本研究探討以合金成分微調及熱處理方式來提升A380鋁合金之機械性質，相關參數包括合金成分微調、鑄件冷卻方式(空冷、水淬)與熱處理(T5與T6)等。實驗主要包括以下兩部份：第一部份利用合金設計原理，於合金內添加微量Sr與Mn來改良脆性共晶矽及富鐵相之形貌，並降低合金之Cu與Fe含量來減少鑄件內脆性Al2Cu(Mg)及富鐵相以改善A380鋁合金之脆性；並透過合金之顯微組織、拉伸性質以及破斷面分析來檢驗其成效。第二部份則採取二階段T5處理及特殊T6處理，針對代表性之三種合金A380、A380S(含微量Sr)及A380MS1(含微量Mn、Sr並降低Cu、Fe含量)進行實驗，並分析比較熱處理之效益。實驗結果顯示，經複合成分微調之A380MS1鋁合金能有效改善A380鋁合金之脆性，在數種改良型合金中具有最佳之抗拉強度、延伸率及品質指數。水淬條件之壓鑄A380、A380S及A380MS1合金經過二階段T5處理後，其抗拉強度分別由鑄造狀態之267、322及352 MPa提升至348、406及396 MPa；顯示三種合金經兩階段T5處理後其抗拉強度可增加42~84 MPa；但延伸率則由4.2%、5.5%及9.8%降低至3.6%、4.5%及6.8%。若採用特殊T6處理，則三種合金之抗拉強度分別可提升至422、440及398 MPa，延伸率則提升至6.4%、5.9%及11.7%。

An investigation on improving the mechanical properties of A380 Al alloy was carried out by means of minor adjustment in alloy compositions and thermal treatment of the alloy. The related experimental variables of concerns included adjustment in certain alloying elements, the cooling rate (air cool and water quench) and heat treatments (T5 and T6). The first part of this study utilized theory of alloy design to improve the ductility of A380 Al alloy. This was conducted by adding small amount of Sr and Mn for modification of the morphology of eutectic Si and Al5FeSi phases, respectively. The results were examined by optical and scanning electron microscopies, tensile test and fractography. The second part of this study utilized a 2-step T5 and a special T6 heat treatment on selected Al alloys included A380, A380S (containing Sr ) and A380MS1 (containing Mn and Sr and with reduced amount of Cu and Fe). The results showed that, among the various A380-type alloys studied, the A380MS1 alloy with compsite-adjustment in alloying elements was proven effective in improving the ductility of A380 alloy and exhibits the best combination of tensile strength, ductility and quality index. The tensile strengths of water-quenched die cast A380, A380S and A380MS1 alloys were found to be increased from their as cast condition of 297, 322 and 352 MPa, respectively, to a 2-step aged condition of 348, 406 and 396 MPa, respectively. This showed an increase in tensile strength ranging from 42 to 84 MPa can be achieved through the 2-step T5 age treatment in these alloys. However, a reduction of ductility in A380, A380S and A380MS1 alloys from their as-case condition of respectively 4.2%, 5.5% and 9.8% to the 2-step aged condition of 3.6%, 4.5% and 6.8% was also noticed. But if a special T6 heat treatment was applied, both of the tensile strength and ductility of the A380, A380S and A380MS1 alloys can be greatly enhanced. By utilizing the special T6 treatment the tensile strength of A380, A380S and A380MS1 alloys can reach values up to 422, 440 and 380 MPa, respectively, and ductility to 6.4%, 5.9% and 11.7%, respectively.

中文摘要 i
目錄 ii
表目錄 viii
圖目錄 x

第一章 導論 1
第二章 文獻回顧 3
2.1鋁合金簡介 3
2.1.1鋁合金的發展與應用 3
2.1.2鑄造用鋁合金的命名方式 4
2.2鋁矽鑄造合金 5
2.2.1添加合金元素對鑄造用鋁矽合金之影響 7
2.2.2鑄造用鋁矽合金之微觀組織 9
2.2.3鑄造用鋁矽合金之機械性質[21, 22] 10
2.3鋁合金高壓鑄造 11
2.3.1高壓鑄造及壓鑄鋁合金材料 11
2.3.2高壓鑄造法之優點[24] 12
2.3.3鋁合金壓鑄件常見之缺陷 13
2.4鋁合金之析出硬化 14
2.4.1析出強化理論 19
2.4.2Al-Si-Mg系合金析出 20
2.4.3Al-Si-Cu 系合金析出 21
2.5鋁合金之脆相改良 23
2.5.1層狀組織共晶Si 23
2.5.2富鐵相β-Al5FeSi 24
第三章 實驗步驟 26
3.1合金熔煉與試片製備 26
3.1.1重力鑄造 26
3.1.2高壓鑄造 28
3.2 化學成分分析 29
3.3 金相觀察 29
3.4時效熱處理 29
3.5機械性質量測 30
3.5.1硬度量測 30
3.5.2拉伸試驗 30
3.6破斷面分析 31
第四章 結果與討論 32
4.1顯微組織 32
4.1.1重力鑄造A380系列鋁合金之微觀組織 32
(1)A380顯微組織 32
(2)添加Mn對A380鋁合金重力鑄造組織之影響 33
(3)添加Sr對A380鋁合金重力鑄造組織之影響 34
(4)同時添加Mn及Sr對A380鋁合金重力鑄造組織之影響 35
(5)降低Fe、Cu含量對A380MS鋁合金重力鑄造組織之影響 36
4.1.2壓力鑄造A380系列鋁合金之微觀組織 36
(1)A380顯微組織 36
(2)添加Sr對A380鋁合金壓力鑄造組織之影響 37
4.1.3固溶處理後重鑄與壓鑄鋁合金之微觀組織 38
(1)重鑄A380系列鋁合金經固溶處理前後之顯微組織 38
(2)壓鑄A380系列鋁合金經固溶處理前後之顯微組織 39
4.2A380鋁合金之T5時效行為 39
4.2.1一階段T5時效 40
4.2.2兩階段T5時效(一周自然時效 + 175°C/3.5h) 40
4.3鑄造狀態A380系列鋁合金之機械性質 42
4.3.1成分微調對重力鑄造A380鋁合金機械性質之影響 42
(1)A380鋁合金之機械性質及其添加Mn與Sr之效果 42
(2)降低Cu含量對A380MS鋁合金之效果 44
(3)降低Fe含量對A380MS鋁合金之效果 44
4.3.2A380、A380S及A380MS1等三種代表性合金之機械性質分析 46
(1)重鑄 A380、A380S及A380MS1鋁合金之機械性質比較 46
(2)壓鑄 A380、A380S及A380MS1鋁合金之機械性質比較 47
4.4拉伸試片破斷面分析 48
4.4.1近破斷區顯微組織 48
4.4.2破斷面SEM觀察 50
4.5T5處理後A380系列鋁合金之機械性質 52
4.5.1重力鑄造試片 52
(1)第一階段(自然時效7天) 52
(2)二階段(自然時效+175°C /3.5小時時效) 53
4.5.2壓力鑄造 55
(1)第一階段(自然時效7天) 55
(2)二階段(自然時效+175°C /3.5小時時效) 56
4.6特殊T6處理後A380系列鋁合金之機械性質 57
4.6.1重力鑄造 58
(1)短時間固溶處理(480°C/15min+淬水) 58
(2)短時間固溶處理+ 175°C/8小時人工時效(特殊T6處理) 59
4.6.2壓力鑄造 59
(1)短時間固溶處理(480°C/15分鐘+淬水) 61
(2)短時間固溶處理+ 175°C/8小時人工時效(特殊T6處理) 62
4.7綜合比較T5及T6處理後A380系列鋁合金之機械性質 63
4.7.1綜合討論T5處理後A380系列鋁合金之機械性質比較 64
(1)重鑄A380鋁合金在不同冷卻條件(空冷、水淬)下機械性質比較 64
(2)壓鑄A380鋁合金在不同冷卻條件(空冷、水淬)下機械性質比較 64
(3)在水淬冷卻條件下重鑄及壓鑄之機械性質比較 65
4.7.2綜合討論T6處理後A380系列鋁合金之機械性質比較 65
(1)重鑄A380鋁合金在不同冷卻條件(空冷、水淬)下機械性質比較 65
(2)壓鑄A380鋁合金在不同冷卻條件(空冷、水淬)下機械性質比較 65
(3)在水淬冷卻條件下重鑄及壓鑄之機械性質比較 66
第五章 結論 67
第六章 參考文獻 69

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