Ti-Al合金γ/α_2界面结构及拉伸变形行为的分子动力学模拟
Molecular Dynamics Simulation of the Structure and Deformation Behavior of γ/α_2 Interface in TiAl Alloys
查看参考文献38篇
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文摘
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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γ和α_2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/α_2界面,激活α_2相的锥面层错;γ/α_2界面为后续的位错和孪生提供形核点。 |
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其他语种文摘
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TiAl alloys with γ-TiAl and α_2-Ti_3AI 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/α_2 interfaces. The interface coherency is found to depend on the thickness ratio of γ lamellae to a2 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 inter-face and the crack nucleation behavior varies with the thickness ratio of γ lamellae to a2 lamellae. The plastic deformation occurs first in the γ region, forming Shockley partial dislocations and then crosses the γ/α_2 interface via slip transfer, activating stacking faults on the pyramidal plane in the α2 region. In this process, the γ/α_2 interface provides nucleation sites for subsequent dislocations and cracks. |
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来源
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金属学报
,2019,55(2):291-298 【核心库】
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DOI
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10.11900/0412.1961.2018.00182
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关键词
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TiAl
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界面
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塑性变形
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力学行为
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分子动力学
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地址
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1.
中国科学院金属研究所, 沈阳, 110016
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中国科学技术大学材料科学与工程学院, 沈阳, 110016
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中国航空综合技术研究所, 北京, 100028
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语种
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中文 |
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文献类型
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研究性论文 |
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ISSN
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0412-1961 |
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学科
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金属学与金属工艺 |
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基金
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国家重点研发计划项目
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国家自然科学基金
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中国航空科学基金
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中科院青促会专项项目
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中科院信息化专项项目
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文献收藏号
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CSCD:6418608
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