Perturbed angular correlation, Rutherford backscattering and channelling experiments were conducted to study the lattice location and annealing behaviour of 110 keV hafnium ions implanted into iron single crystals. It was found that a fraction of 11-25% of the implanted hafnium atoms are located at substitutional sites in an undisturbed environment, while about 50% are located at irregular lattice sites. The remaining fraction are located at or near regular lattice sites in a perturbed local environment. Trapping and detrapping of monovacancies by substitutional hafnium atoms at 200 and 250 K, respectively, as well as hafnium precipitation during annealing at 873 K was observed. The vacancy-hafnium binding energy was determined to be 0.17(3) eV.

We have used the perturbed angular conelation lechnique to study the interaction of inteatitially diffusing nitrogen atoms with subslitutional hafnium atoms implanted in iron. It w s found that after post-implantation of 7.50 eV nitrogen ions a1 450 K, isolated HA", mmplexes with 2 = 1, 2 are formed in the iron mauix.We propose a possible geometrical mniiguration for the HfVNz mmplex. Isochronal annealing experimenls showed nitrogen dissociation from the H". mmplexes at 113 K l k dissociation energy was determined to be 27(2) eV.