(1. 石家莊鐵道大學(xué) 材料科學(xué)與工程學(xué)院，石家莊 050043；
2. 河北省交通工程材料重點(diǎn)實(shí)驗(yàn)室，石家莊 050043；
3. 河北科技大學(xué) 材料科學(xué)與工程學(xué)院，石家莊 050018)
摘 要: 采用攪拌摩擦焊(FSW)對(duì)厚度為6mm的7075鋁合金進(jìn)行不同工藝下的平板對(duì)接試驗(yàn)，使用光學(xué)顯微鏡、顯微硬度儀、X射線衍射儀(XRD)及透射電鏡(TEM)對(duì)接頭微觀組織、顯微硬度及沉淀相種類與形貌進(jìn)行分析。結(jié)果表明：接頭中沉淀相主要有棒狀MgZn2、橢圓狀A(yù)lCuMg以及膠囊狀A(yù)l2CuMg三種，AlCuMg和Al2CuMg強(qiáng)化效果好于MgZn2的。焊核區(qū)(WNZ)中沉淀相主要是AlCuMg與Al2CuMg，顯微硬度較高；相比WNZ，熱機(jī)影響區(qū)(TMAZ)中沉淀相AlCuMg和Al2CuMg相對(duì)較少，MgZn2相對(duì)較多，顯微硬度降低；熱影響區(qū)(HAZ)中的MgZn2相對(duì)更多，顯微硬度進(jìn)一步降低。隨著轉(zhuǎn)速(ω)的增加，WNZ和TMAZ中沉淀相尺寸增大，顯微硬度先升高后降低；HAZ中沉淀相尺寸和數(shù)量變化不大。隨著焊速(v)的增加，WNZ、TMAZ和HAZ中沉淀相數(shù)量增多、尺寸變小，顯微硬度有所上升。
關(guān)鍵字: 7075鋁合金；攪拌摩擦焊工藝；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
