The damage and recovery of neutron irradiated tungsten

Publisher Website
Google Scholar
Abstract
Residual electrical resistivity has been used as an index of the damage present in tungsten irradiated in a nuclear reactor at 4°K and 77°K. A comparison was made between four different types of specimen prepared from cold-drawn wire respectively annealed before irradiation at 2000, 1500, 800°c and not at all. A fifth type of specimen was prepared from wire in a different state of purity. Four stages of recovery have been identified. the first occurring below −170°c, the second between −170 and 350°c with an activation energy rising from 0.25 to 1.7 ev, the third between 350 and 450°c with a single activation energy, of 1.7 ev and the fourth above 450°c. Second-stage recovery was enhanced by the presence of cold-work, affected by impurities and in well-annealed samples after light irradiations it was suppressed. A comparison of recovery with that in other metals leads to the conclusion that vacancies in tungsten migrate at 400°c with an activation energy of 1.7 ev. The general suggestion is advanced that vacancy migration occurs in all metals at a temperature approximately 20% of the absolute melting point T m °K, with an activation energy roughly 5 × 10−6 T m , ev. Recovery in tungsten above −170°c is attributed to the release of interstitials from traps associated with impurity atoms and dislocation lines. The free interstitial is assumed to become mobile below −170°c. The resistance versus dose curve for cold-worked tungsten shows acceleration and this is considered as evidence for the action of spikes on the unstable arrays of vacancies produced by deformation. A quantitative theory of damage and recovery developed from the above model predicts the observed behaviour of the five types of tungsten specimen.

This publication has 22 references indexed in Scilit: