本論文係使用熱膨脹儀對高熵超合金(Al10Ti0.5Cr7Co17Ni60Nb2Mo2W1.5)於常溫(25℃)及高溫(800℃)下進行準靜態荷載之壓縮試驗，以研究其巨觀變形特性與微觀結構。其實驗參數將溫度條件設定為25℃及800℃；應變速率條件設定為0.001s-1、0.1s-1及1s-1。將巨觀分析之機械性質，配合光學顯微鏡(OM)及穿透式電子顯微鏡(TEM)所觀察之微觀結構，建立巨觀與微觀研究之關聯性，最後透過構成方程式模擬材料巨觀特性，以配合工程上之實際運用。
於巨觀研究結果中，可知高熵超合金(Al10Ti0.5Cr7Co17Ni60Nb2Mo2W1.5)於相同應變速率下，會因溫度升高使塑流應力值、加工硬化率、應變速率敏感性係數與理論溫升量下降，而熱活化體積上升；於固定溫度下，會因應變速率增加使熱活化體積下降，而塑流應力值、加工硬化率、應變速率敏感性係數、溫度敏感性係數與理論溫升量上升。將本材料變形行為透過Johnson-Cook model加以模擬，其結果顯示可準確模擬材料於實際情況下之變形行為。
經由光學顯微鏡之微觀觀察分析，可發現在所有測試條件下，均有γ’析出強化相與M6C、M23C6、MC等碳化物強化相，而於高溫環境中強化組織無大量消失，故材料仍可保持一定的高溫強度；透過穿透式電子顯微鏡可觀察到，隨著應變量上升與溫度下降而使差排密度增加，且γ’相有明顯阻擋差排滑移之現象。結合巨觀與微觀實驗結果證明，本材料可經由Bailey-Hirsch type準確描述塑流應力與差排密度間之關係。
關鍵字：高熵超合金、低應變速率、熱膨脹儀、準靜態壓縮、塑流應力值、差排

In this thesis, the quasi-static compression properties and microstructure of the high entropy superalloy (HESA), Al10Ti0.5Cr7Co17Ni60Nb2Mo2W1.5, studied at different temperatures of 25 °C, 800 °C and low strain rate from 0.001s-1 to 1s-1 using the deformation dilatometer.
The results indicate that under the same temperature conditions, the flow stress, work hardening rate, strain rate sensitivity coefficient, temperature sensitivity and theoretical rising temperature of Al10Ti0.5Cr7Co17Ni60Nb2Mo2W1.5, all increase with the increasing strain rate, but decrease with the increasing temperature. However, the thermal activation volume and the activation energy have a completely opposite tendency. The Johnson-Cook model on Al10Ti0.5Cr7Co17Ni60Nb2Mo2W1.5 can be used to describe the deformation behavior.
The optical microstructure shows that the Al10Ti0.5Cr7Co17Ni60Nb2Mo2W1.5 has the precipitation hardening structure, γ’ phase, and carbide-strengthening structure such as M6C, M23C6, MC etc. at all conditions. As the temperature rises, γ' is dissolved back into the base phase, so there is more γ' phase structure at room temperature. However, the strengthened structure of the material does not disappear in a large amount at high temperature, so it still maintains good high temperature strength.
The transmission electron microscope observations indicate that the dislocation density decreases as the temperature is increased or the strain rate is decreased. And found that the strengthened phase γ' in this material has the phenomenon of resisting dislocation slip. Finally, the relationship between the stress and the dislocation density can be explained by using the Bailey-Hirsch equation accurately.
Key words: high entropy superalloy (HESA), low strain rate, the deformation dilatometer, Quasi-static deformation, dislocation density

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