Zn基钎料钎焊烧结NdFeB与DP1180钢接头微观组织及性能

Microstructure and properties of soldering sintered NdFeB permanent magnet to DP1180 steel using Zn-based alloy

摘要:

采用Zn-5Sn-2Cu-1.5Bi(ZSCB)钎料实现了烧结NdFeB永磁材料(NdFeB)与DP1180钢的钎焊连接。在惰性气氛控制的高频感应炉中进行钎焊，采用OM、SEM、EDS、微区XRD和NIM-2000H磁性测试仪等手段分析了接头界面的微观组织结构、NdFeB的磁性能和接头剪切强度。结果表明，NdFeB与ZSCB钎料形成Nd-Fe-Zn和Fe-Zn冶金结合，FeZn13和Fe3Zn10相在DP1180钢侧的界面处形成。焊接温度对NdFeB的磁性能影响较小。与传统方法的粘接相比，接头的剪切强度从32.50MPa提高到44.00MPa，提高了35.38%。由于NdFeB和ZSCB钎料之间的热膨胀系数差异很大，在接近NdFeB的反应层处产生较高的残余应力，导致接头从NdFeB界面处断裂。

Abstract:

In this work, sintered NdFeB permanent magnet (NdFeB) was firstly soldered with DP1180 steel using Zn-5Sn-2Cu-1.5Bi (ZSCB) solder. Soldering was performed in an inert atmosphere control high-frequency induction furnace, and then the microstructure, magnetic properties and shear strength were investigated by optical microscope, scanning electronic microscopy, energy dispersive X-ray analysis, NIM-2000H magnetic tester and mechanical testing machine. Results showed that the interface between NdFeB / ZSCB solder formed metallurgical bonding with Nd-Fe-Zn and Fe-Zn. FeZn13 and Fe3Zn10 phases formed in steel side of the joints. Besides, the soldering temperature had slight influence on the magnetic properties of NdFeB. Finally, compared with adhesive bonding in traditional method, the shear strength of the soldering joints were dramatically improved by 35.38%, from 32.50 MPa to 44.00 MPa. The shear strength was high enough to cause failure in NdFeB side of the joints. Fracture of the joints was caused by large difference thermal expansion coefficient between NdFeB and ZSCB solder as a result of high stress at the reaction layer closing to NdFeB.