Composite Magnet Grain Alignment for Remanence
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Solution Overview
Problem
Conventional Sm—Co and Nd—Fe—B permanent magnets face limitations in improving magnetic performance due to the sacrifice of coercivity when adding magnetic soft phases, and existing nanocomposite technologies struggle with achieving effective inter-grain coupling with small grain sizes.
Innovation Solution
A composite permanent magnet is formed with a matrix of magnetically hard phase grains of 10 nm to 50 μm and embedded magnetically soft phase grains of at least 50 nm with an elongated shape, allowing for improved inter-grain coupling and texture formation through hot-compacting and hot-deforming processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a magnetic soft phase is added to improve remanence and energy product, then magnetic flux density increases, but coercivity is sacrificed
Solution Approach 1:
The patent changes the grain size parameter of the soft phase from conventional small sizes to a specific range (50-500 nm), and controls the hard phase grain size (10 nm to 50 μm). This parameter optimization enables effective inter-grain exchange coupling while maintaining coercivity, resolving the contradiction between improving remanence and preserving coercivity
Solution Approach 2:
The patent creates a composite structure with magnetically hard phase grains (NdFeB, SmCo5, MnBi, or Sm-Fe-C) and magnetically soft phase grains (Fe, Co, FeCo, or Ni) in specific size ratios and distributions. This composite architecture enables simultaneous achievement of high remanence through soft phase contribution and high coercivity through hard phase dominance with optimized inter-grain coupling
2Manufacturing precision
If nanocomposite technology is used to add soft phase grains, then grain size can be controlled, but effective inter-grain coupling requires specific grain size ranges that are difficult to achieve
Solution Approach 1:
The patent specifies precise grain size parameters: soft phase grains of 50-500 nm and hard phase grains of 10 nm to 50 μm. These parameter ranges are optimized to achieve effective inter-grain exchange coupling, where the soft phase grains are large enough to maintain magnetic moment coherence but small enough to provide sufficient interface area for coupling with hard phase grains
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 enhances remanence and energy product density while maintaining coercivity, outperforming conventional sintered and nanocomposite magnets by achieving better grain size and shape alignment for improved magnetic performance.
Implementation Method 1
to achieve good magnetic performance through the inter-grain exchange coupling between two magnetic phases
Implementation Method 2
hot-compacting and hot-deforming processes
Implementation Method 3
hot-compacting and hot-deforming processes
Data Source
AI summary
According to an embodiment, a composite permanent magnet includes a matrix of magnetically hard phase grains having an average grain size of 10 nm to 50 μm; and magnetically soft phase grains embedded within the matrix, and having an average grain size of at least 50 nm, each grain having an elongated shape with an aspect ratio of at least 2:1. According to another embodiment, a composite permanent magnet includes a matrix of magnetically hard phase grains having an average grain size of 10 nm to 50 μm; and magnetically soft phase grains embedded within the matrix, and having an average grain width of at least 50 nm, an average grain height of 20 to 500 nm, and an aspect ratio of at least 2:1. According to yet another embodiment, a method of forming a composite permanent magnet is also provided.