NdFeB Magnet Composition for High Coercivity Without Microcracks
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Solution Overview
Problem
Existing neodymium-iron-boron magnet materials face challenges in achieving optimal coercivity and remanence due to issues with microcracks and reduced compactness caused by high Cu content, despite improvements in Cu and Al additions.
Innovation Solution
Optimizing the formula of neodymium-iron-boron magnets by adjusting the content of elements like Co, Al, Cu, Pr, and Nb, and incorporating a NbxCoy phase in the grain boundary phase, combined with specific aging treatments, to enhance coercivity and maintain high remanence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high Cu content (0.35 wt % or more) is added to improve coercivity, then coercivity is improved, but microcracks form in the magnet after sintering, reducing compactness and strength
Solution Approach 1:
The patent optimizes the Cu content parameter to a specific range (0.2-0.35 wt%) rather than using high Cu content, and introduces Nb (0.1-0.5 wt%) and Co (0.5-1.5 wt%) elements to achieve the desired coercivity without causing microcracks. This parameter optimization resolves the contradiction by finding a balanced composition that improves coercivity while maintaining structural integrity.
Solution Approach 2:
The patent creates a composite grain boundary phase containing Nb, Co, and Cu elements with the formula R-Nb-Co-Cu-Oxide phase. This composite approach allows the beneficial effects of Cu for coercivity improvement while Nb and Co contribute to structural stability, preventing microcrack formation and maintaining compactness.
2Strength
If Al is added to solve microcrack defects, then microcrack formation is reduced, but coercivity and remanence properties still cannot reach theoretical values
Solution Approach 1:
The patent develops a composite grain boundary phase containing multiple elements (Nb, Co, Cu, and oxides) rather than relying solely on Al. This composite phase simultaneously provides crack prevention benefits and enhances magnetic properties through the synergistic effects of Nb and Co, which contribute to both structural integrity and magnetic performance.
Solution Approach 2:
The patent introduces Nb and Co as intermediary elements that mediate between the conflicting requirements of structural integrity and magnetic performance. These elements form a grain boundary phase that acts as an intermediary structure, preventing microcracks while also enhancing coercivity and remanence through their specific contributions to the magnetic properties.
3Force
If the formula is optimized to improve coercivity, then coercivity increases, but maintaining high remanence and squareness becomes challenging
Solution Approach 1:
The patent optimizes multiple compositional parameters simultaneously: Cu (0.2-0.35 wt%), Nb (0.1-0.5 wt%), Co (0.5-1.5 wt%), and B (1.0-2.0 wt%). This multi-parameter optimization allows the formation of a grain boundary phase that simultaneously improves coercivity while maintaining high remanence and squareness through balanced composition control.
Solution Approach 2:
The patent creates a composite grain boundary phase with multiple elements (R-Nb-Co-Cu-Oxide) where each component contributes differently: Nb and Co enhance coercivity, Cu provides structural stability, and the oxide phase maintains remanence. This composite structure resolves the contradiction by distributing functional responsibilities across different elements.
Data Source
AI summary
The invention discloses a neodymium-iron-boron magnet material, a preparation method and use thereof. The neodymium-iron-boron magnet material comprises the following components of: 28-33 wt % of R, wherein R is a rare earth element, and R comprises 27-31.5 wt % of Nd; 0.30-1.3 wt % of Al; 0.35-0.6 wt % of Cu; more than 0 wt %—less than or equal to 0.74 wt % of Co; 0.98-1.2 wt % of B; 62-69 wt % of Fe, wherein wt % is a percentage of the mass of respective component in the total mass of the neodymium-iron-boron magnet material; the neodymium-iron-boron magnet material comprises Nb, and a mass content of'Nb satisfies the following condition: (Pr+Co) wt %≤(1+Nb) wt %. In the present invention, by further optimizing the formula of the neodymium-iron-boron magnet material, the coercivity of the neodymium-iron-boron magnet material prepared is significantly improved while maintaining higher remanence and squareness.