Russian Journal of Non-Ferrous Metals

, Volume 59, Issue 1, pp 32–41 | Cite as

The Influence of Composition and Heat Treatment on the Phase Composition and Mechanical Properties of ML19 Magnesium Alloy

  • A. V. Koltygin
  • V. E. Bazhenov
  • N. V. Letyagin
  • V. D. Belov
Foundry

Abstract

Samples of ML19 magnesium alloy with composition, wt %, (0.1–0.6)Zn–(0.4–1.0)Zr–(1.6–2.3)Nd–(1.4–2.2)Y have been investigated. The influence of Nd, Y, Zn, and Zr on equilibrium phase-transition temperatures and phase composition using Thermo-Calc software is established. The Scheil–Gulliver solidification model is also used. We show the significant liquidus temperature increase if the zirconium content in alloy is higher than (0.8–0.9) wt %. Thus, a higher melting temperature is required (more than 800°C). This is undesirable when melting in a steel crucible. The change in equilibrium fractions of phases at different temperatures in ML19 magnesium alloy with a minimum and maximum amount of alloying elements are calculated. Microstructures of alloys with different amounts of alloying elements in as-cast and heat-treated condition has been studied using scanning electron microscopy (SEM). We investigate the concentration profile of Nd, Y, Zn, and Zr in the dendritic cell of an as-cast alloy. The amount of neodymium and zinc on dendritic cell boundaries increased. A high concentration of yttrium is observed both in the center and on the boundaries of the dendritic cell. A high zirconium concentration is mainly observed in the center of the dendritic cells. A small amount of yttrium is also present in zirconium particles. These particles act as nucleation sites for the magnesium solid solution (Mg) during solidification. The effect of aging temperature (200 and 250°C) on the hardness of the samples after quenching was studied. Aging at 200°C provides a higher hardness. The change in the hardness of quenched samples during aging at 200°C is investigated. Maximum hardness is observed in samples aged for 16–20 h. The two-stage solution heat treatment for 2 h at 400°C and 8 h at 500°C with water quenching and aging at 200°C for 16 h is performed. This heat treatment enables us to get tensile strength 306 ± 8 MPa and yield strength 161 ± 1 MPa with elongation 8.7 ± 1.6%.

Keywords

magnesium cast alloys ML19 Mg–Zr–RE Mg–Zr–Nd–Y–Zn solidification heat treatment phase composition Thermo-Calc 

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References

  1. 1.
    Friedrich, H.E. and Mordike, B.L., Magnesium Technology: Metallurgy, Design Data, Applications, NewYork: Springer, 2006.Google Scholar
  2. 2.
    Mordike, B.L. and Ebert, T., Magnesium: propertiesapplications-potential, Mater. Sci. Eng. A, 2001, vol. 302, no. 1, pp. 37–45.CrossRefGoogle Scholar
  3. 3.
    Rokhlin, L.L., Magnesium Alloys Containing Rare Earth Metals: Structure and Properties, London: Taylor & Francis, 2003.Google Scholar
  4. 4.
    Antion, C., Donnadieu, P., Deschamps, A., Tassin, C., and Pisch A., Hardening precipitation in a Mg–4Y–3RE alloy, Acta Mater., 2003, vol. 51, no. 18, pp. 5335–5348.CrossRefGoogle Scholar
  5. 5.
    Polmear, I.J., Magnesium alloys and applications, Mater. Sci. Technol., 1994, vol. 10, no. 1, pp. 1–16.CrossRefGoogle Scholar
  6. 6.
    Penghuai, F., Liming, P., Haiyan, J., Jianwei, C., and Chunquan, Z., Effects of heat treatments on the microstructures and mechanical properties of Mg–3Nd–0.2Zn–0.4Zr (wt %) alloy, Mater. Sci. Eng. A, 2008, vol. 486, nos. 1–2, pp. 183–192.CrossRefGoogle Scholar
  7. 7.
    Nie, J.F. and Muddle, B.C., Characterisation of strengthening precipitate phases in a Mg–Y–Nd alloy, Acta Mater., 2000, vol. 48, pp. 1691–1703.CrossRefGoogle Scholar
  8. 8.
    Zhao, H.D., Qin, G.W., Ren, Y.P., Pei, W.L., Chen, D., and Guo, Y., The maximum solubility of Y in α-Mg and composition ranges of Mg24Y5–x and Mg2Y1–x intermetallic phases in Mg–Y binary system, J. Alloys Compnd., 2001, vol. 509, no. 3, pp. 627–631.CrossRefGoogle Scholar
  9. 9.
    Chia, T.L., Easton, M.A., Zhu, S.M., Gibson, M.A., Birbilis, N., and Nie, J.F., The effect of alloy composition on the microstructure and tensile properties of binary Mg–rare earth alloys, Intermetallics, 2009, vol. 17, no. 7, pp. 481–490.CrossRefGoogle Scholar
  10. 10.
    Rokhlin, L.L., Dobatkina, T.V., Tarytina, I.E., Timofeev, V.N., and Balakhchi, E.E., Peculiarities of the phase relations in Mg-rich alloys of the Mg–Nd–Y system, J. Alloys Compnd., 2004, vol. 367, nos. 1–2, pp. 17–19.CrossRefGoogle Scholar
  11. 11.
    Mukhina, I.Yu., Duyunova, V.A., Frolov, A.V., and Uridiya, Z.P., Effect of RE alloying on the high-temperature strength of casting magnesium alloys, Metal. Mashinostr., 2014, no. 5, pp. 34–38.Google Scholar
  12. 12.
    Vinotha, D., Raghukandan, K., Pillai, U.T.S., and Pai, B.C., Grain refining mechanisms in magnesium alloys—An overview, Trans. Indian Inst. Met., 2009, vol. 62, pp. 521–532.CrossRefGoogle Scholar
  13. 13.
    Changjiang, S., Qingyou, H., and Qijie, Z., Review of grain refinement methods for as-cast microstructure of magnesium alloy, China Foundry, 2009, vol. 6, pp. 93–103.Google Scholar
  14. 14.
    Polmear, I.J., Light Alloys, Oxford: Butterworth–Heinemann, 2005, 4th ed.Google Scholar
  15. 15.
    Heat Treater’s Guide: Practices and Procedures for Nonferrous Alloys, Chandler, H., Ed., Ohio: ASM International, 1996.Google Scholar
  16. 16.
    Nie, J.F. and Muddle, B.C., Precipitation in magnesium alloy WE54 during isothermal ageing at 250°C, Scr. Mater., 1999, vol. 40, no. 10, pp. 1089–1094.CrossRefGoogle Scholar
  17. 17.
    Nie, J.F., Effects of precipitate shape and orientation on dispersion strengthening in magnesium alloys, Scr. Mater., 2003, vol. 48, no. 8, pp. 1009–1015.CrossRefGoogle Scholar
  18. 18.
    Mengucci, P., Barucca, G., Riontino, G., Lussana, D., Massazza, M., Ferragut, R., and Hassan, Aly E., Structure evolution of a WE43 Mg alloy submitted to different thermal treatments, Mater. Sci. Eng. A, 2008, vol. 479, nos. 1–2, pp. 37–44.CrossRefGoogle Scholar
  19. 19.
    Kumar, N., Choudhuri, D., Banerjee, R., and Mishra, R.S., Strength and ductility optimization of Mg–Y–Nd–Zr alloy by microstructural design, Int. J. Plast., 2015, vol. 68, pp. 77–97.CrossRefGoogle Scholar
  20. 20.
    Feng, H., Liu, H., Cao, H., Yang, Y., Xu, Y., and Guan, J., Effect of precipitates on mechanical and damping properties of Mg–Zn–Y–Nd alloys, Mater. Sci. Eng. A, 2015, vol. 639, pp. 1–7.CrossRefGoogle Scholar
  21. 21.
    Suzuki, M., Kimura, T., Koike, J., and Maruyama, K., Effects of zinc on creep strength and deformation substructures in Mg–Y alloy, Mater. Sci. Eng. A, 2004, vols. 387–389, pp. 706–709.CrossRefGoogle Scholar
  22. 22.
    Andersson, J.O., Helander, T., Hoglund, L., Shi, P.F., and Sundman, B., Thermo-Calc and DICTRA, computational tools for materials science, CALPHAD, 2002, vol. 26, pp. 273–312.CrossRefGoogle Scholar
  23. 23.
    Thermo-Calc Software TTMG3 Magnesium Alloys Database, version 3, accessed June 1, 2017.Google Scholar
  24. 24.
    Gulliver, G.H., The quantitative effect of rapid cooling upon the constitution of binary alloys, J. Inst. Met., 1913, vol. 9, pp. 120–157.Google Scholar
  25. 25.
    Scheil, E., Bemerkungen zur Schichtkristallbildung, Zeitschrift für Metallkunde, 1942, vol. 34, pp. 70–72.Google Scholar
  26. 26.
    Zhang, H., Fan, J., Zhang, L.WuG., Liu, W., Cui, W., and Feng, S., Effect of heat treatment on microstructure, mechanical properties and fracture behaviors of sand-cast Mg–4Y–3Nd–1Gd–0.2Zn–0.5Zr alloy, Mater. Sci. Eng. A, 2016, vol. 677, pp. 411–420.CrossRefGoogle Scholar
  27. 27.
    Rzychon, T. and Kielbus, A., Microstructure of WE43 casting magnesium alloys, J. Achiev. Mater. Manuf. Eng., 2007, vol. 21, pp. 31–34.Google Scholar

Copyright information

© Allerton Press, Inc. 2018

Authors and Affiliations

  • A. V. Koltygin
    • 1
  • V. E. Bazhenov
    • 1
  • N. V. Letyagin
    • 1
  • V. D. Belov
    • 1
  1. 1.National University of Science and Technology “MISiS”MoscowRussia

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