采用等温热压缩实验, 通过计算和对比热激活参数, 并利用EBSD和TEM分析技术, 研究了2099合金在热变形过程中的动态软化机制. 基于Zener-Hollomon参数(Z)和变形温度(T)并结合对热激活参数与微观组织的分析, 给出了2099合金在热变形中的软化机制. 在lnZ≥35.5和T≤380 ℃范围内, 变形以位错的交滑移为主. 在lnZ≤37.4和T≥340 ℃范围内, 由位错的交滑移、攀移以及三维位错网脱缠等变形机制共同控制. 在lnZ≤35.1和T≥420 ℃范围内, 发生了动态再结晶, 此时以位错的交滑移、攀移、动态再结晶以及位错的脱钉为主要软化机制. 动态再结晶形核机制以晶界弓出和亚晶合并共存, 并随着变形温度的升高和应变速率的降低, 亚晶合并形核得到强化.

Dynamic softening mechanism of 2099 alloy was investigated by isothermal compression tests, thermal activation parameters calculation and comparison, EBSD and TEM techniques. On the basis of Zener-Hollomon parameter (Z) and deformation temperature (T), combining thermal activation parameters and microstructures analysis, the softening mechanism of 2099 alloy during hot deformation has been proposed. Dislocation cross slip plays a dominant role under the conditions of lnZ≥35.5 and T≤380 ℃. While, deformation mechanisms such as cross slip, climb of dislocation and unzipping of attractive junction play a joint role when lnZ≤37.4 and T≥340 ℃. Particularly, dynamic recrystallization occurred in the range of lnZ≤35.1 and T≥420 ℃, cross slip, climb and unzipping of dislocation and dynamic recrystallization are the main softening mechanisms in this condition. Dynamic recrystallization nucleation mechanisms are constituted of grain boundaries bulging nucleation and subgrain rotated induced nucleation, and the latter becomes more significant with increasing temperature and decreasing strain rate.