(北京航空航天大学 材料科学与工程学院， 北京 100083)
摘 要: Al-Zn-Mg-Cu系合金在较低温度时效时， 形成2种类型的GP区： GP(Ⅰ)区和GP(Ⅱ)区。 选用7075， 7075+0.58%Li， 7075+0.89%Li和7075+1.0%Li4种合金进行343K, 240h和393K, 24h时效， 以获得GP区， 并通过DSC实验结果， 用Avrami-Johnson-Mehl(AJM) 表达式计算了GP区溶解动力学参数， 从而定量地研究Li对7075合金GP区转变的影响。 结果表明： 经过343K, 240h时效后， 含Li的7075合金的GP(Ⅰ)区溶解激活能较7075合金的略低， Li促进GP(Ⅰ)区的形成； 经过393K, 24h时效后， 2种合金GP区溶解激活能相差不大。
关键字: 7075合金； 7075-Li合金； GP； DSC； 组织转变动力学
（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
