  A new family of high-strength Al-alloys has recently been developed, tailored
for the powder bed fusion-laser beam process. In these alloys, Mn, Cr and Zr
are incorporated in solid solution at amounts up to three times that of
equilibrium in the as-printed state. Mn and Cr-enriched precipitates that form
during printing and heat treatment influence the material's mechanical
properties. In this study, direct imaging of these precipitates was
accomplished through the utilisation of in situ synchrotron-based scanning
X-ray fluorescence. During heat treatment, a selective accumulation of Cr and
Mn in two distinct types of precipitates at grain boundaries was observed.
Additionally, the microstructure at the melt-pool boundary, containing
precipitates found in the as-printed state, remains thermally stable during the
heat treatment. The study demonstrates the significant value of employing
high-sensitivity in-situ X-ray fluorescence microscopy in exploring the
kinetics of sub-micrometre scale precipitation.
