High-dose neutron-irradiation effects in fcc metals at 4.6 K

Abstract

The rate of residual-resistivity increase and the isochronal recovery have been studied on the fcc metals Al, Ni, Cu, Pd, Ag, Pt, and Au irradiated at 4.6 K with reactor neutrons to a dose of about 10' fast neutrons/cm2.The rate of resistivity increase is nonlinear as a function of irradiation-induced resistivity; computer analysis shows that the data are best fitted with an expression having up to third-order terms in hp. There are deviations from simple damage-rate theory in all cases, but an anomalous negative deviation from a linear law (convex curvature) is observed in Ni, Pd, Pt (and Fe). This behavior is most probably caused by a decrease of the specific Frenkel-defect resistivity due to defect clustering, an effect which should contribute in all metals after fast-neutron irradiation to high doses. Saturation values of resistivity and defect concentration as well as recombination volumes have been obtained more accurately than from previous work.The isochronal recovery is compared with previous lower-dose data. Stage I decreases and stage III increases with increasing neutron dose. After high-dose irradiation, correlated recovery in stage III becomes dominant in the case of Al, Cu, Ag, and Au. 165285

Radiation Damage in Metals

“…At an irradiation dose of 10 19 n cm −2 at liquid helium temperature, defect recovery of about 70 to 80% above Stage III was observed in platinum, gold and silver, while complete recovery was obtained in aluminum. For the medium mass atoms nickel, copper and palladium recovery was in the range of 80 to 90% [129]. At irradiation temperatures above Stage III only defect clusters are observed, which in fcc metals consist of vacancy type stacking fault tetrahedra and triangular loops [127].…”

Defect production efficiency in metals under neutron irradiation

“…[7,12,31,38,43,47,63,65,[72][73][74][75]. The data are shown in Table 2 for various metals and types of irradiation.…”

“…The second group (TTB(2)) includes data for dDq=dU ð Þ j Dq¼0 obtained in Refs. [31,[73][74][75] for modified TTB spectrum and corrected as described in Ref. [7].…”

Magnetic Relaxation in Cobalt Following Low-Temperature Electron Irradiation

“…3, suggests that it is due to a simple defect, since saturation of defect concentration with increasing dose, due to overlapping of recombination volumes, is characteristic of simple defect production. The relaxation anneals out between 100 and 250 K; this is the temperature region which, in pure Pd, we would tentatively assign to stage I1 [22]. Furthermore, the relaxation is not observed in the disordered samples and therefore clearly arises from a configuration which only occurs after irradiation of the ordered lattice.…”