Effect Of V/Cr/Mo Substitution Doping On Interfacial Structures And Properties Of Dual-phase γ-TiAl/α₂-Ti₃Al Alloys

As a new generation of key materials for aerospace applications,TiAl based alloys have excellent properties such as low density,high specific strength,good oxidation resistance and high temperature creeping resistance.Dual-phaseγ-TiAl/α₂-Ti₃Al alloy is one of the potential candidates and the interface issues have attracted much attention.In this paper,the geometric structure,energy properties and electronic properties of these systems are studied using first-principles method based on the density functional theory method.And the effects of V/Cr/Mo doping on the interfacial properties ofγ-TiAl/α₂-Ti₃Al were calculated and studied.The results show that the total energy and average formation energy of the substitution doping system are all negative,indicating the system can be prepared by experiments and exist stably.The analysis about Griffith fracture work of the typical systems shows that the bonding strength of the system Cr-H_a5(or Cr-S_a5)and Mo-H_a5(or Mo-S_a5)is weakened,which is very beneficial to improve the ductility of the materials.According to the analysis on the density of states of the typical doped systems,it is argued that the density of state of Cr-d（or Mo-d）and Ti-d electrons of the substitution doping system Cr-S_a5(or Mo-S_a5)increased,while the electron numbers of Al-p and Ti-d orbitals decreased and the strength of p-d orbital hybridization bond is weakened.Thus,the ductility of the TiAl alloy materials can be improved.The charge density map of the（001）plane and populations of the substitution doping system Cr-S_a5(or Mo-S_a5)show that an electron cloud aggregation effect around substitution dopant is induced by the substituting of Cr（or Mo）atom,which forms a region with a slightly higher bonding strength.As a result,the anisotropy degree of the combination of this region with its surrounding area is reduced,which is the intrinsic reason of the improved ductility for such TiAl alloys.