Grain boundary optimization induced substantial squareness enhancement and high performance in iron-rich Sm-Co-Fe-Cu-Zr magnets

Via manipulating the grain boundary optimization process, the grain boundary phases along grain boundaries as well as the micro-twins’ density in grain interiors can be controllable. It is found that the squareness factor was substantially enhanced from 63.4% (a) for original magnet A to 91.0% for optimized magnet B (b), and consequently an excellent maximum energy product of 32.46 MGOe was achieved (b). In addition, based on the grain boundary optimization a further strengthened magnet was achieved, SF = 91.4% and (BH)max = 32.63 MGOe. It is shown that a further squareness-enhancement is possible by optimizing the solution process more carefully, which will further improve the magnetic properties of the Sm-Co-Fe-Cu-Zr permanent magnets.