First-principles calculations on interface stability and migration of H and He in W-ZrC interfaces

摘要

In this work, the stability and adhesion of twelve tungsten-zirconium carbide (W-ZrC) interfaces as well as the migration of hydrogen (H) and helium (He) near the interface were investigated by first-principles calculations. The results of interface energy show that the coherent ZrC(200)(c)/W(100) interface is the most stable configuration with the smallest value in all the investigated stoichiometric structures. The stability of non-stoichiometric ZrC(111)/W(100) and ZrC(111)/W(110) is also analyzed. The electronic structure analysis reveals that the interfacial C-W bonds have a mixed property of covalent and ionic feature. Furthermore, the interface acts as strong traps for H and He with segregation energies of - 0.97 eV and - 2.03 eV, respectively. The diffusion of H and He across the ZrC(200)(c)/W(100) interface demonstrates that H and He atoms can reach the favorable segregation sites at the interface from the W matrix by overcoming energy barriers of about 0.3 eV and 0.58 eV, respectively, but it is quite difficult for the trapped H and He to escape out of the interface due to the higher diffusion energy barriers. Our results agree well with the experimental findings about the microstructure and H isotope retention in W-ZrC alloys.