In this work, pure Cu with excellent strength and ductility (UTS of 271 MPa, elongation to fracture of 43.5%, uniform elongation of 30%) was prepared using cold spray additive manufacturing (CSAM), realizing a breakthrough in the field. An in-depth investigation was conducted to reveal the microstructure evolution, strengthening and ductilization mechanisms of the CSAM Cu, as well as the single splats. The results show that the CSAM Cu possesses a unique heterogeneous microstructure with a bimodal grain structure and extensive infinitely circulating ring-mounted distribution of twinning. Based on the single splat observation, the entire copper particle forms a gradient nano-grained (GNG) structure after high-speed impact deposition. The GNG-structured single splat serves as a unit to build the heterogeneous microstructure with bimodal grain distribution during the successive deposition in CSAM. The results also show that CSAM can achieve synergistic strengthening and ductilization by controlling the grain refinement and dislocation density. This work provides potential for CSAM technique in manufacturing various metallic parts with the desired combination of high strength and good ductility without additional post-treatments.

在这项工作中，采用冷喷涂增材制造 (CSAM) 制备了具有优异强度和延展性（UTS 为 271 MPa，断裂伸长率为 43.5%，均匀伸长率为 30%）的纯铜，实现了该领域的突破。进行了深入研究，以揭示 CSAM Cu 以及单片的微观结构演变、强化和延展化机制。结果表明，CSAM Cu具有独特的异质微观结构，具有双峰晶粒结构和广泛的无限循环环装孪晶分布。基于单次飞溅观察，整个铜粒子在高速冲击沉积后形成梯度纳米晶粒（GNG）结构。GNG 结构的单片作为一个单元在 CSAM 中连续沉积过程中构建具有双峰晶粒分布的异质微结构。结果还表明，CSAM可以通过控制晶粒细化和位错密度来实现协同强化和延展化。这项工作为 CSAM 技术在制造具有高强度和良好延展性的所需组合而无需额外后处理的各种金属部件提供了潜力。