leads the microhardness to decrease. The number of the MgZn2 in HAZ is relatively more and the microhardness is further reduced. With the rotation speed (ω) increasing, the sizes of the precipitated phase WNZ and TMAZ among the joints increase, and the microhardness increases firstly and then decreases. There is little change in the size and number of the precipitated phase among the HAZ. With the weld speed (v) increasing, the numbers of the precipitated phase in WNZ, TMAZ and HAZ increase and the sizes are smaller. Therefore, the microhardness increases.
Key words: 7075 aluminum alloy; friction stir welding process; precipitated phase
