Mutual Influence of Different Hydrogen Concentration in ��-Zirconium System with Vacancies

• DOI: 10.48550/arxiv.1811.09856
• Publication Date: 2018-01-01
• Authors: Li, Heng-Yu; Jia, Hao-Jun; Zhao, Yan-Zhen; Svyatkin, L. A.; Chernov, I. P.
• Keywords: Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences; 7. Clean energy

Hydrogen embrittlement in zirconium alloys is one of current challenges of nuclear reactor containment and can lead to a rapid decrease in mechanical properties of materials. Although many previous studies investigated the mechanism of hydrogen embrittlement at high hydrogen concentration, few studies concentrate on the mechanism at low hydrogen concentration which is before the formation of hydrides (only in the hydrogen complex state). The purpose of this study is to illuminate the formation mechanism of hydrogen complex. We calculate the formation energy Evac binding energy EH, EH-vac using ABINIT software package. For hydrogen atom at different states in lattice, we obtained Evac increased from 26.3% to 84.6% and EH-vac increased from 40.6% to 119.3%. This indicates that the bond between the original Zr atoms is weakened by hydrogen atoms entering the lattice and formation of vacancy is more possible. In addition, vacancies make hydrogen atoms and Zr atoms more closely connected and further increases the vacancies formation. Therefore, hydrogen complexes tend to expand in lattice, the brittleness of hydrogen complex becomes the main cause of hydrogen embrittlement.