Vacancy damage in heavy ion and neutron-irradiated tungsten

Abstract

Abstract Vacancy damage produced by heavy ion, and neutron irradiation, of tungsten, at ambient temperatures, has been examined by both field ion and electron microscopy. Field ion microscopy revealed defects in the form of single vacancies, irregularly shaped voids (compact clusters) containing up to 300 vacancies, ‘dispersed’ clusters, and both perfect and imperfect dislocation loops with Burgers vectors ½a〈111〉 and ⅓a〈112〉, respectively. At least 80% of the damage consisted of small clusters, each containing less than ten vacancies. The only defects that were readily resolved by electron microscopy were dislocation loops, with b = ½a〈112〉 or ½a 〈 111 〉. Less than 10% of the total concentration of vacancies produced by irradiation was in the form of dislocation loops. Similar types of damage were produced by both heavy ion and neutron irradiations. Equivalent densities of damage were produced by doses 1 × 1017 (150 kev) Hg+/m2 and 5.42 × 1023 nf/m2.