A First-principles Study Towards Understanding Interactions Between Impurity Elements (C,N And O) And Hydrogen In Hcp-Zr

Zirconium(Zr)alloy is widely used as the cladding material of nuclear pressurized water reactors due to its good corrosion resistance and excellent mechanical properties.The Zr alloy is in direct contact with water at high temperatures and generates a large amount of hydrogen.When hydrogen(H)concentration reaches the solubility,brittle hydride phases will be formed,and then result in H embrittlement.In the actual use process,the inherent impurities in the material(such as carbon,nitrogen and oxygen)will interact with H,which will have a great impact on the mechanical properties and mechanical properties of the Zr alloy.Therefore,it is of great significance to study the behavior of impurity atoms in Zr and their interaction with H.In this work,we have investigated the behavior of impurity atoms and the impurityhydrogen interactions in hexagonal-closed packed Zr(hcp-Zr)by a first-principles approach.We studied the formation energy of impurity atoms under different occupations,the binding energy of impurity-impurity and the diffusion barrier of impurity atoms in Zr,which revealed the behavior of impurity atoms and determined the most stable occupations of impurity atoms,the interaction between impurities and the best diffusion path of impurity atoms in Zr.By calculating the stability of a single H atom,the interaction of two H atoms,the vacancy formation energy of H atoms,and the diffusion barriers of H atoms in different paths,we revealed the most stable configuration of hydrogen atoms in Zr.We studied the influence of impurity atoms on the behavior of H atom.Our calculation results show that the most stable position of impurity atoms is the octahedral interstitial site and the most stable position of the H atom is the tetrahedral interstitial site.In addition,we discussed the influence of impurity atoms on the diffusion behavior of H.We found that impurity atoms have an attractive effect on H.The existence of impurity atoms will reduce the formation energy of H and make it more stable.The diffusion barrier of H atoms increases when impurities are present,and the presence of impurity atoms inhibits the diffusion of H atoms in Zr.