Structural, electronic, mechanical, and thermodynamic properties of Cu–Ti intermetallic compounds: First-principles calculations

Abstract

In this study, the structural, electronic, mechanical, and thermodynamic properties of Cu–Ti intermetallic compounds (Cu4Ti, Cu2Ti, Cu3Ti2, Cu4Ti3, CuTi, and CuTi2) were predicted using first-principles calculations. The formation enthalpy results show that all Cu–Ti intermetallic compounds are thermodynamically stable, and the thermodynamic stability decreased in the order CuTi > Cu4Ti3 > CuTi2 > Cu2Ti > Cu4Ti > Cu3Ti2. The elastic constants and polycrystalline moduli were obtained using stress-strain method and Voigt-Reuss-Hill approximation. The results show that all Cu–Ti intermetallic compounds are mechanically stable. The anisotropic elasticity increased in the order Cu4Ti < CuTi2 < CuTi < Cu2Ti < Cu4Ti3 < Cu3Ti2. The density of states verified that the Cu–Ti chemical bonds are formed by Cu-3d and Ti-3d hybridizations. In addition, the effects of high pressure (0–40 GPa) and temperature (0–1100 K) on the thermodynamic properties of these Cu–Ti intermetallic compounds were systematically studied based on the Quasi-harmonic Debye model. The isothermal bulk modulus and Debye temperature of these Cu–Ti intermetallic compounds increased with increasing pressure and decreasing temperature. The minimum thermal conductivity has the same order as the formation enthalpy.