尺寸变化对Cu-Nb/C复合线材微观组织及性能的影响

Effect of Size Change on Microstructure and Properties of Cu-Nb/C Composite Wire

采用集束拉拔技术制备出石墨烯包覆铌粉增强Cu-Nb多芯复合线材,线材尺寸为Φ2.0mm时,强度接近400 MPa,导电率达到83%IACS.选取不同尺寸线径(Φ3.0 mm、Φ2.4 mm、Φ2.0 mm)的复合线材,采用XRD衍射仪和SEM扫描电镜等测试手段表征了不同尺寸线材的衍射峰强度、微观组织.结果表明Cu-Nb/C复合线材不易形成一种沿Nb<110>方向的锐利织构.随着线材尺寸的减小,芯丝粉末流动性及变形差,其分布不规则,扭曲、拉伸,甚至出现了空洞,铌粉受压后大面积流出,附着在芯丝表面.最后通过σ-ε曲线图和R-T曲线图可以看出,随着线材直径的减小,抗拉强度增大,导电性降低,变形过程符合铜基复合材料的塑性变形机制.且断口明显看到粉末与铜基体完处于分离状态,没有冶金结合,只是通过较弱的机械力结合在一块,因此复合线材的强度不高,脆性较大.

In this paper,the Cu-Nb multi-core composite wire reinforced with graphene-coated niobium powder was fabricated by drawing technique. When the wire size is Φ2. 0 mm,the strength was close to 400 MPa and the conductivity reaches 83%. The XRD and SEM scanning electron microscopy（ SEM） were used to characterize the diffraction intensity and microstructure of different sizes of wire. The microstructures of the films were characterized by XRD and X-ray diffraction（ XRD） and scanning electron microscopy（ SEM）. The results show that theCu-Nb/C composite wire is less likely to form a sharp texture along the Nb 110 direction.With the decrease of the size of the wire,the dispersion and deformation of the core powder are irregular,distorted,stretched and even empty. The large area of the niobium powder is extruded and attached to the surface of the core wire. Finally,through the σ-ε curve and R-T curve,it can be seen that with the decrease of the diameter of the wire,the tensile strength increases and the conductivity decreases,and the deformation process conforms to the plastic deformation mechanism of the copper matrix composite. And the fracture was clearly seen in the powder and copper matrix finished in a separate state,no metallurgical bonding,but by a weak combination of mechanical force in a piece,so the strength of composite wire is not high,and it has a greater brittleness.