類高熵材料系統中嚴重晶格扭曲效應對熱傳導係數之研究

Lattice Distortion Effect on the Thermal Conductivity in High Entropy Materials Systems

林建豪(Chien-Hao Lin)

指導教授 ： 羅友杰

國立交通大學/工學院/材料科學與工程系所/碩士(2019年)

摘要

近年來許多研究指出，高熵材料因其優秀的熱性能而成為全新的抗輻射材料選擇。然而迄今為止，熱性質與高熵材料中的晶格扭曲效應之間的相關性仍未被充份地釐清。眾所皆知，熱能的傳導是藉由聲子與電子的振動來達成能量轉移的過程。因此晶格扭曲效應所造成的晶格不規則排列勢必會影響熱傳導的過程。故我們透過計算模擬來研究，以保證我們能排除其他因素，只觀察到晶格扭曲效應所帶來的影響。我們使用分子動力學(Molecular Dynamic, MD)模擬方法創建一個具有不同大小原子且具有相同原子化學勢的尺寸可控系統，藉此來模擬原子尺寸差異所引起的嚴重晶格扭曲效應。我們應用Lennard-Jones位能來描述原子間的相互作用。另一方面，我們利用Green-Kubo方法計算熱傳導係數。藉此我們可以討論嚴重晶格扭曲效應對熱傳導係數的影響。此外我們在不同的晶格扭曲系統中設置不同的溫度條件，以研究熱傳導係數的依賴性。

關鍵字

分子模擬 ； 熱傳導係數 ； 高熵合金 ； 分子動力學

並列摘要

Recently, researches have shown that High Entropy Materials are the novel materials for radiation tolerant application because of its promising thermal properties. However, the correlation between thermal properties and lattice distortion remains unclear to date. It has been well-known that thermal energy is transported away by vibration of phonons and electrons. Therefore, how the lattice distortion affects the thermal conductivity can be investigated by computer simulations: Molecular Dynamics. Here we create a system with different size of atoms. In order to focus on the lattice distortion due to atomic size difference alone, we applied Lennard-Jones potential to describe the interatomic interaction and created a size-controllable system with the same chemical potential of atoms.
As a result, we can discuss the effect of lattice distortion on thermal conductivity. Furthermore, we set different temperatures condition in different lattice distortion system to investigate the dependence of thermal conductivity.

並列關鍵字

High entropy allioy ； thermal conductivity ； molecular dynamics ； LAMMPS

參考文獻

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