Dissolution behavior of second phases in 7050 aluminum alloy
LI Ya1, DENG Yun-lai1,2, ZHANG Jin3,4, TIAN Ai-qin1,5, ZHANG Yong1
1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Science and Technology on High Strength Structural Materials Laboratory, Central South University, Changsha 410083, China;
3. Light Alloy Research Institute, Central South University, Changsha 410083, China;
4. State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, China;
5. CRRC Qingdao Sifang Co., Ltd., Qingdao 266111, Shandong, China
Abstract：The dissolution behavior of equilibrium η(MgZn2), T(Al2Mg3Zn3), S(Al2CuMg) and Fe-containing Al7Cu2Fe insoluble phases of hot rolled 7050 aluminum alloy during solid solution treatment was studied. The dissolution kinetics data of the equilibrium phases were obtained by means of in-situ scanning electron microscope tissue detection method. On the basis of bulk diffusion controlled dissolution kinetics models, the effects of curvature and interfacial reaction on atomic migration rate were introduced, and the dissolution kinetics models of η, T and S phases were established. The results show that η and T phases of 7050 aluminum alloy can be completely dissolved within 2 min at the usual solution temperature (470℃); it takes a long time for S phase to completely dissolve, while the Fe-containing phase hardly dissolves; the curvature has little effect on the phase dissolution, but the dissolution rate can be greatly reduced by the interfacial reaction. The predicted results of the second-phase dissolution kinetics models are in good agreement with the measured results, such as η, T and S phase, which can provide guidance for optimizing the solid solution process of Al-Zn-Mg-Cu alloy.
[1] 张新明,吴泽政,刘胜胆,等. 固溶处理对7A55铝合金局部腐蚀性能的影响[J]. 材料工程, 2014(4):26-33. ZHANG X M, WU Z Z, LIU S D, et al. Influence of solution heat treatment on localized corrosion of 7A55 aluminum alloy[J]. Journal of Materials Engineering, 2014(4):26-33.
[2] YANG Y, LI T R, JIA T, et al. Precipitation kinetics of complex precipitate in multicomponent systems[J]. Journal of Iron and Steel Research, International, 2018, 25(10):1086-1093.
[3] XU F S, GUO X B, WU P F, et al. Morphology development and kinetics of plate or rod shaped precipitates in aluminum alloys[J]. Rare Metal Materials and Engineering, 2017,46(4):876-881.
[4] FILBET F, SHU C W. Discontinuous Galerkin methods for a kinetic model of self-organized dynamics[J]. Mathematical Models and Methods in Applied Sciences, 2018, 28(6):1171-1197.
[5] KANG L,CUI Y J, ZHAO G,et al.Precipitation kinetics analysis of the cooling process following the solid solution treatment of 7B50 aluminum alloy[J].Materials Science Forum,2017,898:213-222.
[6] KONGTHEP J,JUIJERM P.Kinetics of precipitation hardening phase in aluminium alloy AA6110[J].Materials Science and Technology,2014,30(14):1815-1819.
[7] WHELAN M J. On the kinetics of precipitate dissolution[J]. Metal Science Journal, 1969, 3(1):95-97.
[8] CHA B, GALBRAITH S C, LIU H, et al. A thermodynamic balance model for liquid film drying kinetics of a tablet film coating and drying process[J]. AAPS Pharm SciTech, 2019, 20(5):209.
[9] LANG P, WOJCIK T, POVODEN-KARADENIZ E,et al.Thermo-kinetic prediction of metastable and stable phase precipitation in Al-Zn-Mg series aluminum alloys during non-isothermal DSC analysis[J].Journal of Alloys and Compounds,2014,609:129-136.
[10] 张蓉,曹秋芳,庞述先,等.Al-Si过共晶合金中初生硅的溶解动力学[J].中国有色金属学报,2000,10(1):89-91. ZHANG R, CAO Q F, PANG S X,et al.Dissolution kinetics of primary silicon for hypereutectic Al-Si alloy[J].The Chinese Journal of Nonferrous Metals,2000,10(1):89-91.
[11] 杨金龙,邓运来,祁小红,等.过饱和7050铝合金固溶体中第二相粒子的析出动力学[J].中南大学学报(自然科学版),2012,43(7):2528-2533. YANG J L, DENG Y L, QI X H,et al.Precipitation kinetics of second-phase particles in supersaturated solid solution of 7050 aluminum alloy[J].Journal of Central South University (Science and Technology),2012,43(7):2528-2533.
[12] MILKEREIT B, BECK M, REICH M,et al.Precipitation kinetics of an aluminum alloy during Newtonian cooling simulated in a differential scanning calorimeter[J].Thermochimica Acta,2011,522(1/2):86-95.
[13] BJØRNEKLETT B I,GRONGA Ø, MYHR O R,et al.Additivity and isokinetic behaviour in relation to particle dissolution[J].Acta Materialia,1998,46(17):6257-6266.
[14] KAMMERER C C, KULKARNI N S, WARMACK B,et al.Interdiffusion in ternary magnesium solid solutions of aluminum and zinc[J].Journal of Phase Equilibria and Diffusion,2016,37(1):65-74.
[15] HILL O F, BRICE J C. The composition of crystals of bismuth silicon oxide[J]. Journal of Materials Science,1974,9(8):1252-1254.
[16] 崔森林.Al合金扩散系数及微结构演变的模拟[D].长沙:中南大学,2012:125. CUI S L.Simulation of diffusion coefficients and microstructure evaluation in Al alloys[D].Changsha:Central South University,2012:125.
2020, Vol. 48 
