Aging treatment of Cu-based alloys is essential to enhance their strength that is desirable for their extensive engineering applications in electrical industry, whereas the underlying mechanism of strengthening is essential for massive manufacturing of these alloys. Here, the microstructure evolution of a supersaturated solid solution Cu-15Ni-8Sn-0.2Nb alloy aged at 400 °C for different time was characterized at atomic scale using state-of-the-art transmission electron microscopy (TEM) and the corresponding mechanical property was also measured. The results reveal that the modulated structure, DO₂₂/L1₂ ordering, and discontinuous precipitation (DP) appeared in the advances of aging time. At the early stage of aging treatment, component modulation waves and satellite spots appeared from spinodal decomposition and the modulation wavelength was identified in the range of 1–7 nm. Subsequently the modulated structures formed -poor-rich solute regions, of which DO₂₂ ordering was present in the Ni-poor region while L1₂ ordering appeared in the Ni-rich region. The sequence of ordering precipitates was further verified by density functional theory (DFT) simulations. Furthermore, orientation relationships and interfacial structures between DO₂₂, L1₂ phases and the parent matrix were determined. The measured hardness of alloy reached a maximum value of 335 HV after aging for 120 min due to the coherence between the two ordering phases and matrix. These results illustrated the importance of aging on structural evolution and mechanical property of Cu-15Ni-8Sn alloy at various heat treatment stages, which could potentially help in manufacturing promising alloys for their extensive engineering applications.

铜基合金的时效处理对于增强其强度至关重要，这对于它们在电气工业中的广泛工程应用而言是必不可少的，而强化的基本机制对于这些合金的大量生产至关重要。在这里，使用最新的透射电子显微镜（TEM）和相应的机械方法，在原子尺度上表征了在400°C时效下不同时间老化的Cu-15Ni-8Sn-0.2Nb合金的过饱和固溶体的组织演变。属性也进行了测量。结果表明，该调制结构为DO ₂₂ / L1 ₂有序的，不连续的沉淀（DP）出现在老化时间的提前阶段。在老化处理的早期阶段，旋节线分解会出现成分调制波和卫星斑点，并且调制波长在1–7 nm范围内。随后，调制结构形成了富贫溶质区域，其中DO ₂₂有序出现在富Ni区域，而L1 ₂有序出现在富Ni区域。有序沉淀的顺序通过密度泛函理论（DFT）模拟得到了进一步验证。此外，DO ₂₂，L1 ₂之间的取向关系和界面结构确定相和母体矩阵。老化120分钟后，由于两个有序相和基体之间的连贯性，合金的测得硬度达到了335 HV的最大值。这些结果说明了时效对不同热处理阶段的Cu-15Ni-8Sn合金的组织演变和力学性能的重要性，这可能有助于制造有前途的合金以用于其广泛的工程应用。