Joining of sintered NdFeB permanent magnet to steel using novel Zn-Sn-Bi-Nd alloy: Microstructure and soldering mechanism

摘要

The steel and sintered NdFeB permanent magnet were successfully connected by a novel Zn-Sn-Bi-Nd alloy. The effects of the soldering temperature (410-450 degrees C) and holding time (20-40 s) on the microstructure and mechanical properties of soldered joints were investigated. The results showed that element Zn diffused to the surface of sintered NdFeB permanent magnet, with the formation of xi -FeZn13/NdFe5.5Zn(B) interfacial layer. Meanwhile, the multilayered Gamma-Fe3Zn10/delta-FeZn10/ xi -FeZn13 phases were observed at the steel side. As prolonging holding time or increasing soldering temperature, the reaction layer grew thicker. The shear strength increased first and then decreased. Therefore, the maximum shear strength (110.7 MPa) was obtained at 430 degrees C for 30 s. Proper reaction layer thickness is beneficial to the improvement of shear strength.