Sm-Co Magnet Composition and Structure for High Squareness
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Solution Overview
Problem
Conventional Sm—Co magnets face challenges in achieving a high squareness ratio while maintaining high magnetization, particularly at high Fe concentrations, due to limitations in coercive force and magnetic energy product (BHmax).
Innovation Solution
A permanent magnet composition expressed as RpFeqMrCutCo100-p-q-r-t, where R is a rare-earth element, M is Zr, Ti, or Hf, and t is Cu, with a metallic structure featuring Th2Zn17 crystal phases and Cu-rich phases, ensuring a small average diameter of cell phases and controlled Cu concentration to enhance coercive force and squareness ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Fe concentration is increased to improve magnetization in Sm—Co magnets, then magnetization is improved, but squareness ratio decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Fe concentration within a specific range (20-40 atomic %) and adjusting the Cu concentration (3-15 atomic %) to achieve optimal balance between magnetization and squareness ratio. The metallic structure parameters are also controlled, with cell phase diameter maintained at 220 nm or less and specific size distribution ratios, to simultaneously achieve high magnetization and high squareness ratio that cannot be obtained by conventional compositions.
2Quantity of substance
If conventional manufacturing methods are used to increase Fe concentration, then magnetization improves, but coercive force decreases
Solution Approach 1:
The patent employs composite materials by creating a dual-phase metallic structure consisting of Th2Zn17 crystal phases (cell phases) and Cu-rich phases. This composite structure, where Cu-rich phases are distributed within the Th2Zn17 matrix, provides both high magnetization from the Fe-containing cell phases and high coercive force from the Cu-rich boundary phases, resolving the contradiction between these two properties.
Solution Approach 2:
The patent applies local quality by creating regions with different compositions and functions: the cell phases (Th2Zn17) provide magnetization with controlled Fe concentration, while the Cu-rich phases at boundaries provide coercive force enhancement. This spatial differentiation of material properties allows simultaneous optimization of both magnetization and coercive force.
3Weight of stationary object
If size and weight reduction is pursued in electronic apparatuses, then compactness improves, but performance requirements become more stringent
Solution Approach 1:
The patent achieves high performance in reduced-size magnets by optimizing compositional parameters (Fe: 20-40 atomic %, Cu: 3-15 atomic %, R: 10.5-12.5 atomic %) and structural parameters (cell phase diameter ≤220 nm, size distribution ratio ≤20%). These precise parameter controls enable high magnetization and high squareness ratio in compact magnet sizes, meeting stringent performance requirements for miniaturized electronic apparatuses.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution results in a high-performance permanent magnet with improved coercive force, squareness ratio, and magnetization, suitable for high-efficiency motors and generators, while maintaining thermal stability and reducing size and weight.
Implementation Method 1
these magnets contain rare-earth elements such as Nd and Sm, which bring about large magnetic anisotropy originating in behaviors of 4f electrons of the rare-earth elements in crystal fields
Implementation Method 2
large magnetic anisotropy originating in behaviors of 4f electrons of the rare-earth elements in crystal fields
Implementation Method 3
Fe and Co contribute to increase in saturation magnetization
Data Source
AI summary
A high performance permanent magnet is provided. The permanent magnet includes a composition represented by a composition formula: RpFeqMrCutCo100-p-q-r-t, and a metallic structure including cell phases having a Th2Zn17 crystal phase and Cu-rich phases having higher Cu concentration than the cell phases. An average diameter of the cell phases is 220 nm or less, and in a numeric value range from a minimum diameter to a maximum diameter of the cell phases, a ratio of a number of cell phases having a diameter in a numeric value range of less than upper 20% from the maximum diameter is 20% or less of all the cell phases.