極細晶材料中，雖然可以藉由晶粒細化得到較高的強度，但同時也會降低材料的延展性。過去研究指出具有雙峰晶粒徑分布的純銅，同時具有高強度及較佳的延展性。本研究利用電鍍製備層狀結構的純鎳試片，藉由控制鍍層的晶粒徑得到具有雙峰晶粒徑分布的顯微組織，探討具有雙峰晶粒徑分布試片的機械性質。由EBSD的分析結果可知，本實驗透過電鍍參數的調控，成功製備出粗晶與細晶的面積比為3~ 0.3的試片。其中細晶區平均晶粒徑約為0.5 μm，粗晶區平均晶粒徑最大達6.0 μm。拉伸試驗結果顯示，於次微米粒徑晶粒中摻雜約35 %的微米晶粒，材料可擁有較佳的強度和延展性，但是當微米粒徑晶粒面積比為62.5 %，其機械性質則與一般電鍍試片差異不大。對純鎳試片而言，雙峰晶粒徑分布對於延展性的提升只有頸縮後伸長量(post uniform elongation)的部分。此外，本研究發現當電鍍之層狀鍍層試片，在經由適當的溫度進行退火熱處理之後，其強度及延展性皆會增加。

The strength of the ultrafine-grained materials is increased with grain refinement, but it will also reduce the ductility. In the previous study, there are higher strength and better ductility for the copper with bimodal distribution of grain size. In this study, Ni with lamellar structure is fabricated by electrodeposition in order to explore the mechanical properties of the materials with bimodal distribution of grain size, which is obtained by controlling the grain size. From the result of EBSD analysis, it shows that the area ratio of coarse grains and fine grains is from 0.3 to 3 by changing the plating parameters. The average grain size of fine grains is about 0.5 μm, and the maximum average grain size of coarse grains is up to 6.0 μm. From the result of tensile test, the materials with 35% of micro-grains embedded regularly inside a matrix of ultrafine grains have better strength and ductility. When the area ratio of micro-grains is up to 62.5%, there is no difference in mechanical properties between the general electrodeposited materials and ones with bimodal distribution of grain size. For pure Ni, the enhancement of ductility for bimodal distribution of grain size is only in post uniform elongation. Otherwise, it is found that the strength and ductility of the material with lamellar structure are increased through the heat treatmeant under the appropriate temperature.

一、 前言 1
二、 文獻回顧 3
2-1 電鍍原理 3
2-1-1 極化 3
2-1-2 法拉第定律 4
2-1-3 脈衝電鍍 5
2-2 微米與奈米材料的機械性質 6
2-2-1變形機制 6
2-2-1-1 堆積理論與Hall-Petch關係式 6
2-2-1-2 晶界滑移 8
2-2-1-3 晶界之差排生成與消失 9
2-2-2 提升微奈米材料延展性的方法 9
2-2-3 雙峰晶粒徑分布與延展性 11
2-2-4 應變硬化與延展性 13
2-3 晶界、晶粒徑與材料變形 14
三、 實驗方法 17
3-1 實驗流程 17
3-2 電鍍製程 17
3-3 微硬度量測 18
3-4 X光繞射分析 18
3-5 冷軋處理 19
3-6 拉伸試驗 19
3-7 退火熱處理 19
3-8 拉伸試片橫截面二次電子影像 19
3-9 背向散射電子繞射分析 20
3-10 穿透式電子顯微鏡分析 20
四、 實驗結果 21
4-1 電鍍試片製備 21
4-2 微結構分析 23
4-2-1 EBSD分析 23
4-2-1-1 層狀鍍層L5試片 25
4-2-1-2 層狀鍍層L9試片 26
4-2-1-3 脈衝試片(P) 27
4-2-1-4 直流電鍍(DC)與冷軋後退火試片(400、500、600) 27
4-2-1-5 冷軋之直流電鍍試片(R) 28
4-2-2 TEM分析 29
4-3 機械性質分析 29
4-3-1 層狀鍍層L5試片 30
4-3-2 層狀鍍層L9試片 30
4-3-3 脈衝試片(P) 30
4-3-4 冷軋之直流電鍍試片(R) 31
4-3-5 直流電鍍(DC)及冷軋後退火(400)試片 31
4-4 拉伸試片斷裂面 31
五、 討論 33
5-1 晶粒徑分析與機械性質 33
5-2 晶粒定義與取向差 36
5-3 雙峰晶粒徑分布及顯微組織 36
5-4 Hall-Petch關係式 37
5-5 電鍍製程缺陷 38
5-6 晶粒大小量測方式 38
六、 結論 40
七、 參考文獻 41

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