中文摘要：

基于三元体系的微观相场动力学模型，从原子层次上模拟了Ni-11at％Al-7at％Cr合金在873K预时效，1023K再时效的组织演化过程，结合原子图像，计算了有序相内序参数分布和体积分数随时间的变化，并与1023K下的单级时效工艺进行了对比。研究结果表明：两种工艺条件下，均析出单一的L12结构有序相，分级时效的沉淀机制为非经典形核长大与失稳分解的混合机制；单级时效的沉淀机制为失稳分解机制；分级时效获得的沉淀相呈45°方向倾斜排列的弥散颗粒状，单级时效获得的沉淀相呈45°方向倾斜的条纹状；分级时效工艺下孕育期缩短，达到平衡时，二者的体积分数相等。

英文摘要：

Based on the microscopic phase-field model, the reageing behavior of Ni-11 at%Al-7at%Cr alloy from 873 K to 1023 K was simulated at atomic-scale, The order parameter profiles and volume fraction of the ordered phase was calculated according to the atomic morphology evolution, and the reageing process from 873 K to 1023 K was compared with ageing at 1023 K. The results show that the precipitated phase are all L12 phase under the two kinds of process, the precipitation mechanism of reageing is the mixture of non-classical nucleation and spinodal decomposition, and the precipitation mechanism of ageing is spinodal decomposition; the precipitated phase under reageing exhibits disperse grain with 45° angle arranged, and the shape of precipitated phase under ageing presents wide striation with 45° angle arranged, the incubation period of ageing is longer than that of reageing, the volume fractions of the ordered phase under these two kind of processes are equal while the equilibrium state reaches.