The role of the Atom Probe in the study of nickel-based superalloys

Nanostructural features of nickel-based superalloys as revealed by Field-Io n Microscopy, Atom Probe (APFIM), and 3D Atom Probe are reviewed. The uniqu e and original information provided by these techniques is discussed on the basis of an extended and almost exhaustive analysis of bibliography over t he last 30 years. Atom Probe techniques are shown to be able to measure the composition of tiny gamma' precipitates, a few nanometer in size, to detec t ordering or subtle clustering effects within the gamma solid solution or gamma' particles. Plane-by plane analysis of (001) planes of the gamma' pha se makes it possible to estimate the degree of order as well as the prefere ntial sites of various addition elements included in superalloys. Due to it s ultrahigh depth resolution, the microchemistry of interfaces and grain bo undaries can also be characterized on an atomic scale. Most salient results will be reviewed, and the specific role of 3D APFIM will be highlighted wi th selected examples. (C) Elsevier Science Inc., 2000. All rights reserved.