Electron structure of γ/α₂ phase boundaries in TiAl based alloys

The valence electron structure of γ/α₂ phase boundaries in lamellar colonies in Ti-47Al-2M (M=Nb, Cr, V) (at. pct) was investigated by the empirical electron theory of solid and molecules (EET) and its bond-length-difference (BLD) method. On this basis, the boundary condition of electron movement was employed in the improved Thomas-Fermi-Dirac (TFD) theory to decide the continuity of the electron density of the lamellar colonies interface and it is found that the γ/α₂ interface is continuous. Furthermore, it is found that adding alloying elements (including Nb, Cr and V) can improve the electron density (ρ) of the γ/α₂ interface, decrease Δρ of the γ/α₂ interface. With the electron structure analysis together with properties analysis, the effect mechanism of alloying elements (Nb, Cr, V) improving mechanical properties of TiAl based alloys was explained.