Ultra-high-resolution chemical analysis by field-ion microscopy, atom probe and position-sensitive atom-probe techniques

Abstract This paper describes some recent results on the use of field-ion microscopy and atom-probe techniques in the study of the fine-scale chemistry of a range of different materials. It is shown that field-ion images of the early stages of precipitation in metallurgical alloys can give morphological information before any significant contrast can be achieved by conventional transmission electron microscopy (TEM), and that the composition of these nanometer-scale particles can be accurately analysed by the use of atom-probe microanalysis. In addition, the recent development of the position-sensitive atom probe (POSAP) allows a three-dimensional composition map to be obtained of the elemental distribution in and around these particles. In this way a more complete picture can be obtained of the morphology and chemistry of complex, fine-scale structures than is readily obtainable from TEM-based techniques.