A HRTEM-EDS-SAED Study of Precipitates in Mg-Zn-Zr Alloy

Year 2024, Volume: 12 Issue: 3, 1752 - 1761, 31.07.2024

Ozgur Duygulu

https://doi.org/10.29130/dubited.1397327

Abstract

In this study, aging heat treatment was performed on extruded Mg-Zn-Zr alloy. Aging was performed on as-extruded samples at 180°C for 1-2-4-8 and 24 hours. Microhardness tests were made to obtain the aging curve. Detailed transmission electron microscopy (TEM) examinations such as selected area electron diffraction (SAED), energy dispersive spectrometry (EDS), and high resolution transmission electron microscopy (HRTEM) were used to investigate the microstructure, second phases, and precipitates. Size, type, and morphologies of second phases and precipitates were studied aided by advanced transmission electron microscopy techniques. With the help of hardness test results peak aged condition was found to be 8 hour aging. TEM examinations were detailed for the 8-hour aged sample. It was observed that the precipitates responsible for age hardening were MgZn2. Moreover, the majority of these precipitates were β’1 phase.

Keywords

TEM, EDS, SAED, Magnesium alloys, Extrusion, Aging

Mg-Zn-Zr Alaşımında Çökeltilerin HRTEM-EDS-SAED Çalışması

Abstract

Bu çalışmada, ekstrüde edilmiş Mg-Zn-Zr alaşımına yaşlandırma ısıl işlemi uygulanmıştır. Yaşlandırma, ekstrüzyon sonrası numuneler üzerinde 180°C'de 1-2-4-8 ve 24 saat süreyle gerçekleştirilmiştir. Yaşlanma eğrisinin elde edilmesi için mikrosertlik testleri yapılmıştır. Mikroyapıyı, ikinci fazları ve çökeltileri araştırmak için seçili alan elektron kırınımı (SAED), enerji dağılım spektrometrisi (EDS) ve yüksek çözünürlüklü geçirimli elektron mikroskobu (HRTEM) gibi ayrıntılı geçirimli elektron mikroskobu (TEM) incelemeleri kullanılmıştır. İkinci fazların ve çökeltilerin boyut, tip ve morfolojileri ileri geçirimli elektron mikroskobu teknikleri desteğiyle incelenmiştir. Sertlik sonuçları yardımı ile pik yaşlanma noktasının 8-saat yaşlanma olduğu bulunmuştur. TEM incelemeleri 8-saat yaşlanma numunesinde detaylandırılmıştır. Yaşlanma sertleşmesinden sorumlu çökeltilerin MgZn2 olduğu gözlemlenmiştir. Ayrıca bu çökeltilerim çoğu β’1 fazıdır.

Keywords

TEM, EDS, SAED, Magnezyum alaşımları, Ekstrüzyon, Yaşlandırma

References

• [1] M. M. Avedesian, and H. Baker, Magnesium and magnesium alloys, ASM Specialty Handbook, Ohio, 1999.
• [2] E.F. Emley, Principles of magnesium technology, Pergamon, Oxford, 1966.
• [3] H. E. Friedrich and B. L. Mordike, Magnesium technology, Vol. 212, Springer-Verlag Berlin Heidelberg, 2006.
• [4] I. J. Polmear, Light alloys, metallurgy of the light elements, Arnold, London, 2006.
• [5] K.U. Kainer and F. V. Buch, The current state of technology and potential for further development of magnesium applications, Magnesium Alloys and Technology, Wiley-VCH, 2003.
• [6] X. Gao and J. F. Nie, “Characterization of strengthening precipitate phases in a Mg–Zn alloy,” Scr. Mater., vol. 56, no. 8, pp. 645–648, 2007.
• [7] J. Buha, “Reduced temperature (22-100 °C) ageing of an Mg-Zn alloy,” Mater. Sci. Eng. A, vol. 492, no. 1–2, pp. 11–19, 2008.
• [8] X. Gao and J. F. Nie, “Structure and thermal stability of primary intermetallic particles in an Mg-Zn casting alloy,” Scr. Mater., vol. 57, no. 7, pp. 655–658, 2007.
• [9] J. F. Nie, “Precipitation and hardening in magnesium alloys,” Metall. Mater. Trans. A Phys. Metall. Mater. Sci., vol. 43, no. 11, pp. 3891–3939, 2012.
• [10] L. Y. Wei, G. L. Dunlop, and H. Westengen, “Precipitation Hardening of Mg-Zn and Mg-Zn-RE alloys,” Metall. Mater. Trans. A, vol. 26, no. 7, pp. 1705–1716, 1995.
• [11] Z. Z. Shi, H. T. Chen, K. Zhang, F. Z. Dai, and X. F. Liu, “Crystallography of precipitates in Mg alloys,” J. Magnes. Alloy., vol. 9, no. 2, pp. 416–431, 2021.
• [12] Y. Yang, S. Yang, and L. Jiang, “Study on the microstructural characteristics of adiabatic shear band in solid-solution treated ZK60 magnesium alloy,” Mater. Charact., vol. 156, no. July, p. 109840, 2019.
• [13] H. Chen, T. Liu, Y. Zhang, B. Song, D. Hou, and F. Pan, “The yield asymmetry and precipitation behavior of pre-twinned ZK60 alloy,” Mater. Sci. Eng. A, vol. 652, pp. 167–174, 2016.
• [14] Y. Yang, Z. Wang, and L. Jiang, “Evolution of precipitates in ZK60 magnesium alloy during high strain rate deformation,” J. Alloys Compd., vol. 705, pp. 566–571, 2017.
• [15] Z. Wang et al., “Effect of aging-treatment on dynamic compression behaviour and microstructure of ZK60 alloy,” Mater. Sci. Technol. (United Kingdom), vol. 37, no. 13, pp. 1117–1128, 2021.
• [16] A. Gorny and A. Katsman, “Precipitation- and stress-influenced coarsening in Mg-based Mg-Zn-Sn-Y and Mg-Zn-Sn-Sb alloys,” J. Mater. Res., vol. 23, no. 5, pp. 1228–1236, 2008.
• [17] C. Hou et al., “Aging hardening and precipitate behavior of a solution-treated Mg-6Zn-4Sn-1Mn (wt.%) wrought Mg alloy,” J. Alloys Compd., vol. 889, p. 161640, 2022.
• [18] M. Klinger. CrysTBox - Crystallographic Toolbox. Institute of Physics of the Czech Academy of Sciences, Prague, 2015. ISBN 978-80-905962-3-8. URL http://www.fzu.cz/~klinger/ crystbox.pdf
• [19] J. Tang, L. Chen, Z. Li, G. Zhao, and C. Zhang, “Formation of abnormal coarse grains and its effects on corrosion behaviors of solution treated ZK60 Mg alloy,” Corros. Sci., vol. 180, no. September 2020, p. 109201, 2021.