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METAL PROCESSING
ArticleName Approaches to the design of the new high-strength casting aluminum alloys of 7xxx series with high iron content
DOI 10.17580/nfm.2016.01.04
ArticleAuthor Akopyan T. K., Belov N. A.
ArticleAuthorData

National University of Science and Technology “MISIS”, Moscow, Russia:

N. A. Belov, Professor of a Chair Casting Technologies and art metal processing

 

1National University of Science and Technology “MISIS”, Moscow, Russia ; 2Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, Moscow, Russia:

T. K. Akopyan, Researcher of Engineering Center “Casting Technologies and Materials”1,2, e-mail: nemiroffandtor@yandex.ru

Abstract

The most high-strength aluminum alloys based on the Al – Zn – Mg – (Cu) system have a significant tendency to form hot cracks during solidification. Additional alloying of 7xxx series alloys with the eutectic forming elements (Fe and Ni) that are slightly soluble in an (Al) solid solution was proposed in order to reduce the hot cracking tendency. In this case, the iron becomes an alloying element, rather than an harmful impurity. Since the appearance of primary crystals of the iron- and nickel-bearing phases is unacceptable, the boundaries of primary crystallization of (Al), Al9FeNi, Al3Ni and Al3Fe phases (the liquidus projection) were computed using Thermo-Calc software. In accordance with the results of thermodynamic calculations of the multicomponent Al – Zn – Mg – Cu – Fe – Ni phase diagram, the new sparingly alloyed alloy ATs6N0.5Zh (Al – 6.3% Zn – 2.1% Mg – 0.2% Cu – 0.4% Fe – 0.6% Ni) based on the (Al) + Al9FeNi eutectic was selected. The results of the fracture surface analysis of the castings after ageing show the mode of fracture is the dimple rupture. Traces of intergrain fracture typical for high-alloyed alloys of the 7xxx series without eutectic inclusions are not observed. Defect-free experimental samples with high mechanical properties (σr ~ 500 МPа, σ0.2 ~ 450 МPа, δ ~ 4.7%) using liquid forging were obtained from the ATs6N0.5Zh alloy.

Research sponsored by the Ministry of Education and Science of the Russian Federation (Agreement 14.578.21.0039 (RFMEFI57814X0039)) in the framework of the Federal Target Program “Researches and developments on priority directions of scientific-technological complex of Russia for 2014–2020” and the grant of the Russian Federation President for Support of the Leading scientific schools, НШ-9899.2016.8.

keywords High-strength aluminum alloys, phase composition, phase diagrams, thermodynamic calculations, castings, mechanical properties
References

1. Polmear I. J. Light Metals: From Traditional Alloys to Nanocrystals. Oxford : Elsevier/Butterworth-Heinemann, 2006. 421 p.
2. Li Jin-feng, Peng Zhuo-wei, Li Chao-xing et al. Mechanical properties, corrosion behaviors and microstructure of 7075 aluminum alloy with various aging treatments. Transactions of Nonferrous Metals Society of China. 2008. Vol. 18. pp. 755–762.
3. Ibrahim M. F., Samuel A. M., Samuel F. H. A preliminary study on optimizing the heattreatment of high strength Al –Cu – Mg – Zn alloys. Materials and Design. 2014. Vol. 57. pp. 342–350.
4. Wenchao Yang, Shouxun Ji, Mingpu Wang, Zhou Li. Precipitation behaviour of Al – Zn – Mg – Cu alloy and diffraction analysis from g0 precipitates in four variants. Journal of Alloys and Compounds. 2014. Vol. 610. pp. 623–629.
5. Adrien J., Maire E., Estevez R., Ehrstrom J. C., Warner T. Influence of the thermomechanical treatment on the microplastic behaviour of a wrought Al – Zn – Mg – Cu alloy. Acta Materialia. 2004. Vol. 52. p. 1653–1661. doi: 10.1016/j.actamat.2003.12.009
6. Xu Fang, Min Song, Kai Li, Yong Du, Dongdong Zhao, Chao Jiang, Hong Zhang. Effects of Cu and Al on the crystal structure and composition of η (MgZn2) phase in over-aged Al – Zn – Mg – Cu alloys. Journal of Materials Science & Technology. 2012. Vol. 47. pp. 5419–5427.
7. Myriam N., Alexis D. Characterisation and modelling of precipitate evolution in an Al – Zn – Mg alloy during nonisothermal heat treatments. Acta Materialia. 2003. Vol. 51. pp. 6077–6094.

8. Xu Fang, Yong Du, Min Song, Kai Li, Chao Jiang. Effects of Cu content on the precipitation process of Al – Zn – Mg alloys. Journal of Materials Science & Technology. 2012. Vol. 47. pp. 8174–8187.
9. Marlaud T., Deschamps A., Bley F., Lefebvre W., Baroux B. Evolution of precipitate microstructures during the retrogression and re-ageing heat treatment of an Al – Zn – Mg – Cu alloy. Acta Materialia. 2010. Vol. 58. pp. 4814–4826. doi: 10.1016/j.actamat.2010.05.017
10. Zolotorevskiy V. S., Belov N. A. Metallovedenie liteynykh aluminievykh splavov (Materials Science of Casting Aluminum Alloys). Moscow : MISiS, 2005. 376 p.
11. Zolotorevskiy V. S., Belov N. A. Materials Science of Casting Aluminum Alloys. MISiS : Moscow, 2005. 376 p.
12. Belov N. A., Zolotorevskiy V. S. Liteynye splavy na osnove aluminievo-nikelevoy evtektiki (nikaliny) kak vozmozhnaya alternativa siluminam (Casting alloys based on aluminum–nickel eutectic (nikalins) as a possible alternative for silumins). Tsvetnye Metally = Non-ferrous metals. 2003. No. 2. pp. 99–105.
13. Belov N. A., Zolotorevskiy V. S. The effect of nickel on the structure, mechanical and casting properties of 7075 aluminum alloy. Materials Science Forum. 2002. 396–402.
14. Pat. 2245383 RF. Aluminum-base material/ Belov N. A. et al. Byull. Izobr. Polezn. Modeli, 2005. No. 3.
15. Belov N. A., Tagiev E. E. Eutectic structures in alloys based on solid solution of the Al – Zn – Mg – Cu system. Izv. Vysh. Ucheb. Zaved., Tsvetn. Met. 1991. Vol. 2. pp. 95–98.
16. Lijun Zhang, Jiong Wang, Yong Du, Rongxiang Hu, Philip Nash, Xiao-Gang Lu and Chao Jiang. Thermodynamic properties of the Al – Fe – Ni system acquired via a hybrid approach combining calorimetry, first-principles and CALPHAD. Acta Materialia. 2009. Vol. 57. pp. 5324–5341. doi: 10.1016/j.actamat.2009.07.031
17. Mondolfo L. F. Structura I svoystva aluminievykh splavov (Structure and Properties of Aluminum Alloys). Moscow : Metallurgiya, 1979. 640 p.
18. Zakharov M. Promyshlennye splavy tsvetnykh metallov (Commercial alloys of non-ferrous metals). Moscow : Metal lurgiya, 1980. 256 p.

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