Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第29卷    第3期    总第240期    2019年3月

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文章编号:1004-0609(2019)-03-0508-09
镁合金中 、 两种孪晶界面的可动性比较
李 亨1,刘 钊1,张 真2,彭金华2

(1. 合肥工业大学 工业与装备技术研究院,合肥 230009;
2. 合肥工业大学 材料科学与工程学院,合肥 230009
)

摘 要: 形变孪生是镁合金的主要塑性变形方式之一,镁合金的两种主要孪晶为 、 孪晶,两种常见孪晶在形貌上存在较大的差异。本文采用分子动力学模拟与微观组织实验观察相结合的手段,研究了两种孪晶压缩过程的应力应变曲线、微观结构以及界面的迁移方式,对比分析两种孪晶界面的可动性。并且从原子运动以及位错滑移的角度,解释两者存在差异的原因。结果表明: 孪晶界迁移所需的应力较 孪晶界迁移所需的应力低,并且 孪晶界的迁移呈现“弓形”方式,而 孪晶界以“台阶”的方式进行迁移。 孪晶界的迁移是B/P面相互转变的过程,因而界面更容易大范围、高速率地迁移;而透射电镜(TEM)观察和模拟结果均显示, 孪晶界面上存在周期性的界面位错,阻碍了孪晶界的移动,并且需有基面位错滑移至孪晶界面处堆积,为 孪晶界的迁移提供能量。

 

关键字: 镁合金; 孪晶; 孪晶;孪晶界面可动性;分子动力学模拟

Mobility comparison of twin interfaces between and for magnesium alloy
LI Heng1, LIU Zhao1, ZHANG Zhen2, PENG Jing-hua2

1. Institute of Industry & Equipment Technology, Hefei University of Technology, Hefei 230009, China;
2. School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China

Abstract:Deformation twinning is one of the main plastic deformation modes of magnesium alloy. Two main types of twin are and . There have great differences between the morphology of two kinds of common twins. tensile twins mostly form in non-basal plane oriented grain. Once the twins have formed, it will expand rapidly, and gradually engulf the matrix. Thus the morphology features of twins are mostly lenticular. However, compression twins mostly form in basal plane oriented grain. After the formation of these twins, it is difficult to expand laterally, and the morphology features of twins are mostly narrow-flake. The combination of molecular dynamics method and microstructure experiment observation is used to establish the atomic models of two kinds of twins. In addition, the size and loading mode of the two models are consistent. This paper contrasts the mobility of two kinds of twin interfaces through analysis of stress-strain curve, microstructure and interface migration mode. And the reasons for the difference interface mobility are explained from the point of view of atomic motion and dislocation slip. The simulation and experimental results show that the stress required for twin boundary migration is lower than that for twin boundary. The migration of twin boundaries presents “bow” shape mode, while twin boundaries migrate with “step” mode. Actually, the migration of twin boundaries is the process of mutual transformation of Basal planes and Prism planes. Interestingly, the atomic arrangements of Basal plane and Prism plane are similar, thus it is easy to implement the mutual conversion process. However, it is found that there are periodic interfacial dislocations on the twin interface by TEM observation and simulation results, and the interfacial dislocations will hinder the movement of twin interface. It is also found that there are basal plane dislocation spiling up at the interface; it can provide energy for the migration of twin boundaries. Therefore, twin boundaries are easier to form large-scale and rapid migration than twin boundaries.

 

Key words: magnesium alloy; twin; twin; mobility of twin interfaces; molecular dynamics simulation

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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