In situ study of defect accumulation in zirconium under heavy ion irradiation

Nano-scale chemical evolution in a proton-and neutron-irradiated Zr alloy

“…Irradiation by heavy ions produces damage cascades smaller than that of neutron-induced cascades, and those of proton irradiations are smaller still [53]. However, the damage rate of heavy ion irradiation is higher than neutron irradiation by a factor of ~10 4 [47,54] and proton irradiation damage rates are higher by a factor of ~10 2 [47], accounting for the relative values of T crit for the Fe-Cr SPP.…”

Irradiation Induced Defect Clustering in Zircaloy-2

“…It was also found that the dislocation loops' size increases and DY decreases with an increase of irradiation temperature until the damage structure declines at 773 K. It was pointed out that in these neutron irradiated samples, there is an absence of radiation damage at 773 K, which is 0.42 of the absolute melting temperature of α-Zr. Ion irradiation studies on pure Zr show similar effects on loop sizes and densities with increasing irradiation temperature, except there was still a formation of large dislocation loops at 773 K [15]. The presence of these loops at 773 K may indicate decreased V-SIA (vacancy/self-interstitial atom) recombination possibilities leaving a high concentration of point defects, which then cluster in the form of dislocation loops.…”

“…The pure zirconium used is the same as the previous paper [15]; is is 99.8% pure with Hf, Sn, Ni, Fe, C, and O present as impurities. The microstructure of pure zirconium is composed of near equiaxed grains of~5 µm diameter.…”

“…The 1 MeV Kr ion irradiation experiments were done at 573 and 773 K from 0.007 to 0.8 dpa. Details of damage calculations, experimental procedures, and data collection methods can be reviewed elsewhere [15]. The nucleation and clustering behaviour of vacancies and interstitials by cascade collapse can be studied by calculating the parameter Defect Yield (DY) first defined by Merkle [23,24],…”

“…It was concluded that Ni ion bombardment at 300 and 400 • C is a reasonable simulation of neutron damage. However, no damage structures were found after irradiation at 600 • C. An in situ heavy ion irradiation investigation was conducted by Idrees et al [15] on pure Zr in order to observe prismatic loops experimentally, particularly at lower doses close to their nucleation threshold as a function of dose and irradiation temperature. It was reported that the small defect clusters (~2 nm) are perfect dislocation loops, with Burgers vector 1 3 1120 .…”