Materials analysis with a position‐sensitive atom probe

Abstract

SUMMARY A position‐sensitive detector has been combined with time‐of‐flight mass spectrometry in the atom probe field‐ion microscope to yield a system in which both chemical identity and spatial information are obtained for individual ions field‐evaporated from the specimen surface. This allows the variations in composition originally present in the sample to be reconstructed in 3‐D with sub‐nanometre resolution. The prototype position‐sensitive atom probe is being used to study phase chemistry in a number of metallurgical alloys, including accurate composition determination of 1–2 nm Cu‐rich precipitates formed in Fe–1.3% Cu–1.4%Ni aged to peak hardness. Other applications of the position‐sensitive atom probe (POSAP) include the analysis of surface layers on superconductors and atom probe studies of semiconductor multiple quantum wells. These initial applications of the instrument are reported, and the limitations and intended improvements to the instrument are discussed.