The effects of Ni addition and aging treatment on the microstructure and properties of Cu?3Ti alloy were investigated. Themicrostructure and phase constituents were characterized by optical microscopy, scanning electron microscopy, X-ray diffractometerand high-resolution transmission electron microscopy, and the hardness and electrical conductivity were measured as well. Theresults show that NiTi phase forms with addition of Ni into as-cast Cu-3Ti alloy during solidification, and the as-cast microstructureevolves from dentrite to equiaxial structure. After aging treatment, coherent metastable β′-Cu4Ti precipitates from the Cu matrix.However, β′-Cu4Ti precipitation phase transforms into equilibrium, incoherent and lamellar Cu3Ti phase after overaging. Meanwhile,aging treatment results in appearance of annealing twins in the residual NiTi phase, and dislocation lines exist in the Cu matrix. Niaddition enhances the electrical conductivity, but decreases the hardness of Cu?3Ti alloy. In the range of experiments, the optimumaging treatment for Cu?3Ti?1Ni alloy is 300 °C for 2 h and 450 °C for 7 h. The hardness and electrical conductivity were HV 205and 18.2%IACS (international annealed copper standard), respectively.
