Effects of grain boundary diffusion of PrCu alloy on microstructure and coercivity of hot deformed (Nd,Ce)-Fe-B magnets

Abstract

The technology of using high abundance rare earth element Ce in permanent magnets has attracted many concerns. In this work, the magnetic properties and microstructures of hot deformed (Nd1-xCex)13.8Fe76.1Co4Ga0.5B5.6 magnets and a selective magnet treated with PrCu grain boundary diffusion process (GBDP) were investigated systematically. It is found that Ce is beneficial to improving the plastic deformation ability of NdFeB magnets. The strongest c-axis orientation is achieved in the HD magnets with Ce concentration of x = 0.3, resulting in good comprehensive magnetic properties of Br = 13.00 kGs, Hcj = 10.12 kOe, (BH)max = 38.42 MGOe. Based on that, the GBDP was implemented on the magnets with the best orientation using Pr68Cu32 ribbons and the magnetic properties of Br = 12.87 kGs, Hcj = 15.65 kOe, (BH)max = 37.48 MGOe were obtained. The results of composition distribution and Curie temperature test of the GBDPed magnets illustrate that Pr diffuses into the (Nd,Ce)2(Fe,Co)14B grains to substitute Ce, which not only improves the Curie temperature of the grains, but also enhances the magnetic performance of the magnets. Through GBDP, the thermal stability of magnets has also been improved.