R-T-B Sintered Magnet Coercivity via Mn and Al
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
R-T-B based sintered magnets face challenges with low Curie temperature and significant coercivity variation with temperature, requiring increased coercivity without using expensive heavy rare-earth elements like Dy and Tb, while maintaining minimal decrease in magnetization.
Innovation Solution
An R-T-B based sintered magnet composition including 12-15 at% rare-earth element, 5-8 at% boron, 0.1-1 at% Al, 0.02-0.5 at% Mn, and a transition metal T, with Fe as the main ingredient, where Mn is added to minimize deterioration in magnetic properties and increase coercivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy rare-earth elements such as Dy and Tb are added to increase coercivity, then the coercivity of the magnet is improved, but the production cost increases significantly and resource availability becomes restricted
Solution Approach 1:
The patent changes the chemical composition parameters by adding specific elements (Al, Ga, In, Sn, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W) in controlled amounts to modify the grain boundary phase properties, thereby achieving high coercivity without relying on expensive heavy rare-earth elements
Solution Approach 2:
The patent replaces expensive heavy rare-earth elements (Dy, Tb) with cheaper alternative elements that can achieve similar or better coercivity enhancement, making the magnet production more cost-effective and sustainable
2Reliability
If additive elements such as Al are increased to increase coercivity, then the coercivity is improved, but the Curie temperature and magnetization of the main phase decrease
Solution Approach 1:
The patent applies local quality by concentrating additive elements (Al, Ga, In, Sn, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W) in the grain boundary phase rather than allowing them to distribute throughout the main phase, thereby enhancing coercivity locally at grain boundaries while preserving the magnetic properties of the main phase
Solution Approach 2:
The patent uses the grain boundary phase as an intermediary medium where additive elements are preferentially located to exert their coercivity-enhancing effect, thereby mediating between the need for high coercivity and the need to maintain high Curie temperature and magnetization in the main phase
3Reliability
If additive elements such as Al are increased to increase coercivity, then the coercivity is improved, but the magnetization of the main phase decreases
Solution Approach 1:
The patent applies local quality by concentrating additive elements (Al, Ga, In, Sn, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W) in the grain boundary phase rather than allowing them to distribute throughout the main phase, thereby enhancing coercivity locally at grain boundaries while preserving the magnetic properties of the main phase
Solution Approach 2:
The patent uses the grain boundary phase as an intermediary medium where additive elements are preferentially located to exert their coercivity-enhancing effect, thereby mediating between the need for high coercivity and the need to maintain high Curie temperature and magnetization in the main phase
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An R-T-B based sintered magnet according to the present invention has a composition comprising: 12 at% to 17 at% of a rare-earth element R; 5.0 at% to 8.0 at% of boron B; 0.1 at% to 1.0 at% of Al; 0.02 at% to less than 0.5 at% of Mn; and a transition metal T as the balance. The rare-earth element R is at least one element selected from the rare-earth elements, including Y (yttrium), and includes at least one of Nd and Pr. The transition element T includes Fe as its main element.