5083鋁合金等軸晶鑄造材擁有比強度高、耐蝕性佳、熱均勻膨脹性佳等優點。近來常應用於半導體產業中大型加熱腔體的材料，或以薄型板材的型態應用於某些半導體機械零組件上。一般而言，摩擦攪拌銲接可改善傳統熔接熱影響區弱化的問題。吾人利用與FSW相同原理的FSP製程，將其施予5083等軸晶鑄造材，並探討其銲道區域拉伸性質的表現。一方面作為FSW在本材料中做為銲接技術是否可行的參考。另一方面，當薄型板材需作彎曲加工時，若在其將產生劇烈變形處施予FSP，評估其是否有助提升其耐加工性。
本研究中以拉伸測試來檢驗FSP後機械性質是否有所提升。發現母材經摩擦攪拌製程後，其銲道區域的均勻沿伸率由10%提升至18%左右，總延伸率則由11%提升至22%。一方面以拉伸性質中的應變硬化指數評估母材在摩擦攪拌前後均勻沿伸率的差異。發現經摩擦攪拌製程者應變硬化指數提升，代表其抵抗頸縮的能力較佳，故均勻延伸性質提高。推測乃由於其晶粒、第二相晶出物（Al6(Mn,Fe)、Al6Mn）尺寸與分佈均勻化所致。另一方面則進行拉伸破斷面附近的次表面觀察，藉以推測導致破斷發生的裂縫形成與傳播與第二相之間的關聯性。發現母材與攪拌後銲道區試片，其破斷面附近的Al6(Mn,Fe)均有碎裂的情形發生，推測為Al6(Mn,Fe)為裂縫形成起始點。其中，母材Al6(Mn,Fe)碎裂後出現大規模裂縫，因此頸縮後並未有太多的應變量即發生破壞。經摩擦攪拌者其裂縫規模小且裂縫間距大，因此在頸縮發生後而破壞發生前尚進行一段非均勻的彈塑性變形。综合以上，FSP對於延性有正面提升之效。然而，在相同應變量下的強度探討上，發現雖晶粒與第二相均細化，而強度未見顯著差異，應有其他更有力的主導因素存在，本研究未對此深入探討。
5083鋁合金拉伸過程中，拉伸曲線上經常出現抖動的現象。文獻中推論其為固溶的鎂原子與移動的差排交互作用，因而產生動態應變時效現象。本研究以動態應變時效發生的臨界應變量與抖動振幅（應力降）加以評估。藉以推測FSP對5083等軸晶鑄造材動態應變時效發生難易的影響。發現FSP銲道區的試片拉伸其臨界應變量變小、應力降變大。由此可推測，FSP造成微觀組織改變有促進動態應變時效發生的效果。

Fully-annealed 5083 Al casting alloy (5083C) has an equiaxed grain structure. Because of its high specific tensile strength, great corrosion resistance, and uniform expansion properties, it has been used to manufacture the cases of heating furnaces in semiconductor industry in recent years. Sometimes, 5083C Al thin sheets are also used to produce some components of semiconductor equipments. Friction stir welding (FSW) is a solid-state joining process providing better mechanical properties than fusion welding process. Friction stir processing (FSP) is an emerging technique based on the principle of FSW. In this research, it was investigated the tensile properties for the stir zone of Al alloy 5083C to judge the FSW technique is suitable for Al alloy 5083C. The results of this research also could help us to know if the FSP technique can modify the working properties of Al alloy 5083C thin sheets under severe bending strain.
The results of tensile test show that FSP technique increase the uniform elongation from 10% to 18%, and total elongation from 11% to 22%. In addition, the strain hardening exponent ‘n’ is found to increase with the FSP technique. It means that FSP technique is helpful to improve the resistance to instable deformation. According to the previous studies we conjecture that the strain hardening exponent should increase as a result of grain and intermetallic compounds (Al6(Mn,Fe),Al6Mn) refinement and homogenization. Besides, it can be inferred the relationship between cracks and intermetallic compounds (IMC) by observations of the microstructures near fracture surface. It is always found that the IMC Al6(Mn,Fe) near the fracture surface was broken in all tensile specimens. So, we conjecture that Al6(Mn,Fe) is the beginning of the cracks. Because of the large cracks in 5083C during tensile test, the specimens is broken rapidly after necking occurring. It is found that the cracks near fracture surface in the FS-processed tensile specimens are smaller and homogenously distributed. So, the FS-processed tensile specimens deformed remarkably after necking. FSP technique enhances the ductility of 5083C. Microstructures of Al alloy 5083C could be obviously refined and homogenized by FSP technique, however the strength is not increased. There might be some key factors that we did not concern to affect the strength.
Dynamic strain aging or serrated yielding has been wildly investigated in Al alloy 5083. But the effect of FSP technique to dynamic strain aging was not concerned in previous studies. In this study, critical strain and stress drop are used to analyze dynamic strain aging. The results show that critical strain decreases and stress drop increases after FSP.

1. L. F. Mondolfo, “Aluminum Alloys Structure & Properties”, Chapter
4-3, pp. 806-842, 1976.
2. I. J. Polmear “Light Alloys Metallurgy of the Light Metals”, pp. 15-
123, 1980.
3. John E. Hatch, “Aluminum Properties and Physical Metallurgy”,
Chap9, pp. 356-367, 1985.
4. Taylor Lyman, Howard E. Boyer, “Welding and Brazing”, Metals
Handbook, Vol. 6, pp. 296-336, 1971.
5. W. M. Thomas, E. D. Nicholas, “Friction stir welding for the
Transportation industries”, Materials & Design, Vol. 18, Nos. 4/6, pp.
269-273, 1997.
6. R. W. Fonda, J. F. Bingert, K. J. Colligan, “Development of grain
structure during friction stir welding”, Scripta Materialia, 51, pp.
243-248, 2004.
7. Wang Deqing, Liu Shuhua, ”Study of friction stir welding of
aluminum”, Journal of Materials Science, 39, pp. 1689-1693, 2004.
8. W. B. Lee, Y. M. Yeon, S. B. Jung, “The improvement of mechanical
properties of friction-stir-welded A356 Al alloy”, Materials Science
and Engineering A, 355, pp. 154-159, 2003.
9. Rajiv S. Mishra, “Friction stir processing technologies”, Advanced
Materials and Processes, pp. 43-46, 2003.
10. R. S. Mishra, Z. Y. Ma, “Friction stir welding and processing”,
Material Science and Engineering, R50, pp. 1-78, 2005.
11. M. P. Miles, M. W. Mahoney, T. W. Nelson, R. S. Mishra, “Finite
element simulation of plane-strain thick plate bending of friction-stir
processed 2519 aluminum”, TMS Annual Meeting，Friction Stir
Welding and ProcessingⅡ, pp. 253-258, 2003.
12. Mendelson, “Plasticity：Theory and Application”, pp. 1-133, 1968.
13. Wei Wen, Yumin Zhao, J. G. Morris, “The effect of Mg precipitation
on the mechanical properties of 5xxx aluminum alloys”, Materials
Science and Engineering A, 392, pp. 136-144, 2005.
14. I. S. Kim, M. C. Chaturvedi, “Serrated flow in Al-5%Mg alloy”,
Materials Science and Engineering, 37, pp. 165-172, 1979.
15. Taylor Lyman, Howard E. Boyer, “Metallography, Structure and
Phase Diagrams”, Metals Handbook, Vol. 8, pp. 251-434, 1973.
16. Yingchun Chen, Huijie Liu, Jicai Feng, “Friction stir welding
characteristics of different heat-treated-stated 2219 aluminum alloy
plates”, Materials Science and Engineering A, 420, pp. 21-25, 2006.
17. H. Liu, M. Maeda, H. Fujii, K. Nogi, “Tensile properties and fracture locations of friction-stir welded joints of 1050-H24 aluminum alloy”, Journal of Materials Science Letters, 22, pp. 41-43, 2003.
18. 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 Transaction A, Vol. 29A, pp. 1955-1964, 1997.
19. Yutaka S. Sato, Mitsunori Urata, Hiroyuki Kokawa, Keisuke Ikeda, “Ha11-Petch relationship in friction stir welds of equal channel angular-pressed aluminum alloys”, Materials Science and Engineering A, 354, pp. 298-305, 2003.
20. Wei Wen, J. G. Morris, “An investigation of serrated yielding in 5000
serries aluminum alloys”, Materials Science and Engineering
A, 354, pp. 279-285, 2003.
21. D. Thevent, M. Mliha-Touati, A. Zeghloul, “The effect of
precipitation on the Portevin-Le Chatelier effect in an Al-Zn-Mg-Cu
alloy”, Materials Science and Engineering A, 266, pp. 175-182, 1999.
22. Y. Estrin, M. A. Lebyodkin, “The influence of dispersion particles
on the Portevin-Le Chatelier effect：from average particle
characteristics to particle arrangement”, Materials Science and
Engineering A, 387-389, pp. 195-198, 2004.
23. E. Pink, A. Grinberg, “Stress drop in serrated flow curves of Al5Mg”,
Acta metall. Vol. 30, pp. 2153-2163, 1982.
24. 陳錦修，「兩相共晶鋁合金213K至673K之拉伸特性研究」，國
立成功大學材料及工程學系，博士論文，22-38頁，民國85年。
25. K. Chihab, C. Fressengeas, “Time distribution of stress drops, critical
strain and crossover in the dynamics of jerky flow”, Materials Science
and Engineering A, 356, pp. 102-107, 2003.
26. X-M. Cheng, J.G. Morris, “The anisotropy of the Portevin-Le
Chatelier effect in aluminum alloys”, Scripta mater., 43, pp. 651-658,
2000.
27. Matthew Wagenhofer, MarjorieAnn Erickson-Natishan, Ronald W.
Armstrong, Frank J. Zerilli, “Influences of strain rate and grain size
on yield and serrated flow in commercial Al-Mg alloy 5086”, Scripta
Materialia, Vol. 41, No. 11, pp.1177-1184, 1999.
28. Erwin Pink, Patrick Bruckbauer, Herbert Weinhandl, “Stress-drop
rates in serrated flow of aluminum alloys”, Scripta Materialia, Vol.
38, No. 6, pp. 945-951, 1998.
29. Erwin Pink, Adolfo Grinberg, “Serrated flow in a ferritic stainless
steel”, Materials Science and Engineering, 51, pp. 1-8, 1981.
30. Kamel Chihab, Hakim Ait-Amokhtar, Khaidre Bouabdellah,
“Serrated Yielding due to Portevin-Le Charelier effect in commercial
Al-Mg alloys”, Ann. Chim. Sci. Mat., 27, pp. 69-75, 2002.
31. Norman E. Downling, “Mechanical Behavior of Materials”, Chapter
12, pp. 552-553, 1993.
32. E. Martin, A. Forn, R. Nogue, “Strain hardening behaviour and
temperature effect on Al-2124/SiCp”, Journal of Materials
Processing Technology, 143-144, pp. 1-4, 2003.
33. 汪俊延，「塑性不均勻性對[111]纖維織構鋁擠型材的織構強化與
擬超塑性變形之效應」，國立成功大學材料及工程學系，博士論
文，民國86年。
34. A. Fawzy, R. H. Nada, “Effect of grain diameter on the tensile
characteristics of thermally deformed Ag-4.4wt% Cu alloy”, Physica
B, 371, pp. 5-11, 2006.
35. S. Nagarjuna, M. Srinivas, K. Balasubramanian, D. S. Sarma,
“Effect of Modulations on yield stress amd strain hardenin exponent
of solution treated Cu-Ti alloys”, Scripta Materialia, Vol. 38, No. 9,
pp. 1469-1474, 1998.
36. S. Latha, K. Laha, K. B. S. Rao, S. L. Mannan, “Comparative study of
tensile flow parameters in forged and rolled 9Cr-1Mo steel”, Int. J.
Ves. & Piping, 67, pp. 155-160, 1996.
37. Zhang Fan, Huang Mingzhi, Shi Deke, “The relationship between
the strain-hardening exponent n and the Microstructure of metals”,
Matrials Science and Engineering A, 122, pp. 211-213, 1989.
38. Wei Wen, W. C. Liu, J. G. Morris, “The effect of Mg2Al3 and of
MnAl6 on texture evolution during isothermal annealing and
subsequently on formability of CC AA5182 Al alloy”, Materials
Science and Engineering A, 380, pp. 191-207, 2004.
39. N. Selvakumar, R. Narayanasamy, “Phenomenon of strain hardening
behaviour of sintered aluminum performs during cold axial forming”,
Journal of Materials Processing Technology, 142, 347-354, 2003.
40. William D. Callister, “Materials Science and Enginering An
Introduction”, Chapter 6, pp.131, 1999.
41. T. Takaai, T. Daito, “Observation of voids and cracks on ductile
fracture process in tensile test of 5083 aluminum alloy plate”, J. Japan
Inst. of Light Metals, Vol. 33, pp. 67-75, 1983.
42. Goutam Das, Sabita Ghosh, S. K. Sahay, “Use ball indentation
technique to the determine the change of tensile properties of SS316L
steel due to cold rolling”, Materials Letters, 59, pp. 2246-2251, 2005.
43. Taylor Lyman, Howard E. Boyer, “Metallography, Structure and
Phase Diagrams”, Metals Handbook, Vol. 8, pp. 124, 1973.
44. D. J. Lloyd, “The Deformation of commercial aluminum-magnesium
alloys”, Metall. Trans. A, Vol. 11A, pp. 1287-1294, 1980.
45. 鐘長偉，「加工硬化型Al-Mg合金振動破壞特性之預變量及含Mg
量效應探討」，國立成功大學材料及工程學系，碩士論文，22頁，
民國92年。
46. M. Guerra, C. Schmidt, J. C. McClure, L. E. Murr, A. C. Nunes,
“Flow patterns during friction stir welding”, Materials
Characterization, 49, pp. 95-101, 2003.
47. Won-Bae Lee, Yun-Mo Yeon, Seung-Boo Jung, “The joint properties
of dissimilar formed Al alloys by friction stir welding according to
the fixed location of materials”, Scripta Materialia, 49, pp. 423-428,
2003.