The interfacial twin boundary phases tailored by ?-stabilizers in ?-Ti alloys: A first-principles study

The origins of interfacial twin boundary (ITB) phases at {112}111f and {332}113f twin boundaries (TBs) in beta-Ti alloys are not well characterized yet. In this work, the local structural features of TBs plus ITB-omega and ITB-alpha '' phases are carefully investigated with first-principles calculations. It shows the formation of ITB-omega at (112)[111]f and (332)[113]f TBs are favorable in kinetics, especially the former is further favorable in interfacial energy. Both ITB-omega phases are internally driven by the energy reduction induced by the beta ->omega transformation. Whereas, the formation of ITB-alpha '' at (332)[113]f TB is infeasible in kinetics and the ITB-alpha '' is most likely the accompanying or untransformed alpha '' particle assisting (332)[113]f twinning. The formation of ITB phases are highly associated with the types and concentrations of beta-stabilizers. The origins and how the ITB-omega and ITB-alpha '' can be tailored by the beta-stabilizers of Mo, Nb and V are clearly demonstrated.

Automated summary

The local structural features of interfacial twin boundary (ITB) phases at {112}111f and {332}113f twin boundaries (TBs) in beta-Ti alloys are investigated using first-principles calculations. It is found that the formation of ITB-omega at (112)[111]f and (332)[113]f TBs is favorable in kinetics, and the former is further favorable in terms of interfacial energy. The ITB-omega phases are driven by the energy reduction induced by the beta ->omega transformation. On the other hand, the formation of ITB-alpha '' at (332)[113]f TB is infeasible in kinetics and it is likely to be the accompanying or untransformed alpha '' particle assisting (332)[113]f twinning. The origins and tailoring of the ITB-omega and ITB-alpha '' phases by beta-stabilizers such as Mo, Nb, and V are clearly demonstrated.