Formation Mechanism of Thixotropic Microstructure of AM60 Alloy during Solidification

Abstract:

A research field on semi-solid metal processing is the preparation of semi-solid slurry with non-dendritic microstructure. Nowadays, with the technological innovation of semi-solid slurry preparation, people turn to produce the non-dendritic semisolid microstructure by locally cooling of the alloy melt during solidification. Therefore, it is necessary to investigate the formation mechanism of the non-dendritic microstructure formation because the primary phase undergoes a specially controlled nucleation and growth which distinctly different from the commom solidification. In this paper, the semisolid slurry of AM60 alloy was produced by Self-Inoculation Method (SIM), and the microstructure evolution of primary α-Mg was investigated by water quenching method and metallographic analysis. The results indicate that the semisolid microstructure of AM60 alloy produced by SIM composed of small and globular α-Mg particles, and these grains undergone a coarsing process during quiescent holding. The solid substrate caused by the fusion of solid particles and the dendritic fragments caused by melt flow caused the grain multiplication, and then the grain undergone a steadily growth because of the uniform temperature distribution, resulting in the increase of grains density and a small grain size of the AM60 semisolid slurry.

• Periodical: Advanced Materials Research (Volumes 1030-1032)
• Pages: 86-89
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1030-1032.86
• Online since: September 2014
• Authors: Bo Xing*
• Keywords: AM60 Alloy, Formation Mechanism, Solidification, Thixotropic Microstructure

References

[1] M.C. Flemings: Metallurgical and Materials Transaction A. Vol. 22A (1991), p.957.

[2] Z. Fan: International Materials Reviews. Vol. 2(2002), p.1.

[3] M. C. Flemings, J. Yurko, R. A. Martinez: The 8th International Conference on Semi-Solid Processing of Alloys and Composites. Limassol, Cyprus, (2004).

[4] J. M. M. Molenaar, L. Katgerman, W. H. Kool: Journal of Materials Science, Vol. 21 (1986), pp.389-394.

[5] S. S. Wu, X. P. Wu, Z. H. Xiao: Acta Materialia, Vol. 52 (2004), p.3519.

[6] M. N. Ahmadabadi, F. Pahlevani, P. Babaghorbani: China Foundry, Vol. 1(2008), p.36.

[7] M. C. Flemings, R. A. Martinez, A. M. Figueredo, U.S. Patent, 20020096231. (2002).

[8] J. Jayaraj, E. Fleury, K. B. Kim et a: Metals and Materials International, Vol. 3(2005), p.257.

[9] H. M. Guo, X. Q. Luo, A. S. Zhang, et al: Transactions of Nonferrous Metals Society of China, Vol. 8(2010, p.1361.