We studied an Fe-Co-Mo Maraging steel designed for high performance cutting applications. The microstructure contains long-range ordered nanoscale domains of a B2 phase within a body-centred cubic Fe-Co matrix. These domains substantially lower the impact toughness of this steel. In this work, we have applied a combination of atom probe microscopy and neutron diffraction to study the details of the chemical and structural order within the nanoscale ordered domains.
We determined the precise species-specific site occupancy frequencies in the B2 phase from spatial distribution maps computed from the atom probe data. We compared these results with the ordering factor measured via neutron scattering and a simulation of a 50 x 50 x 50 atoms cell where atom probe-like noise was introduced via a dithering function. The frequency of site occupancy defects will be discussed in terms of the mechanical properties of the steel.