Influence of Alloying Additions (Nb, Cr, V, Cu) on the Mechanical Behavior of γ-TiAl

Abstract

The influence of alloying elements (Nb, Cr, V, Cu) on the mechanical properties of $\gamma$-TiAl alloys is investigated using first-principles calculations. The cluster expansion method is employed to determine the ground state configurations of the alloyed systems. The resulting formation energies are used to construct energy diagram. The analysis reveals that the formation energy is generally lower when alloying elements occupy the Ti sublattice. Elastic stiffness tensors are computed by applying small strains to the ground state structures, and the elastic constants are derived by averaging the values obtained from the Voigt model and the Reuss model. Further, the elastic moduli, Young's modulus, bulk modulus, and shear modulus demonstrate an increasing trend with alloying concentration, indicating enhanced material stiffness. The fracture toughness $K_{IC}$, which exhibits significant improvement with the addition of alloying elements, is estimated. These findings underscore the critical role of alloying elements in optimizing the mechanical behavior of $\gamma$-TiAl alloys especially for enhancing the fracture toughness.