Stability and Growth Kinetics of Deformation Twin Embryos in Multicomponent Metastable BCC Ti-Based Alloys

Deformation twinning provides critical plastic deformation mechanisms to tune the strength and ductility of complex concentrated alloys. However, physical mechanisms that determine the types/magnitudes of twinning in these alloys (especially metastable BCC Ti-based alloys) are still unclear due to the complex potential energy landscape related to plastic deformations and diffusionless phase transformations. We applied computational and experimental studies to understand and tune the correlations between diffusionless phase transformations and deformation twinning in these alloys at various compositions and temperatures. First-principles calculations were performed to study the structures and energy stability of different phases related to the twinning path. Atomistic simulations with both classical and machine learning interatomic potentials were conducted to further analyze the nucleation and growth mechanisms of twin embryos in both binary alloys and multicomponent alloys. These atomistic simulation results combined with crystallographic theory can provide quantitative energetic criteria to select the twinning activities based on the phase stability in metastable BCC Ti-based alloys.