Influence of Severe Plastic Deformation on the Magnetic Properties of Sm‐Co Permanent Magnets

High pressure torsion (HPT) is presented as a new fabrication route to produce bulk Sm‐Co magnets with a strongly refined microstructure down to the nanometer regime. The initial powders, based on the compositions SmCo₅, Sm₂Co₇ and Sm₂Co₁₇, are compacted and subsequently deformed by HPT. The microstructural evolution in dependence on the applied deformation parameters is characterized by electron microscopy and the effect of HPT on the phase stability is monitored by synchrotron X‐ray diffraction. An increasing amount of applied strain leads to a stronger reduction in grain size while strain localization counteracts a homogeneous microstructural refinement. The positive effect of elevated deformation temperatures is demonstrated for Sm₂Co₁₇, which promotes homogeneous grain refinement, but causes strain induced phase transformations at the same time, strongly affecting the magnetic behavior. SQUID magnetometry is used to characterize the magnetic properties after HPT‐deformation, which indicates the formation of a magnetic texture depending on the respective phase.

This article is protected by copyright. All rights reserved.