RTB Permanent Magnet Composition Tolerant to High Carbon Content
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Solution Overview
Problem
The development of neodymium-iron-boron magnet materials faces challenges in achieving high coercivity and remanence without relying on expensive heavy rare earth elements and in maintaining uniform magnetic properties while controlling production costs, as high carbon content can lead to decreased performance and uneven grain size.
Innovation Solution
An RTB-based permanent magnet material is developed with specific compositions, including 29.5-33.5 wt% R', 0.106-0.26 wt% C, ≤0.07 wt% O, 0-5.0 wt% X (where X includes Cu, Al, Ga, Co, Zr, Ti, Nb, and Mn), 0.90-1.2 wt% B, and 61.4-69.5 wt% Fe, which improves performance without heavy rare earths and maintains excellence even with high carbon content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy rare earth elements (Dy or Tb) are added to improve coercivity and remanence, then magnetic performance is enhanced, but material cost increases dramatically and resource availability decreases
Solution Approach 1:
The patent replaces expensive heavy rare earth elements with lighter, more abundant rare earth elements (Pr, Nd, Sm, Eu, Gd) that can achieve similar magnetic performance. This substitution principle uses cheaper alternative materials to resolve the contradiction between performance and cost.
Solution Approach 2:
The patent optimizes the compositional parameters of the R-T-B system by controlling the ratios of rare earth elements (R), boron (T), and iron (B), along with adding specific amounts of aluminum (0.1-1.0 wt%) and copper (0.1-1.0 wt%). This parameter optimization allows achieving high coercivity and remanence without relying on expensive heavy rare earths.
2Manufacturing precision
If carbon content is controlled strictly to maintain uniform grain size and performance, then magnetic uniformity is improved, but production complexity and cost increase
Solution Approach 1:
The patent converts the typically harmful effect of carbon impurities into a beneficial feature by deliberately adding carbon (0.01-0.5 wt%) to the R-T-B-Al-Cu system. The carbon content is controlled to optimize grain boundary properties and magnetic performance, transforming what was previously considered an impurity to be controlled away into a useful alloying element.
Solution Approach 2:
The patent changes the approach to carbon from strict control/minimization to optimized incorporation. By setting a specific carbon content range (0.01-0.5 wt%) and combining it with aluminum and copper additions, the patent achieves uniform grain structure and excellent magnetic performance without requiring overly complex production controls.
3Manufacturing precision
If production process is strictly controlled to achieve uniform magnetic properties, then product quality is improved, but manufacturing cost and time increase
Solution Approach 1:
The patent employs self-organizing mechanisms during solidification where the R-T-B-Al-Cu system naturally forms uniform grain structures and phase distributions through controlled compositional ratios. This self-organization reduces the need for intensive process control and post-processing interventions, thereby improving productivity while maintaining quality.
Solution Approach 2:
The patent creates a composite R-T-B-Al-Cu system with multiple elements working synergistically. The combination of rare earths, boron, iron, aluminum, and copper forms a complex but balanced material system that achieves uniform magnetic properties through the interactions of its components, reducing the need for strict process control.
Data Source
Figure 1
AI summary
An RTB-based permanent magnet material, a preparation method thereof, and an application thereof. The RTB-based permanent magnet material comprises the following components: R': 29.5 to 33.5 wt.%, wherein R' comprises Pr, and the content of Pr is ≥8.85 wt.%; C: 0.106 to 0.26 wt.%; O: ≤ 0.07wt.%; X: 0 to 5.0 wt.%, wherein X is one or more of Cu, Al, Ga, Co, Zr, Ti, Nb and Mn; B: 0.90 to 1.2 wt.%; and Fe: 61.4 to 69.5 wt.%. The RTB-based permanent magnet material can improve the performance of a permanent magnet material without employing heavy rare earths. There is no need to control the content of carbon introduced in the process, and the magnet exhibits excellent performance even with a high carbon content.