The resolution of three-dimensional atom probe (3DAP) is known to be mainly
controlled by the aberrations of the ion trajectories near the surface of
the specimen. A model has been developed to compute the ion trajectories in
3D near a sharp hemispherical electrode defined at the atomic scale. Simul
ations were applied on one-phase binary alloys. The influence of the evapor
ation fields of chemical species is studied. Simulated desorption images ar
e consistent with experiments in both ordered alloys and random solid solut
ion. An extra loss in the lateral resolution is observed in disordered allo
ys as compared to purl metals. The predicted order of evaporation provided
by this model is in excellent agreement with experiments. The stacking sequ
ence of atomic planes reconstructed from simulated data is shown to be dist
urbed in a similar way as observed in real experiments with 3DAP. (C) 2000
Elsevier Science B.V. All rights reserved