Journal of Korea Foundry Society (한국주조공학회지)

Korea Foundry Society (한국주조공학회)
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Effect of Zn additions on the Mechanical Properties of High Strength Al-Si-Mg-Cu alloys

Zn 첨가량에 따른 Al-Si-Mg-Cu계 합금의 미세조직 및 기계적 특성변화

  • Received : 2019.05.28
  • Accepted : 2019.06.12
  • Published : 2019.06.30
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Abstract

In this study, the effects of Zn additions on the mechanical properties of Al-Si-Mg-Cu alloys were investigated by increasing the amount of Zn up to 8wt.%. As the Zn content was increased up to 6 wt.%, the yield strength and elongation changed linearly without any significant changes in the size and shape of the main reinforcement phase. However, it was confirmed by SEM observation that the Mg-Zn phase formed between the reinforcement phases when the amount of Zn added exceeded 7wt.%. A Mg-Zn intermetallic compound formed between the $Mg_2Si$ phase, becoming a crack initiation point under stress. Thus, the formation of the Mg-Zn phase may cause a sharp decrease in the elongation when Zn at levels exceeding 7 wt.%. It was also found that the matrix became more brittle with increasing the Zn content. From these results, it can be concluded that the formation of the Mg-Zn intermetallic compound and the brittle characteristics of the matrix are the main causes of the remarkable changes in the mechanical properties of this alloy system

Keywords

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Fig. 1. Design of the mold; (a) cylinder mold, (b) Y-block

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Fig. 2. ASTM E8M standard specimen used for tensile test.

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Fig. 3. Schematic illustration of Cracking analysis for intermetallic compound.

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Fig. 4. SEM image of the A alloy.

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Fig. 5. Optical microstructure of the Al-6Si-4Mg-2Cu alloys; (a) A alloys, (b) B alloys, (c) C alloys, (d) D alloys, (e) E alloys, (f) F alloys.

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Fig. 6. SEM images and EDS analysis of Al-6Si-4Mg-2Cu alloys; (a) A alloys, (b) B alloys, (c) C alloys, (d) D alloys, (e) E alloys, (f) F alloys.

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Fig. 7. Ternary phase diagram of Al-Mg-Zn alloys (at.%).

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Fig. 8. SEM images of the F alloys; (a) as cast microstructue, (b) Mg-Zn intermetallic compound.

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Fig. 9. Comparison of experimental results with the values of the Labusch’s model of A~F alloys.

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Fig. 10. Variation of tensile behavior with increasing amount of Zn in A~F alloys; (a) stress-strain curve, (b) variation of mechanical properties.

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Fig. 11. SEM images of Mg-Zn intermetallic compound in F alloys.

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Fig. 12. Schematic illustration of fracture mechanism : (a) A~D alloys, (b) E~F alloys.

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Fig. 13. Cracking analysis related to the intermetallic compound in the Al-Si-Mg-Cu alloys : (a) A alloy, (b) F alloy.

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Fig. 14. Fractography of specimen ; (a) A alloys, (b) F alloys.

Table 1. Chemical composition of Al-6Si-4Mg-2Cu-XZn alloys.

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Table 2. Chemical composition of Al-6Si-4Mg-2Cu alloy.

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Table 3. EDS point analysis of Al-6Si-4Mg-2Cu-8Zn alloys.

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Table 4. Function of Labusch’s Model.

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Table 5. Rockwell hardness test results according to Zn addition in A~F alloys.

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Table 6. Tensile test result according to the Zn addition in Al-6Si-4Mg-2Cu-XZn alloys.

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Table 7. EDS results of Al-Si-Mg alloys.

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References

  1. B. M. Al-Alawi and T. H. Bradley, Appl. Energy, "Analysis of corporate average fuel economy regulation compliance scenarios inclusive of plug in hybrid vehicles", 113 (2014) 1323-1337. https://doi.org/10.1016/j.apenergy.2013.08.081
  2. J. Hirsch and T. Al-Samman, Acta Mater., "Superior light metals by texture engineering: Optimized aluminum and magnesium alloys for automotive applications", 61 (2013) 818-843. https://doi.org/10.1016/j.actamat.2012.10.044
  3. W.S. Miller, L. Zhuang, J. Bottema, A.J. Wittebrood, P. De Smet, A. Haszler and A. Vieregge, Materials Science and Engineering A., "Recent development in aluminium alloys for the automotive industry", 280 (2000) 37-49. https://doi.org/10.1016/S0921-5093(99)00653-X
  4. F. Wang, H. Liu, Y. Ma and Y. Jin, Mater. Des., "Effect of Si content on the dry sliding wear properties of spray-deposited Al-Si alloy", 25 2004 (163-166). https://doi.org/10.1016/j.matdes.2003.08.005
  5. Q. G. Wang and C.J. Davidson, Journal of Materials Science 36, "Solidification and precipitation behavioer of Al-Si-Mg casting alloys", 6 (2001) 739-750. https://doi.org/10.1023/A:1004801327556
  6. Kim BJ, Jung SS, Hwang JH, Park YH and Lee YC, "Effect of eutectic Mg2Si phase modification on the mechanical properties of Al-8Zn-6Si-4Mg-2Cu cast alloy", 9 (2019) 32. https://doi.org/10.3390/met9010032
  7. C. H. Caceres, C. J. Davidson and J. R. Griffiths, Mater. Sci. Eng. A, "The deformation and fracture behaviour of an AlSiMg casting alloy", 197 (1995) 171-179. https://doi.org/10.1016/0921-5093(94)09775-5
  8. N. Chawla and Y. L. Shen, Adv. Eng. Mater., "Mechanical behavior of particle reinforced metal matrix composites", 3 (2001) 357-370. https://doi.org/10.1002/1527-2648(200106)3:6<357::AID-ADEM357>3.0.CO;2-I
  9. U. Cocen, K. Onel and I. Ozdemir, Compos. Sci. Technol., "Microstructures and age hardenability of Al-5%si-0.2%Mg based composites reinforced with particulate SiC", 57 (1997) 801-808. https://doi.org/10.1016/S0266-3538(97)00049-3
  10. L. Lochte, A. Gitt, G. Gottstein, and I. Hurtado, Acta Mater., "Simulation of the evolution of GP zones in Al-Cu alloys: an extended Cahn-Hilliard approach", 48 (2000) 2969-2984. https://doi.org/10.1016/S1359-6454(00)00073-2
  11. O. Ryen, B. Holmedal, O. Nijs, E. Nes, E. Sjolander and H.-E. Ekstrom, Metall. Mater. Trans. A Phys. Metall. Mater. Sci., "Strengthening mechanisms in solid solution aluminum alloys", 37 (2006) 1999-2006. https://doi.org/10.1007/s11661-006-0142-7
  12. A. I. Haruna and I. U. Abhulimen, International Journal of Scientific & Technology Research, "Effect of macro additions of zinc and nickel on the mechanical and microstructural properties of a modified 7xxx aluminium alloy", 3 (2014) 94-99.
  13. X. Wang, M. Guo, J. Luo, J. Zhu, J. Zhang and L. Zhuang, Mater. Charact., "Effect of Zn on microstructure, texture and mechanical properties of Al-Mg-Si-Cu alloys with a medium number of Fe-rich phase particles", 134 (2017) 123-133. https://doi.org/10.1016/j.matchar.2017.10.012
  14. W. X. Shu et al., Mater. Sci. Eng. A, "Tailored Mg and Cu contents affecting the microstructures and mechanical properties of high-strength Al-Zn-Mg-Cu alloys", 657 (2016) 269-283. https://doi.org/10.1016/j.msea.2016.01.039
  15. A. P. Tsai, J. Non. Cryst. Solids, "A test of Hume-Rothery rules for stable quasicrystals", 334-335 (2004) 317-322. https://doi.org/10.1016/j.jnoncrysol.2003.11.065
  16. X. Wang, Q. dong Nie, X. liang Ma, J. long Fan, T. liang Yan and X. lin Li, Trans. Nonferrous Met. Soc. China (English Ed.), "Microstructure and properties of co-continuous (${\beta}$-TCP+MgO)/Zn-Mg composite fabricated by suction exsorption for biomedical applications", 27 (2017) 1996-2006. https://doi.org/10.1016/S1003-6326(17)60224-3
  17. H. Liang, S. L. Chen and Y. A. Chang, Metall. Mater. Trans. A Phys. Metall. Mater. Sci., "A thermodynamic description of the Al-Mg-Zn system", 28 (1997) 1725-1734. https://doi.org/10.1007/s11661-997-0104-8
  18. M. Liu et al., Mater. Sci. Eng. A, "Precipitation kinetics and hardening mechanism in Al-Si solid solutions processed by high pressure solution treatment", 712 (2018) 757-764. https://doi.org/10.1016/j.msea.2017.12.033
  19. L. Li, Y. Liu, H. Gao and Z. Gao, Journal of Materials Science: Materials in Electronics, "Phase formation sequence of hightemperature Zn - 4Al - 3Mg solder", 24 (2013) 336-344. https://doi.org/10.1007/s10854-012-0751-4
  20. J. Li, Z. Qu, R. Wu and M. Zhang, Mater. Sci. Eng. A, "Effects of Cu addition on the microstructure and hardness of Mg - 5Li - 3Al - 2Zn alloy", 527 (2010) 2780-2783. https://doi.org/10.1016/j.msea.2010.01.021