Tao Lu

TL;DR: In this paper, a genetic algorithm was applied to search the energy minimization configuration of vacancy clusters in α-Fe, and molecular statics calculations and dynamics annealing relaxation were employed to calculate the formation and binding energies of vacancies and 3D vacancy or vacancy-hydrogen (H) clusters on (111, (011) and (211) planes.

TL;DR: In this article, the hydrogen isotope permeation and retention behavior of a representative high-entropy alloys, CoCrFeMnNi, has been mainly checked by a gas-driven permeation device and a thermal desorption spectra device.

TL;DR: In this paper, a gas-driven permeation (GDP) device was used to study the behavior of creep-resistant, Al 2 O 3 -forming HTUPS austenitic stainless steels.

Abstract: Polished F82H steel samples were exposed to He plasmas with an ion incident energy of ~80 eV at 773–873 K to three central exposure fluences: 6 × 1024, 1 × 1025 and 4 × 1025 He m−2. Pinholes with diameters less than 70 nm are densely distributed on all exposed samples, resulting from the formation and bursting of blisters. Further, tendril-like features in maze-like patterns on the top of terrace-like ridges are visible for the sample exposed to 4 × 1025 He m−2 in the beam center. EDS indicates that the tendrils are tungsten enriched. Voids with different sizes and shapes with a depth up to 3.5 µm are observed across the sample exposed to 1 × 1025 He m−2. Over the area exposed to a fluence of up to 2 × 1024 He m−2, variations of wavy morphology and blisters are also observed, which could correlate with the crystallographic orientation at the surface. These He pre-exposed F82H steel samples were subsequently subjected to the conditions near the plasma edge in the EAST tokamak for 367 D plasma pulses of varied durations. It is found that the tendril-like features are partially destroyed by these plasma exposures. These results suggest that the properties of the material likely undergo substantial changes due to expected plasma exposure in a tokamak environment. The bursting of blisters and erosion of W-enriched tendrils would introduce additional impurities that could negatively influence the operation of a fusion device.