Phase Diagram of Mg-Zn-Gd System Alloy at Mg Rich Corner and its Application in the Development of Two New Alloys

Abstract:

The Mg-rich corner of the equilibrium phase diagram of the Mg-Zn-Gd system has been calculated in detail using the phase diagram calculation software PANDAT and the thermodynamic database for Mg alloys. The calculated phase diagram includes the liquidus projection, isothermal sections and vertical sections. It is found that an increase of Zn content in the Mg-Gd alloy reduces the phase field of α-Mg + GdMg5. Based on the calculated phase diagrams, two alloys, Mg-5.5Zn-2Gd-0.5Zr and Mg-1.6Gd-5.5Zn-0.5Zr (wt.%), denoted as ZGK620 and ZGK616, were developed and their solidification and precipitation processes were analyzed in detail. The optimized thermal mechanical processing and heat-treatment processes were defined by referring to the calculated phase diagrams of the Mg-Zn-Gd system.

• Periodical: Materials Science Forum (Volume 765)
• Pages: 3-7
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.765.3
• Online since: July 2013
• Authors: Yong Chun Guo, Jian Ping Li, Jin Shan Li, Zhong Yang, Ping Wang
• Keywords: CALPHAD, Mg-Zn-Gd Phase Diagram, Phase Equilibrium

References

[1] M. Yamasaki, T. Anan, S. Yoshimoto, Y. Kawamura, Mechanical properties of warm-extruded Mg-Zn-Gd alloy with coherent 14H long periodic stacking ordered structure precipitate, Scripta Mater. 53 (2005) 799-803.

DOI: 10.1016/j.scriptamat.2005.06.006

[2] C.L. Mendis, K. Enhanced, K. Hono, Age hardening in a Mg-2.4at.% Zn alloy by trace additions of Ag and Ca, Scripta Mater. 57 (2007) 485-488.

DOI: 10.1016/j.scriptamat.2007.05.031

[3] H. Somekawa, A. Singh, T. Mukai, High fracture toughness of extruded Mg-Zn-Y alloy by the synergistic effect of grain refinement and dispersion of quasicrystalline phase, Scripta Mater. 56 (2007) 1091-1094.

DOI: 10.1016/j.scriptamat.2007.02.024

[4] Z. Yang, J.P. Li, Y.C. Guo, T. Liu, F. Xia, Z.W. Zeng, M.X. Liang, Precipitation process and effect on mechanical properties of Mg-9Gd-3Y-0.6Zn-0.5Zr alloy, Mat. Sci. Eng. A 454-455 (2007) 274-280.

DOI: 10.1016/j.msea.2006.11.047

[5] Y.C. Guo, J.P. Li, J. Li, Z. Yang, J. Zhao, F. Xia, Minxian Liang, Mg-Gd-Y system phase diagram calculation and experimental clarification, J. Alloys Compd. 450 (2008) 446-451.

DOI: 10.1016/j.jallcom.2006.10.125

[6] J.P. Li, Z. Yang, T. Liu, Y.C. Guo, F. Xia, J.M. Yang, M.X. Liang, Microstructures of extruded Mg-12Gd-1Zn-0.5Zr and Mg-12Gd-4Y-1Zn-0.5Zr alloys, Scripta Mater. 56 (2007) 137-140.

DOI: 10.1016/j.scriptamat.2006.09.008

[7] N. Saunders, Phase diagram calculations for eight glass forming alloy systems, Calphad 9 (1985) 297-309.

DOI: 10.1016/0364-5916(85)90001-x

[8] P.J. Spencer, A brief history of CALPHAD, Calphad 32 (2008) 1-8.

[9] F. von Buch, J. Lietzau, B. L. Mordike, A. Pisch, R. Schmid-Fetzer, Development of Mg-Sc-Mn alloys, Mat. Sci. Eng. A 263 (1999) 1-7.

DOI: 10.1016/s0921-5093(98)01040-5

[10] J. Gröbner, R. Schmid-Fetzer, Selection of promising quaternary candidates from Mg-Mn-(Sc, Gd, Y, Zr) for development of creep-resistant magnesium alloys, J. Alloys Compd. 320 (2001) 296-301.

DOI: 10.1016/s0925-8388(00)01480-8

[11] M. Ohno, D. Mirkovic, R. Schmid-Fetzer, Phase equilibria and solidification of Mg-rich Mg-Al-Zn alloys, Mat. Sci. Eng. A421 (2006) 328-337.

DOI: 10.1016/j.msea.2006.02.006