Novel Bimorphological Anisotropic Bulk Nanocomposite Materials with High Energy Products

TLDR

Nanostructuring hard and soft magnetic materials aims to create next‑generation ultrastrong permanent magnets with fewer rare‑earth elements, but conventional hard/soft nanocomposites suffer from random crystallographic orientations and monomorphous equiaxed grains that yield inferior magnetic performance compared to pure rare‑earth magnets. The study aims to fabricate a novel bimorphological anisotropic bulk nanocomposite comprising oriented SmCo rod‑shaped hard grains and Fe(Co) equiaxed soft grains. The authors employ a multistep deformation process to produce a bulk nanocomposite with oriented SmCo rods and Fe(Co) equiaxed grains (~10 nm, ~28 wt %). The resulting nanocomposite achieves a record 28 MGOe energy product, a 58 % improvement over the best pure rare‑earth magnet, and demonstrates that lower‑cost, stronger nanocomposites are feasible.

Abstract

Nanostructuring of magnetically hard and soft materials is fascinating for exploring next-generation ultrastrong permanent magnets with less expensive rare-earth elements. However, the resulting hard/soft nanocomposites often exhibit random crystallographic orientations and monomorphological equiaxed grains, leading to inferior magnetic performances compared to corresponding pure rare-earth magnets. This study describes the first fabrication of a novel bimorphological anisotropic bulk nanocomposite using a multistep deformation approach, which consists of oriented hard-phase SmCo rod-shaped grains and soft-phase Fe(Co) equiaxed grains with a high fraction (≈28 wt%) and small size (≈10 nm). The nanocomposite exhibits a record-high energy product (28 MGOe) for this class of bulk materials with less rare-earth elements and outperforms, for the first time, the corresponding pure rare-earth magnet with 58% enhancement in energy product. These findings open up the door to moving from a pure permanent-magnet system to a stronger nanocomposite system at lower costs.