Modulating microstructure and magnetic properties of sintered Nd-Fe-B magnets through Al-Ga element doping

Doping with trace amounts of low-melting-point elements is an effective method to enhance the magnetic properties and optimize the microstructure of Nd-Fe-B magnets. In this study, the influence of different Al-Ga doping ratios on the magnetic properties and microstructure of sintered magnets was investigated through systematic design and experimental analysis. It was found that the magnetic properties of the magnets show non-linear changes with variations in the Al-Ga ratio. The microstructure of the magnets was significantly improved with an increased proportion of the Ga element, as evidenced by an increase in Nd-rich phases surrounding the boundaries of the main-phase grains and a more rounded appearance of the main-phase grains, as well as a reduction in sharp corners and protruding parts. When the mass ratio of the added alloy is m（Al）∶m（Ga）=0∶100, the remanent magnetization, coercivity and maximum magnetic energy product of the magnets are 1.387 T, 1 358 kA/m and 367.7 kJ/m³, respectively. This study shows that modulating the Al-Ga doping ratio can significantly influence the magnetic properties of Nd-Fe-B magnets, providing new insights and fundamentals for the preparation of high-performance magnets.