Core-Shell Rare Earth Magnet Grain Structure
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Solution Overview
Problem
Existing rare earth magnets face challenges in achieving excellent magnetic anisotropy while reducing the amount of expensive rare earth elements like Nd, and existing methods for substituting these elements with lighter ones often result in deteriorated magnetic properties and high material costs.
Innovation Solution
A rare earth magnet with a core-shell crystal grain structure, where the core is rich in inexpensive elements like Ce or La and the outer shell is rich in Nd, Pr, or Dy, achieving magnetic decoupling and maintaining coercive force, with an average grain size of 1,000 nm or less to prevent demagnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Nd is substituted by light rare earth elements such as Ce and La to reduce material cost, then material cost is reduced, but magnetic properties are significantly deteriorated
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core region contains light rare earth elements (Ce, La) for cost reduction while the shell region contains heavy rare earth elements (Dy, Tb) for maintaining magnetic properties. This spatial differentiation of composition allows simultaneous optimization of both cost and performance.
Solution Approach 2:
The patent uses composite materials by combining different rare earth elements in a core-shell configuration within the same crystal grain. The composite structure of (R1,R2)2Fe14B phase with differentiated rare earth distribution creates synergistic effects that overcome the limitations of using either light or heavy rare earth elements alone.
2Quantity of substance
If anisotropization is attempted using light rare earth elements to reduce cost, then material cost is reduced, but coercive force decreases significantly
Solution Approach 1:
The patent places heavy rare earth elements (Dy, Tb) specifically in the shell region surrounding the core, creating local high-coercivity zones at the grain boundaries and outer regions. This localized concentration of high-coercivity material maximizes the coercive force contribution while minimizing the overall amount of expensive heavy rare earth elements required.
Solution Approach 2:
The patent segments the crystal grain into core and shell regions with different rare earth element compositions. The shell region is specifically engineered to provide anisotropization and high coercive force, while the core region provides volume and structural stability with cheaper light rare earth elements.
3Strength
If crystal grain is refined to nanoscale to increase coercive force, then coercive force is improved, but manufacturing complexity increases
Solution Approach 1:
The patent controls the average crystal grain size parameter within the range of 100 nm to 10 μm, optimizing it to achieve high coercive force while remaining manufacturable. This parameter optimization balances the benefits of nanoscale refinement with the practical constraints of manufacturing processes.
Data Source
AI summary
To provide a rare earth magnet ensuring excellent magnetic anisotropy while reducing the amount of Nd, etc., and a manufacturing method thereof.A rare earth magnet comprising a crystal grain having an overall composition of (R2(1-x)R1x)yFe100-y-w-z-vCowBzTMv (wherein R2 is at least one of Nd, Pr, Dy and Tb, R1 is an alloy of at least one or two or more of Ce, La, Gd, Y and Sc, TM is at least one of Ga, Al, Cu, Au, Ag, Zn, In and Mn, 0<x<1, y=12 to 20, z=5.6 to 6.5, w=0 to 8, and v=0 to 2), wherein the average grain size of the crystal grain is 1,000 nm or less, the crystal grain consists of a core and an outer shell, the core has a composition of R1 that is richer than R2, and the outer shell has a composition of R2 that is richer than R1.