Oxygen-induced interfacial structure selection, dopant segregation and adhesive strength of α/β interfaces in titanium alloys

The dopant segregation and interfacial strengthening in multi-phase engineering alloys have been extensively investigated to understand bonding behavior and enhance mechanical properties by employing density functional theory (DFT). However, the properties of interface involving dynamical/mechanical unstable structures, e.g., β-Ti at low temperatures, are still obscured. We employed DFT with tailored restrictive relaxation to comprehensively investigate the structure, segregation and strength of α/β interface in titanium alloys. The results provide a new insight to the inconsistency of α/β interface types between theoretical calculations and experimental observations, i.e., the hollow-type interface would be destroyed by inevitable oxygen impurities. Moreover, many reported segregation behaviors observations are rationalized in the case of single doping. Boron is screened as the most effective strengthening element, and origin of interface hardening is revealed by electronic structure analysis. Furthermore, we explore the promising selections of X-O co-strengthening strategy to promote environment-friendly development of titanium alloys.