Table 1 Crystalline structures, cluster formulas, the total atom number Z of cluster structural unit in Ti-Al(-Nb) phases, in which the Fermi vector k_F and atomic density ρ_a are also involved.

α-Ti

hP-Mg

[Al-Ti₆Ti₆]Ti₃

Ti (Al-doped)

16.01

13.62

56.68

α (limit Al)

hP-Mg

[Al-Ti₆Ti₆]AlTi₂

Ti_87.5Al_12.5

—

—

—

α₂ (Ti₃Al)

hP-Ni₃Sn (D0₁₉)

[Al-Ti₆Ti₆]Al₃

Ti₇₅Al₂₅

16.05

13.80

59.50

α₂ (Ti₇₀Al₂₃Nb₇)

hP-Ni₃Sn (D0₁₉)

[Al-Ti₆Ti₅Nb₁]Al₃

Ti_68.75Al₂₅Nb_6.25

—

—

—

γ (TiAl)

tP-AuCu (L1₀)

[Al-Al₄Ti₈]Al₃

Ti₅₀Al₅₀

15.89

14.02

61.38

O (Ti₂AlNb)

oC-HgNa

[Al-Ti₄Ti₂Ti₂Nb₂Nb₂]Al₃ = [Al-Ti₈Nb₄]Al₃

Ti₅₀Al₂₅Nb₂₅

15.74

13.78

56.73

B2 (Ti(Al,Nb))

cP-CsCl

[Al-Ti₈(Al,Nb]₆](Al,Nb)

Ti₅₀(Al,Nb)₅₀

16.05

13.60

56.68

β-Ti (>882 °C)

cI-W

[Al-Ti₈Ti₆]Ti

Ti (Al-doped)

16.26

13.42

55.09

ω-Ti

hP-AlB₂

[Al-Ti₂Ti₁₂]Ti

Ti (Al-doped)

16.27

13.65

58.05