Analytical W-H, H[sbnd]H and H[sbnd]He interatomic potentials for a W-H-He system

Tungsten (W) is regarded as a primary candidate for plasma-facing materials in nuclear fusion devices. Within fusion reactors, high-energy neutron irradiation leads to the accumulation of numerous defects within materials, including vacancies, interstitial atoms, dislocations, and dislocation loops. The deuterium-tritium fusion reaction and neutron transmutation generate a substantial amount of helium (He) atoms in W, subsequently influencing the permeation and retention behavior of hydrogen (H) isotopes in W. The synergistic effects between these damages and H/He directly dictate the performance of W in fusion reactors. A profound understanding of the interaction mechanisms between irradiation-induced defects and H/He in fusion reactor materials constitutes a fundamental basis for their application. To systematically investigate the behavior of H/He in W, we constructed a new ternary potential for the W-H-He system, building upon a rigorous selection of existing W-He potentials. Utilizing structural and energetic data of defect clusters interacting with H/He in W, derived from first-principles calculations, and considering properties such as H/He diffusion, a lattice relaxation fitting method was applied to successfully establish a ternary W-H-He potential. Based on the current potential, a comprehensive evaluation was conducted, revealing good agreement between the interaction binding energies of various irradiation defects with H/He and the results obtained from first-principles calculations. We further explored the dynamics behavior of nanoscale H[sbnd]He-void. It was clearly observed that H and He perfectly formed a typical core-shell structure within nanovoids, with He located internally and H externally, which aligns with experimental observations. Consequently, the new W-H-He potential provides a powerful tool for exploring the synergistic effects of irradiation defects and H/He in W.