LaCe-Rich NdFeB Magnet Grain Boundary Design for High Coercivity
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Solution Overview
Problem
The challenge is to prepare a high-performance neodymium-iron-boron magnet rich in La and Ce that reduces production costs and facilitates sustainable utilization of rare earth resources while maintaining or enhancing magnetic properties, without relying on heavy rare earth elements.
Innovation Solution
A method involving separate smelting and casting of LaCe-free and HRE-free main and auxiliary phase alloys, followed by mixing, pressing, and sintering, with a subsequent diffusion treatment to enrich La and Ce in the grain boundary phase, enhancing coercivity and magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional sintering methods are used for NdFeB magnets, then manufacturing cost is reduced, but coercivity and magnetic performance deteriorate
Solution Approach 1:
The patent applies parameter changes by modifying the sintering temperature (reducing from conventional high temperatures to 900-1100°C) and controlling the cooling rate (5-10°C/min) to achieve both cost reduction and maintenance of high coercivity properties in the NdFeB magnet
Solution Approach 2:
The patent uses composite materials by incorporating grain boundary phase compositions (such as Cu, Al, Ga, or their combinations) into the NdFeB matrix, creating a composite structure that enhances coercivity while allowing lower-cost conventional sintering processes
2Reliability
If high-coercivity methods are used for NdFeB magnets, then magnetic performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent optimizes sintering parameters (temperature range 900-1100°C, holding time 5-15 minutes) and cooling rates (5-10°C/min) to achieve high coercivity without requiring expensive ultra-high-temperature or multi-stage sintering processes
Solution Approach 2:
The patent applies local quality by creating a specific grain boundary phase distribution with controlled composition (Cu, Al, Ga, or combinations) that locally enhances coercivity at grain boundaries while maintaining overall cost-effectiveness
3Reliability
If lace-rich structure is created in NdFeB magnet, then coercivity is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-alloying the grain boundary phase elements (Cu, Al, Ga, or combinations) into the NdFeB composition before sintering, which automatically forms the desired lace-rich structure during the sintering process without requiring subsequent complex heat treatment or surface modification steps
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
This approach effectively avoids performance reductions due to LaCe entering main phase grains, reduces manufacturing costs, and promotes balanced utilization of rare earth resources by improving coercivity and magnetic properties through enhanced grain boundary phase distribution and HRE diffusion.
Implementation Method 1
high-coercivity lace-rich neodymium-iron-boron permanent magnet... comprising a matrix phase and a grain boundary phase... where the grain boundary phase has a lace-rich structure
Implementation Method 2
The invention provides a low-cost high-coercivity lace-rich neodymium-iron-boron permanent magnet... comprising a matrix phase and a grain boundary phase
Implementation Method 3
the sintering, the cooling rate is controlled at 5-10°C/min
Data Source
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Figure 3~4
AI summary
Disclosed in the present disclosure are a low-cost high-coercivity LaCe-rich neodymium-iron-boron permanent magnet, and a preparation method therefor and the use thereof. The permanent magnet is prepared by mixing and sintering an LaCe-free and HRE-free neodymium-iron-boron main phase alloy and an LaCe-M alloy. In the present disclosure, an LaCe-free main phase alloy and an LaCe-M auxiliary phase alloy are respectively smelted at first, and then, same are subjected to powder preparation, mixing, pressing, and sintering, such that a the performance reduction performance defect of a magnet caused by LaCe entering main phase crystal grains is effectively avoided; and moreover, the manufacturing cost of the magnet is reduced, and the balanced and sustainable utilization of rare earth resources is realized. Moreover, in the present disclosure, the depth and concentration of HRE diffused into the magnet are effectively improved by using the characteristics of a low melting point and high flowability of an LaCe-rich crystal boundary phase, thereby facilitating improving the uniformity of components and structure distribution in the magnet.