Atomic-scale understanding of martensitic transformation and transition-induced twinning in deformed Fe-Mn alloys

• Molecular dynamics simulations reveal that Fe-Mn alloys with 10%–30% Mn all undergo phase transformations and {112}<111>BCC deformation twinning, but follow distinct FCC- and/or HCP-related deformation paths depending on Mn content. • Increasing Mn content raises the stacking fault energy, retards slip system activation and stacking fault formation, and delays the FCC→ε-martensite and ε-martensite→BCC transitions at intersections of ε-martensitic bands. • Mn alloying increases yield strength and reduces elastic modulus of Fe-Mn alloys, while deformation twins enhance work hardening and delay necking and fracture. • These atomic-scale insights provide a theoretical basis for designing and optimizing high-performance steels through tailored Mn content and deformation pathway control.