Three-dimensional Atom Probe Analysis Research Articles

Local magnification effects in the atom probe

Differences in the local magnification and curvature of phases in field evaporated field ion specimens have been shown to be an important consideration in atom probe analysis. A series of experiments has been performed on a high purity iron-45% chromium alloy that has been aged within a low temperature miscibility gap to produce a chromium-enriched α' phase and an iron-rich α phase. The effects of local magnification on field ion and field evaporation microscopy, and on three-dimensional and probe aperture atom probe analyses are discussed. It has been shown that the average composition of an atom probe experiment should be calculated from the number of atoms of each element divided by the total number of atoms but that the distance scale should be determined from distance-monitored type experiments. The reason for this is that the greater number of atoms per unit area in a darkly imaging region exactly compensates for the reduced probability of being sampled by the probe aperture.

Local magnification effects in the atom probe

Abstract Differences in the local magnification and curvature of phases in field evaporated field ion specimens have been shown to be an important consideration in atom probe analysis. A series of experiments has been performed on a high purity iron-45% chromium alloy that has been aged within a low temperature miscibility gap to produce a chromium-enriched α' phase and an iron-rich α phase. The effects of local magnification on field ion and field evaporation microscopy, and on three-dimensional and probe aperture atom probe analyses are discussed. It has been shown that the average composition of an atom probe experiment should be calculated from the number of atoms of each element divided by the total number of atoms but that the distance scale should be determined from distance-monitored type experiments. The reason for this is that the greater number of atoms per unit area in a darkly imaging region exactly compensates for the reduced probability of being sampled by the probe aperture.