使用中子/同步輻射及機械性能測試對兩相材料之塑性研究; Microplasticity Study of Advanced Structural Materials Coupling Neutron/Synchrotron Scattering with Mechanical Testing

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題名:	使用中子/同步輻射及機械性能測試對兩相材料之塑性研究;Microplasticity Study of Advanced Structural Materials Coupling Neutron/Synchrotron Scattering with Mechanical Testing
作者:	黃爾文
貢獻者:	化學工程與材料工程學系
關鍵詞:	材料科技
日期:	2010-08-01
上傳時間:	2011-07-11 17:59:26 (UTC+8)
出版者:	行政院國家科學委員會
摘要:	金屬玻璃(MGs)擁有獨特的機械性能，包括了: 超高的強度，極低的磨耗，極大的彈性區間，同時，在對抗疲勞與腐蝕都有異於一般傳統金屬材料的優勢。但是，在室溫下，其有限的延展性與隨之而來的破裂，尤其是在拉伸方向的極有限的延性，大大地減低了金屬玻璃實用的價值。近來，一個新興的玻璃金屬基材複合材料(BMGMCs)，似乎能解決前述MGs 的延性問題。可是，目前為止，並沒有一個完整的機制能把這所觀測到的延性成因解釋清楚。本研究計畫使用中子/同步輻射繞射以及巨觀的機械性能測試來探討其成因。透過繞射的實驗，我們可以藉由繞射峰的位置隨巨觀形變的改變，推算出晶格的應變。同時，透過對繞射峰形的分析，我們可以推估塑變所造成的微結構變化。由這兩個微觀尺度的資訊，我們可以再進一步的和巨觀的機械性能與隨之而來的吸(放)熱量測做計算，進而可了解形變過程中，以塑變形式儲存的形變量。從計劃的執行而言，本研究將綜合，實驗與理論計算兩部分，以研究塑變與相應的析出相與基材之間的交互作用。為了將兩相間的交互作用研究系統化，本計畫會研究另一個經奈米析出相強化的合金以作為比較。首先，透過對超合金的研究，我們可逐步建立微觀與巨觀參數於塑變過程中的變化關係，並且以理論模型加以分析，了解兩相 (奈米晶相與基材晶相)之間的交互作用。進而作為BMGMCs 研究的參考。接著，我們再藉由超合金建立起的研究模型，來研究BMGMCs。如此一來，我們就可驗證已被觀測到的部份機制，包含了: 塑變引進晶化機制對非晶相基材的合理性。除此之外，我們還可多加比較，環境溫度，形變模式等對形變機制的影響。透過以上對兩種兩相合金的系統化比較，我們可以逐步推估出塑變的機制，進而對未來結構材料的設計，提供了具體參考的參數。通過本計劃，將建立起對塑變以及基材與析出相(兩相)反應間的量化資訊。此資訊將有利於拓展未來設計先進結構材料時，權衡相矛盾參數間的機制。本計劃亦將有助於推廣並訓練學生，結合實驗與計算的能力。更細節的部份，學生們還可以學習到，如何設計機械性能試驗，分析繞射數據，並統整以上的資訊，來作微觀機制對巨觀性能的理論描述。 Metallic Glasses (MGs) demonstrate very unique mechanical properties, such as large elastic deformation limits, good fatigue and corrosion resistances. However, poor room-temperature ductility and catastrophic failure, especially in tension, severely limit MGs’ application. Recently, the crystalline precipitates within the bulk-metallic-glass-matrix composites (BMGMCs) seem to be able to enhance the ductility. However, the universal mechanism to describe the ductility of BMGMCs under plastic deformation is still unclear. The present research proposal addresses this question by studying the fundamental deformation mechanisms of BMGMCs and their interactions at different time and length scales through the coupled neutron/synchrotron diffraction and mechanical testing. The goal is to develop a new mesoscale model of BMGMC plasticity. The diffraction results will yield both the elastic interactions from the diffraction-peak-position evolution and the plastic information from the evolution of the peak profile. The microscopic variables will be compared with the bulk mechanical measurements and the heat evolution to describe the damage accumulation. A joint experimental and theoretical modeling effort is proposed to study the plasticity and interplay between the strengthening phase and the matrix in both of the BMGMC and the nano-precipitate-strengthening superalloys, as reference. First, by experimentally examining the behavior of the nano-precipitate-strengthening superalloys coupling the in-situ neutron diffraction and comparing it to macrostructually-based thermal mechanical responses on crystal plasticity, a detailed reference of the joined deformation and micro-plasticity processes will be developed from which it will be possible to make the reference to the aforementioned BMGMCs’ plasticity. Second, the validity of mechanical-deformation-induced crystallization for the BMGMCs will be examined, and a parametric map will be built to outline the dependence of the environmental temperature and deformation modes on the plasticity of the BMGMCs. Moreover, the comparisons of the above two types of the two-phases metallic alloys, we can investigate the plasticity in terms of the microstructure mechanisms for the design of the future structural metallic materials. The ability to quantitatively describe the plasticity and the interaction between the precipitate and the matrix phases is a critical step towards a mechanistic understanding of deformation properties, as well as ductility and toughness enhancement methods of the advanced structural materials. The proposed research will provide excellent an opportunity for the graduate and undergraduate students to participate in an experimental/computing synergistic research that includes micromechanisms investigating, advanced mechanical testing, and diffraction characterization 研究期間：9908 ~ 10007
關聯:	財團法人國家實驗研究院科技政策研究與資訊中心
顯示於類別:	[化學工程與材料工程學系 ] 研究計畫

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