| 研究生: |
徐梓益 Tiz-Yi Hsu |
|---|---|
| 論文名稱: |
Cu/Mg比對Al-Cu-Mg-Ag合金熱穩定性之影響 |
| 指導教授: |
李勝隆
Sheng-Long Lee |
| 口試委員: | |
| 學位類別: |
碩士 Master |
| 系所名稱: |
工學院 - 機械工程學系 Department of Mechanical Engineering |
| 畢業學年度: | 90 |
| 語文別: | 英文 |
| 論文頁數: | 50 |
| 中文關鍵詞: | 熱穩定性 |
| 外文關鍵詞: | Al-Cu-Mg-Ag, thermal stability |
| 相關次數: | 點閱:12 下載:0 |
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Al-Cu-Mg-Ag合金為一可熱處理型鋁合金,強化相Ω相及θ’相析出受Cu/Mg比影響。由於Ω相在鋁基地主要滑動面{111}α上析出,且Ω相具高溫穩定性,不僅可增加材料機械強度,亦使材料於高溫長時間下有好的熱穩定性。由於Al-Cu-Mg-Ag合金析出行為受Cu/Mg比影響,本研究探討不同Cu/Mg比對Al-Cu-Mg-Ag合金熱穩定性之影響。
實驗設計四種Cu/Mg比(Mg含量)試片,分別為29(0.16wt.% Mg)、19(0.25 wt.% Mg)、8(0.56 wt.% Mg)、4(1.12 wt.% Mg)的Al-4.6Cu-Mg-0.6Ag(wt.%)合金,經T7熱處理後置於高溫107℃、135℃、155℃持溫1000小時後,以光學顯微鏡(OM)、電子微探儀(EPMA)、導電度(%IACS)、微差掃描熱分析(DSC)、掃描式電子顯微鏡(SEM)與穿透式電子顯微鏡(TEM)分析微結構變化,機械性質測試則進行拉伸試驗與硬度試驗,透過機械性質的分析,以了解Cu/Mg比對Al-Cu-Mg-Ag合金於高溫下之微結構上的差異,如何影響合金機械性質及熱穩定性。
含1.12wt.%Mg的合金,因Mg含量過高,加工硬化現象極為明顯,造成擠型性不佳,極易於擠型時產生巨大的裂縫,故不對其進行熱穩定性研究。
由DSC及TEM分析可知,合金於T7熱處理後,隨著Mg含量的增加(Cu/Mg比降低),Ω相析出量增加且漸為主要強化相;由熱穩定性的硬度曲線可知,硬度曲線的下降幅度,隨Mg含量的增加(Cu/Mg比降低)而趨緩,由此可知,合金中Ω相愈多,於高溫長時間時效的熱穩定性愈好。
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