# Coercivity enhancement of selective laser sintered NdFeB magnets by grain boundary infiltration

## TL;DR

This paper demonstrates that grain boundary infiltration with specific alloys significantly enhances the coercivity of selective laser sintered NdFeB magnets, addressing a key limitation in additive manufacturing of these magnets.

## Contribution

It introduces a novel grain boundary diffusion process using low-melting alloys to substantially increase coercivity in laser sintered NdFeB magnets.

## Key findings

- Coercivity increased from 0.65 T to 1.5 T.
- Formation of Nd-rich grain boundary phase and Tb-rich shell.
- Maintained nano-scale grain size enhances coercivity.

## Abstract

Laser powder bed fusion is a well-established additive manufacturing method that can be used for the production of net-shaped Nd-Fe-B sintered magnets. However, low coercivity has been one of the drawbacks in the laser powder bed fusion processed Nd-Fe-B magnets. In this work, we have demonstrated that the grain boundary diffusion process using low-melting Nd-Cu, Nd-Al-Ni-Cu, and Nd-Tb-Cu alloys to the selective laser sintered NdFeB magnets can results in a substantial enhancement of coercivity from 0.65 T to 1.5 T. Detailed microstructure investigations clarified formation of Nd-rich grain boundary phase, introducing Tb-rich shell at the surface of Nd2Fe14B grains, and maintaining the grain size in nano-scale are responsible for the large coercivity enhancement.