R-T-B Permanent Magnet Composition for Br and High-Temperature HcJ
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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, with existing compositions either compromising on Br or HcJ.
Innovation Solution
An R-T-B based permanent magnet with specific compositions including Al, Ga, and Zr, within defined mass percentage ranges, and optionally Cu and C, to achieve improved Br and HcJ in a balanced manner, utilizing a manufacturing process involving alloy preparation, pulverization, pressing, sintering, and aging treatment to maintain crystal structure and magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing R-T-B based permanent magnet compositions are used, then either residual flux density (Br) at room temperature or coercivity (HcJ) at high temperatures can be improved, but not both simultaneously in a well-balanced manner
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of multiple elements (R: 30.00-33.00 mass%, B: 0.70-0.88 mass%, Al: 0.01-0.07 mass%, Ga: 0.40-1.00 mass%, Zr: 0.10-1.60 mass%) to achieve a balance between Br at room temperature and HcJ at high temperatures. This systematic adjustment of compositional parameters resolves the contradiction by finding an optimal parameter space where both magnetic properties are simultaneously improved.
Solution Approach 2:
The patent employs composite materials by combining multiple rare earth elements (Nd, Pr, Dy, Tb) with iron group elements and boron in specific proportions. This composite approach allows the material to exhibit both high residual flux density at room temperature and high coercivity at elevated temperatures, overcoming the limitation of single-composition magnets that could only optimize for one temperature range.
2Quantity of substance
If R content is increased to improve magnetic properties, then residual flux density improves, but coercivity at high temperatures deteriorates
Solution Approach 1:
The patent applies local quality by introducing specific elements (Ga and Zr) at controlled concentrations to address the high-temperature coercivity issue in regions where it is most needed, while maintaining the overall R content for high residual flux density. This localized compositional adjustment allows different parts of the magnetic material to contribute differently to overall performance.
Solution Approach 2:
The patent uses Al as an intermediary element that mediates between the R content and high-temperature coercivity. By controlling Al content within a specific range (0.01-0.07 mass%), it enables the system to maintain both high R content for flux density and sufficient coercivity at elevated temperatures, acting as a buffer between conflicting requirements.
3Reliability
If B content is increased to improve coercivity, then HcJ improves, but residual flux density deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing B content within a narrow range (0.70-0.88 mass%) and coordinating it with other elemental compositions. This precise parameter control ensures that the material achieves sufficient coercivity through the synergistic effect of multiple elements rather than relying on excessive B content, thereby maintaining high residual flux density.
Data Source
AI summary
An R-T-B based permanent magnet contains Al, Ga, and Zr. The R content is greater than or equal to 30.00 mass % and less than or equal to 33.00 mass %, the B content is greater than or equal to 0.70 mass % and less than or equal to 0.88 mass %, the Al content is greater than 0 mass % and less than or equal to 0.07 mass %, the Ga content is greater than or equal to 0.40 mass % and less than or equal to 1.00 mass %, and the Zr content is greater than 0.10 mass % and less than or equal to 1.60 mass %.