The Effect of Symmetrically Tilt Grain Boundary of Aluminum on Hydrogen Diffusion

Yuhao Wang,Lingxiao Li,Zhiqiang Xu,Pei Zhao,Haijun Wang,Jiyan Liu

doi:10.3390/met12020345

Abstract

High-strength aluminum alloys are widely used in industry. Hydrogen embrittlement greatly reduces the performance and service safety of aluminum alloys. The hydrogen traps in alumi-num profoundly affect the hydrogen embrittlement of aluminum. Here, we took a coinci-dence-site lattice (CSL) symmetrically tilted grain boundary (STGB) Σ5(120)[001] as an example to carry out molecular dynamics (MD) simulations of hydrogen diffusion in aluminum at dif-ferent temperatures, and to obtain results and rules consistent with the experiment. At 700 K, three groups of MD simulations with concentrations of 0.5, 2.5 and 5 atomic % hydrogen (at. % H) were carried out for STGB models at different angles. By analyzing the simulation results and the MSD curves of hydrogen atoms, we found that, in the low hydrogen concentration of STGB models, the grain boundaries captured hydrogen atoms and hindered their movement. In high-hydrogen-concentration models, the diffusion rate of hydrogen atoms was not affected by the grain boundaries. The analysis of the simulation results showed that the diffusion of hydro-gen atoms at the grain boundary is anisotropic.

Highlights

Hydrogen is one of the important factors that causes the performance degradation of metal parts, reducing service life and endangering service safety [1,2,3]
The results showed that the diffusion rate of hydrogen at the grain boundaries was higher than that in the crystals in the environment of higher hydrogen concentration [24]
The average of the squares of atomic displacements was the diffusion of hydrogen atoms at different and chose calledWe thesimulated mean square displacement (MSD)

Summary

Introduction

Hydrogen is one of the important factors that causes the performance degradation of metal parts, reducing service life and endangering service safety [1,2,3]. High-strength aluminum alloys are widely used in aerospace and other fields due to their high strength–. The hydrogen embrittlement of aluminum alloys has a great impact on the development of industry, which is manifested in the reduction in the mechanical properties of the material and the fracture of aluminum alloy parts. The hydrogen embrittlement of aluminum alloys and the hydrogen embrittlement mechanism have received extensive attention from scholars. The diffusion of hydrogen in metals is an important issue in the study of the hydrogen embrittlement of metals. According to the diffusion mechanism, Fick’s law can be used to describe the diffusion of hydrogen in metals [4,5]:

Methods

Results

Conclusion