Precipitate modification in PH13-8 Mo type maraging steel

The evolution of precipitates in PH13-8 Mo type stainless maraging steel alloyed with Cu was investigated during aging at 525 °C. Atom probe tomography was used to follow the evolution of precipitates with respect to type and chemical composition. It was found that Cu modifies the precipitation sequence in such alloys. Instead of Ni3(Ti,Al) and G-phase the formation of NiAl and G-phase occurred. The modification of the precipitation sequence is due to the incorporation of Cu in NiAl precipitates. However, both types of precipitates develop out of an undefined precursor phase, in contrast to other Cu-alloyed PH13-8 Mo maraging steel grades.