Bulk anisotropic multiphase nanohybrid magnets fabricated from compound precursors

Abstract

Abstract Bulk anisotropic RT7/α-Fe(Co)+Nd2Fe14B/α-Fe (RT7 denotes Sm(CoFeCuZr)7 phase) multiphase nanohybrid magnets have been designed and prepared by High-Pressure Thermal Compression (HPTC), using a blend of Nd9Fe85.5Cu1.5B4 amorphous and SmCo-based amorphous-nanocrytalline powders as precursors. The resulting HPTC magnet is composed of alternating RT7/α-Fe(Co) and Nd2Fe14B/α-Fe nanocomposite layers along the pressure direction. A (00l) crystallographic texture for the RT7 and Nd2Fe14B nanocrystals has been achieved in the RT7/α-Fe(Co) and Nd2Fe14B/α-Fe layers, respectively. The RT7/α-Fe(Co) layer comprises elongated RT7 nanocrystals (8–13 nm in thickness and 13–20 nm in length) and approximately equiaxed α-Fe(Co) nanograins with an average size of ∼13 nm. The Nd2Fe14B/α-Fe layer consists of lath-shaped Nd2Fe14B nanograins (15–30 nm in thickness and 30–55 nm in length) and approximately equiaxed α-Fe nanograins with an average size of ∼19 nm. The HPTC magnet exhibits a maximum energy product of 25 MGOe, with a high soft-magnetic fraction of ∼30 wt%, and a low coercivity temperature coefficient of β(RT-250 °C) = −0.28% oC−1. Our work provides an alternative approach to yielding high-performance bulk multiphase nanohybrid magnets.