W-K-TiC alloys with different titanium carbide concentration (0.05, 0.1, 0.25, 1) wt.% were fabricated through spark plasma sintering (SPS) method. Single shot thermal shock tests with a length of 5 ms and 100 shots thermal shock tests with a length of 1 ms were carried out. The microstructure and Vickers micro-hardness of each sample were investigated. It is revealed that the surface of the samples began to recrystallize after thermal shock tests, and the samples with 5 ms for single shot had more serious recrystallization than the samples with 1 ms for 100 shots because of its higher surface temperature after thermal shock tests. The samples were annealed at 1400 °C, 1600 °C, 1800 °C, respectively. It is shown that the addition of TiC particles could slow down recrystallization of W-K-TiC alloy, and its recrystallization temperature can reach to between 1400 °C and 1600 °C.

•Novel WKMoTiY alloy is fabricated by Spark plasma sintering successfully.•The Mo doping mechanically alloy with tungsten and occupy tungsten lattice.•The Mo doping results in a decreasing of Vickers micro-hardness.•Appropriate amount of Mo improves the properties on thermal shock resistance.WKMoTiY powder were mechanically alloyed (MA) and then consolidated through spark plasma sintering (SPS). Four different concentrations of molybdenum, i.e., (0, 2, 5, 10) wt%, were applied to investigate the behavior of the alloys. The microstructure, Vickers micro-hardness and thermal shock behavior were analyzed. It is found that the molybdenum doping can mechanically alloy with tungsten and occupy tungsten lattice, which results in a correspondingly decrease of Vickers micro-hardness and thermal conductivity at the room temperature. Among the molybdenum doped samples, WK-2wt% MoTiY alloy displays highly enhanced resistance against thermal shock. It is suggested that appropriate molybdenum doping in WKMoTiY alloy is beneficial in consolidating and improving its thermal shock resistance.

•SPS sintered yttrium doped W–K was prepared and its microstructure and mechanical properties were characterized.•The single and multiple shots thermal shock performance of W-K-Y under 0.37 GW/m2 were comparably studied.•The damage after thermal shock showed a proper mass fraction for yttrium doping.•Moderate yttrium doping (<0.5 wt%) in W-K can improve its thermal shock resistance.Novel tungsten-based W-K-Y alloys were sintered by spark plasma sintering (SPS) method using fine-grained yttrium doped tungsten-potassium (W-K) powder. The relative density, microstructure, hardness and the resistance to thermal shock damage of the sintered samples were characterized. With the enhanced Y doping, the grain size decreased and the hardness increased. Thermal shock test under 0.37 GW/m2 heat load showed that low yttrium doping (0.05 wt%, 0.1 wt% and 0.5 wt%) in W-K-Y alloys can improve the resistance to thermal shock damage comparing with traditional commercial W-K, while high yttrium doping (1 wt%) easily leads to crack formation. This study will provide helpful information to optimize the preparation of tungsten-based plasma facing materials through composite tuning.

•Al–K–Si doped tungsten powder was spark plasma sintered.•Sintering parameters were tuned according to density, grain/bubble size, etc.•A two-step sintering scheme was designed to reduce Al/Si impurity.•Potassium was detected inside the bubbles through energy dispersive spectroscopy.Dense potassium-doped tungsten (W–K) ingots with homogeneously dispersed nanoscaled bubbles were fabricated by spark plasma sintering (SPS) using Al–K–Si (AKS) doped tungsten powder. Parameters such as sintering temperature, holding time and sintering pressure were considered to tune the grain size, density, microhardness, bubble formation and impurity contents. In addition, a two-step sintering scheme was designed to reduce Al/Si impurity contents and enhance the density. The sample prepared by the two-step sintering scheme displays both inter- and intra-granular nanocomposites, which is expected to have better creep resistance, high bending strength and fracture toughness. Potassium was detected inside the bubbles, determining the crucial role in the bubble formation process, and thus leading to compatible properties as plasma-facing material.

A kind of uranium-selective sorbent has been studied using graphene oxide nanoribbons (GONRs) from the unzipping of multiwalled carbon nanotubes as a solid matrix and amidoxime (AO) as a functional group. Amidoxime-functionalized GONRs (AOGONRs) were successfully prepared by chemical grafting technology and characterized by scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, elemental analysis, thermogravimetric analysis and X-ray photoelectron spectroscopy. The as-prepared AOGONRs were applied to adsorb U(VI) from aqueous solutions and exhibited a high sorption capacity towards U(VI) due to the strong chelation of AO to U(VI). It can be noted that the uranium sorption on the AOGONRs was pH-dependent, ionic strength-independent, fast, endothermic, spontaneous and a pseudo-second order process. The U(VI) sorption amount reached up to 2.112 mmol g−1 (502.6 mg g−1) at pH = 4.5 and T = 298 K. The sorption study performed in a simulated nuclear industry effluent demonstrated that the new sorbent had a desirable selectivity towards U(VI) ions over a range of competing metal ions. The results suggest that AOGONRs may be a potential and suitable candidate for the separation of U(VI) from various uranium-containing water samples.

•Traditional W–K with different potassium contents were tested under ELM-like high heat load.•SPS sintered W–K was prepared and its thermal shock performance was comparably studied.•The damage after thermal shock showed a decreasing tendency as potassium content increase.•SPS sintered W–K showed better performance than traditional W–K in the thermal shock test.The effect of potassium doping on the thermal shock behavior of tungsten is investigated in this paper. Traditional W–K samples with different potassium contents were tested by an electron beam at an absorbed power density of 0.37 GW/m2. It shows that the damage after thermal shock test is smaller with potassium content increasing, but the cracking threshold is not improved. It suggests that for traditional W–K sample the potassium bubbles do have some pinning effects on tungsten but not enough to prevent cracking in transient high heat load. The thermal shock behavior of spark plasma sintered W–K (SPS–WK) was comparably studied. In SPS–WK, potassium bubbles not only distribute along the grain boundaries but also retain inside the grains. Size of the potassium bubbles inside the grains is in the range of 20–100 nm. This microstructure leads to higher thermal shock resistance and no obvious damage occurred after transient high heat load at 0.37 GW/m2. This may provide some important information to improve thermal shock resistance for W–K PFM.

Effects of helium plasma irradiation on spark plasma sintering (SPS) W-K, pure W and traditionally sintered commercial W-K have been studied, concerning the density, grain size and potassium content as the influence factors. Pinholes are formed under 120 eV He ions at 600 °C and 1 × 1023 m−2 fluence on the surface of all samples. It is found that SPS-sintered W-K shows the best irradiation resistance among the present samples, and SPS-sintered pure W exhibits higher irradiation tolerance than commercial W-K. Different He-plasma tolerance was observed among the SPS-sintered W-K samples due to varied potassium content and grain size. In addition, the microstructure evolution under helium irradiation, the growth-migration of helium bubbles and their interactions of potassium bubbles have also been discussed.