High-Performance Anisotropic Nanocomposites with a Novel Core/shell Microstructure

Anisotropic nanostructures of magnetically hard and soft materials are fascinating for exploring next-generation ultrastrong permanent magnets with less expensive rare-earth elements. It is a big challenge fabricating high-performance nanocomposites due to the difficulty in controlling the grain size of the soft phase. Here, surfactant-assisted low-temperature chemical coating (LTCC) is adopted to fabricate SmCo₅@FeCo nanocomposites. A uniform coating layer of the soft phase ranging from 5 to 15 nm FeCo particles is obtained. Both high coercivity H_c of 17.2 kOe and high energy product (BH)_max of 29.4 MGOe in the optimal anisotropic SmCo₅@FeCo nanocomposites with 15 wt % soft phase coating had been successfully fabricated, which has an enhancement of 31% compared with that of the uncoated single SmCo₅ phase. The excellent performance is ascribed to nanosized grains of both soft and hard phases and a high remanence ratio M_r/M_s of 0.976. These results made a big step toward synthesizing a stronger bulk nanocomposite system.