High strength and excellent softening resistance Cu-15Ni-8Sn alloy by Ti addition

Cu-15Ni-8Sn alloy is commonly utilized in various applications because of its exceptional strength, elasticity, and softening resistance. Ti microalloying has been employed to enhance the mechanical properties of Cu-15Ni-8Sn alloy. By adding 0.5 wt.% Ti, the peak-ageing tensile strength, microhardness, and elastic modulus of the Cu-15Ni-8Sn alloys reach 1401.3 MPa, 479.3 Hv, and 154.7 GPa, respectively, representing the greatest comprehensive performance reported in previous literature. Additionally, the Ti microalloying significantly enhances the softening resistance of Cu-15Ni-8Sn alloys. After ageing at 400°C for 10 h, the tensile strength of the Cu-15Ni-8Sn-0.5Ti alloy decreases by only around 150 MPa, whereas the alloy without Ti addition experiences a decrease close to 350 MPa. Quantitative analysis reveals that the observed improvements can be attributed to the Ti microalloying inhibiting the dislocation annihilation and the formation of discontinuous precipitation during the ageing process, while simultaneously promoting the precipitation of Ni3Ti. This study provides a theoretical basis for preparing a high-performance Cu-15Ni-8Sn alloy by microalloying.