使用分子模擬研究鎳基奈米析出強化合金的塑性變形; Molecular Dynamics Study for Plastic Deformation of the Nano- Precipitate Strengthened Ni-base Alloy

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Title:	使用分子模擬研究鎳基奈米析出強化合金的塑性變形;Molecular Dynamics Study for Plastic Deformation of the Nano- Precipitate Strengthened Ni-base Alloy
Authors:	黃育立;Yu-Lih,Huang
Contributors:	化學工程與材料工程學系
Keywords:	分子動力學;析出強化;中子小角度散射;molecular dynamics;precipitation hardening;small angle neutron scattering
Date:	2013-07-30
Issue Date:	2013-08-22 11:39:01 (UTC+8)
Publisher:	國立中央大學
Abstract:	本篇論文利用中子繞射和電子掃瞄式顯微鏡所量測到的數據，建構出分子動力學模擬的系統，並將實驗單軸拉伸後的結果與電腦模擬拉伸的結果進行比較。我們利用了以下幾種分析方式:視覺化及量化分析析出相幾何參數、晶格間距的估計、中心對稱參數的分析。由以上的分析結果，可以證明我們所建構的系統和實驗上的量測有可以比較的依據。藉此了解在拉伸過程中，析出相和基材如何的交互影響，並且透過分子動力學模擬的優勢，檢視在形變過程中所發生的現象，並將現象與分析結果一起進行討論。 We have recently reported an in-situ neutron-diffraction experiments, simultaneously illuminating the diffraction of the matrix and the strengthening nano precipitates. An irreversible neutron-diffraction-profile evolution of the nano precipitates is observed. However, due to the limited measuring time, there is no conclusive trend of the nano-precipitate deformation behavior subjected to the greater stress levels. Hence, in the present work, molecular-dynamics simulations are applied to reveal the deformation mechanisms of the nano precipitate and its interaction with the surrounding matrix. The microstructure size, dislocation content, and structural parameters of the nano precipitates, quantified by X-ray, transmission electron microscopy, and small-angle neutron scattering, are used as the simulation input and reference. The simulation results show that there are two competing deformation mechanisms, which lead to the fluctuation of the nano-precipitate-diffraction widths, occurring during the higher plastic deformation stages. Based on the comparable reported measurements and the current simulated results, we successfully developed a molecular dynamics simulation approach. The development is presented in this paper.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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