Using the Ti–Al System to Understand Plasticity and Its Connection to Fracture and Fatigue in α Ti Alloys

The Ti–Al system, specifically with Al wt pct ranging from approximately 4 to 14 pct, has served as a model system for exploring the deformation behavior of the hexagonal close-packed α phase of Ti alloys. The system has enabled exploration of nearly all aspects of deformation and failure across length scales from atoms to the continuum, in addition to being of value for both experimental and model method development. Here, we provide a review of what has been learned over the past 60 years on fundamental Ti deformation behavior using the model Ti–Al system including topics such as dislocation motion, crystallographic slip, grain-scale deformation, creep, and fracture.