Controlling the nucleation of multiple precipitates in precipitation-strengthened steel through Mo partitioning

Abstract

In this study, atom probe tomography and first-principles calculations were used to investigate the influence of Mo addition on multiple precipitates, including isolated NiAl-based precipitates as well as NiAl-based and Cu-rich co-precipitates, in high-strength ferritic steel. The co-NiAl-based precipitates were experimentally confirmed to be nucleated from the abundance of Cu atoms. The addition of Mo accelerated the nucleation process of Cu-rich precipitates and structural transformation of co-precipitates, led to a considerable increase in the nucleation rate of NiAl-based precipitates, and slightly promoted isolated NiAl-based precipitates. The results were discussed from the perspective of lattice misfits and mixing enthalpy.