Sm-Co Permanent Magnet Composition for High Coercive Force
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Solution Overview
Problem
Existing rare-earth cobalt permanent magnets lack excellent coercive force and squareness, which are crucial for high-performance magnetic applications.
Innovation Solution
A sintered compact permanent magnet with a composition of 23-27 wt% rare-earth elements, 22-27 wt% Fe, 0.3-2.5 wt% Mn, 4.0-5.0 wt% Cu, and the remainder consisting of Co and unavoidable impurities, featuring crystal grains with Th2Zn17-type and RCos-type structures, and grain boundary phases with Cu concentrations of 45 at% or higher, achieving large grain sizes and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Cu concentration in grain boundary phases is increased to improve coercive force, then the magnetic stability is enhanced, but the manufacturing precision and compositional control become more difficult
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Cu concentration in the grain boundary phase within a specific range (45-70 at%). This parameter optimization ensures sufficient Cu content to form an effective pinning phase for high coercive force and magnetic stability, while avoiding excessive Cu that would create manufacturing difficulties. The defined compositional range balances performance requirements with manufacturing feasibility.
Data Source
AI summary
A permanent magnet having excellent magnetic properties and a device including such a permanent magnet are provided. A permanent magnet consists of a sintered compact having a composition consisting of R: 23 to 27 wt % (R is a sum total of rare-earth elements including at least Sm), Fe: 22 to 27 wt %, Mn: 0.3 to 2.5 wt %, Cu: 4.0 to 5.0 wt %, and a remainder consisting of Co and unavoidable impurities, in which the sintered compact contains a plurality of crystal grains and grain boundary phases, and a concentration of Cu in at least a part of the grain boundary phases is 45 at % or higher.