A transmission electron microscopy (TEM) study using weak-beam imaging has been addressed in order to assess the microstructure of NiAl (100) single-crystals subsequently to irradiation at room temperature with 700 keV nickel ions up to 10(15) cm(-2) or 1.5 dpa, namely, defect cluster formation and respective depth distribution. This work shows that the incoming ions undergo channeling along the [100] crystallographic direction and that the actual projected range is approximately 500 nm instead of the 250 nm simulated value. A detailed analysis of the TEM micrographs evidences a defect cluster depth location which is accurately fitted using the sum of two Gaussian distributions. In this frame, the effective diffusion coefficient, the diffusion length, and the mixing efficiency are calculated on the basis of the straggle broadening with increasing fluence (or dose). (C) 2003 Elsevier Science Ltd. All rights reserved.