| Abstract Scope |
Metastable multicomponent alloys can achieve exceptional mechanical properties by combining competing deformation mechanisms, such as diffusionless phase transformations, twinning, and dislocation slip. However, predicting how these mechanisms compete across composition and loading conditions remains a major challenge. Here, molecular dynamics simulations are used to investigate deformation-mode nucleation in metastable β-Ti-based alloys from binary Ti–Nb to multicomponent Ti-Mo-Nb systems. We show that twinning pathways emerge through reversible β-α" martensitic transformations, consistent with crystallographic theory. The dominant deformation mode and preferred twinning-plane orientation are governed by two key energetic metrics: the free-energy barrier for β-α" transformation and the misfit strain energy of phase boundaries. These quantities vary systematically with temperature, composition, and stress state, explaining transitions observed experimentally. Extending to ternary alloys, yield strengths predicted from nucleation-based metrics, without fitting parameters, agree well with experiments. This framework provides a physically grounded route for designing metastable multicomponent alloys with tunable strength and ductility. |
