Structural stability, mechanical properties and stacking fault energies of TiAl3 alloyed with Zn, Cu, Ag: First-principles study

Abstract

The structural stability of D022 TiAl3 alloyed with Zn, Cu and Ag are systematically investigated using first-principles calculations. There is a phase transition from D022 to L12 with the increasing of the concentrations of Zn, Cu and Ag, respectively. Based on the predicted elastic constants and Pugh's ratio, the ductility of TiAl3 are improved due to the phase transition. The generalized stacking fault energies and cleavage energies are also presented. The reduced unstable stacking fault energy and antiphase boundary energy of 〈110〉{001} slip systems may weaken the stability of D022 TiAl3. Furthermore, Rice and Zhou–Carlsson–Thomson criterions are used to reveal the brittle/ductile mechanism, which is in agreement with Pugh's view. Finally, the electronic properties are also presented. The DOS suggests that weakened p–d interactions between Al and Ti atoms but enhanced d–d interactions between Ti and alloying atoms in TiAl3 result in the improvement of ductility.