本研究係應用含鋯(Zr)、無錳(Mn)，成份接近AA7075的Al-Mg-Zn-Zr(Z7)鋁合金，來探討鋯元素含量對中高強度鋁合金熱處理製程的影響。
在本研究內應用硬度量測、拉伸試驗、導電度量測、應力腐蝕測試、穿透式電子顯微鏡觀察（TEM）等方法，求出適用於Z7鋁合金之T6、T73與RRA熱處理製程之參數組合，再將研究結果與AA7005鋁合金的研究結果及文獻資料進行分析比較，探討Zn、Mg、Zr等合金元素對熱處理製程之影響。
適用於此Al-Mg-Zn-Zr鋁合金之各種熱處理參數分別為T6:470℃/50min.+60℃/4hr.+120℃/22hr.;T73:470℃/50min.+60℃/4hr.+107℃/8hr.+168℃/6hr.;RRA:T6+180℃/20min.+120℃/22hr.。實驗結果經分析比較後顯示，含鋯之Al-Mg-Zn-Zr鋁合金具有相當於AA7075鋁合金的強度及延展度，較一般Al-Mg-Zn合金(AA7005)為佳的機械性質，具有較低的抗應力腐蝕性。

The objective of this study is to investigate the effect of Zr content on the heat treatment processes of medium-high aluminum alloys using Mn-Free Al-Mg-Zn-Zr(Z7) aluminum alloy as a carrier. Hardness test, tensile test, electrical conductivity measurement, transmission electron microscopy and stress corrosion test were conducted to seek for the most proper combinations of process parameters for the T6, T73, and RRA heat-treatment processes of this Al-Mg-Zn-Zr alloy. Experimental results were, then, compared with those previously obtained from AA7005 aluminum alloy and with results obtained from literature to study the effect of Zr content on the heat-treatment process of medium-high strength aluminum alloy.
Experimental results should that the most suitable process parameters for T6 temper are 470℃/50min.+60℃/4hr.+120℃/22hr.；for T73 temper are：470℃/50min.+ 60℃/4hr.+ 107℃/8hr.+ 168℃/6hr.；and for RRA are：T6 + 180℃/20min. 120℃/22hr.。
Analyses also revealed that the addition of Zr alloying element can enhance the mechanical strength of Al-Mg-Zn alloy at the expense of the stress corrosion cracking resistance.

[1] 蔡幸甫，“輕金屬產業的發展趨勢”，工業材料，166期，pp.165-168，民國89年。
[2] J. J. Thompson, E. S. Tankins and V. S. Agarwala, “ A Heat Treatment for Reducing Corrosion and Stress Corrosion Cracking susceptibilities in 7xxx Aluminum Alloys,” Materials Performance, Vol. 26, pp. 45-52, 1987.
[3] T.H. Sanders, Jr. and E.A. Starke, Jr., “The Relationship of Microstructure to Monotonic and Cyclic Straining of Two Age Hardening Aluminum Alloys,” Metallurgical Trans.,Vol. 7A, pp. 1407-1418, 1976.
[4] D. A. Hardwick, A. W. Thompson and I. M. Bernstein, “The effect of Copper Content and Microstructure on the Hydrogen Embrittlement of Al-6Zn-2Mg Alloys,” Corrosion Science, Vol. 28, pp.1127-1137, 1988.
[5] M.O. Speidel, “Stress Corrosion Cracking of Aluminum Alloys,” Metallurgical Transaction A, Vol. 6A, pp.631-642, 1975.
[6] B. M. Cina, “Aluminum Industrial Products,” NASA Contractor Reports, U. S. Patent 3856584, 1974.
[7] A. F. Oliveira, Jr., M. C. de Barros, K. R. Cardoso, D. N. Travessa, “The Effect of RRA on The Strength and SCC Resistance on AA7050 and AA7150 Aluminum Alloys,” Mater. Sci. and Eng. A 379, pp. 321-326, 2004.
[8] M .B. Hall and J. W. Martin, “Effect of Retrogression Temperature on the Properties of an RRA (Retrogressed and Re-aged) 7150 Aluminum Alloy,” Zeitschrift fuer Metallkunde, Vol. 85, pp. 134-139, 1994.
[9] N.C. Danh, K. Rajan, and W. Wallace, “A TEM Study of Microstructural Changes during Retrogression and Reageing in 7075 Aluminum,” Metall. Trans. A, Vol. 14A, pp.1843-1850, 1983.
[10]R. T. Holt, V. R. Parameswaran and W. Wallace, “RRA Treatment of 7075- T6 Aluminum Components,” Canadian Aeronautics and Space Journal, Vol. 42, pp. 83-87, 1996.
[11]劉國雄，林樹均，葉均蔚，鋁及鋁合金的製造，民國74年。
[12]D. R. Askeland and P. P. Phule, The Science and Engineering of Materials, 4th Edition, Thomson Learning, p. 594, 2003.
[13]M.O. Speidel, “Stress Corrosion Cracking of Aluminum Alloys,” Metallurgical Transaction A, Vol. 6A, pp.631-642, 1975.
[14]R. Troiano, Transaction, ASM, Vol. 52, p.54, 1960.
[15]M .B. Hall and J. W. Martin, “Effect of Retrogression Temperature on the Properties of an RRA (Retrogressed and Re-aged) 7150 Aluminum Alloy,” Zeitschrift fuer Metallkunde, Vol. 85, pp. 134-139, 1994.
[16]W. H. Hunt, Jr. and J. T. Staley, “Light-Weight Alloys for Aerospace Application,” Warrendale, PA, TMS., pp.111-120, 1989.
[17]J. Robinson and P. Flynn, “Effects of Thermal Treatments on the Stress Corrosion Cracking Resistance of Forgings of the Aluminum Alloy 7010,” Key Engineering Materials,Vol. 99-100, pp.143-150, 1995.
[18]W. Wallace, J. C. Beddoes, M. C. deMalherbe, “A New Approach to the Problem of Stress Corrosion Cracking in 7075-T6 Aluminum,” Aero. And Space J., Vol. 27, pp.222-232, 1981.
[19]Ohnishi and Shiota, “Heat Treatment To Reduce The Susceptibility Al-Zn-Mg-Cu Alloy to Stress Corrosion Cracking,” 輕金屬, Vol. 36, pp.647-656, 1986.
[20]M. U. Islam and W. Wallace, “Retrogression and Re-aging Response of 7475 Aluminum Alloy,” Met. Technol., Vol. 10, pp.386-392, 1983.
[21]K. Rajan M. U. Islam and W. Wallace, “Retrogression and Reaging Response of 7475 Aluminum Alloy,” Met. Technol., Vol. 10, pp.386-392, 1983.
[22]J.K. Park and A.J. Ardell, “Microstructures of the Commercial 7075 Al Alloys in the T651 and T7 Tempers,” Metallurgical Transaction A, Vol. 14A, pp.1957-1965, 1983.
[23]D.A. Porter, K.E. Easterling, Phase Transformation in Metals and alloy, 2nd, pp.144-147, 1992.
[24]J. J. Thompson, E. S. Tankins and V. S. Agarwala, “ A Heat Treatment for Reducing Corrosion and Stress Corrosion Cracking susceptibilities in 7xxx Aluminum Alloys,” Materials Performance, Vol. 26, pp. 45-52, 1987.
[25]X. Z. Li, V. Hansen, J. Gjφnnes and L.R.Wallenberg, “HREM Study and Structure Modeling of the η’ Phase, the Hardening Precipitates in Commercial Al-Zn-Mg Alloys,” Acta Mater. 47, pp. 2651-2659, 1999.
[26]L.K. Berg, J. Gjφnnes, V. Hansen, X.Z. Li, M. Knutson-Wedel, G. Waterloo, D. Schryvers and L.R. Wallenberg, “GP-Zones in Al-Zn-Mg Alloys and their Role in Artificial Aging,” Acta Mater, Vol. 49,pp.3443-3451, 2001.
[27]P. N. T. Unwin, R. B. Nicholson, “The Nucleation and Initial Stages of Growth of Grain Boundary Precipitates in Al-Zn-Mg and Al-Mg alloys,” Acta Metallurgica, Vol. 17, pp. 1379-1393, 1969.
[28]J.C. Werenskiold, A. Deschamps, Y. Brechet, “Characterization and Modeling of Precipitation Kinetics in an Al-Zn-Mg Alloys,” Materials Science and Engineering A, Vol. A293, pp.267-274, 2000.
[29]P. B. F. Brown, “Stress Corrosion Cracking of High Strength Steels, the Theory of Stress Corrosion Cracking in Alloys,” NATO, Brusels, pp.235-356, 1971.
[30]Donald O. Sprowls, “Stress-Corrosion Cracking,” edited by Russel H. Jones, Materials Park, ASTM International, pp.363-365, 1992.
[31]T. D. Burleigh, “The Postulated Mechanism for Stress Corrosion Cracking of Aluminum Alloys,” Corrosion, Vol. 47, pp.89-98, 1991.
[32]T. Magnin, P. Rieux, “The Relation Between Corrosion Fatigue And Stress Corrosion Cracking In Al-Zn-Mg Alloys,”Scripta METALLURGICA, vol. 21, pp. 907-911, 1987.
[33]R. Troiano, Transaction, ASM, Vol. 52, p.54, 1960.
[34]D. Altenpohl, “Aluminum and Aluminum Legierungen,” Springer Verlag, p. 773, 1965.
[35]T. Engdahl, V. Hansen, P.J. Warren, K. Stiller, “Investigation of fine scale precipitates in Al-Zn-Mg alloys after various heat treatments,”Materials Science and Engineering A 327 (2002)59-64.
[36]Liu Sheng-dan, Zhang Xin-ming, Chen Ming-an, You jiang-hai, Zhang Xiao-yan, “Effect of Zr content on quench sensitivity of AlZnMgCu alloys,”Trans. Nonferrous Met. Soc. China 17(2007)787-792
[37]Jiang Li Ning, DaMing Jiang, X Gang Fan, Zhong Hong Lai, Qing Chang Meng, Dian Liang Wang, “Mechanical properties and microstructure of Al-Mg-Mn-Zr alloy processed by equal channel angular pressing at elevated temperature ,”Materials Characterization 59(2008)306-311.
[38]P.Z. Zhao, T. Tsuchida, “Effect of fabrication conditions and Cr, Zr contents on the grain structure of 7075 and 6061 aluminum alloys,”Materials Science and Engineering A 499(2009)78-82.
[39]F. M. Mazzolani, Aluminum and Aluminum Structure, 2nd ed, pp.7-8, 1987.
[40]K. Ito, N. Nakashima, “Effect of Fine Zr-Compound on the Formation of Structure of Solution Annealed Al-Zn-Mg -Cu alloys,” Journal of Japan Institute of Light Metals, Vol. 35, pp. 147-153, 1985.
[41]M. Kanno, Bin-lung Ou And Goroh Itoh, “Quench Sensitivity of Some Age-hardenable Aluminum Alloys,” Proceedings of the 2nd international conference of aluminum alloys, pp.1-6, 1990.
[42]T.H. Sanders, Jr. and E.A. Starke, Jr., “The Relationship of Microstructure to Monotonic and Cyclic Straining of Two Age Hardening Aluminum Alloys,” Metallurgical Trans.,Vol. 7A, pp. 1407-1418, 1976.
[43] D. A. Hardwick, A. W. Thompson and I. M. Bernstein, “The effect of Copper Content and Microstructure on the Hydrogen Embrittlement of Al-6Zn-2Mg Alloys,” Corrosion Science, Vol. 28, pp.1127-1137, 1988.
[44] B. Sarkar, M. Marek and E. A. Starke, Jr., “The Effect of Copper Content and Heat Treatment on the Stress Corrosion Characteristics of Al-6Zn-2Mg-X Cu Alloys,” Metallurgical Transaction A, Vol. 12A, pp. 1939-1943, 1981.
[45]黃清添，析出製程參數對AA7005鋁擠型合金機械性質與抗應力腐蝕之影響，國立台灣科技大學機研究碩士論文，民國92年。
[46]ASTM Standards B597,”Standard Practice for Heat Treatment of Aluminum Alloys,”1992.
[47]王俊閔，7075厚板材料RRA熱處理之研究，國立台灣科技大學機研所碩士論文，民國89年。
[48]ASTM Standards E112-96, “Standard Test Method for Determining Average Grain Size,”2003.
[49]ASTM Standards E18-02, “Rockwell Hardness and Rockwell Superficial Hardness of Metallic Materials,”2003..
[50]ASTM Standards B557-94,”Standard Test Methods of Tension Testing Wrought and Cast Aluminum-and Magnesium-Alloy Products,”1994.
[51]ASTM Standards G39-90,”Standard Practice for Preparation and Use of Bent-Beam Stress-Corrosion Test Specimens,”1994.
[52]ASTM Standards G103-89,”Standard Test Method for Performing a Stress-Corrosion Test of Low Copper Containing Al-Zn-Mg Alloys in Boiling 6% Sodium Chloride Solution,”1994.
[53]R.E. Reed-Hill and R. Abbaschian, Physical Metallurgy Principles, 3rd Edition, pp.523-525, 1991.
[54]Metals Handbook, 9th ed., Vol. 4 Heat Treating, p. 716, 1982.
[55]柯漢光，7075鋁合金厚板材料RRA熱處理之研究，淡江大學機械工程研究所碩士論文，民國七十六年六月
[56]V.M. Plyatskii, Extrusion Casting, Primary Sources, p. 58,1965.
[57]B. Sarkar, M. Marek and E.A. Starke. Jr., ”The Effect of Copper Content and Heat Treatment on the Stress Corrosion Characteristics of Al-6Zn-2Mg-X Cu Alloys”Metallurgical Transaction A, Vol.12A, pp.1939-1943, 1981.
[58]W. Wallace, J. C. Beddoes, M. C. deMalherbe, “A New Approach to the Problem of Stress Corrosion Cracking in 7075-T6 Aluminum” Aero. And Space J., Vol. 27, pp222-232, 1981.
[59]J. J. Thompson, E. S. Tankins and V. S. Agarwala, “ A Heat Treatment for Reducing Corrosion and Stress Corrosion Cracking susceptibilities in 7xxx Aluminum Alloys,” Materials Performance, Vol. 26, pp. 45-52, 1987.
[60]L.K. Berg, J. Gjφnnes, V. Hansen, X.Z. Li, M. Knutson-Wedel, G. Waterloo, D. Schryvers and L.R. Wallenberg, “GP-Zones in Al-Zn-Mg Alloys and their Role in Artificial Aging,” Acta Mater, Vol. 49,pp.3443-3451, 2001.
[61]V. Hansen, L. k. Berg, M. Knutson-Wedel, K. Stiller, G. Waterloo and J. Gjφnne, “Energy Filter Electron Diffraction and Atom Probe Investigation of Artificial Ageing in an Al-Zn-Mg Alloy,” in: H.A.C. Benavides, M.J. Yacaman (Eds.), Proceeding s of Electron Microscopy 1998, ICEM14, Cancun, Mexico, pp. 161-162, 1998.
[62]J.K. Park and A.J. Ardell, “Microstructures of the Commercial 7075 Al Alloys in the T651 and T7 Tempers,” Metallurgical Transaction A, Vol. 14A, pp.1957-1965, 1983.
[63]Donald R. Askeland, Pradeep P. phule, The Science and Engineering of Materials, International Student Edition, Ch19.