A Method of Observing Fine Precipitates in Alloys with a Field-ion Microscope
A method of observing a few atom-layer thick precipitates in alloys with FIM is described. On the spherical crystal surface of an FIM specimen, many atomic planes are exposed. On the low-index planes, the topmost surface layer is nearly circular and has a relatively large diameter of 5 to 10 nm. It is pointed out that when a thin precipitate plate intersects the middle of the top layer, a clear field-ion image of the precipitate atoms can be obtained without a disturbance by the image of matrix atoms. From the images of a copper monolayer in aluminum and of a nitride plate in iron, the image formation mechanism on the low-index surfaces are discussed.