Mo–S–Ti composite films deposited by magnetron sputtering were irradiated by 2 MeV Au ²⁺ with a high fluence of 3.3 × 10 ¹⁵ ion cm ⁻² . Upon intense bombardment by 2 MeV Au ²⁺ , the Mo–S–Ti thin film exhibits sensitivity to radiation-induced amorphization at room temperature. Afterwards, thermal annealing experiments on the irradiated thin films were conducted over the temperature range of 200 °C–900 °C. Subsequent annealing experiments found that the effect of heavy ion irradiation on Mo–S–Ti films was a reversible reaction, with the irradiation-damaged MoS ₂ lattice being completely self-repaired by thermal annealing. In the annealing temperature range of 200 °C–600 °C, no evidence of an amorphous to recrystallized transition was observed. When the temperature was increased to as high as 700 °C, the damaged MoS ₂ molecules were well recrystallized. HRTEM images of irradiated samples annealed at 700 °C strikingly found that the self-repaired MoS ₂ crystallites preserving long range ordering were still rearranged in an intrinsic (0 0 2) crystal orientation. MoS ₂ nanocrystals that survived the ion bombardment step may provide some nucleus for subsequent MoS ₂ grains growing dominantly in the (0 0 2) direction in thermal annealing. Compared with the difficult recrystallization in thermal annealing, the irradiation-amorphized MoS ₂ phases were easily self-repaired under friction. The low transition potential barrier from irradiation-induced amorphization to crystallization, achieved by mechanical working, may be an important reason for the quick recrystallization.

In this study, the nano-multilayer film was prepared by alternating deposition of MoS₂/Ti composite layer and amorphous C layer, and the irradiation damage effect was studied by the heavy ion bombardment experiment of 2 MeV Au²⁺. The results show that the irradiation region of the film is about 500 nm deep. The MoS₂ crystal inside the MoS₂/Ti composite layer in the irradiation-affected area is destroyed by incident Au²⁺ ions and turns into a disordered state. With the increase of irradiation dose, the hardness of the film increases from 1.58 to 3.28 GPa, and the wear life of the film decreases sharply from 3 × 10⁴ to 5 × 10³ r due to the destruction of the internal crystal and the embrittlement of the structure. In addition, with the increase of irradiation dose, the interlayer interface is gradually blurred and the interlayer diffusion is gradually aggravated.

Neutron irradiation as well as the presence of helium (He) significantly affects fuel inventory in plasma-facing materials. To investigate the synergistic effects of neutron and He irradiation on deuterium (D) retention behaviors in tungsten, heavy- and He-ion sequentially irradiation experiments were performed with various He fluence and/or heavy-ion damage levels, and then the samples were exposed to low-energy D plasmas at 450 K. It is shown that even a low He concentration of 0.5 atomic parts per million (appm) increases D concentration in the heavy-ion damaged region, which increases further with increasing He concentration under the parameters selected in this work (up to a maximum He concentration of 2.1 appm). The total D inventory in tungsten bulk also increases with He fluence due to the increase in D concentration both in the heavy-ion damaged region and the region irradiated by He-ion only. Furthermore, heavy-ion and He-ion successive irradiation slightly increases D retention in tungsten compared to the individual He ions irradiation. Similar to single heavy-ion damaged tungsten, the saturation of D retention is observed as heavy-ion irradiation damage above 0.2 dpa at a fixed He fluence.