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Grain boundary (GB) engineering is crucial in the austenitic stainless steel (ASS) design for nuclear energy applications. In this work, the influence of different GB structures on radiation defect recombination and radiation-induced segregation (RIS) at different temperatures were investigated using molecular dynamics simulation. Four typical GBs in ASSs were selected as model structures. Results showed that GBs remained stable at various temperatures and they all exhibited better self-healing performance than single crystals in terms of radiation defects. However, except Σ3(112) GB, other three GBs cannot inhibit the radiation induced segregation, while promoting the radiation defect recombination. Calculation results showed that the higher Σ value of GBs can lead to a greater lattice mismatch near GBs, which not only results in stronger sink strength for radiation induced defects, but also provides more sites for solute atoms and causes greater segregations eventually. Owing to the intrinsic low Σ and large inclination angle characteristic, Σ3(112) GB achieves an excellent balance between the defect-absorption and RIS. This phenomenon provides a feasible route for the future GB design in ultra-high radiation tolerant materials. [ABSTRACT FROM AUTHOR]

Interstitial strengthening is one of the main approaches to improving the mechanical properties of high-entropy alloys (HEAs), but its effects on the irradiation resistance of HEAs need further study. Here, we investigated the irradiation-induced defects and swelling of Fe38Mn40Ni11Al4Cr7 HEAs with different carbon contents under 5 MeV Xe23+ irradiation at 300 °C and 500 °C. Results show that the irradiation-induced swelling was significantly suppressed as the carbon content increased. Under the observation of TEM, the size of irradiation-induced dislocation loops also decreases with increasing carbon content. By comparing the effects of carbon content at different temperatures on the evolution of defects, the pinning effect of interstitial carbon on irradiation-induced defects of HEAs was proposed and analyzed. Carbon atoms, which are stabilized in the octahedron clearance of HEAs with FCC structure, not only promote the recombination of point defects by enhancing the sluggish diffusion effect of HEAs, but also pin the common 1/3 <111> faulted loops caused by irradiation. This pinning effect is the main mechanism of interstitial carbon for improving the irradiation resistance of HEAs below 300 °C. In summary, this study provides an essential experimental basis for the irradiation effects of carbon-doped HEAs and strives to reveal the effect of interstitial carbon on irradiation-induced defects at different temperatures. [ABSTRACT FROM AUTHOR]

With the guidance of density functional theory (DFT), a high-performance hafnium (Hf) cathode for an air/water vapor plasma torch is designed and the concepts and principles for high performance are elucidated. A quasi-nanocrystalline hexagonal close-packed (HCP) Hf-La 2 O 3 cathode based on these design principles is successfully fabricated via a powder metallurgy route. Under identical voltage and temperature conditions, the thermal emission current density of this quasi-nanocrystalline Hf-La 2 O 3 cathode is ≈20 times greater than that of conventional Hf cathodes. Additionally, its cathodic lifespan is significantly extended. Quasi-nanocrystalline Hf-La 2 O 3 products are manufactured into cathode devices with standard dimensions. This fabrication process is straightforward, requires minimal doped oxides, and is cost-effective. Consequently, the approach offers substantial performance enhancements over traditional Hf melting methods without incurring significantly additional costs., (© 2024 Wiley‐VCH GmbH.)