Phase-field simulation of the coupled evolutions of grain and twin boundaries in nanotwinned polycrystals

作     者：Yuanyuan DA Yuyang LU Yong NI 

作者机构：CAS Key Laboratory of Mechanical Behavior and Design of MaterialsDepartment of Modern Mechanics University of Science and Technology of China 

出 版 物：《Applied Mathematics and Mechanics(English Edition)》 (应用数学和力学（英文版）)

年 卷 期：2018年第39卷第12期

页      面：1789-1804页

核心收录：

学科分类：08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0802[工学-机械工程] 0701[理学-数学] 0801[工学-力学（可授工学、理学学位）] 

基　　金：Project supported by the National Natural Science Foundation of China(No.11672285) the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB22040502) the Collaborative Innovation Center of Suzhou Nano Science and Technology the Fundamental Research Funds for the Central Universities 

主　　题：nanotwin grain growth stress effect phase-field simulation 

摘      要：Nanotwinned polycrystals exhibit an excellent strength-ductility combination due to nanoscale twins and grains. However, nanotwin-assisted grain coarsening under mechanical loading reported in recent experiments may result in strength drop based on the Hall-Petch law. In this paper, a phase-field model is developed to investigate the effect of coupled evolutions of twin and grain boundaries on nanotwin-assisted grain growth. The simulation result demonstrates that there are three pathways for coupled motions of twin and grain boundaries in a bicrystal under the applied loading, dependent on the amplitude of applied loading and misorientation of the bicrystal. It reveals that a large misorientation angle and a large applied stress promote the twinning-driven grain boundary migration. The resultant twin-assisted grain coarsening is confirmed in the simulations for the microstructural evolutions in twinned and un-twinned polycrystals under a high applied stress.