石墨与铜钎焊接头的界面微观组织及性能

Microstructure and Properties of Brazed Graphite and Copper Joints

对石墨与铜采用非晶态TiZrNiCu钎料进行了真空钎焊。采用光学显微镜(OM OLMPUS)、扫描电镜(SEM,S-4700)、电子探针(EPMA,JXA8600)等分析手段对接头的界面微观组织进行观察分析,研究结果表明,钎缝中主要是金属间化合物生成相,如Cu-Ti,Cu-Zr,Ni-Ti系等,裂纹易产生于焊缝中尺寸较大的一个金属间化合物相上,Cu基固溶体的存在可以阻碍或延缓裂纹的扩展,对提高接头性能有利。在该实验条件下在950℃/15min工艺参数下获得的接头的电阻率低于5 mΩ,平均电阻为3.3mΩ,接头的抗剪强度为16.34MPa满足该接头作为换向器接头的使用要求。

Graphite was joined to copper using amorphous TiZrNiCu filler foil by vacuum brazing. Joint interface was analyzed by several methods, such as optical microscope, SEM, EDS and EPMA. The results showed that Cu-Ti, Cu-Zr and Ni-Ti compounds distributed on the interface and cracks tended to occur at large-size compounds. Cu-based solid solution can prevent or slow down the crack propagation, which is favorable for the joint strength. When the joint is brazed at 950℃ for 5rain, the resistance of joint is below 5 mΩ and the average resistance is 3.3mΩ, while the joint shear strength reaches 16.34MPa. All of these meet the demand of the joint as a diverter.