(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 中南大学 有色金属材料科学与工程教育部重点实验室，长沙 410083；
3. 河南科技大学 材料科学与工程学院，洛阳 471023；
4. 浙江天宁合金材料有限公司，金华 321002；
5. 深圳市中金岭南有色金属股份有限公司，深圳 518040)
摘 要: 采用下引连铸工艺制备了d 11 mm Cu-4%Ag合金棒坯，棒坯具有高轴向取向柱状晶组织，表面质量良好，断后伸长率达到35.0%，可直接进行拉拔加工成d 0.04 mm微细丝，无中间退火的累积冷变形量达99.998%。拉拔过程中，在一般变形阶段，棒材变形机制为位错滑移，形成了较多的位错胞，晶内发生微区晶体转动，随应变量增大，剪切变形程度加剧，晶内形成了较多的切变带；在大变形阶段，通过各种动态回复机制如纳米孪晶、位错墙的亚晶化，层状界面，实现大塑性变形。随着变形量的增加，棒材的抗拉强度和硬度分别由铸态的245 MPa和63.4 HV增加至变形量99.7%时的655 MPa和187 HV，而导电率由90.3% IACS则降低至82.2% IACS。上述下引连铸-连续拉拔加工方式制备Cu-Ag合金微细丝材具有短流程、高效率的优势，提供了新的思路。
关键字: Cu-Ag合金；下引连铸；定向凝固；拉拔；力学性能
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China;
3. School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023
4. Zhejiang Tianning Alloy Material Co., Ltd., Jinhua 321002, China；
5. Shenzhen Zhongjin Lingnan Nonfemet Co., Ltd., Shenzhen 518040, China）
Abstract:A d 40 μm Cu-4%Ag alloy wire with high strength and high electrical conductivity was prepared by continuously directional solidification and cold drawing. The evolutions of microstructure and properties were investigated by means of optical microscope observation, electron microscopes observation, hardness test, tensile test, and electrical conductivity measurement. The results show that the continuous columnar grain structure uniformly distributes along the solidification direction in the as-cast alloy. The drawing process is divided into different stages, corresponding to the main deformation mechanism of the dislocation slip and twinning, the microcrystalline rotation, the dynamic recovery, the evolution of layered interface, and partial dynamic recrystallization. After the deformation with the area reduction ratio of 99.7%, the tensile strength, hardness and electrical conductivity of the alloys are 655 MPa, 187 HV and 82.2%IACS, respectively.
Key words: Cu-Ag alloy; downward continuous casting; directional solidification; drawing; mechanical properties
