7075鋁合金具有高比強度的特性，屬於高強度型的鋁合金；A356鋁合金擁有良好的鑄造性，經常以鑄造件被使用。在工業零件或運動商品上，常有需要承受較高應力的部位，以及需要以鑄造成型的部位。因此在應用上，7075鋁合金與A356鋁合金之接合有其必要性。本實驗以摩擦攪拌銲接進行兩者之異質接合。分別將7075鋁合金置於Advancing side，A356鋁合金置於Retreating side (簡稱，AS7)；和與其相反位置 (簡稱，AS3)。隨後進行異質接合，探討異質材料之彼此相對變形阻抗與攪拌時銲道的流動行為之關係。並且改變進給速率 (0.55 mm/s、0.29 mm/s)，進而控制銲道的入熱量。探討入熱量對銲道內微觀組織之影響。
根據實驗結果顯示，在垂直銲道方向拉伸後發現，AS7-0.55、AS3-0.55與AS3-0.29試料皆破斷在A356的熱影響區，且UTS值皆相近。AS7-0.29因為SZ區產生攪拌填補不良所造成之缺陷，使得強度還有延性下降。
AS7-0.55、AS3-0.55與AS3-0.29在SZ區皆分為三區 (7075、A356、機械冶金區)。在機械冶金區產生相變化，此相為7075之Mg與A356之Si在摩擦攪拌後所產生，其為大小約為1~2µm之Mg2Si。三組不同參數之SZ區的混合度不同，AS7-0.55最佳，其次為AS3-0.29，最後是AS3-0.55；混合度越佳時，SZ區的機械冶金區越多。在平行銲道方向拉伸時，SZ區的強度及延伸率與機械冶金區之面積呈現正相關趨勢之特性；AS7-0.55的機械性質均優於AS3-0.29；AS3-0.55銲道內產生類似Lazy-S之氧化介在物導致強度偏低。

7075 alloy is a high strength aluminum alloy, and the A356 alloy has excellent casting property. For the application, combination of 7075 and A356 alloys are necessary. In this study, the friction stir welding is applied for welding 7075 alloy and A356 alloy. In friction stir welding, the flowing behavior and heat quantity will affect the microstructure of welded zone. Furthermore, influences of different microstructures on tensile properties should be considered. Thus, with different welding speed and different welding positions of 7075/A356 specimens, the effects of heat quantity and flowing behavior on microstructures and tensile properties of dissimilar friction stir welded 7075 and A356 are investigated.
According to the tensile testing which performed along the direction perpendicular to welding direction, the fracture of AS7-0.55, AS3-0.55, and AS3-0.29 are all occurred at the HAZ of A356, and their UTS are similar. The strength and elongation of AS7-0.29 are decreased due to the defects of SZ which resulted from its worse flowing ability.
The SZ of AS7-0.55, AS3-0.55, and AS3-0.29 specimens can be separated into three parts (7075, A356, and mechanical alloying zone). The phase transformation will be taken place in the mechanical alloying zone. A new second phase of Mg2Si produced when violent friction occurred between 7075 and A356. The mechanical alloying zone of AS7-0.55 is larger than AS3-0.29, and AS3-0.55 displays the least of all. According to the tensile testing which performed along the direction longitudinal to welding direction, the strength and elongation are increased with rising the area of mechanical alloying zone, so the tensile mechanical properties of AS7-0.55 is better than AS3-0.29. The

existed Lazy-S compound at SZ results in decreasing the tensile strength of the AS3-0.55 specimens.

1. W. B. Lee, Y. M. Yeon, S. B. Jung, “The Joint Properties of Dissimilar Formed Al Alloys by Friction Stir Welding According to the Fixed Location of Materials”, Scripta Materials, vol. 49, 2003, pp.423-428.
2. J. E. Hatch, “Aluminum Properties and Physical Metallurgy”, American Society for Metals, Metals Park, Ohio, 1984, pp.79-83, 134-197.
3. E. F. Bradley, A. R. Putnam, “Metals Handbook, Properties and Selection：Nonferrous Alloys and Pure Metals”, American Society for Metals, Metals Park, Ohio, vol. 2, 1979, pp.129-132, 164-167.
4. L. J. Feng, P. Z. Wei, L. C. Xing, “Mechanical Properties, Corrosion Behaviors and Microstructures of 7075 Aluminium Alloy with Various Aging Treatments”, Transcations of Nonferrous Metals Society of China, vol. 18, 2005, pp.755-762.
5. A. Karaaslan, I. Kaya, H. Atapek, “Effect of Aging Temperature and of Retrogression Treatment Time on the Microstructure and Mechanical Properties of Alloy AA7075”, Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, vol. 49, 2007, pp.20-24.
6. J. W. Pridgeon, E. L. Langer, “Metals Handbook, Metallography and Microstructures”, American Society for Metals, Metals Park, Ohio, vol. 9, 1985, pp.367-368.
7. M. B. Massalski, “Metals Handbook, Binary Alloy Phase Diagrams”, American Society for Metals, Metals Park, Ohio, vol., 1984, pp.165.
8. S. Shivkumar, C. Keller, D. Apelian, “Aging Behavior in Cast Al-Si-Mg Alloys”, AFS Trans., vol. 98, 1990, pp.905-911.
9. 劉文海，『鋁合金潛力產品與前景分析』，金屬工業發展研究中心出版，民國95年，7-10頁。
10. J. Q. Su, T.W. Nelson, R. Mishra, M. Mahoney, “Microstructural Investigation of Friction Stir Welded 7050-T651 Aluminium”, Acta Materialia, vol. 51, 2003, pp.713-729.
11. TWI：www. Twi. Co. uk
12. K. V. Jata, S. L. Semiatin, “Continuous Dynamic Recrystallization during Friction Stir Welding of High Strength Aluminium Alloys”, Scripta Materialia, vol. 43, 2000, pp.743-749.
13. T. R. McNelley, S. Swaminathan, J. Q. Su, “Recrystallization Mechanisms during Friction Stir Welding/Processing of Aluminum Alloys”, Scripta Materialia, vol. 58, 2008, pp.349-354.
14. G. Liu, L. E. Murr, C-S. Niou, L. C. McClure, “Microstructure Aspects of the Friction Stir Welding of 6061-T6 Aluminum”, Scripta Materialia, vol. 37, 1997, pp.355-361.
15. Y. S. Sato, H. Kokawa, S. Jogan, “Microstructural Evolution of 6063 Aluminum During Friction Stir Welding”, Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, vol. 30, 1999, pp. 2429-2437.
16. 黃展鴻，『摩擦攪拌7075鋁合金組織特性及拉伸性質之後熱處理效應探討』， 國立成功大學材料科學與工程學系研究所碩士論文， 民國95年。
17. M. W. Mahoney, C. G. Rhodes, J. G. Flintoff, R. A. Spurling, W. H. Bingel, “Properties of Friction Stir Welded 7075 T651 Aluminum”, Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, vol. 29, 1998, pp.1955-1964.
18. R. S. Mishra, M. W. Mahoney, S. X. Mcfadden, N. A. Mara, “High Strain Rate Superplasticity in a Friction Stir Processed 7075 Al Alloy”, Scripta Materialia, vol. 42, 1999, pp.163-168.
19. H. Kakimoto, “Study on Application of FSW to Aircraft”, Journal of the Japan Society for Technology of Plasticity, vol. 46, 2005, pp.939-943.
20. M. A. Sutton, A. P. Reynolds, B. Yang, “Mixed Mode I/II Fracture of 2024-T3 Friction Stir Welds”, Engineering Fracture Mechanics, vol. 70, 2003, pp.2215–2234.
21. P. Cavaliere, R. Nobile, F.W. Panella, A. Squillace, “Mechanical and Microstructural Behaviour of 2024-7075 Aluminium Alloy Sheets Joined by Friction Stir Welding”, International Journal of Machine Tools & Manufacture, vol. 46, 2006, pp.588-594.
22. R. Zettler, S. Rodrigues, A. Blanco “Dissimilar Al to Mg Alloy Friction Stir Welds” Advance Engineerung Materials, vol. 8, 2006, pp.415-421.
23. J. Kwon, K. Suzuki, T. Imai, N. Saito “Joining of 5083 and 6061 Aluminum Alloys by Friction Stir Welding” Journal of Materials Science Letters, vol. 22, 2003, pp.353-356.
24. A. C. Somasekharan, L. E. Murr, “Microstructure in Friction Stir Welded Dissimilar Magnesium Alloys and Magnesium Alloys to 6061-T6 Aluminum Alloy”, Materials Characterization, vol. 52, 2004, pp.49-64.
25. M. Maeda, H. J. Liu, H. Fujii, T. Shibayanagi, “Temperature Field in the Vicinity of FSW Tool during Friction Stir Welding of Aluminium Alloys”, Welding in the World, vol. 49, 2005, pp. 69-75.
26. 社團法人溶接學會， 『摩擦攪拌接合』， 產報出版株式會社， 平成18年，163-165頁。
27. K. Colligan, “Material Flow Behavior During Friction Stir Welding of Aluminum”, Welding Journal, vol. 78, 1999, pp. 229-237.
28. H. Fujii, Y. G. Kim, T. Tsumura, T. Komazaki, K. Nakata “Estimation of Material Flow in Stir Zone during Friction Stir Welding by Distribution Measurement of Si Particles”, Materials Transactions, vol. 47, 2006, pp.224- 232.
29. M. Guerraa, C. Schmidta, J.C. McClurea, L.E. Murra, A.C. Nunesb, “Flow Patterns during Friction Stir Welding”, Materials Characterization, vol. 49, 2003, pp.95-101.
30. O. Frigaard, O. Grong, O.T. Midling, Seventh International Conference, INALCO’98, 1998, pp.197-207.
31. Y. G. Kima, H. Fujii , T. Tsumura, “Three Defect Types in Friction Stir Welding of Aluminum Die Casting Alloy”, Materials Science and Engineering, vol. 415, 2006, pp.250-254.
32. Y. M. Hwang, Z. W. Kang, Y. C. Chiou, H. H. Hsu, “Experimental Study on Temperature Distributions with in the Workpiece during Friction Stir Welding of Aluminum Alloys”, International Journal of Machine Tools & Manufacture, vol. 48, 2008, pp.778-787.
33. Y. Li, L. E. Murr, J. C. McClure, “Flow Visualization and Residual Microstructures Associated with the Friction Stir Welding of 2024 Aluminum to 6061 Aluminum”, Materials Science and Engineering vol. A271, 1999, pp. 213-223.
34. H. B. Chen, K. Yan, T. Lin, S. B. Chen, C. Y. Jiang, “The Investigation of Typical Welding Defects for 5456 Aluminum Alloy Friction Stir Welds”, Materials Science and Engineering , vol. 433, 2006, pp. 64-69.
35. H. Takahara, M. Tsujikawa, S.-W. Chung, Y. Okawa, S. Oki, K. Higashi, “Optimum Processing and Tool Controls for Three-Dimensional Friction Stir Welding”, Materials Transactions, vol. 49, 2008, pp. 1911-1914.
36. Y. S. Sato, H. Takauchi, S. Hwan, C. Park, H. Kokawa, “Characteristics of the Kissing Bond in Friction Stir Welded Al alloy 1050”, Materials Science and Engineering, vol. A405, 2005, pp.333-338.