R-T-B Sintered Magnet Composition for High Br and Thermal Coercivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing R-T-B sintered magnets face challenges in achieving high remanence and elevated temperature stability while maintaining coercivity, with previous methods either compromising room temperature coercivity or being difficult to scale in mass production.
Innovation Solution
A R-T-B sintered magnet composition is optimized with a main phase of R2Fe14B and a grain boundary phase containing R-T-(M1, M2) and R-M2-C phases, with specific atom concentrations and the addition of elements like Sn and C to form R-M2-C phases, which enhances both room temperature and elevated temperature stability without significant drops in remanence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy rare earth elements like Dy and Tb are substituted for part of R to improve magnetocrystalline anisotropy, then coercivity at elevated temperature is improved, but resource supply risk increases and cost increases
Solution Approach 1:
The patent changes the compositional parameters by adding specific elements (Sn: 0.01-0.5 atom%, C: 0.01-1.0 atom%) to the R-T-B magnet system. These parameter changes modify the grain boundary phase composition and structure, enabling improved elevated temperature coercivity without relying on heavy rare earth elements like Dy and Tb.
Solution Approach 2:
The patent creates a composite grain boundary phase structure containing R-T-(M1, M2) and R-M2-C phases. This composite structure combines multiple elements with different functions: Sn and C form carbide phases that enhance thermal stability, while the R-T-(M1, M2) phase provides grain boundary control. The synergistic combination achieves high temperature coercivity improvement without heavy rare earth substitution.
2Reliability
If the grain boundary phase structure is controlled to improve coercivity, then elevated temperature performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent simplifies manufacturing by controlling only a few key parameters: Sn content (0.01-0.5 atom%), C content (0.01-1.0 atom%), and the ratio of M1 to M2 elements. These parameter changes automatically lead to the formation of the desired R-T-(M1, M2) and R-M2-C grain boundary phases through standard sintering processes, avoiding complex multi-step structural control procedures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The optimized composition achieves high remanence and satisfactory elevated temperature stability with improved coercivity at both room and elevated temperatures, minimizing the drop in remanence and ensuring consistent magnetic properties.
Implementation Method 1
substitute heavy rare earth elements like Dy and Tb for part of R to improve the magnetocrystalline anisotropy of R 2 T 14 B phase
Implementation Method 2
structural control of grain boundary phase
Implementation Method 3
R-T-B sintered magnet
Implementation Method 4
forming a structure containing a first grain boundary phase consisting of 20 to 40 atom% of R, 60 to 75 atom% of T, and 1 to 10 atom% of M and a second grain boundary phase
Data Source
Figure 1
AI summary
A R-T-B sintered magnet comprising a main phase of R2Fe14B and a grain boundary phase exhibits a high Br and elevated-temperature stability. The magnet is composed of 12.5-17.0 atom% of R which is typically Nd and Pr, 4.5-5.5 atom% of B, at least 70 atom% of T which is Fe and Co, 0.1-3.0 atom% of M1 which is typically Al, Cu or Ga, 0.01-0.5 atom% of M2 which is typically Sn, 0.05-1.0 atom% of M3 which is typically Zr, and up to 0.8 atom% of O, and the balance of C, N and incidental impurities. The grain boundary phase contains a R-T-(M1, M2) phase and a R-M2-C phase.