First-principles investigation of structural, mechanical and electronic properties for Cu–Ti intermetallics

To design a high-performance Cu–Ti intermetallic coating, first-principles calculation is conducted to systematically investigate the phase stability, mechanical and electronic properties of the Cu–Ti binary intermetallics. The phase stability and mechanical properties are studied by calculating the formation enthalpy and independent elastic constants, respectively. The calculated formation enthalpy indicates that β-Cu₄Ti, CuTi and CuTi₂ are stable phases at 0 K, while α-Cu₄Ti, Cu₃Ti, Cu₃Ti₂, and Cu₄Ti₃ are metastable phases. In addition, the mechanical properties of Cu–Ti intermetallics present a positive correlation with their formation enthalpy. The electronic structures of the Cu–Ti intermetallics are evaluated by analyzing the bonds character to reveal the bonding characteristics, which is crucial to the phase stability and mechanical properties. Among the Cu–Ti intermetallics studied, CuTi phase exhibits the highest stability, hardness and a higher brittleness among all Cu–Ti intermetallics, while other Cu–Ti intermetallics show good toughness. Based on the calculated results, a high strength Cu–Ti intermetallic coating consisting of hard CuTi particles on a ductile Cu₄Ti₃ matrix is proposed.