Tungsten segregation in α2 + γ titanium aluminides

Abstract

Atom probe field ion microscopy investigations of α2 + γ Ti-47%Al-2%Cr-l.8%Nb doped with 0.15% B and 0.2% W indicate that the tungsten segregates to both γγ and α2γ interfaces. The interfacial coverage of tungsten at a specific γγ interface was estimated to be 2.3% which yields a segregation enhancement factor of ~ 14. Initial results give no appreciable evidence of boron segregation to interphase interfaces. Interfacial segregation of tungsten supports the previous observation that tungsten additions stabilize the α2 lamellae against dissolution during aging.