臺灣博碩士論文加值系統

純銅擁有優異的導電性質，使得銅被廣泛運用在導電材料上。然而純銅也因機械強度低、耐磨性差，使其運用在接點材料或電極材料上受到限制。本研究嘗試以純Cu、Ti、B粉末為起始原料，利用機械合金化法製造高強度、高導電度之顆粒強化型銅基材料 (TiB2/Cu)。經機械合金法製備之粉末，在還原性氣氛中熱壓燒結製成塊材。實驗結果顯示：Ti、B元素在球磨30 hr時間內，持續固溶進入銅的晶格中在30 hr球磨過程中，並無任何新相生成，TiB2強化相僅在後續退火階段中生成，而且TiB2生成量主要是與退火溫度有關，和球磨時間並無明顯關連。此外，由顯微組織觀察中可以發現增加熱壓時間將可以有效消除熱壓塊材內的孔洞。由EPMA分析中發現Ti、B二元素在塊材中的分佈位置是重疊的，而且兩者含量的原子百分比接近2：1，此現象暗示Ti、B二元素將在退火階段反應成TiB2。熱壓所得塊材之微觀結構主要是由兩種顏色對比的相組成：白色的相富含Cu；灰色的相包含Cu以及大量的Ti、B元素。由於電子漂移主要是經由富含Cu的白色區塊，所以白色相面積較大的熱壓試片將表現較佳的導電度、較低的電阻值。藉由分析塊材的硬度值，可以發現到塊材的硬度除了和白色及灰色相在塊材內的相對分佈狀況有關，也和TiB2在灰色相中的分佈狀況有關。

Pure copper has excellent electrical conduction property and uses extensively as a conductive material. However, the strength and wear property of the pure copper are so low that its use on the contact or electrode material is limited. In this study pure elemental powders of Cu, Ti, and B were used to fabricate high strength and high electric conductive Cu-based composites with TiB2 as strengthening particles by the mechanical alloying technique. The milled powders were sintered in a vacuum hot-pressing furnace in a reducing atmosphere. The experimental result shows that during the milling of the initial powders up to 30 hrs, Ti and B elements continuously dissolve into the Cu lattice. No new phases were detected in this period. TiB2 phase was only formed by the subsequent annealing. The quantity of TiB2 created depends mainly on the annealing temperature and has little dependence on the milling time. From the microstructural observation, increasing the hot-pressing time can effectively eliminate the pores present in the bulk materials. The results from EPMA analysis showed that the distribution of Ti and B elements on the Cu matrix was overlapped. Quantitative analysis showed that the relative content of these two elements was close to 2 to 1, which indicated that these two elements were combined to form TiB2 during the annealing process. The microstructure of the bulk sample has primarily two regions with different contrast. The white region is rich in Cu and the gray region contains, besides Cu, larger amount Ti and B atoms. Electron migration passes readily through the white Cu-rich region. Therefore, materials with greater white region will show greater conductivity and smaller resistivity. From the hardness values of the bulk samples, it is inferred that the hardness of the bulk sample is determined by the relative size of the white region and the gray region which contains TiB2 particles, the distribution of TiB2 in the gray region.

Table of Contents
摘要……………………………………………………………………Ⅰ
Abstract……………………………………………………………...Ⅱ
Table of Contents………………………………………………...Ⅳ
List of Figures……………………………………………………..Ⅵ
List of Tables………………………………………………….…ⅩⅡ
Chapter 1: Introduction………………………………………...1
Chapter 2: Literature Review………………………………...4
2.1 Metal Matrix Composites (MMCs) ………………………………..4
2.2 The manufacture of TiB2/Cu alloy by mechanical alloying………5
2.3 Orowan theory of dispersion strengthening…………………..…...8
2.4 The influence of microstructure on the electrical conductivity…11
Chapter 3: Experimental Procedures………………….…12
3.1 The Mechanical Alloying…………………………………………..12
3.2 X-ray Diffraction Analysis……………………………………...…13
3.3 Thermal Analysis…………………………………………………..13
3.4 Anneal Treatment………………………………………………….14
3.5 Optical Microscope Analysis………………....……………………14
3.6 Hot Pressing Process…………………………………….…………15
3.7 Electron Probe Microanalysis.……………………………………15
3.8 Resistivity Measurement…………………………………………..16
3.9 Hardness Measurement…………………………………………...17
Chapter 4: Results and Discussion………………………...18
4.1 Cu-Ti-B Powder Mixtures Subjected to Mechanical Alloying
and Subsequent Annealing Treatment…………………………..18
4.1.1 Optical Microscopic Observation of the Milled Powders……..18
4.1.2 X-ray Diffraction Analysis………………………………………19
4.1.3 Thermal Analysis………………………………………………...21
4.2 Bulk Cu-Ti-B Materials Obtained after Mechanical Milling
and Hot-pressing…………………………………………………...21
4.2.1 Optical Microscopic Observations……………………………...22
4.2.2 X-ray Diffraction Analysis………………………………………23
4.2.3 Electron Probe Microanalysis…………………………………..24
4.2.4 Resistivity Analysis………………………………………………25
4.2.5 Hardness Analysis………………………………………………..27
Chapter 5. Conclusions………………………………………...31
References…………………………………………………………..33

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