用差热法分析Al-Zn-Mg-Cu-Li合金组织转变动力学及TTT曲线

Analysis of Kinetics and TTT Curves for Microstructure Transformation in Al-Zn-Mg-Cu-Li Alloy by DSC

采用差热法(DSC)对Al-Zn-Mg-Cu-Li合金在393K,24h和393K,3.5h+433K,12h时效过程中的组织转变动力学进行了分析,并用Avrami-Johnson-Mehl(AJM)表达式计算了GP区和η′相转变的动力学参数,进而得出了这两种组织转变的动力学表达式。根据TTT曲线的物理意义,对动力学表达式进行数学变形后得到了TTT曲线的数学表达式。通过该表达式计算的GP区和η′相转变的TTT动力学曲线与实验结果具有很好的一致性。

DSC （Differential Scanning Calorimetric） techniques were used to investigate the kinetics of microstructure transformation of Al-Zn-Mg-Cu-Li alloy during aging at 393 K, 24 h and 393 K, 3.5 h＋433 K, 12 h. The kinetics parameters for GP zones and η′ phase transformation were calculated by using Avrami-Johnson-Mehl（AJM） equation, and the kinetic expresses about both above microstructure transformation are further gained. On the basis of TTT curves, the kinetic expresses were modified to get the mathematic modes of TTT curves. It is prove that the mathematic modes are agreement with trial results.