Production of thick high-performance sintered neodymium magnets by grain boundary diffusion treatment with dysprosium–nickel–aluminum alloy

A novel grain boundary diffusion (GBD) treatment with a Dy–Ni–Al eutectic alloy powder allowed Dy to penetrate into sintered plates of Nd–Fe–B magnet as thick as 5 mm. The coercivity of the magnet was increased from a value of 1160 kA/m (14.5 kOe) to 1760 kA/m (22 kOe). This was achieved without any marked decrease in remanance and with a high squareness.

Research highlights
► Grain boundary diffusion treatment using Dy–Ni–Al eutectic alloy was performed.
► Dy penetrated into sintered plates of Nd–Fe–B magnet as thick as 5mm.
► The coercivity of the magnet was increased from a value of 1160kA/m to 1760kA/m.
► The magnet after the treatment kept a high value in remanence and squareness.