Atom Probe Tomography
Our group focuses on applying atom probe tomography (APT) to a range of advanced materials with an emphasis on correlating APT with other experimental and computational techniques.
The Research Group for Atom Probe Tomography at the Max-Planck-Institut für Eisenforschung was established in 2009 in conjunction with the installation of a local electrode atom probe, Cameca LEAP 3000X HR. In August 2015, a second instrument, a state-of-the art LEAP 5000 XS was the first of its kind installed in the world. Its wide field-of-view, increased detection efficiency and new generation of UV lasers has already allowed a broadening of the range of application of the technique.
Atom Probe Tomography (APT) is a high-resolution characterization technique that provides three-dimensional elemental mapping with near-atomic resolution. Insights from APT help understand phase formation & transformations, segregation at interfaces, partitioning between phases among others. The group aims to advance the understanding of structural and functional advanced materials behaviour by using the atomic-scale information obtained from APT, and has developed strengths in correlative approaches.
First, we have pushed to combine experiments with theory & simulations. Strong ties have been established with the group of D. Ponge (Mechanism-based Alloy Design) as well as the Computational Materials Science department of J. Neugebauer, particularly with the group of T. Hickel (Computational Phase Studies). These have resulted, for example, in new understanding of phase formation in steel or of the mechanical properties of hard coatings.
Second, new hardware development lead by Michael Herbig has enabled a range of electron microscopy techniques to be applied directly to specimens that are subsequently analysed by APT as summarised in the figure below.
This has allowed to gain additional information which has brought unique insights into the relationship between structure and composition, for instance the level of segregation of C as a function of the misorientation between grains.
Atom probe tomographic characterization of pearlitic steel wires cold drawn to different drawing strains. 3D carbon atom maps in both longitudinal (parallel to the drawing direction) and transverse cross section views (perpendicular to the drawing direction). Blue arrows mark some of the subgrain boundaries decorated with carbon atoms.[less]
Atom probe tomographic characterization of pearlitic steel wires cold drawn to different drawing strains. 3D carbon atom maps in both longitudinal (parallel to the drawing direction) and transverse cross section views (perpendicular to the drawing direction). Blue arrows mark some of the subgrain boundaries decorated with carbon atoms.
Data from electron microscopy is also used to inform and improve atom probe reconstruction. More advanced methodologies for reconstructing and extracting structural information from atom probe data are currently being explored in order to push the analytical performance of the technique.