Sm-Co Magnet Composition and Aging for Coercive Force
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Solution Overview
Problem
There is a need for a high-performance permanent magnet with improved coercive force, magnetization, and squareness ratio, particularly in Sm-Co-based magnets, where increasing Fe concentration often compromises these properties.
Innovation Solution
A permanent magnet with a composition of R p Fe q M r Cu t Co 100-p-q-r-t, where R is a rare-earth element, M is Zr, Ti, or Hf, and Cu is present in a Cu-rich phase with a concentration of 30 at% or more, and a Th 2 Zn 17 crystal phase, optimized through specific aging treatments 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-based magnets, then magnetization increases, but squareness ratio decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Fe concentration within 20-35 at% and Cu concentration within 3-8 at%, along with specific aging treatment temperatures (700-900°C) and times (10-100 hours). These parameter optimizations enable achieving both high magnetization (≥1.40 T) and excellent squareness ratio (≥0.92) simultaneously, resolving the contradiction between improving magnetization and maintaining squareness ratio in Sm-Co-based magnets.
2Quantity of substance
If Fe concentration is increased to improve magnetization, then magnetization increases, but coercive force decreases
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: Fe concentration (20-35 at%), Cu concentration (3-8 at%), aging treatment temperature (700-900°C), and aging treatment time (10-100 hours). This multi-parameter optimization achieves high magnetization (≥1.40 T) while maintaining high coercive force (≥800 kA/m), resolving the contradiction between improving magnetization and maintaining coercive force in Sm-Co-based magnets.
3Manufacturing precision
If Cu concentration is increased to improve squareness ratio, then squareness ratio improves, but magnetization decreases
Solution Approach 1:
The patent applies parameter changes by optimizing Cu concentration within 3-8 at% (not excessively high) and Fe concentration within 20-35 at%, combined with specific aging treatment conditions (700-900°C for 10-100 hours). This balanced parameter optimization achieves excellent squareness ratio (≥0.92) while maintaining high magnetization (≥1.40 T), resolving the contradiction between improving squareness ratio and maintaining magnetization.
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 achieves a high coercive force, excellent squareness ratio, and increased magnetization, making it suitable for high-performance applications in motors and power generators while maintaining thermal stability.
Implementation Method 1
rare-earth elements such as Nd and Sm are contained to bring about large magnetic anisotropy resulting from behaviors of 4f electrons of the rare-earth elements in a crystal field
Implementation Method 2
a number of intersections of Cu-rich phases existing in an area of 1 μm square is 10 or more and 120 or less
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A permanent magnet includes: a composition expressed by a composition formula: RpFeqMrCutCo100-p-q-r-t (R is at least one element selected from rare-earth elements, M is at least one element selected from Zr, Ti, and Hf, 10.5 ≤ p ≤ 12.5 at%, 23 ≤ q ≤ 40 at%, 0.88 ≤ r ≤ 4.5 at%, 4.5 ≤ t ≤ 10.7 at%); and a metal structure containing a Th2Zn17 crystal phase and a Cu-rich phase having a Cu concentration higher than that of the Th2Zn17 crystal phase. In a cross section including a c-axis of the Th2Zn17 crystal phase, a number of intersections of the Cu-rich phases existing in an area of 1 µm square is 10 or more.