Investigation into the impact of the W/TiC heterogeneous interface on helium behavior by first-principles calculation

TiC addition could effectively refine the grain size and enhance the radiation tolerance of the first wall W material in fusion reactors. The W/TiC interface serves as a crucial defect for capturing He atoms and forming He clusters. In this work, the properties of the W/TiC interface and the behaviors of helium at the interface have been investigated using the first-principles calculations. Among these, the interface energy, work of adhesion, bonding density, and charge density difference are used to discuss the interfacial stability. It was found that the W(110)/TiC(100) interface exhibits smaller interface energy and larger work of adhesion compared to other interfaces. Considering helium behavior at the W(110)/TiC(100) interface, the dissolution and segregation energies confirm that the interface structure plays a crucial role in trapping and segregation of helium. The W and TiC layers near the interface contain the trapping regions. The diffusion of helium from bulk W and TiC to their respective capture zones requires overcoming barrier energies of 0.23 eV and 0.41 eV, respectively. The trapped helium prefers to gather at the interface rather than escape from the W-TiC alloys along the interfacial passageway. The helium cluster at the interface exhibits regular structures, and the misfit dislocation intersections (MDIs) at the interface can accommodate only six helium atoms. These calculation results provide theoretical support for a deeper understanding of experimental findings and the dispersion of TiC in strengthened tungsten.