使用同步輻射X光與分子動力模擬研究鋯基非晶質合金複合材料之塑性形變機制; Micromechanisms Study of a Dendrite/Zr-based Bulk-metallic-glass Composite Subjected to Plastic Deformation via In-situ Synchronou X-ray Measurements and Molecular Dynamics Simulation

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Title:	使用同步輻射X光與分子動力模擬研究鋯基非晶質合金複合材料之塑性形變機制;Micromechanisms Study of a Dendrite/Zr-based Bulk-metallic-glass Composite Subjected to Plastic Deformation via In-situ Synchronou X-ray Measurements and Molecular Dynamics Simulation
Authors:	廖哲儀;Liao,Jer-Yi
Contributors:	化學工程與材料工程學系
Keywords:	非晶質合金;同步輻射X光;分子動力模擬
Date:	2013-07-11
Issue Date:	2013-08-22 11:39:58 (UTC+8)
Publisher:	國立中央大學
Abstract:	非晶質合金在室溫時，具有高硬度，高強度、高楊氏模數與高彈性形變能力，也有良好的耐腐蝕性與耐磨耗性。但是此材料的缺點為缺乏延展性，當施加的外力超過材料的彈性形範圍時，材料就會在無預警的情形下突然斷裂，因此限制了非晶質合金的應用範圍。許多文獻藉由不同的製程方式，改良非晶質合金的延展性，本篇論文所研究的非晶質合金，也已經有增加其延展性，但由於目前影響非晶質合金延展性的機制尚不明瞭，因此本篇論文藉由不同的實驗，觀察材料在受外力時的微觀結構變化，去分析其影響的機制。本實驗先由高能量X光繞射對材料進行測量，再由分析材料所產生的繞射峰，獲得材料之晶格應變(lattice strain)。接著比照文獻，建構出本研究之材料內結晶相的模型，並由材料在不同壓縮循環時的晶格應變變化，引用文獻的機制來解釋此現象。再利用高解析掃描穿透式電子顯微鏡影像(HR-TEM)、能量散射光譜儀(EDS)、三維斷層掃描(three-dimensional tomography)與分子動力模擬(Molecular dynamics)佐證我們建構的模型與解釋機制之正確性，進而了解影響材料延展性的機制。 In the current study, a Zr-based BMG that contains a dendritic crystalline phase performs remarkably large plastic strain. The plastic-deformation micromechanisms of the dendrite/Zr-based bulk-metallic-glass-matrix composite (BMGMC) are revealed. A three-dimensional (3-D) tomography experiment was carried out using the European Synchrotron Radiation Facility (ESRF). The correlating successive images qualitatively indicate the load-sharing micromechanisms. Meanwhile, we simultaneously measured the Bragg peaks with in-situ synchrotron x-ray. During loading-unloading cycles, there is asymmetric Bragg-peak evolution subjected to different levels of deformation. The in-situ peak profile analyses suggest that there is asymmetric load sharing between the amorphous matrix and the crystalline dendrites. The relationship between the microstructures and mechanical properties of the BMGMC materials are summarized.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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