Fe-B熔體可鑄造成網絡狀合金的微觀結構。研究顯示，熔融狀態的Fe₈₄B₁₆在275 K 過冷時將發生形態轉變。實驗結果指出熔融狀態的Fe-B合金存在一亞穏液態互溶區。該互溶區範圍為Fe₈₄B₁₄.到Fe₈₂B₁₈.。Fe-B網絡狀合金的微觀結構，由一個易碎的Fe₃B子網絡和一個具延展性的αFe子網絡組成。因此Fe-B網絡狀合金擁有具吸引性的物理性能。 / 由於Fe₈₄B₁₆網絡狀合金並不存在任何微孔，因此我們可推斷合金在結晶的過程中，兩個子網絡的固體/液體界面將一起生長。而且，在固體/液體界面前並不具有硼原子的濃度梯度。因此我們提出了一個生長模型來分析Fe-B網絡狀合金來自掃瞄電子顯微鏡和透射電子顯微鏡的檢測結果。Fe-B網絡狀合金的結晶動力學和微觀結構均得到解釋。研究顯示，合金中的兩個子網絡均擁有特定的生長方向，並且以樹枝晶的方式來生長。 / Molten Fe₁₀₀-{U+2093}B{U+2093} melts, where x = 14 to 18, can be cast into ingots of network morphology. It was found that there is a morphological transition in molten Fe₈₄B₁₆.with undercooling of 275 K. The experimental results indicate that there is a metastable liquid miscibility gap in undercooled Fe-B melts. The network morphology consists of two interconnected subnetworks, which are αFe subnetwork and Fe₃B subnetwork respectively. The Fe-B network alloys have attractive mechanical properties. / As micropore does not exist in the Fe₈₄B₁₆ network ingot, it is proposed that the solid/liquid interfaces of the two subnetworks advance together during solidification. In addition, there is no composition gradient of boron atoms at the growth front. A growth model is proposed to explain the results by scanning electron microscopy and transmission electron microscopy. It was found that there is special crystallinity in Fe₈₄B₁₆ network ingots. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wong, Tak Cheung = 鐵硼網狀合金的形成和結晶動力學 / 黃德彰. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references. / Abstracts also in Chinese. / Wong, Tak Cheung = Tie peng wang zhuang he jin de xing cheng he jie jing dong li xue / Huang Dezhang. / Abstract --- p.ii / Acknowledge --- p.iv / List of Table --- p.vii / List of Figures --- p.viii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Phase diagram --- p.1 / Chapter 1.1.1 --- Undercooling --- p.1 / Chapter 1.2 --- Nucleation and Growth --- p.2 / Chapter 1.2.1 --- Homogeneous Nucleation --- p.3 / Chapter 1.2.2 --- Heterogeneous Nucleation --- p.3 / Chapter 1.2.3 --- Growth --- p.6 / Chapter 1.2.3.1 --- Growth of Pure Metal --- p.6 / Chapter 1.2.3.2 --- Solid/Liquid interface stability --- p.7 / Chapter 1.2.3.3 --- Solidification of Single Phase Binary Alloys --- p.8 / Chapter 1.2.3.3.1 --- Equilibrium Solidification --- p.8 / Chapter 1.2.3.3.2 --- Non-Equilibrium Solidification --- p.8 / Chapter 1.2.3.3.3 --- Morphology Change --- p.9 / Chapter 1.2.3.4 --- Solidification of the Binary Eutectic Alloy --- p.10 / Chapter 1.2.3.4.1 --- Growth of Lamellar Eutectics --- p.10 / Chapter 1.2.3.4.2 --- Off-Eutectic Alloys --- p.11 / Chapter 1.3 --- Binary Systems with a Solid Miscibility Gap --- p.11 / Chapter 1.4 --- Phase Separation Mechanisms in a Solid Miscibility Gap --- p.12 / Chapter 1.4.1 --- Nucleation and Growth --- p.12 / Chapter 1.4.2 --- Spinodal Decomposition --- p.13 / Chapter 1.4.4.1 --- The initiation of Spinodal Decomposition --- p.13 / Chapter 1.4.4.2 --- Diffusion Equation of Spinodal Decomposition --- p.14 / Chapter 1.4.4.3 --- Solution to the Modified Diffusion Equation --- p.17 / Figures --- p.18 / References / Chapter Chapter 2 --- Experimental --- p.29 / Chapter 2.1 --- Preparation of fused silica tube --- p.29 / Chapter 2.2 --- Alloying and fluxing --- p.29 / Chapter 2.3 --- Undercooling --- p.30 / Chapter 2.4 --- Sample Preparation --- p.31 / Chapter 2.4.1 --- Cutting, Grinding and Polishing --- p.31 / Chapter 2.4.2 --- Sample preparation for Scanning Electron Microscopy (SEM) --- p.32 / Chapter 2.4.3 --- Sample preparation for Transmission Electron Microscopy (TEM) --- p.32 / Chapter 2.5 --- Microhardness Test --- p.33 / Chapter 2.6 --- Compression Test --- p.33 / Chapter 2.7 --- Microstructure Analysis --- p.34 / Chapter 2.7.1 --- Scanning Electron Microscopy Analysis --- p.34 / Chapter 2.7.2 --- Transmission Electron Microscopy Analysis --- p.34 / Chapter 2.7.3 --- Indexing Diffraction Patterns --- p.34 / Figures --- p.36 / Chapter Chapter 3 --- Formation of Fe-B network alloys --- p.38 / Chapter 3.1 --- Abstract --- p.38 / Chapter 3.2 --- Introduction --- p.39 / Chapter 3.3 --- Experimental --- p.40 / Chapter 3.4 --- Results --- p.42 / Chapter 3.5 --- Discussion --- p.47 / Chapter 3.6 --- Conclusions --- p.48 / Figures --- p.50 / References --- p.69 / Chapter Chapter 4 --- SEM and TEM studies of Fe84B16 70 alloys of network morphology --- p.70 / Chapter 4.1 --- Abstract --- p.70 / Chapter 4.2 --- Introduction --- p.71 / Chapter 4.3 --- Background --- p.71 / Chapter 4.4 --- Experimental --- p.73 / Chapter 4.5 --- Results --- p.74 / Chapter 4.6 --- Discussions --- p.81 / Chapter 4.7 --- Conclusions --- p.85 / Figures --- p.87 / References --- p.106
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_328592 |
| Date | January 2012 |
| Contributors | Wong, Tak Cheung., Chinese University of Hong Kong Graduate School. Division of Physics. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, bibliography |
| Format | electronic resource, electronic resource, remote, 1 online resource (1 v. (various pagings)) : ill. (some col.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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