I. INTRODUCTION
A significant part of the latest efforts aimed at the improvement of the performance and decreasing cost of the Nd-Fe-B permanent magnets—materials of great technological importance—has focused on the modification of grain boundaries. These regions play a critical role in the beginning and propagation of the magnetization reversal, having a disproportional effect on the coercivity and, through the , on the maximum operating temperature of the magnet. The infiltration treatment, also known as the “grain boundary diffusion process,” was originally introduced to allow for a targeted delivery of the Dy and Tb atoms into the sintered magnets [Hirota 2006], locally rising the anisotropy field of the Nd2Fe14B phase where it was most necessary.