Thermodynamics and kinetics of martensitic transformation in iron-based alloys via Bain path: Models and atomistic simulations

Martensitic transformation (MT) is critical for optimizing the strength–ductility synergy in advanced high-strength steels, particularly those undergoing quenching and partitioning treatments. However, the underlying mechanisms governing MT remain inadequately understood, due to the lack of comprehensive studies that concurrently integrate thermodynamics and kinetics in multi-solute systems. In this study, MT in Fe-based alloys via the Bain path was explored using a novel Z-fixed method combined with first-principles calculations across 20 systems and configurations. By analyzing the energy–c/a, volume–c/a, and Ly/Lx–c/a relationships, we quantitatively extract thermodynamic driving forces, kinetic energy barriers, and transition states, while capturing the volumetric and lattice distortions accompanying the MT. Our results reveal that solute additions influence magnetic interactions, density of state, and phase stability, leading to an inverse relationship between driving force and energy barrier, across all systems and configurations. By integrating thermodynamic and kinetic metrics, we introduce a generalized stability descriptor capable of capturing solute-mediated effects on MT. These predictions are supported by model calculations, experimental data, molecular dynamics, and ab initio molecular dynamics simulations, which collectively demonstrate rapid MT in FeSi and FeC systems and pronounced suppression in FeMn and FeMnSiC alloys. These insights provide predictive guidance for tailoring MT path via solute engineering, facilitating the design of dual-phase steels with refined nanostructures and superior mechanical properties.