A First-principles Study On The Intermediate Transition Layer Of Ti/Al Intermetallic Composites In Ti/Al Layered Composites

In this paper,the elastic properties and electronic properties of Ti₃Al,TiAl,TiAl₂,and TiAl₃ alloy phases in the titanium-aluminum intermediate transition layer are calculated based on first-principles based on density functional theory.The mechanical properties,thermodynamic properties and electronic properties of various Ti-Al intermetallic compounds under different pressures were studied respectively.In addition,TiAl₃ is used as an example to discuss the interface between the Al matrix and the intermediate transition layer,which provides theoretical guidance for the further optimization of the TiAl layered composite material.The calculation results show that:(1)The formation energy results of the four Ti-Al intermetallic compounds show that the most stable of the four structures is TiAl₂ and then TiAl₃,TiAl,Ti₃Al.(2)The four Ti-Al intermetallic compounds all have more excellent mechanical properties than Ti and Al,and with the increase of Ti content,the bulk modulus and shear modulus of the four compounds gradually decrease,and the toughness gradually increase.The four titanium-aluminum transition layer alloy phases have metallicity,and Ti₃Al has the best metallicity and TiAl₂ has the worst metallicity.(3)As the pressure increases,the thermodynamic stability of the four compounds decreases,that is,as the pressure increases,the energy stability of the material decreases.The elastic modulus and Poisson's ratio,B/G analysis showed that as the pressure increases,the elastic properties of the four materials increase and the ductility gradually improves.The thermal expansion coefficient,heat capacity and Debye temperature of the four materials vary with temperature and pressure.(4)When the interface of the low index surface of Al forms an interface with TiAl₃,the wettability and interface bonding strength of the interface are best when the phase relationship is Al(111)/TiAl₃(112).In addition,when the Ti atoms in TiAl₃ are directly When directly bonding with Al atoms on the Al(111)plane and the interface stacking position is stacked at the central position,the maximum wettability of the interface bonding energy is better,and the most stable bonding interface is formed.