First-Principles Simulation on Structure-Property of Ti-Al Intermetallic Compounds

Crystal structure, mechanical and electronic properties of Ti-Al intermetallic compounds were studied using first-principles implemented in CASTEP. At 0 K, 0 GPa, thermodynamically stable structures are TiAl₃, TiAl₂, TiAl, Ti₃Al. Unit cells of TiAl₃, TiAl₂, TiAl are evolutions of face-centered cubic Al. Structure of Ti₃Al is similar to Ti, which is hexagonal close packing structure. Mechanical properties were calculated. It was found that with increasing of Ti molar fraction, their bulk modulus are approximate equivalent. But shear modulus and Vickers hardness decrease, and so did Pugh ratios. It shows that toughness became better. At last, density of state and Mulliken population analysis were simulated. Bonding nature of Ti-Al is a combination of metallic, covalent and weak ionic.