Magnetic hardening strategy for high-performance Sm(CoFeCuZr) sintered permanent magnets prepared by dual-alloy process

To improve the overall magnetic properties of Sm(CoFeCuZr) z sintered magnets, a dual-alloy sintering process that involves mixing high-iron, low-copper powders with low-iron, high-copper powders was systematically investigated. The results demonstrate that this method significantly improves the Cu-lean phenomenon at the grain boundaries, achieves multiscale uniform microstructures, greatly enhances the pinning field strength, and ultimately produces a high-performance dual-alloy magnet with a maximum energy product (( BH ) max ) exceeding 240 kJ/m 3 and an intrinsic coercivity ( H cj ) exceeding 2400 kA/m. In particular, when 35 wt.% of low-iron, high-copper alloy powder is incorporated, the dual-alloy magnet achieves a remanence of 1.13 T, H cj of 2691.2 kA/m and ( BH ) max of 248 kJ/m 3 . To evaluate the overall magnetic performance, the sum of H cj (in kA/m) and ( BH ) max (in kJ/m 3 ) is used as a combined parameter, yielding a value of 2939.2. Compared with single-alloy magnets of the same composition, the dual-alloy sintering process yields magnets with a more uniform elemental distribution and superior magnetic properties.