The evolution behavior of the γ″ phase of IN718 superalloy in a temperature/stress coupled field was investigated. Results showed that the coarsening rate of the γ″ phase was significantly accelerated in the temperature/stress coupled field. Based on the detail microstructural and crystal defect analysis, it was found that the coarsening rate of the γ″ phase with applied stress was significantly higher than that without stress. The main reasons for the increase in the coarsening rate of the γ″ phase are as follows: the vacancy formation energy is decreased by the applied stress, which leads to an increase in the vacancy concentration; in the temperature/stress coupled field, the Nb atoms easily combine with vacancies to form complexes and diffuse with the complexes, resulting in a significant increase in the Nb atom diffusion coefficient; Nb atom diffusion is the key control factor for the coarsening of the γ″ phase.

研究了IN718高温合金γ″相在温度/应力耦合场中的演化行为。结果表明，在温度/应力耦合场中，γ″相的粗化速率显着加快。基于详细的显微组织和晶体缺陷分析，发现施加应力的γ″相的粗化率明显高于无应力的。γ″相粗化率增加的主要原因如下：外加应力降低了空位形成能，导致空位浓度增加；在温度/应力耦合场中，Nb原子容易与空位结合形成配合物并随配合物扩散，导致Nb原子扩散系数显着增加；