Study on Helium Diffusion in bcc Tungsten Under Uniaxial Stress Field by Molecular Dynamics Simulation

ZHANG Jing; ZHOU Liangfu; CHEN Shuangqiang; HE Wenhao; SU Xue; YANG Dongyan; LI Yuhong

doi:10.11804/NuclPhysRev.36.02.261

The effect of uniaxial stress field along <100> and <111> crystal direction on the diffusion of a single helium atom in bcc tungsten was studied by molecular dynamics simulation. Our calculation shows that the stress strain caused the phase transition of tungsten metal and the initio phase transition strain decreases with the increase of temperature. The initial strain of phase transition is near the strain where stress reaches the maximum value. The diffusion coefficient of a single helium atom in tungsten metal decreases with the increase of strain. The helium diffusion coefficient decreases linearly along the <100> crystal direction, while the <111> crystal direction shows a fluctuating trend. Fitting the Arrhenius equation, the results show that when the crystal strain along <100> reaches +1.5% and the Arrhenius equation is no longer applicable; however, the Arrhenius equation still applies when the crystal strain along <111> increases by +5%. The helium diffusion activation energy along the crystal direction <111> was obtained, the results showed that the helium diffusion activation energy decreases with the increase of strain, indicating that the strain enhanceds the mobility of a single helium atom in tungsten.

Study on Helium Diffusion in bcc Tungsten Under Uniaxial Stress Field by Molecular Dynamics Simulation

1. School of nuclear science and technology, Lanzhou University, Lanzhou 730000, China;

2. North China University of Water Resources and Electric Power, Zhengzhou 450045, China

Funds: National Natural Science Foundation of China (11775102, 11475076)

Received Date: 2018-11-12

Rev Recd Date: 2019-02-12

Publish Date: 2019-06-20

Key words:

Abstract: The effect of uniaxial stress field along <100> and <111> crystal direction on the diffusion of a single helium atom in bcc tungsten was studied by molecular dynamics simulation. Our calculation shows that the stress strain caused the phase transition of tungsten metal and the initio phase transition strain decreases with the increase of temperature. The initial strain of phase transition is near the strain where stress reaches the maximum value. The diffusion coefficient of a single helium atom in tungsten metal decreases with the increase of strain. The helium diffusion coefficient decreases linearly along the <100> crystal direction, while the <111> crystal direction shows a fluctuating trend. Fitting the Arrhenius equation, the results show that when the crystal strain along <100> reaches +1.5% and the Arrhenius equation is no longer applicable; however, the Arrhenius equation still applies when the crystal strain along <111> increases by +5%. The helium diffusion activation energy along the crystal direction <111> was obtained, the results showed that the helium diffusion activation energy decreases with the increase of strain, indicating that the strain enhanceds the mobility of a single helium atom in tungsten.

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Study on Helium Diffusion in bcc Tungsten Under Uniaxial Stress Field by Molecular Dynamics Simulation

doi: 10.11804/NuclPhysRev.36.02.261

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