At high pressures, a new graphite intercalation compound (GIC) HfC₂ was predicted. We calculate structure and properties of HfC₂ at 0 GPa using first-principles method. Lattice parameters of HfC₂ with geometrical optimization based on GGA-PBESOL, GGA-PW91 and LDA are almost the same. With phonon dispersion curve and elastic constant, dynamical and mechanical stability of structure were verified, respectively, which meant that HfC₂ could exist stability at 0 GPa. Calculated bulk modulus and shear modulus of HfC₂ are 265 GPa and 118 GPa, respectively, and Pugh ratio k<0.57. With analysis of electron density and density of states, Hf-C and C-C bond showed covalent, metallically. That is reason why it has high bulk modulus and ductility. At last, we calculated bond length, bulk modulus, shear modulus and Pugh ratios of HfC₂ in pressures ranging from 0 GPa to 500 GPa.

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.