A study of neutron irradiation damage in copper and a dilute copper-boron alloy

Abstract

Transmission electron microscopy has been used to examine irradiation-induced damage in pure copper and in a solid solution copper-0.001 w/o boron alloy after simultaneous neutron irradiation to an integrated fast neutron dose of 1.1 × 10²⁰ cm⁻² at ∼ 60°c. The results demonstrate that the resolvable damage differs considerably in these materials, both in its initial distribution and in its post-irradiation annealing behaviour these differences are considered to be a consequence of the transmutation of the boron-10 atoms in the alloy. After post-irradiation annealing, the damage in both materials clearly consists of two components; coarsely distributed dislocation segments and loops and a finer distribution of small clusters. The annealing behaviour of both components has been examined closely after annealing between 350°c and 650°c, the temperature range in which the principal changes occurred, and the morphology and nature of the loops comprising the coarser component have been determined. Consideration is given to the mechanisms involved in the annealing of the damage, particular emphasis being placed on accounting for the significant influence exerted by the boron, helium and lithium atoms. Spherical precipitates, believed to result from aggregation of lithium atoms, have been observed in the alloy after annealing between 450°c and 650°c. However, helium bubbles could not be detected and the possible reasons for this are discussed.