Phase Equilibria of the Cu-Sn-Ti Ternary System at 450 °C

C1990HP is a kind of commercial Cu alloy containing 3.5 wt.% Ti. It has unique mechanical and physical properties. Thus, C1990HP is regarded as a highly promising lead-frame material in electronic packaging. Sn is a base element used for lead-free solders. The knowledge of the Cu-Sn-Ti phase equilibrium plays a crucial role in understanding the interfacial reactions between C1990HP and Sn-based solders, however the phase equilibria information of this system is still lacking. The isothermal section of the Cu-Sn-Ti ternary system at 450 °C was experimentally determined. The phase equilibrium results confirmed the existence of two kinds of ternary compounds τ1-CuSnTi and τ2-CuSn3Ti5, which are only stable within a narrow composition range. No additional ternary compounds were found. Moreover, the Sn3Ti5 and Sn5Ti6 binary phases have considerable solubility of Cu. Meanwhile, the isothermal section was found to contain 17 three-phase regions, 33 two-phase regions and 17 single-phase regions.