以稀土過渡金屬合金粉對燒結NdFeB磁體晶界擴散及磁性強化效應之研究

Magnetic properties enhancement of sintered NdFeB magnets by grain boundary diffusion with alloy powders of rare earth element and transition metal

陳傳欣

指導教授 ： 張文成

國立中正大學/理學院/物理學系/碩士(2016年)

摘要

本實驗探討以不同成分之低熔點合金粉為擴散源對5 mm厚度燒結釹鐵硼磁石晶界擴散效應和磁特性的影響以及對添加不同過渡元素之稀土合金粉之抗氧化能力進行研究。第一部分探討添加Cu、Co、Al的稀土合金粉對磁石晶界擴散效應。結果顯示相同合金材料在相同熱處理條件下，隨著合金熔點下降，合金粉流動性增加，擴散效率提高，磁石的本質矯頑磁力(iHc)也隨之提升。不同擴散源中TbCu合金粉之效益高於 TbAl 、TbCo合金粉，Tb0.75Cu0.25合金粉最高可提升磁石iHc達10.8 kOe。而輕稀土Nd、Pr添加Cu進行晶界擴散效益也較其添加Co的合金粉來得好，其中沾覆Pr0.7Cu0.3合金粉進行晶界擴散其本質矯頑磁力可提升3.5KOe。第二部分探討添加Co或Cu的Tb或Dy合金粉作為擴散源之抗氧化能力。結果顯示將平均粒徑約30 m的合金粉靜置在大氣下五天，添加Co的重稀土合金粉抗氧化能力較佳。第三部分探討不同磁石在高溫環境下的磁特性，以TbCu合金粉作為擴散源之M (iHc=15-17 kOe)等級燒結 NdFeB 磁石室溫下iHc可達到商業UH磁石等級(iHc=24-26 kOe)，且結果顯示其在高溫特性的表現上也很優異。

關鍵字

稀土合金粉 ； 晶界擴散 ； 燒結釹鐵硼磁石

並列摘要

This study investigated the effect of various low melting point rare earth alloy powders on the grain boundary diffusion efficiency and magnetic properties for 5-mm thickness sintered NdFeB magnet. The first part discusses the effect of Cu, Co, Al-containing heavy rare earth alloy powder on the grain boundary diffusion efficiency. Under the same heat treatment conditions, the intrinsic coercive force (iHc) of the magnet was enhanced with the decrease of melting point of the alloy powders due to the increased flow ability during diffusion. The effectiveness of TbCu alloy powders is better than TbAl or TbCo alloy powders, the optimal ∆iHc of 10.8 kOe could be obtained for the case of using Tb0.75Cu0.25 powders. In contrast, for the same light rare earth M (Pr or Nd), the effect of MCu powders is better than MCo powders. The optimal ∆iHc of 3.5 kOe was obtained for the case of using Pr0.7Cu0.3 powders. The second part compares the antioxidation capability of DyCu, DyCo, TbCu and TbCo powders. It was found that average particle size of about 30 μm alloy powders were capable to sustain the atmosphere for five days without degrading the diffusion efficiency and the intrinsic coercivity. Among them, Co-containing rare earth powders are superior to those of Cu- containing rare earth powders. The third part investigates the magnetic properties of GBD-NdFeB magnets at high temperatures. Results show that using TbCu alloy powder as a diffusion source on M-grade (iHc=15-17 kOe) sintered NdFeB magnet can level up its room temperature iHc to UH-grade (iHc=24-26 kOe), and it has great magnetic properties at high temperatures.

並列關鍵字

rare earth alloy powder ； grain boundary diffusion ； sintered NdFeB magnet

參考文獻

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