V-4Cr-4Ti alloy is one of the candidate structural materials for future fusion reactors due to its desirable characteristics. In our previous research, MAX-phase-dispersion-strengthened vanadium alloy (V-4Cr-4Ti-1.5Y-0.3Ti₃SiC₂), prepared through mechanical alloying, showed excellent thermal stability and creep resistance and was expected to have good radiation resistance. This study investigates the effects of 2.5 MeV V²⁺ ion irradiation on V-4Cr-4Ti-1.5Y-0.3Ti₃SiC₂ and V-4Cr-4Ti alloys at 500 °C, with peak damage of 0.8, 3.5, and 6.1 dpa. Transmission electron microscopy and nanoindentation were used to examine the changes in microstructure and hardness before and after irradiation. The microscopic analysis reveals that dispersed nanoparticles maintained good stability under irradiation. Defect clusters grow with increasing irradiation doses in both materials. The nanoindentation results show that V-4Cr-4Ti-1.5Y-0.3Ti₃SiC₂ has higher initial hardness and lower irradiation hardening, indicating better resistance to radiation hardening than V-4Cr-4Ti. This research serves as a valuable reference for the assessment of the irradiation resistance of Ti₃SiC₂-dispersion-strengthened V-4Cr-4Ti alloy.

In order to figure out the migration and deposition of impurities on the first wall of HL-2A/2M tokamak, Peking University and Southwestern Institute of Physics are co-developing a deuteron RFQ as part of the in situ ion-beam diagnostic for the material. The RFQ, which operates at 162.5 MHz, is designed to accelerate a 10-mA deuteron beam from 40 keV up to 1.5 MeV. Key design considerations and the final design parameters are presented. The RFQ has been conditioned at a 1% duty factor for 80 h at RF cavity power of 55 kW. The specific shunt impedance of the cavity is 221 kΩ·m by measuring the bremsstrahlung spectrum. The intrinsic Q-value after the high-power tests measured by the Ring-Down method is 13,780. Beam commissioning has been taken place during the first half of 2021, and the beam measurements include beam current and energy of ²H⁺ ion. A 10 mA ²H⁺ beam was successfully accelerated through the RFQ.

After being self-ion implanted at 400 °C and 550 °C, the microstructure and irradiation hardness of kilogram-scale V-4Cr-4Ti alloys were studied using a transmission electron microscope (TEM) and nano-indentation test technology. Irradiation was performed using self-ions (V²⁺) at 2.5 MeV with design influences of 1.15 × 10¹⁵ ions cm⁻², 4.59 × 10¹⁵ ions cm⁻², and 9.17 × 10¹⁵ ions cm⁻², so that the peak damages of V-4Cr-4Ti alloys are 1, 4, and 8 dpa, respectively. Compared with the 400 °C samples, the 550 °C samples exhibited a higher-density number of dislocation loops and increased hardness and reached saturation at lower irradiation doses. The irradiation temperature was mainly responsible for these differences, and the potential mechanism for its effect on the irradiation behavior was discussed.

Nano-sized tungsten exhibits superior properties due to its high-density grain boundaries’ strengthening. The high-quality nano-sized powder is essential for sintering nano-sized tungsten bulks through powder metallurgy techniques. In this study, nano-sized tungsten powder was successfully synthesized by mechanochemical methods using mixed WO₃ and Mg powders. The effects of processing parameters on the morphology and microstructure of synthesized powder were thoroughly investigated. The results reveal that the thermite reaction of WO₃ and Mg is almost complete after 5 min of ball milling at a speed of 300 rpm. The average grain size of the tungsten powder decreases with the increasing milling duration and speed. Optimal average grain size and purity were achieved at a milling speed of 300 rpm and a milling duration ranging from 30 to 120 min. Moreover, centrifugation sieving further reduces the average grain size of tungsten powder to 19.5 nm. In addition, the entire mechanochemical process can be divided into two stages: the reaction stage and the grain size refinement stage.

The stability of nanoparticles (NPs) in ODS steel is an important factor affecting their long-term service behavior. In the current work, the 9Cr-ODS steel samples were irradiated using 3.5 MeV Fe¹³⁺ ion irradiation up to 20 dpa at 350–650 °C, and the microstructure stability was studied using the transmission electron microscope. The correlation between the particle coarsening rate and the irradiation depth has been investigated. The results show that fine Y-Ti-O NPs undergo coarsening under irradiation at 350 and 500 °C, and the coarsening rate shows a trend of first increasing and then decreasing with the increase in depth. NP coarsening reached its peak at a certain depth, and the peak depth increased with the increase in irradiation temperature. While the coarsening was inhibited at 650 °C, almost no changes in particle size were observed, only slightly coarsening at the end of the irradiation layer. In addition, b = 1/2 type dislocation loops were dominant at 350 °C, and the formation of b = type dislocation loops was confirmed at 500 °C. Dislocation lines were formed at 650 °C. Additionally, the segregation of Cr, O, C, Y, and Ti toward the surface in the irradiated layer was observed due to the surface effect. The stability of NPs with irradiation temperature is discussed.