Investigation into the Impact of the W/Tic Heterogeneous Interface on Helium Behavior by First-Principles Calculations

Abstract

TiC addition could effectively refine the grain size and enhance the radiation tolerance of the first wall W material in fusion reactors. W/TiC interface serves as a crucial defect for capturing He atoms and forming He clusters. In this work, the properties of W/TiC interface and the behaviors of helium at the interface have been investigated by the first-principles calculations. Among, the interface energy, work of adhesion, bonding density, and charge density difference are used to discuss the interfacial stability. It 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 the trapping and segregation of helium. The W and TiC layers near the interface contain the trapping regions. Helium must overcome the barrier energies of 0.23 eV and 0.41 eV from the bulk W and TiC to trapping regions, respectively. The trapped helium prefers to gather at the interface rather than escape out the W-TiC alloys along interfacial passageway. Helium cluster at the interface exhibits the regular structures, and every MDIs at the interface has only a capacity of six helium atoms. These calculation results provide theoretical support for a deeper understanding of experimental findings and the dispersion of TiC in strengthened tungsten.

Keywords: W/TiC interface, Helium behaviors, first-principles