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

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 CW 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. •The coherent ZrC(200)C/W(100) interface shows the highest interfacial stability with the lowest interface energy.•The bonding between the interfacial C and W atoms has a mixed property of strong covalent and ionic bond.•The interface acts as strong traps for both H and He.•The diffusion energy barriers of H and He along the interface are much lower than those across the interface.•The zero-point energy has a strong influence on the diffusion barriers of H and He across the interface.