Ag含量对竖引连铸Cu-Ag合金组织和性能影响

Effect of Ag content on microstructure and properties of Cu-Ag alloy prepared by vertical continuous casting

采用冷型三室真空竖引连铸的方法制备了含Ag量分别为1、2、4和20 mass%的Cu-Ag合金。利用光学显微镜、扫描电镜、金属导体电阻率仪和电子拉伸试验机等研究了Ag含量对Cu-Ag合金铸态杆坯组织和性能的影响。结果表明:冷型竖引连铸工艺制备的Cu-Ag合金杆坯具有近似平行于轴向的柱状晶显微组织结构。Ag含量对Cu-Ag合金显微组织和性能具有显著影响。Cu-Ag合金铸态杆坯的显微组织主要由α-Cu基体和Ag粒子组成,Ag颗粒在Cu基体中分布均匀。Cu-1Ag合金的铸态组织基本由初生α相构成,未见明显的共晶组织。Cu-2Ag合金的显微组织主要由枝晶组成,小共晶团均匀的分散在枝晶臂间。Cu-4Ag合金的显微组织开始显示出扩展的分枝。Cu-20Ag合金的显微组织中出现围绕树突的连续网状结构。合金的抗拉强度随Ag含量增高逐渐升高,合金的导电率随Ag含量增高逐渐降低,Cu-20Ag合金的强度和导电率分别为284 MPa和79.7%IACS。

Cu-Ag alloys which containing 1,2,4 and 20 mass%Ag were prepared by cold-type three-chamber vacuum vertical lead continuous casting. The effect of Ag content on microstructure and properties of the as-cast Cu-Ag alloys bar billet was studied by means of optical microscope, scanning electron microscopy, metal conductor resistance meter and electronic tensile tester. The results show that the Cu-Ag alloy billet prepared by cold-type vertical continuous casting process has columnar crystal microstructure approximately parallel to axial direction. The Ag content has a significant effect on the microstructure and properties of the as-cast Cu-Ag alloys. The microstructure of the as-cast Cu-Ag alloy bar billet is mainly composed of α-Cu matrix and Ag particles, and the Ag particles are uniformly distributed in the Cu matrix. The microstructure of the as-cast Cu-1 Ag alloy is basically composed of primary α phase, there is no obvious eutectic structure. The microstructure of the as-cast Cu-2 Ag alloy is mainly composed of dendrites, and small eutectic groups are uniformly dispersed between dendrite arms. The microstructure of the as-cast Cu-4 Ag alloy begins to show extended branching. A continuous network structure surrounding the dendrites appears in the microstructure of the as-cast Cu-20 Ag alloy. With the increase of the Ag content, the tensile strength of the as-cast alloys increases, the conductivity decreases, and the strength and conductivity of the as-cast Cu-20 Ag alloy are 284 MPa and 79.7% IACS, respectively.