摘 要
鎂合金為最輕的結構金屬，因其具有良好的比強度、比剛性、導(散)熱性、制震性、電磁遮蔽性及材料回收性等優異的特性，廣泛應用於各種3C產業、汽車工業與自行車等需結構輕量化的工業上。故大量廢料及產品回收的問題日益凸顯，因目前業界所用的液相回收製程有著高污染、高耗能、高成本及高危險性等缺點，因此，本研究探討不同熱處理及熱機處理條件對其固相回收擠製材之機械性質及微結構的影響，找出鎂合金AZ91D固相回收的最佳製程參數。
研究結果顯示不同鎂合金AZ91D屑料狀態(新生、強制氧化及實際廢料)會影響固相回收製程後之機械性質。實際廢料>強制氧化料>新生料，抗拉強度由新生屑料274.3MPa分別提升8.5％及15.5％至297.7MPa及316.7MPa，主要原因為材料的氧化層在擠製過程中碎裂成強化相顆粒。
固相回收材以170 ℃時效處理，其尖峰時效為時效時間16hrs，其中新生料及強制氧化料之抗拉強度分別為371.1及382.3MPa。另AZ91D強制氧化料固相回收擠製材最佳之熱機處理製程為：軋前350℃退火處理+軋後400℃退火處理，此時抗拉強度為335.6MPa，降伏強度為233.5MPa，伸長率為8.1%。

Abstract
Magnesium alloy is a kind of lightest structure metal. As it has strong tensile stress and toughness, good conductivity and vibration absorber, electromagnetic cover and easy material recycling, magnesium alloy could be the best choice for 3C products for Aircraft chamber and automobile non-structure requirement material. It becomes wildly used in 3C manufacturing, automobile industry and bicycle etc. light structural industries. Large dumping and product recycle problem becomes outstanding.
The research work is to introduce how the solid-state magnesium alloy could be recycled. Various heat treatment approaches and different heat treatment conditions are selected to investigate into the alloy mechanical property and its microstructure performance. It is expected to find out the best result data to strengthen the magnesium alloy AZ91D solid-state recycle process. The result of research as following: (1) The actual waste magnesium alloy can be recycled by the solid-state recycle process and the tensile stress of this recycled material is 316.7MPa. (2) The peak aging is aged at 170℃ temperature and 16hrs, the ultimate tensile stress of specimen which oxidized at 300℃ is 382.3MPa. (3) The best parameter of TMT (Thermo Mechanical Treatment) process of solid-state recycle process is 350oC pre-crunched process plus 400oC pro-tempering heat treatment. The tensile stress could reach 335.6MPa, yield stress 233.5.2MPa and extension rate 8.1%.

參考文獻
1.J. Y. Wang, W. P. Hong, P. C. Hsu, C. C. Hsu and S. Lee: Materials Science Forum, 419-422 (2003), pp.165-170.
2.Y. Kojima and S. Kamado: Materials Science Forum, 488-489 (2005), pp.9-16
3.陳勇宏，AZ31及AZ61鎂合金之晶粒細化與鈑片成形研究，國立中央大學，機械工程研究所，民國93年6月，第1頁。
4.N. A. El-Mahallawy, M. A. Taha, E. Pokora and F. Klein “On the influence of process variables on the thermal conditions and properties of high pressure die-cast magnesium alloys”, Journal of Materials Processing Technology 73 (1998), pp.125-138.
5.A. Mwembela, E. B. Konopleva and H. J. McQueen “Microstructural Development In Mg Alloy AZ31 During Hot Working”, Scripta Materialia, Vol. 37, No. 11, pp. 1789-1795, 1997.
6.蔡幸甫，“鎂合金成型產業現況及發展趨勢”，工業材料雜誌266期，民國98年2月，pp.49~53。
7.鎂合金產業技術及市場發展趨勢專題調查，工研院資中心ITIS計畫，2004，pp.5-6
8.葉信宏、王正全、周雅靜、陳易聰、李秀文，“鎂合金表面處理製程廢料回收再利用”，永續產業發展雙月刊，March 15，2004，pp.57
9.H. Takuda, T. Yoshii and N. Hatta “Finite-element analysis of the formability of a magnesium-based alloy AZ31 sheet”, Journal of Materials Processing Technology 89-90 (1999) 135-140.
10.H. Takuda, H. Fujimoto and N. Hatta “Modelling on flow stress of Mg-Al-Zn alloys at elevated temperatures”, Journal of Materials Processing Technology 80-81 (1998) 513-516.
11.Michael M Avedesian, Hugh Baker. ASM Speciality Handbook – Magnesium and Magnesium Alloys. Ohio, ASM International,1999.
12.Norsk Hydro Databank, Norsk Hydro Research Center Porsgrunn, 1996.
13.Cahn RW, Haasen P, Kramer EJ(ed). Materials Science and Technology – A Comprehensive Treatment in Matucha KH(ed). Structure and Properties of Nonferrous Alloys, Weinheim, VCH, Vol.1996.
14.Jona F, Marcus P M. Magnesium under Pressure: Structure and Phase Transition. J Phys Condens Matter, Vol.15,2003,pp.7727.
15.楊智超，鎂合金材料特性及新製程發展，工業材料，Vol.152,1999, pp.72-73.
16.戴光勇，鎂合金表面處理技術(下)，材料與社會，Vol.25,1989,pp.27.
17.F.A. Lowenheim, Morden Electroplating, Wiley, New York, 1974.
18.Shigeharu Kamado,日本鎂合金工業現況及研究趨勢，台灣鎂合金協會，2001, pp.60.
19.賴耿陽，“非鐵金屬材料”，復漢出版社，1998，pp.174~191.
20.ASM, “Magnesium Alloys”, Metals Handbook 9th Edition, Vpl.6, 1985, pp.314~434.
21.ASM Handbook Vol.3, “Alloy Phase Diagrams”, 1992, pp.276
22.張永耀，“金屬熔銲學”，徐氏基金會，下冊，1976，pp.134~170.
23.郭子強，熱處理對AZ91D 鎂合金顯微組織與電化學性質影響之研究，國立成功大學，材料科學及工程學系，民國93年6月，第17~18頁。
24.H. Proffit., “Magnesium and Magnesium Alloys”, AMS Hanbook, Vol. 2, pp.798
25.唐乃光，“鎂合金壓鑄技術手冊”，金屬工業研究發展中心，pp.23
26.Y. Chino, M. Mabuchi, T. Hoshika, J. S. Lee, K. Shimojima, H. Hosokawa, Y. Yamada and H. Iwasaki: Materials Science Forum, 488-489 (2005), pp.567-570
27.Y. Chino, R. Kishihara, K. Shimojima, C. Wen, H. Iwasaki and M. Mabuchi: Proc. of the 4th Pac. Rim Int. Conf. on Advanced Mater and processing, held from 11-14 Dec. (2001), pp.1291-1294
28.K. Kondoh, T. Luangvaranunt and T. Aizawa: Keikinnzoku, 51 (2001), pp.516-520(in Japanese)
29.K. Kondoh, T. Luangvaranunt and T. Aizawa: Materials Transcions, 43,[3] (2002), pp. 322-325
30.D. Lee, J. Lee and C. Lee: Keikinnzoku, 45 (1995), pp.391-396(in Japanese)
31.M. Inoue, T. Yamaguchi, R. Hirasawa and Y. Kojima: Proc. of the Asian Symposium on Ecotechnology-TOYAMA’94, Toyama, Japan, 1 (1995), pp.129-134
32.Tetsuo Aida, Norio Takatsuji, Kenji Matsuki, Shigeharu Kamado and Yo Kojima: Journal of Japan Institute of Light Metals, 54 (2004), pp.532-537.
33.堀 茂德、浜野 勇、長火田一拓、田村 健、阿倍 睦、田井英男，輕金屬，Vol.44,1994,pp.231.
34.Metals Handbook 9th, Vol.4,Heat Treating,pp.744-753.
35.J. F. Humphreys, R. W. Cahn, P. Haasen and E. J. Kramer, “Recrystallization and Recovery", in Materials Science and Technology, Vo1.15, 1991, pp.371
36.蔡東霖，利用ECAE及退火處理細化鋁鎂合金晶粒，國立中山大學，材料科學研究所，民國89年6月，25-33頁。
37.D. Hull and D.J. Bacon, “Introduction to dislocations", 3rd edition, Pergamon Press,1984,pp.208.
38.S.P.Gupta, “Kinetics of discontinuous coarsening of cellular precipitate in a Ni-8.5 at.%Sn alloy", Acta Metal1.,Vo1.35,N0.3, 1987, pp.747-757.
39.T. Mohri, T. Nishiwaki, T. Kinoshita, H. Iwasaki , M. Mabuchi, M. Nakamura, T. Ashina, T. Aizawa and K. Higashi, “Microstructure and Tensile Properties of Rolled Mg-5.5mass%-0.6mass%Zr Alloy", Mater.Trans., JIM,Vo1.41(9),2000,pp.1154-1156.
40.H. Takuda, S. Kikuchi and N. Hatta, “Possibility of Grain Refinement for Superplasticity of Mg-Al-Zn Alloy by Pre-deformation”, J. Mater. Sci., Vol.27, 1992, pp.937-940.
41.CJ. Peel, B. Evans, C.A. Baker, D.A. Bennett and P.J. Gregson, Proceeding of the second international Aluminum-Lithium Conference, The Metallurgy Society of AIME, California USA, Apri1, 1983, pp.363-392.
42.黃振賢，”金屬熱處理”，文京圖書公司，Vol.2，1986，pp.111.
43.Verhoven, Physical Metallurgy, 1974,pp.363-414.
44.Cahn R W 著，非鐵合金的結構與性能，第八卷，丁道云等譯，北京，科學出版社，1999。
45.劉正，張奎，曾小勤，”鎂基輕質合金理論基礎及其應用”，北京，機械工業出版社，2002。
46.Kubota K, Mabuchi M, higashi K. “Review Processing and Mechanical Properties of Fine-grained Magnesium Alloys,” Journal of Materials Science, Vol.34, 1999, pp.2255-2262.
47.Baker C, Lorimor G W, Unswroth W. Magnesium Technology. Proc. 49th Conf., International Magnesium Association, 1992.
48.Kaibysher R O, Galier A M, Sokolov B K. The Physics of Metals and Metallography, Vol.78, 1994, pp.209.
49.Hansen N. Metall Trans A, Vol.16A,1985, pp.2167.
50.W.A. Anderson and R.F. Mehl. Trans Met. Soc. AIMW, Vol.161,1945, pp.140.
51.張津、章宗和，“鎂合金及應用”，化學工業出版社，2004.7，pp.264-268
52.T. Aizawa, K. Halada and T. G. Gutowski: Materials Transactions, Vol.43 No.3 (2002) pp.390-396.
53.Y. Kojima, T. Aizawa, S. Kamado and K. Higashi: Materials Science Forum, 419-422 (2003), pp.3-20.
54.Gronostajski J, Marciniak H, Matuszak A. “New methods of aluminium and aluminium-alloy chips recycling.” J Mater Process Technol 2000; 106:34–9.
55.Lee J.S., Yasumasa C, Hosokawa H, Shimojima K, Yamada Y, Mabuchi M. “Deformation characteristics at elevated temperature in recycled 5083 aluminum alloy by solid state recycling.” Mater Trans 2005; 46: 2637–40.
56.Yasumasa C, Lee J.S., Yusuke N, Koichi O, Mamoru M.. “Mechanical properties of Mg-Al-Ca alloy recycled by solid-state recycling.” Mater Trans 2005; 46:2592–5.
57.Tekkaya A.E., Schikorra M., Becker D., Biermann D., Hammer N., Pantke K.. “Hot profile extrusion of AA-6060 aluminum chips.” Journal of Materials Processing Technology, Apr. 2009, Vol. 209 Issue 7, p3343-3350
58.Fogagnolo J.B., Ruiz-Navas E.M., Simón M.A., Martinez M.A.. “Recycling of aluminium alloy and aluminium matrix composite chips by pressing and hot extrusion.” Journal of Materials Processing Technology, Dec. 2003, Vol. 143-144, p792-795
59.Zubizarreta C., Giménez S., Martín J.M., Iturriza I.. “Effect of the heat treatment prior to extrusion on the direct hot-extrusion of aluminium powder compacts.” Journal of Alloys & Compounds, Jan. 2009, Vol. 467, p191-201
60.L. Wen, Z. Ji, X. Li. “Effect of extrusion ratio on microstructure and mechanical properties of Mg–Nd–Zn–Zr alloys prepared by a solid recycling process.” Materials Characterization, Volume 59, Nov. 2008, p1655-1660.
61.Yasumasa C, Ryuji K, Koji S, Hiroyuki H, Yasuo Y, Cuie W, “Superplasticity and cavitation of recycled AZ31 magnesium alloy fabricated by solid recycling process.” Mater Trans 2002; 43: pp2437–42.
62.Yasumasa C, Masaaki K, Koji S, Hiroyuki H, Yasuo Y, Hajime I, “Blow forming of Mg alloy recycled by solid-state recycling.” Mater Trans 2004; 45: pp361–4.
63.Mamoru M, Kohei K, Kenji H. “New recycling process by extrusion for machined chips of AZ91 magnesium and mechanical properties of extruded bars.” Mater Trans 1995; 36:1249–54.
64.Liu Y, Li YY, Zhang DT, Ngai TL, Chen WP. “Microstructure and properties of AZ80 magnesium alloy prepared by hot extrusion from recycled machined chips.” Trans Nonferr Met Soc China 2002; 12: 882–5.
65.Lee DM, Lee JS, Lee CH. “The microstructure and mechanical properties of extruded machined chips for AZ91D magnesium alloy.” J Jpn Inst Light Met 1995; 45: 391–6
66.Masaru N, Mamoru M, Kohei K, Kenji H. “Relationship between extrusion ratio and mechanical properties of extruded machined-chips of AZ91 magnesium alloy.” J Jpn Soc Powder Powder Metall 1995; 42: 373–7
67.Jiang JF, Luo SJ. “Reheating microstructure of refined AZ91D magnesium alloy in semi-solid state.” Trans Nonferr Met Soc China 2004; 14: pp1074–81.
68.Ji ZS, Hong Y, Zhao M. “Lathe process of AZ91D magnesium alloy chips used in semi-solid thixomolding.” Trans Nonferr Met Soc China 2005;15(Special 3): pp236–40.
69.Yasumasa C, Tetsuji H, Mamoru M. “Mechanical and corrosion properties of AZ31 magnesium alloy repeatedly recycled by hot extrusion.” Mater Trans 2006; 47: pp1040–6.
70.Liu XF, Yan W, Chen GX.“The experimental study on recrystallization of magnesium alloy AZ31B during plastic deformation.” J Plast Eng 2005;12: pp10–3.
71.Y. Chino, R. Kishihara, K. Shimojima, H. Hosokawa, Y. Yamada, C. Wen, H. Iwasaki and M. Mabuchi: Materials Transactions, Vol.43 No.10 (2002), pp.2437-2442.
72.Y. Chino, M. Mabuchi, S. Otsuka, K. Shimojima, H. Hosokawa, Y. Yamada, C. Wen and H. Iwasaki: Materials Transactions, Vol.44 No.7 (2003), pp.1284-1289
73.Y. Chino, M. Mabuchi, H. Iwasaki, A. Yamamoto and H. Tsubakino: Materials Transactions, Vol.45 No.08 (2004), pp.2509-2515
74.M. Mabuchi, K. Kubota and K. Higashi: Materials Transactions, JIM, Vol.36 No.10 (1995), pp.1249-1254
75.S. Matsuoka, T. Goshima, T. Murai, F. Nakagawa: “The Extrusion of Compaction Molding billets Used of Magnesium Alloy Chips”, The Proceedings of the 59th Japanese Joint Conference for Technology of Plasticity, Nov. 7-9 2008.
76.M. Hu, Z. Ji, X. Chen, Z. Zhang, “Effect of chip size on mechanical property and microstructure of AZ91D magnesium alloy prepared by solid state recycling.” Materials Characterization 59, 2008, pp385-389