**6. Conclusion**

*Transition Metal Compounds - Synthesis, Properties, and Application*

from the interaction between Ti-3d and Al-3p. Sometimes, a high DOS value at Fermi level means unstable structures in some degree. In this work, the values of total DOS at Fermi level of Ti3Al, B2-TiAl, and γ-TiAl compounds are 10.8 eV, 3.4 eV,

*The total and partial density of states (DOS) for: (a)* α*2-Ti3Al, (b) B2-TiAl, (c)* γ*-TiAl.*

**104**

**Figure 2.**

In this chapter, we have studied the structural, elastic, and electronic properties of titanium aluminide intermetallic compounds using first-principles calculations based on density functional theory (DFT). The use of the GGA-PBE approximation for the exchanging correlation potential allowed us to obtain good results of the electronic structure. B2-TiAl, γ-TiAl, and α2-Ti3Al are thermodynamically stable according to both thermodynamical and mechanical criteria. Whereas, B2-TiAl compound is mechanically unstable. Besides, elastic properties showed that these alloys are more resistant to deformation along *a-* and *c-axis*. Moreover, the C66 value is significantly lower than C44 suggesting; thus, that the (001)[100] deformation would be easier than (010)[100] deformation for these alloys. Based on the electronic structure, titanium aluminide binary compounds are composed of both metallic bonds and covalent bonds. α2-Ti3Al shows the strongest metallic bonding character.
