The Refinement Mechanism of La-Ce Binary Alloy on Primary α Phase in A356 Alloy under Electromagnetic Stirring

Abstract:

The refining effects of La-Ce binary alloy on the primary α phase in semisolid A356 alloy prepared by electromagnetically stirred were researched, in which the refinement mechanism of the binary alloy on primary α phase were emphatically approached. The different amount of La-Ce was added into A356 melt, the melt was poured at 620°C and slightly electromagnetically stirred for 15s with an electromagnetic stirrer which was controlled by frequency conversion, then it was isothermally held at 615°C for 10min. The shape and size of primary α phase were measured, and the distribution of La and Ce was researched by SEM and EDS. The results indicated that the RE elements were easy to uniformly distribute around the primary α phase under electromagnetic stirring, and had the obvious refining effect on primary α phase in semisolid A356 alloy, in which there was the finer primary α phase with particle-like in the melt. The refinement mechanism of La-Ce binary alloy under electromagnetic stirring was concerned with the eutectic reaction between RE elements and Al in the melt, in which the α-Al phase resulted from the Al-RE eutectic reaction could serve as the nucleating site of the primary α phase during solidification of A356 alloy. The other reactant from the Al-RE eutectic reaction, Al₁₁Ce₃, was also directly used as nucleation of α phase during the solidification.

• Periodical: Solid State Phenomena (Volumes 217-218)
• Pages: 340-346
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.217-218.340
• Online since: September 2014
• Authors: Zheng Liu*, Hao Lin Luo, Qing Chun Chen
• Keywords: Electromagnetic Stirring, Eutectic Reaction, Primary α Phase, Rare Earth, Semi-Solid

References

[1] S. Nafisi, D. Emadi, Effects of electromagnetic stirring and superheat on the microstructural characteristics of Al-Si-Fe alloy, Mater. Sci. Eng. 432A (2006) 71-83.

DOI: 10.1016/j.msea.2006.05.076

[2] X. M. Liu, Z. Liu, Y. M. Hu, Research on effect of La on microstructure in semi-solid A356 alloy, Advanced Material Research. 139-141(2010) 693-697.

DOI: 10.4028/www.scientific.net/amr.139-141.693

[3] L. N. Yu, X. F. Liu, The relationship between viscosity and refinement efficiency of pure aluminum by Al-Ti-B refiner, J. Alloys and Compounds, 425(2006) 245-250.

DOI: 10.1016/j.jallcom.2006.08.257

[4] M. Hosseinifar, D. V. Malakhov, The sequence of intermetallics formation during the solidifi- cation of an Al-Mg-Si alloy containing La, Metall. Mater. Trans. 42A(2011) 825-832.

DOI: 10.1007/s11661-010-0453-6

[5] K. Nogita, H. Yasuda, M. Yoshiya, The role of trace element segregation in the eutectic modification of hypoeutectic Al-Si alloys, J. Alloys and Compounds. 489(2010) 415-420.

DOI: 10.1016/j.jallcom.2009.09.138

[6] E. A. Torre, R. Pérez-Bustamante, J. Camarillo-Cisneros, Mechanical properties of the A356 aluminum alloy modified with La/Ce, J. Rare Earths. 31(2013) 811-817.

DOI: 10.1016/s1002-0721(12)60363-9

[7] Z. Liu, Y. M. Hu, X. M. Liu, Research on refining mechanism of yttrium on primary α-Al in semi-solid Al alloy, Acta Metallurgica Sinica. 23(2010) 277-284.

[8] Z. Liu, F. Y. Wang, K. Cao, Application of frequency conversion in preparation of semisolid A356 alloy slurry, Advanced Materials Research. 430-432(2012) 886-889.

DOI: 10.4028/www.scientific.net/amr.430-432.886

[9] M. Reisi, B. Niroumand, Effects of stirring parameters on rheocast structure of Al-7. 1wt% Si alloy, J. Alloys and Compounds. 470(2009) 413-419.

DOI: 10.1016/j.jallcom.2008.02.104

[10] Y. Z. Xiao, H. S. Ma, G. M. Lu, Effective nucleation particles in grain refining of Al-Ti-B master alloy, The Chinese J. Nonferrous Metals. 7(1997) 137-139.