About this Abstract |
| Meeting |
2026 TMS Annual Meeting & Exhibition
|
| Symposium
|
Dilute Alloying and Impurity Effects on Phase Transformations
|
| Presentation Title |
Role of Mo in the Phase Transformation of η-Ni3Ti to Austenite in Fe-Ni-Ti-Mo-Based Maraging Steels |
| Author(s) |
Dong-Hyun Kim, Gunyoung Yoon, Yoon-Uk Heo |
| On-Site Speaker (Planned) |
Dong-Hyun Kim |
| Abstract Scope |
Maraging steels achieve their ultra-high strength from the precipitation of intermetallic compounds during aging. In Fe-Ni-Ti-based steels, DO24 η-Ni3Ti precipitate is a key hardening phase. Notably, after prolonged aging, these precipitates at the grain boundaries transform into austenite (γ). The transformation sequence was reported as the η-Ni3Ti → γ'-Ni3Ti → γ, driven by coherent strain and Fe diffusion. In contrast, Fe-Ni-Ti-Mo maraging steels exhibit an accelerated transformation of η to γ at the grain boundaries. The detailed study concludes the origin of the accelerated phase transformation by the following reasons: (i) the rapid heterogeneous nucleation of γ at the η surface, (ii) the absence of the formation of intermediate phase γ'-Ni3Ti, resulting in a direct transformation of η to γ. Based on microstructure characterization using transmission electron microscopy (TEM), atom probe tomography (APT), and first-principles calculations, the role of Mo in the phase transformation of η to austenite is elucidated. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Iron and Steel, Characterization, Phase Transformations |