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Tungsten is a primary material in plasma-facing components (PFCs), but several disadvantages limit its application in fusion reactors. This work examined tungsten–niobium (W–Nb) alloys as potential PFC materials and investigated their response to low-energy helium ion irradiation. W–Nb powders were milled for 25 and 36 h, and the W–Nb samples were exposed to 50 and 80 eV helium ion irradiation with a flux of 1.5 × 10 22 ions/m 2  s at 1230 °C. The sample with a dense structure and obtained after a 25-h milling exhibited enhanced anti-irradiation performance. Sufficient energy can be provided to promote helium ion migration in the matrix, resulting in the formation of nanotendrils. Furthermore, in W–Nb alloys, the Nb-rich regions are more attractive to helium ions and thus provide protection to the tungsten matrix. [ABSTRACT FROM AUTHOR]

Fatigue pre-cracking performance and fracture toughness in polycrystalline tungsten (W) and molybdenum (Mo) have been investigated in relation to grain boundary (GB) configuration with respect to the crack advance direction. Sub-sized, single edge notched bend (SENB) specimens with three different orientations, R-L (ASTM notation) for a forged Mo rod and L-S and T-S for a rolled W plate, were pre-cracked in two steps: fully uniaxial compression fatigue loading to provoke crack initiation and its stable growth from the notch root, and subsequent 3-point bend (3PB) fatigue loading to extend the crack. The latter step intends to minimize the influence of the residual tensile stresses generated during compression fatigue by moving the crack tip away from the plastic zone. It is shown that fatigue pre-cracking performance, especially pre-crack extension behavior, is significantly affected by the specimen orientation. The R-L orientation, giving the easiest cracking path, permitted crack extension completely beyond the plastic zone, while the L-S and T-S orientations with the thickness cracking direction of the rolled plate sustained the crack lengths around or possibly within the plastic zone size due to difficulty in crack advance through an aligned grain structure. Room temperature fracture toughness tests revealed that the 3PB fatigued specimens exhibited appreciably higher fracture toughness by about 30% for R-L, 40% for L-S and 60% for T-S than the specimens of each orientation pre-cracked by compression fatigue only. This indicates that 3PB fatigue provides the crack tip front out of the residual tensile stress zone by crack extension or leads to reduction in the residual stresses at the crack tip front. Strong dependence of fracture toughness on GB configuration was evident. The obtained fracture toughness values are compared with those in the literature and its strong GB configuration dependence is discussed in connection with the appearance of pop-in. [ABSTRACT FROM AUTHOR]

W-2%vol Y 2 O 3 composite material were prepared by wet-chemical and rolling methods. A comparative study was conducted with commercially pure tungsten. The laser thermal shock and the damage behavior of the material after helium ion irradiation were studied. The damage behavior was analyzed through X-ray diffractometry, field emission scanning electron microscopy, focused ion beam, field emission transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Results showed that W–Y 2 O 3 composite material have higher resistance to laser thermal shock than pure tungsten. Helium ion irradiation further illustrated that the cracking caused by laser thermal shock is dominated by intergranular cracks. In addition, tungsten matrix damage is associated with grain orientation deformation after the helium ion irradiation of pure tungsten and W–Y 2 O 3 composite material, and the grain orientation resistance to helium ion irradiation damage is higher than that to increasing grain boundary density. Several helium bubbles were found in the tungsten matrix, the fuzz structure, and the Y 2 O 3 particles, and all the helium bubbles were polyhedral rather than spherical. • W–Y 2 O 3 composite possess higher thermal shock resistance than pure tungsten. • Compared with increasing grain boundary density, grain orientation is more favorable to resist irradiation damage. • Helium bubbles were observed in the Y 2 O 3 particles. • The reported helium bubbles were polyhedral rather than spherical. [ABSTRACT FROM AUTHOR]

To study the D 2 retention behavior of W–ZrC/Sc 2 O 3 composites, mirror-polished samples prepared by spark plasma sintering (SPS) were exposed to different irradiation doses at room temperature (RT). TDS measurements were subsequently performed from RT to 900 K. Results revealed that Sc 2 O 3 particles did not benefit the D 2 + ion irradiation resistance, whereas W–1vol% ZrC/2 vol% Sc 2 O 3 composites showed superior irradiation resistance over other samples. D 2 implantation was also performed at 523 K with the irradiation dose of 1 × 1020 D 2 +/m2 to study the influence of temperature on D 2 retention during the capture process, which could apparently decrease D 2 retention by low-energy traps. Only small dislocation loops or precipitates were observed in W–1vol% ZrC/2 vol% Sc 2 O 3 sample after irradiation up to 1.0✕1021 D 2 +/m2. • The effect of ZrC/Sc 2 O 3 doping on irradiation resistance behavior of W materials was investigated. • 1 vol% ZrC/2 vol% Sc 2 O 3 composite possess better irradiation resistance than SPS/W. • Increasing implantation temperature decrease D 2 retention by low-energy traps. [ABSTRACT FROM AUTHOR]