Abstract:Nano- spherical L12-γ"" phase coherent precipitation-strengthened Cu-Ni-Al alloys exhibit excellent mechanical properties and certain electrical conductivity, enabling them widely used in the fields of rail transportation and marine transportation. However, there is currently a lack of systematic studies on the relationship between the microstructural evolution and performance. In this study, the Cuy(Ni3/4Al1/4)100-y (y=75.00, 80.00, 85.71, 90.00, 93.75) alloys with the fixed Ni∶Al atomic ratio of 3∶1 were prepared, and the connection between the properties (hardness, electrical conductivity, and softening temperature) of and their composition and microstructure was investigated. The results showed that there existed a large amount of annealing twinning and nano-spherical L12-γ"" phases in the microstructure of the alloys after low-temperature aging treatment. The strengthening mechanism of Cu-Ni-Al alloys included both grain refinement strengthening and precipitation strengthening. With the increase of Cu content (decrease of Ni+Al content), the content of annealing twinning and the precipitation content of L12-γ"" phase decreased. Consequently, the hardness, yield strength, and ultimate tensile strength of the alloys decreased. The electrical conductivity of the alloy was correlated with the content of solutes dissolved in Cu matrix. Finally, the potential of the alloy for high-temperature applications was evaluated through softening temperature tests. This study provided an effective experimental and theoretical basis for the composition design of high-performance Cu-Ni-Al alloys.