Nd-Fe-B Casting Strips with Nucleation-Assisted Grain Refinement
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Solution Overview
Problem
Current methods for preparing sintered neodymium-iron-boron (Nd-Fe-B) magnetic materials face challenges in improving the microstructure of alloy casting strips, which directly affects the magnetic properties of the final products, as existing techniques are not effective in enhancing the material's microstructure during the strip casting process.
Innovation Solution
The method involves using nucleation-assisted alloy particles with specific compositions, such as Pr-Nd, Fe, and B, to improve the microstructure of Nd-Fe-B alloy casting strips by controlling the addition time and smelting conditions, facilitating the formation of tetragonal-phase columnar crystals and enhancing the coercivity of the magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional smelting methods are used to prepare Nd-Fe-B alloy casting strips, then the production process is simple, but the microstructure quality and magnetic properties of the final products are insufficient
Solution Approach 1:
The patent applies preliminary action by preparing nucleation-assisted alloy particles in advance before the main smelting process. These pre-prepared particles with specific compositions (Pr-Nd-Fe-B) are stored and then added to the molten alloy at the appropriate time to induce controlled nucleation and improve microstructure quality without complicating the overall process
Solution Approach 2:
The nucleation-assisted alloy particles serve as an intermediary substance that mediates between the molten alloy and the desired microstructure. These particles act as nucleation sites that facilitate controlled crystal formation, improving the microstructure quality of the casting strips while maintaining process simplicity
2Strength
If nucleation-assisted alloy particles are added during smelting, then the intrinsic coercivity of magnets is improved, but the residual magnetism is slightly reduced
Solution Approach 1:
The patent applies parameter changes by carefully controlling the composition parameters of the nucleation-assisted alloy particles (specific ratios of Pr-Nd, Fe, and B) and the addition timing during smelting. By adjusting these parameters, the process achieves improved intrinsic coercivity while minimizing the reduction in residual magnetism through optimized particle composition and addition rate
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 significantly improves the metallographic phase quality and intrinsic coercivity of the magnets while slightly reducing residual magnetism, leading to better magnetic performance.
Implementation Method 1
nucleation-assisted alloy particles...facilitating the formation of tetragonal-phase columnar crystals
Implementation Method 2
facilitating the formation of tetragonal-phase columnar crystals
Data Source
Figure 1(a)~2(b)
AI summary
The present disclosure belongs to the technical field of preparation of rare earth permanent magnetic materials, and in particular, relates to a preparation method of improved sintered neodymium-iron-boron (Nd-Fe-B) casting strips. The preparation method includes the following steps: firstly nucleation assisted alloy particles used for sintered Nd-Fe-B casting strips are prepared, all elements are weighted as follows: 26.68-28% of Pr-Nd, 70-72.5% of Fe and 0.90-1% of B, and a Pr element in two elements of Pr-Nd accounts for 0-30wt%; the compounded materials are smelted and poured through a conventional technology to obtain alloy strips, then the alloy strips are crushed into particles with diameter of 1-10mm by a mechanical crushing method, to be used as nucleation assisted alloy particles used for the sintered Nd-Fe-B casting strips; secondly, Nd-Fe-B casting strips are prepared: the prepared intermediate materials are smelted and melted into molten steel according to a conventional sintered Nd-Fe-B smelting technology, and then are refined; after the intermediate materials are fully melted, the nucleation assisted alloy particles are added according to the weight percent of 3-6 wt%; and after the nucleation assisted alloy particles are added, smelting is performed for 3-15 minutes under the condition that power is reduced by 150-250 KW, pouring is performed, and final Nd-Fe-B alloy casting strips are obtained. The metallographic phase quality of the Nd-Fe-B casting strips prepared by the technology and the technique is obviously improved, and the intrinsic coercivity Hcj of magnet finished products prepared by the casting strips is obviously improved.