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Free keywords:
FIELD-ION EMITTER; NUMERICAL-CALCULATION; TOMOGRAPHY; TEMPERATURE;
EVAPORATION; OPTIMIZATION; IRRADIATION; MICROSCOPY; EVOLUTION; DETECTORMicroscopy; Atom probe; Quantitative analysis; Field evaporation; Preferential
evaporation; Copper;
Abstract:
The difference in quantitative analysis performance between the voltage-mode and laser-mode of a local electrode atom probe (LEAP3000X HR) was investigated using a Fe-Cu binary model alloy. Solute copper atoms in ferritic iron preferentially field evaporate because of their significantly lower evaporation field than the matrix iron, and thus, the apparent concentration of solute copper tends to be lower than the actual concentration. However, in voltage-mode, the apparent concentration was higher than the actual concentration at 40K or less due to a detection loss of matrix iron, and the concentration decreased with increasing specimen temperature due to the preferential evaporation of solute copper. On the other hand, in laser-mode, the apparent concentration never exceeded the actual concentration, even at lower temperatures (20K), and this mode showed better quantitative performance over a wide range of specimen temperatures. These results indicate that the pulsed laser atom probe prevents both detection loss and preferential evaporation under a wide range of measurement conditions. (C) 2017 Elsevier B.V. All rights reserved.
