Structural evolution of Al-8%Si hypoeutectic alloy by ultrasonic processing

doi:10.1016/j.jmst.2017.07.018

Abstract

Abstract:

High intensity power ultrasound was respectively introduced into three different solidification stages of Al-8%Si hypoeutectic alloy, including the fully liquid state before nucleation, the nucleation and growth process of primary α(Al) phase and L → (Al) + (Si) eutectic transformation period. It is found that both the primary α(Al) phase and (Al + Si) eutectic structure were refined by different degrees with various growth morphologies depending on the ultrasonic treatment stage. Based on the experimental results, the cavitation-induced nucleation due to the high undercooling caused by the collapse of tiny cavities was proposed as the major reason for refining the primary α(Al) phase. Meanwhile, obvious eutectic morphological change was observed only when ultrasound was directly introduced in the eutectic transformation stage, in which typical divorced eutectics and (Al + Si) eutectic cells with symmetrical flower shape were formed at the top of the alloy sample. The introduction of ultrasound in each solidification stage also improves the yield strength of Al-8% Si alloy to a diverse extent.

Key words: Solidification, Microstructure, Metals and alloys, Power ultrasound, Refinement

Wang J.Y., Wang B.J., Huang L.F.. Structural evolution of Al-8%Si hypoeutectic alloy by ultrasonic processing[J]. J. Mater. Sci. Technol., 2017, 33(11): 1235-1239.

Figures/Tables 3

Fig. 1. Microstructure and size distribution of primary α(Al) phase in solidified Al-8%Si alloy samples: (a) static; ultrasound applied in (b) stage I, (c) stage II and (d) stage III. The insets in (a), (b), (c) and (d) are the corresponding cooling curves; (e) size distribution of primary α(Al) phase. ds, dI, dIIand dIII represent the grain size of primary α(Al) phase in Al-8%Si alloy samples under static condition, with ultrasonic treatment in stages I, II and III, respectively. f is the distribution probability of size distribution for primary α(Al) phase.

Fig. 2. SEM images of (Al + Si) eutectic structure in Al-8%Si alloy: (a) eutectic morphology formed during static solidification; (b) enlarged view of zone A shown in (a); (c) eutectic microstructure formed at the sample top (0-3 mm) when ultrasound was applied in stage III. The inset shows the location of this morphology; (d) enlarged view of zone B shown in (d); (e) eutectic structure formed at the sample top (3-6 mm) of the sample when ultrasound was applied in stage III. The inset shows the location of this morphology; (f) enlarged view of zone C shown in (e); (g) spacing of eutectic (Si) phase λ; (h) size distribution of eutectic (Si) phase L. The subscripts S, I, II and III stand for the solidified alloy samples under static condition and with ultrasonic treatment in stages I, II and III, respectively. f is the distribution probability of size distribution for primary α(Al) phase.

Fig. 3. Compressive stress-strain curves of Al-8%Si hypoeutectic alloy samples with different ultrasonic treatment stages. The inset shows the change of yield strength.

References

[1]	R.V. Reyes, T.S. Bello, R. Kakitani, T.A. Costa, A. Garcia, N. Cheung, J.E. Spinellia, Mater. Sci. Eng. A 685 (2017) 235-243.
[2]	M. Okayasu, S. Takeuchi, T. Shiraishi, Int. J. Cast. Metal. Res. 26(2013) 105-113.
[3]	H. Kaya, A. Aker, J. Alloys Compd. 694(2017) 145-154.
[4]	Z. Qian, X. Liu, D. Zhao, G. Zhang, Mater. Lett. 62(2008) 2150-2153.
[5]	G. Timelli, D. Caliari, J. Rakhmonov, J. Mater. Sci. Technol. 32(2016) 515-523.
[6]	P. Nageswararao, D. Singh, R. Jayaganthan, J. Mater. Sci. Technol. 30(2014) 998-1005.
[7]	N. Haghdadi, A. Zarei-Hanzaki, H.R. Abedi, O. Sabokpa, Mater. Sci. Eng. A 549 (2012) 93-99.
[8]	N. Haghdadi, A. Zarei-Hanzaki, H.R. Abedi, D. Abou-Ras, M. Kawasaki, A.P. Zhilyaev, Mater. Sci. Eng. A 651 (2016) 269-279.
[9]	W. Zhai, Z.Y. Hong, X.L. Wen, D.L. Geng, B. Wei, Mater. Des. 72(2015) 43-50.
[10]	R.R. Chen, D.S. Zheng, J.J. Guo, H.S. Ding, Y.Q. Su, H.Z. Fu, Mater. Sci. Eng. A 653 (2016) 23-26.
[11]	R.R. Chen, D.S. Zheng, T.F. Ma, H.S. Ding, Y.Q. Su, J.J. Guo, H.Z. Fu, Ultrason. Sonochem. 38(2017) 120-133.
[12]	D. Shu, B.D. Sun, J.W. Mi, P.S. Grant, Metall. Mater. Trans. A 43 (2012) 3755-3766.
[13]	Z. Liu, Q. Han, Z. Huang, J. Xing, Y. Gao, Chem. Eng. J. 263(2015) 317-324.
[14]	W. Zhai, B.J. Wang, H.M. Liu, L. Hu, B. Wei, Sci. Rep. 6(2016) 36178.
[15]	W. Zhai, H.M. Liu, Z.Y. Hong, W.J. Xie, B. Wei, Ultrason. Sonochem. 34(2017) 130-135.
[16]	X. Jian, H. Xu, T. Meek, Q. Han, Mater. Lett. 59(2005) 190-193.
[17]	X. Jian, T.T. Meek, Q. Han, Scr. Mater. 54(2006) 893-896.
[18]	S. Wu, S. Lü, P. An, H. Nakae, Mater. Lett. 73(2012) 150-153.
[19]	G. Wang, M.S. Dargusch, M. Qian, D.G. Eskin, D.H. StJohn, J. Cryst. Growth 408 (2014) 119-124.
[20]	F. Wang, D. Eskin, T. Connolley, J. Mi, J. Cryst. Growth 435 (2016) 24-30.
[21]	J.R.G.Sander, B.W. Zeiger, K.S. Suslick, Ultrason. Sonochem. 21(2014) 1908-1915.
[22]	T.V. Atamanenko, D.G. Eskin, M. Sluiter, L. Katgerman, J. Alloys Compd. 509(2011) 57-60.
[23]	Y. Han, K. Li, J. Wang, D. Shu, B. Sun, Mater. Sci. Eng. A 405 (2005) 306-312.
[24]	J.D. Hunt, K.A. Jackson, Nature 211 (1966) 1080-1081.
[25]	H. Huang, D. Shu, D.J. Zeng, F. Bian, Y. Fu, J. Wang, B. Sun, Scr. Mater. 106(2015) 21-25.
[26]	F. Wang, I. Tzanakis, D. Eskin, J. Mi, T. Connolley, Ultrason. Sonochem. 39(2017) 66-76.
[27]	H.K. Feng, S.R. Yu, Y.L. Li, L.Y. Gong, J. Mater. Process. Technol. 208(2008) 330-335.
[28]	A. Das, H.R. Kotadia, Mater. Chem. Phys. 125(2011) 853-859.
[29]	W. Zhai, Z.Y. Hong, W.J. Xie, B. Wei, Chin. Sci. Bull. 56(2011) 89-95.
[30]	W. Kurz, D.J. Fisher, Switzerland, 1998, pp. 30-36.
[31]	V. Vijayan, K.N. Prabhu, Int. J. Cast Metal Res. 29(2016) 345-349.
[32]	X.P. Niu, B.H. Hu, I. Pinwill, H. Li, J. Mater. Process. Technol. 105(2000) 119-127.