机械孪晶强韧化微观力学机制的原位实验研究

项目名称： 机械孪晶强韧化微观力学机制的原位实验研究

项目编号： No.11202183

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 刘嘉斌

作者单位： 浙江大学

项目金额： 24万元

中文摘要： 机械孪晶强韧化是与生长孪晶强韧化不相同的另一种有效提高材料强度和韧性的新途径，能使铜合金和钢铁材料达到800~1000 MPa的抗拉强度和20%~60%的延伸率综合力学性能水平，对指导新型结构材料强韧化设计有重要意义。本项目拟以机械孪晶强韧化效应为核心研究内容，以高分辨透射电镜系统倾转和动态原位拉伸为主要实验手段，研究位错与机械孪晶微结构演变，建立机械孪生机制，揭示机械孪晶对位错运动的阻碍方式，构建机械孪晶强化物理模型。以经典位错弹性力学为理论依据，以大规模分子动力学计算为模拟工具，计算机械孪晶应力场及其对位错的应力作用，模拟位错与孪晶交互作用的微结构变化，验证实验所建立的孪生机制和强化模型。最后，通过实验结合理论，阐明机械孪晶强韧化效应的微观力学机制。

中文关键词： 机械孪晶；强韧化；位错；透射电镜；分子动力学

英文摘要： Mechanical twinning induced strengthening and toughening (MTIST), which is different from the growth twinning induced strengthening and toughening, is the key technique to enhance the strength and toughness of materials. Based on MTIST the strength of 800 MPa and 60~80% plasticity could be obtained in copper alloys and steels. It plays an important role in developing key engineering materials with high strength and high toughness. In this study, major attention will be focused on MTIST. Systematic tilt and in-situ deformation in high resolution transmission electron microscopy will be adopted as main experiment method. The evolution of dislocation and mechanical twin will be investigated, and the way for mechanical twin baffling dislocation will be analyzed. The mechanism of mechanical twin formation and strengthening would be established. The dislocation elastic mechanics and molecular dynamics simulations will be used to analyze the stress state of mechanical twin and applied stress on dislocation. The microstructure evolution after dislocation interacting with twin boundary will be simulated. By experiments combined with theory analysis, the micromechanics mechanism of mechanical twinning strengthening will be established.

英文关键词： Mechanical twin；strengthening and toughening；dislocations；transmission electron microscopy；molecular dynamic simulation