In this study, novel Zn-Sn-xBi high-temperature solders were designed to join sintered NdFeB permanent magnets and steel. The effect of Bi addition on the corrosion resistance and mechanical properties of the soldered joints was systematically investigated. The results indicated that introducing Bi with specific content obviously decreased the undercooling of the solder. Reducing the undercooling by promoting the solidification process and the formation of Bi precipitates as nucleation sites could refine the microstructure. The improvement of corrosion resistance was attributed to the finer microstructure and the Bi precipitates serving as anodic barriers. Moreover, the sound soldered joints were obtained with finer $\beta$-Sn dendrites and a more uniform distribution of Bi precipitates when appropriate Bi was added. The shear strength of the soldered joint with 5 wt% Bi addition was 36.6% higher than the shear strength of the ZS soldered joint.

在这项研究中，新型的Zn-Sn-xBi高温焊料被设计用来连接NdFeB烧结永磁体和钢。系统地研究了Bi添加对焊接接头的耐腐蚀性和机械性能的影响。结果表明，引入特定含量的Bi明显降低了焊料的过冷度。通过促进凝固过程和形成Bi沉淀作为成核位点来减少过冷，可以改善微观结构。耐蚀性的提高归因于更精细的微观结构和Bi沉淀物作为阳极阻挡层。而且，可以得到更精细的良好焊接接头$\beta$当添加适当的Bi时，-Sn枝晶和Bi沉淀物的分布更加均匀。添加了5 wt％Bi的焊接接头的剪切强度比ZS焊接接头的剪切强度高36.6％。