臺灣博碩士論文加值系統

摘要
本實驗採用成份為Ndx-2.5Dy2.5Febal.Co1Cu0.1B1.2 ( wt﹪) (x＝31.5、30.5、30.0及29.3)、 Nd30.5-yDyyFebal.Co1Cu0.1B1.2 ( wt﹪)(y＝2.5、3.5、5.0及9.0)及 Nd29.5-yDyyFebal.Co1Cu0.1B1.2 ( wt﹪)(y＝1.0、1.5及2.0)之薄片鑄錠，以粉末冶金的方法製造微米晶燒結 Nd-Fe-B永久磁石。探討隨稀土元素總量改變及Dy元素含量置換對磁石之磁性值及熱穩定性的影響，且比較由薄片鑄錠及薄板鑄錠製成燒結磁石之磁性質。
本實驗結果如下：
1. 在製程中發現，因為鑄錠之韌性提升，當總稀土元素含量≦30.5 wt﹪之薄片鑄錠不適用球磨粉碎來做細粉碎。
2. 總稀土元素含量減少，可增加2：14：1相之比率，且減少非磁性富釹相（Nd-rich）之量，而提升Br值及(BH)max值，但iHc也隨之下降。當合金成份為Nd26.8Dy2.5Febal.Co1Cu0.1B1.2 ( wt﹪)時，其磁性值Br＝14.12kG、iHc＝13.28kOe，而(BH)max高達47.41MGOe。
3. 當以Dy置換部分Nd含量於Nd30.5-yDyyFebal.Co1Cu0.1B1.2 ( wt﹪)合金磁石時，可提高磁石的磁異方性場，而增加其本質矯頑磁力。最佳本質矯頑磁力之磁石成份為Nd21.5Dy9Febal.Co1Cu0.1B1.2 ( wt﹪)，其磁性值Br＝12.05kG、iHc＝21.41kOe及(BH)max＝34.32MGOe；其高溫係數α＝-0.10 %/℃及β＝-0.52 %/℃；其臨界溫度（Tth）為235℃、工作溫度（Tw）高達243℃及衰退溫度（Tdeg）為256℃。
4. 當本研究所採用薄片鑄錠之總稀土元素含量(29.3 wt﹪)較薄板鑄錠少時，由於薄片鑄錠中仍無α-Fe相的生成，且2：14：1相之比率提升，使得經由薄片鑄錠製成磁石之Br及(BH)max值皆較薄板鑄錠所製得磁石為佳。比較薄片鑄錠及薄板鑄錠在相同成份為Nd29Dy2.5Febal.Co1Cu0.1B1.2 (wt﹪)所製得磁石之磁性值，發現薄片鑄錠製成磁石之Br及(BH)max較低，而iHc較高。
5. 將合金中總稀土元素及Dy含量再做調整，當合金成份為Nd28Dy1Febal.Co1Cu0.1B1.2 (wt﹪)時，磁石磁性值Br＝14.50kG、iHc＝8.74kOe及(BH)max可高達50.23 MGOe。

This research is to adopt strip casting ingots, its components being Ndx-2.5Dy2.5Febal.Co1Cu0.1B1.2 ( wt﹪)(x=31.5, 30.5, 30.0 and 29.3), Nd30.5-yDyyFebal.Co1Cu0.1B1.2 ( wt﹪)(y=2.5, 3.5, 5.0 and 9.0) and Nd29.5-yDyyFebal.Co1Cu0.1B1.2 ( wt﹪)(y=1.0, 1.5 and 2.0), to produce the Nd-Fe-B type sintered permanent magnets by powder metallurgy process. To probe into the influence of magnetic properties and thermal stability with the variation of total rare earth content and the substitution of Dy concentration. Besides, the magnetic properties of magnets manufactured with strip casting and slab casting ingots are compared.
The following results are obtained:
1. In comparison with the slab casting ingots, strip casting ingots with TRE≦30.5wt﹪is not suitable for pulverizing by ball milling process due to the increment of toughness of the ingots.
2. As reducing the total rare earth content, the Br and (BH)max of the magnets become higher due to the increase of the volume fraction of Nd2Fe14B phase and the decrease of the amount of Nd-rich phase during sintering. The optimum magnetic properties of Br=14.12kG, iHc=13.28kOe and (BH)max=47.41MGOe could be achieved in Nd26.8Dy2.5Febal.Co1Cu0.1B1.2(wt﹪) magnet。
3. The Substitution of Dy for Nd in Nd30.5-yDyyFebal.Co1Cu0.1B1.2 ( wt﹪) improves the coercivity and thermal stability of the magnet. The optimum magnetic properties of Br=12.05kG, iHc=21.41kOe, (BH)max=34.32 MGOe and the excellent work temperature of Tw=243℃ could be achieved in Nd21.5Dy9Febal.Co1Cu0.1B1.2(wt﹪) magnet。
4. Even though the total rare earth element content decreased to 29.3 wt﹪, no α-Fe phase is found in strip casting ingots. Accordingly, Br and (BH)max of sintered permanent magnets produced by strip casting ingots could be higher than those by slab casting ingots. However, with the same composition, the Br and (BH)max of magnets produced by strip casting ingots are slightly lower than those made by slab casting ingots.
5. The optimum magnetic properties of Br=14.50kG, iHc=8.74kOe and (BH)max=50.23MGOe are achieved in the rare earth lean Nd28Dy1Febal.Co1Cu0.1B1.2(wt﹪) magnet made with strip casting ingots.

目 錄
中文摘要………………………………………………………………….I
英文摘要………………………………………………………………..III
致謝……………………………………………………………………...V
目錄…………………………………………………………………… VII
表目錄………………………………………………………………….X
圖目錄………………………………………………………………….XII
第一章 緒論……………………………………………….1
1-1 前言………………………………………………1
1-2 磁性材料分類簡介….……………………………7
1-3 稀土永久磁石之發展簡介………………………10
1-4 釹鐵硼合金之顯微結構簡介………..…………....18
1-5 燒結NdFeB磁石在應用上之等級分類…………...20
1-5-1 高磁能積型..…..…………………………………...20
1-5-2 高溫型等級………………………………………...22
1-6 研究動機與目的…………………………………23
第二章 理論基礎………………………………………….25
2-1 材料磁性起源…………………………..……….25
2-2 磁性體分類……………….…………………………26
2-3 磁滯曲線………………….………………………29
2-4 稀土磁石之矯頑機制…………….……………….33
2-4-1反向磁區孕核成長型機構……………...34
2-4-2 磁區壁栓固型機構……………………….…35
2-4-2單磁區/微晶型機構….……………………35
2-5矯頑機制之基本理論……………………………..37
2-6 微關結構與本質矯頑磁力的關係…………….….44
2-6-1晶粒大小與本質矯頑磁力的關係……..…45
2-7 NdFeB系磁石自旋再轉向性質……………….48
第三章 實驗方法…………………………………………51
3-1 實驗流程………………………………………51
3-2 合金設計………………………………………53
3-3 微米晶燒結永磁材料之製備…………………54
3-3-1 母合之購置……………………………..54
3-3-2 粉碎……………………………………..54
3-3-3 填粉、振動、配向、真空封裝及冷均壓.55
3-3-4 燒結及熱處理…………………………...56
3-4 分析與量測…………………………………..57
3-4-1 磁性量測………………………………...57
3-4-2 圍觀組織………………………………57
3-4-3熱穩定性量測……………………………57
3-4-4 XRD結構鑑定…………………………58
3-4-5低溫磁性量測……………………………59
3-4-6 極圖量測………………………………..59
第四章 實驗結果與討論…………………………………………...60
4-1 球磨及氣流粉碎方法對薄片鑄錠製成燒結NdFeB磁石磁
性之影響……………………………………………60
4-2 改變稀土元素總量對燒結NdFeB磁石之合金效應……63
4-2-1薄片鑄錠的顯微結構..…………………….63
4-2-2 X-ray繞射圖及結構分析……………………65
4-2-3 室溫磁性及磁石顯微結構………………….67
4-2-4高溫穩定性 ……………………………….72
4-2-5 低溫磁性值…………………………………75
4-2-6 矯頑機制之探討……………………………..80
4-3 置換Dy元素對燒結NdFeB磁石之合金效應…85
4-3-1薄片鑄錠的顯微結構………………………85
4-3-2 X-ray繞射圖及結構分析..………………86
4-3-3 室溫磁性及磁石顯微結構……..…..……89
4-3-4 高溫穩定性…….……………………..97
4-3-5低溫磁性值……………..……………99
4-3-6 矯頑機制之探討…….………………104
4-3-7 氫脆粉碎及機械粉碎方法對薄片鑄錠製成燒
結NdFeB磁石磁性之影響…………107
4-3-8 極圖量測………..……………………. ..110
4-4 薄片鑄錠與薄板鑄錠製成磁石之磁性比較……114
4-5 高性能永久磁石………………………………117
第五章 結論………………………………………………….118
第六章 參考文獻…………………………………………….121

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