(中南大學(xué) 輕質(zhì)高強結(jié)構(gòu)材料國家級重點實驗室，長沙 410083)
摘 要: 本文通過耦合Estrin-Mecking(E-M)位錯密度模型，建立了金屬動態(tài)回復(fù)微觀組織演變的多相場模型，并研究多晶鎢在溫度1523~1723 K和應(yīng)變率0.001~1 s-1范圍內(nèi)發(fā)生動態(tài)回復(fù)過程的力學(xué)響應(yīng)行為，分析其應(yīng)力-應(yīng)變曲線、平均晶粒尺寸和動態(tài)回復(fù)體積分?jǐn)?shù)等變化規(guī)律。結(jié)果表明：在不同溫度和應(yīng)變率條件下模擬獲得的應(yīng)力-應(yīng)變曲線和位錯密度分布與實驗研究相吻合；隨著溫度升高，動態(tài)回復(fù)過程中晶界存在細(xì)微移動，平均晶粒尺寸相應(yīng)地增大，且溫度越高愈顯著。通過量化分析動態(tài)回復(fù)體積分?jǐn)?shù)，發(fā)現(xiàn)提高溫度或應(yīng)變率均可加速動態(tài)回復(fù)進程，這與已有理論和實驗結(jié)果一致。
關(guān)鍵字: 動態(tài)回復(fù)；相場法；位錯密度；鎢；微觀組織模擬
（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
