(北京航空航天大學 材料科學與工程學院， 北京 100083)
摘 要: Al-Zn-Mg-Cu系合金在較低溫度時效時， 形成2種類型的GP區(qū)： GP(Ⅰ)區(qū)和GP(Ⅱ)區(qū)。 選用7075， 7075+0.58%Li， 7075+0.89%Li和7075+1.0%Li4種合金進行343K, 240h和393K, 24h時效， 以獲得GP區(qū)， 并通過DSC實驗結(jié)果， 用Avrami-Johnson-Mehl(AJM) 表達式計算了GP區(qū)溶解動力學參數(shù)， 從而定量地研究Li對7075合金GP區(qū)轉(zhuǎn)變的影響。 結(jié)果表明： 經(jīng)過343K, 240h時效后， 含Li的7075合金的GP(Ⅰ)區(qū)溶解激活能較7075合金的略低， Li促進GP(Ⅰ)區(qū)的形成； 經(jīng)過393K, 24h時效后， 2種合金GP區(qū)溶解激活能相差不大。
關(guān)鍵字: 7075合金； 7075-Li合金； GP； DSC； 組織轉(zhuǎn)變動力學
ZHANG Yong-gang, CHEN Chang-qi
（School of Materials Science and Engineering,
Beijing University of Aeronautics and Astronautics, Beijing 100083, China）
Abstract:Two types of GP zones, GP(Ⅰ) zone and GP(Ⅱ) zone, are formed during aging at lower temperature in Al-Zn-Mg-Cu alloys.The influence of Li on the GP zones transformation was studied for 7075， 7075+0.58%Li, 7075+0.89%Li and 7075+1.0%Li alloys after solution treatment followed by aging at 343K for 240h and at 393K for 24h by using DSC. The kinetic parameters for GP zones dissolution were calculated by using Avrami-Johnson-Mehl(AJM) equation.It is found that Li accelerates GP(Ⅰ) zone transformation and suppresses GP(Ⅱ) zone. The activation energy for GP zone dissolution in 7075-Li alloy is lower slightly than that in 7075 alloy aged at 343K, but basically equal to that in 7075 alloy aged at 393K.
Key words: 7075 alloy; 7075-Li alloy; GP zone; DSC; kinetic parameter for microstructure transformation
