Search

The defect structure in fusion neutron irradiated Ni and Ni+25 at% Fe has been studied by positron lifetime spectroscopy. The positron trapping is used as a defect indicator. Two lifetime components τ 1 and τ 2 are resolved. It is found that the number of vacancies in vacancy clusters is larger than 11. The recovery stage in Ni+25 at% Fe is shifted from 750 to 850 K.

Small-angle scattering of annealed electron-irradiated copper shows that isolated monovacancies persist through recovery stage III. The scattering appearing at small angles after annealing between 260 K and 300 K can be accounted for by the condensation of self-interstitials to form small dislocation loops.

After the quenching of polycrystalline zinc, a simple defect is observed between annealing temperatures 150 K ⩽ T A ⩽ 240 K. Arguments are given for a vacancy type defect being mobile in recovery stage III in Zn.

High purity polycrystalline magnesium samples near 4.7°K that are irradiated with 0.4 MeV electrons give an annealing behavior which is not characteristic of a simple kinetic process. It is shown that one can experimentally use a combined isothermal and isochronal annealing procedure to obtain partial resolution of the recovery data.

It is shown that the experimental data on lead permit an unambiguous assignment of recovery stage III to the migration of self-interstitials and of recovery stage IV to monovacancy migration.

The 175°K recovery stage observed in irradiated high resistivity p-type silicon is not affected by the presence of a high concentration of oxygen, contradicting the thought that the migration of the neutral vacancy is responsible.