- 學位論文
以分子動力學分析奈米多層膜Au/Cu的機械性質與變形機制
Analysis of mechanical properties and deformation mechanism of multilayered Au/Cu films using molecular dynamics simulations
摘要
本文是以分子動力學法則探討奈米多層膜Au/Cu之機械性質，本文分成三大部份，分別是奈米拉伸、奈米壓縮和奈米壓痕。三大部份又分別探討三種效應:層數、速度以及溫度，並從所有的模擬試驗觀察內部結構變化。結果顯示奈米多層膜Au/Cu的材料強度會隨著層數的增加而增強;拉伸速度效應則是發現拉伸速度過快可能會使模型無法生成差排釋放應力，並直接進行破裂現象、拉伸溫度效應則是溫度越高的模型內部原子的能量越高，能量越高的模型結構越容易形成無次序性的結構;壓縮模擬試驗發現層數增加模型可以有效的釋放應力使材料可以繼續進行壓縮，速度效應發現速度過於快速會導致模型內部累積缺陷過快，並導致無法釋放應力，提早模型過壓縮;壓痕模擬試驗發現壓痕器接觸最上面一層的是Cu層的話模型硬度較高，而接觸的是Au層則是較低,改變壓痕器下降速度，壓痕器速度快模型中生成缺陷的結構改以無次序結構為主，而差排數量反而下降,改變溫度不太能改變模型材料的強度。
並列摘要
In this study, the mechanical properties of nano-multilayer Au/Cu are investigated by molecular dynamics. This article divided into three parts: tension, compression, and indentation. The multilayers, speed, and temperature effects are investigated. In addition, the structure deformations are examined. The result show that strength and yielding of material increasing with increasing the number of layers in tension experiment. For the tensile speed effect, a higher tensile speed suppresses the formation of dislocation for releasing the stress. The temperature effect shows that the energy increases with increasing temperature. The model of structure is present by other structure. The proportion of other structure is more than HCP and FCC structure; Next, The compression simulation tests show that increase of layer number can release the stress from model. The compression speed effect show that the defect is rapidly accumulated, causing it cannot release the stress to fast in the model and the model will be fast cracked; Finally, indentation simulation tests find that the model with Cu surface has a higher hardness than that Au with surface. The speed effect show that the other structure is higher rate when the indentation has been indented with high speed. We also find out the dislocation is decreased when the other structure is increased. The temperature effect show that the model’s hardness can’t be changed by temperature.
參考文獻
延伸閱讀
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