Improving Compositional Accuracy in APT Analysis of Carbides Using a Decreased Detection Efficiency
Journal article, 2019

The composition of carbides in steel, measured by atom probe tomography, can be influenced by limitations in the ion detector system. When carbides are analyzed, many ions tend to field evaporate from the same region of the specimen during the same laser or voltage pulse. This results in a so-called multiple event, meaning that several ions impact the detector in close proximity both in time and space. Due to a finite detector dead-time not all ions can be detected, a phenomenon known as detector pile-up. The evaporation behavior of carbon is often different than the evaporation behavior of metals when analyzing alloy carbides, leading to preferential loss of carbon ions, and a measured carbon concentration below the expected value. This effect becomes stronger as the overall detection efficiency gets higher. Here, the detection efficiency was deliberately reduced by inserting a grid into the flight-path, which resulted in a higher and more correct carbon concentration, accompanied by an increase in the statistical uncertainty.

detection efficiency

multiple hits


atom probe tomography



Deodatta Shinde

Chalmers University of Technology

Mattias Thuvander

Chalmers, Physics, Microstructure Physics

Arbab Rehan

Uddeholms AB

Sebastian Ejnermark

Uddeholms AB

Krystyna Marta Stiller

Chalmers, Physics, Microstructure Physics

Microscopy and Microanalysis

1431-9276 (ISSN) 1435-8115 (eISSN)

Vol. 25 2 454-461

Subject Categories

Materials Engineering

Physical Sciences

Metallurgy and Metallic Materials


Chalmers Materials Analysis Laboratory

Areas of Advance

Materials Science





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