R-T-B Rare Earth Magnet Alloy with Dy Concentration Gradient
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Solution Overview
Problem
Conventional techniques face challenges in achieving high coercivity and orientation rate for R-T-B system rare earth permanent magnets, as increasing Dy concentration improves coercivity but reduces remanence, and methods to enhance coercivity while maintaining high orientation rate are insufficient.
Innovation Solution
An alloy material comprising multiple R-T-B system alloys with different compositions and a metal powder, where the alloy with the highest Dy content contains 17% or more Dy and a 5% or greater Dy concentration difference, along with a metal powder like Al, Fe, Si, Ta, or Ti, is used to improve coercivity and orientation rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If Dy concentration in R-T-B system alloy is increased to improve coercivity, then coercivity is improved, but remanence is reduced
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the grain boundary phase has high Dy concentration (improving coercivity locally) while the main phase maintains optimal composition (preserving remanence). The Dy concentration in grain boundary phase is 17% or more, while the overall alloy Dy content is controlled at 2-20%, achieving localized enhancement without global compromise.
Solution Approach 2:
The patent changes the parameter distribution of Dy concentration from uniform to non-uniform. By controlling Dy concentration in grain boundary phase to be 17% or more while maintaining overall Dy content at 2-20%, and controlling grain boundary phase volume fraction at 5-50%, the patent achieves high coercivity through parameter optimization without sacrificing remanence.
2Force
If grain size is reduced to improve coercivity, then coercivity is improved, but orientation rate is reduced
Solution Approach 1:
The patent optimizes the parameter of grain size within a specific range (3-6 μm) to balance coercivity and orientation rate. By controlling grain size to 3-6 μm and grain boundary phase volume fraction to 5-50%, the patent achieves high coercivity while maintaining adequate orientation rate during magnetic field alignment.
Data Source
Figure 1
AI summary
An alloy material for an R-T-B system rare earth permanent magnet having a high orientation rate and high coercivity (Hcj), and a method for producing an R-T-B system rare earth permanent magnet using the alloy material are provided. In such an alloy material for an R-T-B system rare earth permanent magnet, a plurality of R-T-B system alloys having different compositions and a metal powder are included, the respective R-T-B system alloys are formed of R which is composed of two or more kinds selected from rare earth elements, T which is composed of a transition metal essentially containing Fe, B, and unavoidable impurities, a first alloy having the greatest Dy content among the plurality of R-T-B system alloys contains 17 mass% or greater of Dy, and a Dy concentration difference between the first alloy and a second alloy having the least Dy concentration difference with respect to the first alloy among the plurality of R-T-B system alloys is 5 mass% or greater.