Behaviours of nitrogen atoms in irradiated iron and iron alloy revealed by internal friction and electron microscopy

The structure changes of iron and an iron aLIa), induced b), neutron irradiation and annealing were investigated from the atomistic point of view . T hree kinds of materials, i .e. high /Juri(y iron, pure iron, and an iron nickel alloy, were irradiated in the B elgian reactor BR-2. Experiments on Snoek internal friction p eaks and electron microscopy were pe,formed. It is concluded that in slowly cooled iron alloy, in which carbon atoms are rather stab ly precipitated, nitrogen atoms are trapped b), irradiation induced point d~fects to form complexes, which together with interstitial elllsters contribute to the irradiation hardening .