强磁场对Cu-25Ag合金凝固、拉拔组织及导电性能的影响

Effect of High Magnetic Field on Solidified Structure, Drawn Structure and Electrical Conductivity of Cu-25Ag Alloys

摘要:

在有无磁场条件下进行Cu-25Ag (%, 质量分数, 下同) 合金凝固实验，并对铸锭进行冷拉拔处理，系统的研究强磁场对Cu-25Ag合金凝固组织、拉拔组织以及复合材料电导率的影响。发现有无磁场条件下合金凝固组织和拉拔组织都有所不同。无磁场条件下初生Cu一次枝晶较长，以柱状枝晶方式生长，在试样顶部，枝晶生长方向沿弧形径向；在试样中部，生长方向与试样轴向夹角约45°；试样下部，生长方向与试样轴向夹角约90°。另外，共晶组织壁厚较薄，两相分布不均匀，片层间距较大。强磁场条件下初生Cu一次枝晶变短，以胞状枝晶方式生长，在试样顶部，枝晶生长方向沿弧形径向，试样中部和下部，枝晶生长方向与试样轴向夹角约90°。共晶组织壁厚较大，两相分布比较均匀，片层间距较小。冷拉拔后，共晶网状结构被拉长、变细，形成纤维结构，无磁场条件试样中共晶纤维厚度和间距较小，强磁场试样中共晶纤维厚度和间距较大。随着纤维组织厚度不断减小，试样的电导率降低，并且相同变形量下有无磁场条件的试样电导率有所差别。对强磁场下合金凝固组织及拉拔组织影响机理进行了探讨，并分析了纤维组织对复合材料电导率的影响机制

Abstract:

The solidification experiment of Cu-25%Ag alloy used in high field magnet was carried out under HMF (high magnetic field), then the ingots were cold drawn into wires. The solidified structure, drawn structure and electrical conductivity were investigated systematically. In the case of no HMF, it is found that the columnar Cu dendrites is longer, moreover, on top of the sample the dendrites grow along the radial direction of the arc; on the middle part, the angle between the dendrites growing direction and axis of the ingot is about 45°; on the bottom part, the angle is about 90°. In other sides, the thickness of eutectic is thinner, the two phases present a non-uniformity distribution and the lamellar spacing is larger. In the case of HMF, the cellular Cu dendrites is shorter, moreover, on top of the sample the dendrites grow along the radial direction of the arc; on the middle and bottom parts the angle between the dendrites growing direction and axis of the ingot is about 90°, the thickness of eutectic is thicker, the two phases present a uniformity distribution, and the lamellar spacing is smaller. After cold drawn treatment, the eutectic “net” structure changes into filamentary structure. The thickness and spacing of the eutectic filamentary are thinner in the case of no HMF, but the thickness and spacing of the eutectic filamentary are thicker with in the case of HMF. By the influence of the filamentary structure, the electrical conductivity of the wires is different with and without HMF