Defect recovery behavior of neutron irradiated molybdenum and tungsten of two purity levels

Effect of transmutation elements Re and Ta on the vacancy formation and dissociation behaviors in W bulk

“…The above results are consistent with earlier firstprinciples calculations in body-centered cubic (bcc) W [18][19]. Isochronal anneals suggest that the principal recombination regions were observed at about 0.15 Tm, 0.22 Tm and 0.31 Tm (Tm is the tungsten melting temperature) [20], which shows a phased stage for the point defect recovery. In addition, the recovery curve for annealed W indicates that the stage Ⅲ in the quenching process is generally attributed to the vacancies' migration with activation energy of 1.7 eV at 700 K. The calculation model of the monovacancy diffusion in pure W represents that multiple nearest neighbor jumping styles play an important role in the diffusion coefficient, especially at the temperature over 2/3 of Tm [21].…”

Hardness and electrical resistivity of molybdenum in the post-irradiated and annealed conditions

“…The increase in the electrical resistivity of molybdenum following irradiation results from the creation of transmutation products and the creation of point defects such as vacancies and interstitials, defect clusters, dislocation loops, and voids, while the change in hardness after irradiation results from the formation of defects that have a strong influence on dislocation mobility, such as loops and voids [13,26,37,39]. The defects that produce the largest increase in electrical resistivity are recovered at Stage III annealing temperatures (%160°C), which are less than the irradiation temperatures (270-1100°C) so that recovery of these defects would occur during the irradiations [26,[42][43][44][45][46]. The defects produced by irradiation at 270°C and 605°C are expected to be a high number density of small dislocation loops and/or voids that are shown to have a relatively small effect on properties that are controlled by electronic conduction mechanisms such as electrical resistivity, but have a strong effect on dislocation mobility.…”

“…5 shows recovery of electrical resistivity values at 400-500°C, which is slightly lower than the Stage V recovery temperature [21]. Significant recovery of electrical resistivity for irradiated molybdenum is reported to begin at Stage III recovery temperatures (%160°C) [26,[42][43][44][45][46]. Since Stage III recovery in molybdenum would occur at a temperature less than the irradiation temperatures (270-605°C), recovery of these defects would occur during the irradiations.…”

Stability of concentration-related self-interstitial atoms in fusion material tungsten

“…[14] However, the recovery curves have been obtained and discussed by measuring the electrical resistivity change with temperature. The isochronal anneals suggested that principal recombination regions can be observed at about 0.15T m , 0.22T m , and 0.31T m (T m is tungsten melting temperature), [15][16][17][18] which showed a phased stage for the point defect recovery. The recovery of the Frenkel pair defects was found to be nearly complete at 44 K. [15] Electron-irradiated tungsten results on relaxation strength versus stress direction suggested that the interstitials are probably 110 split rather than 111 .…”