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金属学报  2019, Vol. 55 Issue (2): 291-298    DOI: 10.11900/0412.1961.2018.00182
  本期目录 | 过刊浏览 |
Ti-Al合金γ/α2界面结构及拉伸变形行为的分子动力学模拟
涂爱东1,2, 滕春禹3, 王皞1(), 徐东生1, 傅耘3, 任占勇3, 杨锐1
1 中国科学院金属研究所 沈阳 110016
2 中国科学技术大学材料科学与工程学院 沈阳 110016
3 中国航空综合技术研究所 北京 100028
Molecular Dynamics Simulation of the Structure and Deformation Behavior of γ/α2 Interface in TiAl Alloys
Aidong TU1,2, Chunyu TENG3, Hao WANG1(), Dongsheng XU1, Yun FU3, Zhanyong REN3, Rui YANG1
1 Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
2 School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China
3 Laboratory of Fundamental Research, AVIC China Aero-Polytechnology Establishment, Beijing 100028, China
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摘要: 

采用分子动力学方法,通过考察共格和半共格界面,发现体系总能量随两相厚度比变化,得到2种界面相互转变的临界片层厚度;对不同片层厚度的Ti-Al合金进行垂直界面的拉伸加载,发现共格界面的屈服强度高于半共格界面,断裂行为随γα2相的厚度比变化。塑性变形首先发生在γ相一侧,形成Shockley偏位错,进而通过剪切传递方式穿过γ/α2界面,激活α2相的锥面层错;γ/α2界面为后续的位错和孪生提供形核点。

关键词 TiAl界面塑性变形力学行为分子动力学    
Abstract

TiAl alloys with γ-TiAl and α2-Ti3Al dual-phase lamellar structure possess not only excellent high temperature performance but also density only about half of traditional superalloys. Such lamellar structure largely determines the mechanical properties of TiAl alloys. However, there is still a lack of understanding on the atomic structure of lamella, as well as their influence on the mechanical behaviors. For this reason, molecular dynamics with an embedded-atom potential is employed to investigate the energies of both the coherent and semi-coherent γ/α2 interfaces. The interface coherency is found to depend on the thickness ratio of γ lamellae to α2 lamellae, and there exists a critical lamella thickness, below/above which the interface is coherent/semi-coherent. Tensile loading perpendicular to the lamella interface indicates that the yield strength of coherent interface is higher than that of semi-coherent interface and the crack nucleation behavior varies with the thickness ratio of γ lamellae to α2 lamellae. The plastic deformation occurs first in the γ region, forming Shockley partial dislocations and then crosses the γ/α2 interface via slip transfer, activating stacking faults on the pyramidal plane in the α2 region. In this process, the γ/α2 interface provides nucleation sites for subsequent dislocations and cracks.

Key wordsTiAl    interface    plastic deformation    mechanical behavior    molecular dynamics
收稿日期: 2018-05-07     
ZTFLH:  TG146.2  
基金资助:资助项目 国家重点研发计划项目No.2016YFB0701304,国家自然科学基金项目No.51671195,航空科学基金项目No.20160292002,中科院青促会专项项目No.2015151及中科院信息化专项项目No.XXH13506-304
作者简介:

作者简介 涂爱东,男,1991年生,硕士生

引用本文:

涂爱东, 滕春禹, 王皞, 徐东生, 傅耘, 任占勇, 杨锐. Ti-Al合金γ/α2界面结构及拉伸变形行为的分子动力学模拟[J]. 金属学报, 2019, 55(2): 291-298.
Aidong TU, Chunyu TENG, Hao WANG, Dongsheng XU, Yun FU, Zhanyong REN, Rui YANG. Molecular Dynamics Simulation of the Structure and Deformation Behavior of γ/α2 Interface in TiAl Alloys. Acta Metall Sin, 2019, 55(2): 291-298.

链接本文:

https://www.ams.org.cn/CN/10.11900/0412.1961.2018.00182      或      https://www.ams.org.cn/CN/Y2019/V55/I2/291

图1  2种共格界面近邻原子沿[110]γ或[112?0]α2方向的投影,界面处近邻2层原子沿[111]γ或[0001]α2方向的投影,及界面处的广义层错能量曲面
图2  γ/α2 半共格界面顶视图及图中方框区域的2个原子层在[111]γ或[0001]α2方向的投影
图3  体系总能与γ和α2片层厚度的关系曲面及体系总能与α2片层厚度的关系曲线
图4  Thompson四面体的几何构型和一些重要的变形矢量,共格和半共格界面产生的Shockley偏位错,及它们从γ穿过界面滑移到α2相,α2相内锥面层错被激活过程的示意图
图5  当γ/α2厚度比为1∶1和2∶1时,共格界面拉伸过程中的原子构型
图6  当γ/α2厚度比为1∶1和2∶1时,半共格界面在拉伸过程中的原子构型
图7  具有不同两相厚度的共格界面和半共格界面在拉伸时的应力-应变曲线
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