Cerium-Added NdFeB Magnet Grain Boundary Structure for Higher Coercivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The addition of cerium to neodymium-iron-boron magnets decreases their magnetic properties due to the formation of low-magnetic REFe2 phase in the grain boundary, leading to poor coercivity and magnetic isolation effects.
Innovation Solution
A cerium-added RE-T-B-M series sintered neodymium-iron-boron magnet with a sandwich grain boundary phase comprising a RE-rich phase, a Fe-rich phase, and a REFe2 phase, where the RE-rich phase forms the first layer, the Fe-rich phase the second layer, and the REFe2 phase the third layer, with cerium accounting for 3.0-15.0% by mass, enhancing magnetic isolation and coercivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cerium is added to reduce costs, then manufacturing cost is reduced, but magnetic properties deteriorate due to formation of low-magnetic REFe2 phase
Solution Approach 1:
The grain boundary phase is segmented into three distinct layers: an inner layer rich in Ce and Al, an intermediate layer with balanced composition, and an outer layer rich in Fe and B. This segmentation prevents the formation of continuous low-magnetic REFe2 phase while maintaining cost benefits of cerium addition.
Solution Approach 2:
Different regions of the grain boundary phase are given different compositions tailored to their specific functions: the inner layer optimizes for magnetic isolation, the intermediate layer for structural stability, and the outer layer for magnetic property enhancement. This local optimization resolves the contradiction between cost reduction and magnetic property maintenance.
2Ease of manufacture
If high amount of cerium is added, then cost is reduced, but coercivity decreases due to poor magnetic isolation effect of REFe2 phase
Solution Approach 1:
The grain boundary phase is designed as a composite structure combining multiple phases (Ce-rich phase, Al-containing phase, Fe-rich phase) in a layered configuration. This composite structure provides both the cost benefits of high cerium content and the magnetic isolation properties needed for high coercivity.
3Quantity of substance
If REFe2 phase is formed in grain boundary, then cerium utilization is improved, but magnetic isolation effect weakens and reverse domain movement increases
Solution Approach 1:
The solution transitions from a uniform single-phase grain boundary structure to a three-layered hierarchical structure. This dimensional complexity in the grain boundary phase allows cerium to be effectively utilized while preventing the harmful continuous distribution of REFe2 phase, thereby maintaining magnetic isolation.
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 sandwich grain boundary structure effectively suppresses reverse domain movement, improving coercivity and magnetic isolation, maintaining high magnetic properties even with high cerium content.
Implementation Method 1
the RE-rich phase in the grain boundaries is enriched in the periphery of the main phase grains, forming the first layer of grain boundary layer
Implementation Method 2
The rare earth elements in the REFe2 phase adjacent to the first layer of grain boundary layer can precipitate out and diffuse into the RE-rich phase
Implementation Method 3
The magnetic isolation effect of the pure REFe2 phase is weak, the ability to suppress reverse domain movement in the demagnetizing field is poor, and the coercivity of the magnet is low
Data Source
AI summary
The present disclosure discloses a cerium-added RE-T-B-M series sintered neodymium-iron-boron magnet, which relates to the technical field of neodymium-iron-boron permanent magnets, the structure of the magnet contains a RE2Fe14B main phase, a RE-rich phase, a REFe2 phase, and a sandwich grain boundary phase, wherein the sandwich grain boundary phase includes a RE-rich phase, a Fe-rich phase, and a REFe2 phase, and in the sandwich grain boundary phase, starting from the side near the grains of RE2Fe14B main phase, the first layer is the RE-rich phase, the second layer is the Fe-rich phase, and the third layer is the REFe2 phase, where RE includes cerium element and at least one of other rare earth elements, and the cerium element accounts for 3.0-15.0% by mass of the total elements, T is iron element and cobalt element, B is boron element, and M is Al, Cu, Ga, and Ti elements. A cerium-added RE-T-B-M series sintered neodymium-iron-boron magnet according to the present disclosure can alleviate the negative effects on the magnet due to the addition of cerium element.