Understanding the synergistic Co-Mo effect in maraging steels: redistribution of solute atoms

JK Lee and SG Kim and DH Lee and BJ Lee, ACTA MATERIALIA, 294, 121171 (2025).

DOI: 10.1016/j.actamat.2025.121171

Maraging steels achieve ultrahigh strength through precipitation hardening using intermetallic compounds. In these steels, Co enhances strength by promoting the precipitation of Mo-based intermetallic compounds. This phenomenon, known as the synergistic Co-Mo effect, is the key factor for their exceptional strength. However, the underlying mechanism of this synergistic effect remains unclear. In this study, to determine the cause of the synergistic Co-Mo effect, we investigated the redistribution of solute atoms using atomistic Monte Carlo (MC) simulations. Specifically, we developed neural network potentials tailored for this study and employed them in the MC simulations. Our simulations revealed that the co-addition of Co and Mo resulted in compositional separation into Mo-rich/Co-lean and Mo-lean/Co-rich regions, which we propose as the cause for the synergistic Co-Mo effect. Furthermore, we confirmed that this compositional separation is closely related to interactions among solute atoms.

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