Grain boundary segregation in Al–Mn electrodeposits prepared from ionic liquid

Among the various preparation methods for nanocrystalline alloys, ionic liquid electrodeposition at low temperature is of interest for its scalability and efficiency. To achieve nanostructures with stabilized structures, it is desirable to directly deposit alloys in which the grain boundaries are decorated with a segregated alloying element. Here a combination of atom-probe tomography and aberration-corrected scanning transmission electron microscopy are used to confirm that in Al–Mn nanocrystalline alloys deposited from an ionic liquid, Mn is slightly segregated at grain boundaries in the as-deposited condition. The apparent heat of grain boundary segregation is calculated to lie between 1100 and 1500 J mol⁻¹, which aligns reasonably well with a value calculated using a Miedema-based segregation model, and which is also in line with a more refined CALPHAD-type estimation if it is assumed that the Al–Mn deposits are not fully equilibrated at the deposition temperature.