(中南大学 轻质高强结构材料国家级重点实验室，长沙 410083)
摘 要: 本文通过耦合Estrin-Mecking(E-M)位错密度模型，建立了金属动态回复微观组织演变的多相场模型，并研究多晶钨在温度1523~1723 K和应变率0.001~1 s-1范围内发生动态回复过程的力学响应行为，分析其应力-应变曲线、平均晶粒尺寸和动态回复体积分数等变化规律。结果表明：在不同温度和应变率条件下模拟获得的应力-应变曲线和位错密度分布与实验研究相吻合；随着温度升高，动态回复过程中晶界存在细微移动，平均晶粒尺寸相应地增大，且温度越高愈显著。通过量化分析动态回复体积分数，发现提高温度或应变率均可加速动态回复进程，这与已有理论和实验结果一致。
关键字: 动态回复；相场法；位错密度；钨；微观组织模拟
（National Key Laboratory of Science and Technology for National Defense on High-strength Structural Materials, Central South University, Changsha 410083, China）
Abstract:Coupling with the Estrin-Mecking(E-M) dislocation density model, a multiphase field model was established to simulate the dynamic recovery process of tungsten in this work. The mechanical response behavior of polycrystalline tungsten during the dynamic recovery process was studied under the circumstances that strain rate ranging from 0.001 s-1 to 1 s-1, and temperature ranging from 1523 K to 1723 K. The dependences of the stress-strain curves, average grain size and dynamic recovery volume fraction on strain rate and temperature were carefully analyzed. The results reveal that stress-strain curves and dislocation density distribution at different temperatures and strain rates are in good agreement with experimental observations. As the temperature increases, the grain boundaries moves slightly, and the averaged grain size increases accordingly. Moreover, by quantifying the volume fraction of dynamic recovery, it is found that increasing the temperature or strain rate can accelerate the dynamic recovery process. This agrees well with previous theories and experimental results.
Key words: dynamic recovery; phase-field method; dislocation density; tungsten; microstructure evolution simulation
