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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/88961
標題: | AA7075 鋁合金之人工時效對溫成形及烤漆之奈米析出物以及機械性質研究 A study on Precipitation evolution and Mechanical property of artificial aged AA7075 followed by warm forming and paint baking treatment |
作者: | 鄒翔琳 Hsiang-Lin Tsou |
指導教授: | 楊哲人 Jer-Ren Yang |
關鍵字: | AA7075 鋁合金,η' 析出物,η 析出物,T6 時效,GP zone,穿透式電子顯微鏡,溫成形及烤漆, AA7075 aluminum alloys,η' precipitates,η precipitates,T6 artificial aging,GP zone,TEM,Warm forming and paint baking, |
出版年 : | 2023 |
學位: | 碩士 |
摘要: | 本篇論文探討7075鋁合金之熱處理對於析出物及機械性質的影響,藉由不同時間之人工時效,比較出對於後續之溫成型與烤漆熱處理之影響,透過量化析出物以及觀察析出物之演化,詳細探討析出物經過不同熱處理對於析出強化的貢獻。
於人工時效的階段,主要析出強化相為η' 析出物,透過穿透式顯微鏡 (Transmission Electron Microscope, TEM)量化析出物,探討尺寸大小、數量密度、與體積分率對於機械性質引響,並且利用TEM進行析出物鑑定。量化結果分析顯示尺寸大小、數量密度、與體積分率隨人工時效時間增長而增加,因此T6時效階段達到最高機械強度。除此之外,透過量化析出物可得人工時效能增加η' 析出物的熱穩定性,引響後續溫成型與烤漆熱處理之析出行為。 透過量化分析,可得η' 析出物經人工時效十小時與溫成型及烤漆熱處理可得最大尺寸約5 nm之長度,且機械強度接近T6時效階段,而超過十小時之人工時效後,進行溫成型與烤漆熱處理導致η' 析出物尺寸、數量密度、與體積分率遞減,因為較長人工時效使析出物具有穩定性,所以在溫成型階段不易熔回基地,導致烤漆階段之η' 為新析出,而具有穩定性之η' 析出則生長成η 析出物,從量化分析結果也可得知η 析出物之尺寸、數量密度、與體積分率都在增加。 This study investigates the influence of heat treatments on the precipitation behaviors and mechanical properties in 7075 aluminum alloys. Various time durations of artificial aging time are conducted to observe the effect of artificial aging on warm forming and paint baking heat treatments. By quantifying precipitates and observing precipitation evolutions, this research discusses the strengthening of precipitates undergoing through artificial aging followed by warm forming and paint baking heat treatments. η' precipitates are the dominant strengthening phase during artificial aging stage. Thus, Transmission Electron Microscopy is utilized to analyze and quantify the sizes, number density, and the volume percent of η' precipitates regarding to the mechanical properties. Meanwhile, TEM also identifies the structure of the precipitates. The quantification result showed that the sizes, number density, and the volume percent of η' precipitates increase with longer artificial aging time. Hence, T6 heat treatments yield the highest mechanical strength. Meanwhile, η' precipitates gain thermal stability according to quantifying results affecting the precipitation behavior during warm forming and paint baking heat treatments. Precipitation quantification results showed that artificial ageing for ten hours followed by warm forming and paint baking heat treatment resulted η' precipitates achieving the largest size about 5 nm, yielding mechanical strength near T6 levels. Meanwhile, artificial aging over ten hours followed by warm forming and paint baking heat treatments cause η' precipitates to decrease in sizes, number density, and the volume percent. Since η' precipitates are more thermal stable with longer artificial aging treatments. Thus, η' precipitates and GP zones are not easily dissolved into the matrix during warm forming stage. Longer artificial aging followed by warm forming and paint baking resulted newly formed η' precipitates while stable η' precipitates transform into η precipitates during paint baking treatment. Hence, quantification result showed an increase of size, number density, and the volume percent for η precipitates. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/88961 |
DOI: | 10.6342/NTU202302816 |
全文授權: | 同意授權(全球公開) |
顯示於系所單位: | 材料科學與工程學系 |
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