R-T-B Magnet Composition for Br-Coercivity Balance
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Solution Overview
Problem
Existing R-T-B based permanent magnets face challenges in achieving a well-balanced improvement of residual flux density (Br) at room temperature and coercivity (HcJ) at high temperatures, along with a high squareness ratio (Hk/HcJ) while maintaining optimal composition and microstructure.
Innovation Solution
An R-T-B based permanent magnet with specific composition ranges for elements like R, Co, B, Al, Cu, Ga, and Zr, along with optional C, O, and N, is developed, including an R content of 30.00-33.00 mass % and Co content of 0.80-3.00 mass %, which satisfies HcJH≥600 and BrL+(HcJH/3)≥1565, and has a squareness ratio of 92.0% or more at room temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the composition of R-T-B based permanent magnet is optimized to improve residual flux density (Br) at room temperature, then Br is improved, but coercivity (HcJ) at high temperatures deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ranges of multiple elements (R: 30.00-33.00 mass%, Co: 0.80-3.00 mass%, B: 0.70-0.83 mass%, Al: 0.00-0.20 mass%, Cu: 0.10-1.50 mass%, Ga: 0.40-1.00 mass%, Zr: 0.10-1.60 mass%) to simultaneously optimize both Br at room temperature and HcJ at high temperatures. This multi-parameter optimization resolves the contradiction by finding the optimal composition window where both magnetic properties are enhanced.
Solution Approach 2:
The patent employs composite material principles by creating a multi-element R-T-B based permanent magnet system that combines rare earth elements (R), transition metals (Fe, Co), boron, and additional alloying elements (Al, Cu, Ga, Zr). This composite approach allows synergistic interactions between elements to improve both residual flux density and coercivity, overcoming the trade-off between these two properties.
2Reliability
If the composition is adjusted to improve coercivity (HcJ) at high temperatures, then HcJ is improved, but residual flux density (Br) at room temperature deteriorates
Solution Approach 1:
The patent resolves this contradiction through parameter changes by establishing specific composition ranges that balance high-temperature coercivity and room-temperature residual flux density. The controlled addition of Cu (0.10-1.50 mass%) and Ga (0.40-1.00 mass%) along with precise R and B content optimization enables simultaneous improvement of both properties, eliminating the need to sacrifice one for the other.
3Manufacturing precision
If specific composition ranges are used to achieve high squareness ratio (Hk/HcJ) at room temperature, then squareness ratio is improved, but manufacturing complexity increases
Solution Approach 1:
The patent addresses manufacturing complexity by defining clear, quantifiable composition ranges for each element (e.g., R: 30.00-33.00 mass%, B: 0.70-0.83 mass%). These specific parameter specifications provide straightforward manufacturing guidelines that achieve high squareness ratio (≥92.0%) without requiring complex process control, making the solution industrially feasible.
Data Source
AI summary
[Summary] Provided is an R-T-B permanent magnet that contains Al, Cu, Ga, and Zr. The R content is 30.00-33.00 mass %, the Co content is greater than 0.80 mass % but no greater than 3.00 mass %, the B content is 0.70-0.83 mass %, the Al content is greater than 0 mass % but less than 0.20 mass %, the Cu content is greater than 0.10 mass % but less than 1.50 mass %, the Ga content is 0.40-1.00 mass %, and the Zr content is greater than 0.10 mass % but no greater than 1.60 mass %.