Microstructure Evolution in Melt Conditioned Direct Chill (MC-DC) Casting of Fe-Rich Al-Alloy

Abstract:

In order to fabricate high quality aluminium products, it is first essential to produce high quality billets/slabs. One of the key objectives associated with casting processes is to be able to control the as-cast structure. A novel direct chill (DC) casting process, the melt conditioned direct chill (MC-DC) casting process, has been developed for production of high quality aluminium billets. In the MC-DC casting process, a high shear device is submerged in the sump of the DC mould to provide intensive melt shearing, which in turn, disperses potential nucleation particles, creates a macroscopic melt flow to uniformly distribute the dispersed particles, and maintains a uniform temperature and chemical composition throughout the melt in the sump. The effect of intensive shearing on the complex microstructure evolution observed after MC-DC is explained on the basis of nucleation and growth behavior. Complete suppression of typical columnar grain growth and significant equiaxed grain refinement is observed. The solidification mechanisms responsible for the significant grain refinement by intensive shearing and the morphological evolution of Mg₂Si and Fe–containing intermetallic phases are discussed.

• Periodical: Advanced Materials Research (Volume 1019)
• Pages: 90-95
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1019.90
• Online since: October 2014
• Authors: H.R. Kotadia*, J.B. Patel, H Tian Li, F. Gao, Z. Fan
• Keywords: Al Alloy, Fe Intermetallics, Grain Refinement, Intensive Shearing, Solidification

References

[1] J.R. Davies (Ed. ), Aluminum and aluminium alloys, ASM International, 1993, OH.

[2] H.T. Li, Y. Wang, Z. Fan, Mechanisms of enhanced heterogeneous nucleation during solidification in binary Al-Mg alloys, Acta Mater. 60 (2012) 1528-1537.

DOI: 10.1016/j.actamat.2011.11.044

[3] J.B. Patel, A.K. Prasada Rao, B. Jiang, Y.B. Zuo, Z. Fan; 9th Int. Conf. Magnesium Alloys and their Applications, Vancouver, BC, Canada (2012) 731-736.

[4] A. Das, H.R. Kotadia, Effect of high-intensity ultrasonic irradiation on the modification of solidification microstructure in a Si-rich hypoeutectic Al-Si alloy, Mater. Chem. Phys. 125 (2011) 853–859.

DOI: 10.1016/j.matchemphys.2010.09.035

[5] J. B Patel, H. T. Li, X. Mingxu, S. Jones, S. Kumar, K. O'Reilly, Z. Fan, Melt conditioned direct chill casting (MC-DC) process for production of high quality aluminium alloy billets, submitted to 14th Inter. Conf. Aluminium Alloys, Trondheim, Norway, (2014).

DOI: 10.4028/www.scientific.net/msf.794-796.149

[6] H.R. Kotadia, N. Hari Babu, H. Zhang, Z. Fan, Microstructural refinement of Al-10. 2%Si alloy by intensive shearing, Mater. Lett. 64 (2010) 671–673.

DOI: 10.1016/j.matlet.2009.12.033

[7] X. Cao, J. Campbell, The solidification characteristics of Fe-rich intermetallics in Al-11. 5Si-0. 4Mg cast alloys Metall. Mater. Trans. A, 35 (2004) 1425-1435.

DOI: 10.1007/s11661-004-0251-0

[8] D. G. McCartney, Grain refining of aluminium and its alloys using inoculants, Inter. Mater. Rev. 34 (1989) 247–260.

DOI: 10.1179/imr.1989.34.1.247

[9] Z. Fan, Y.B. Zuo and B. Jiang, Apparatus and method for liquid metals treatment, Application No. 1015498. 7, 2010, UK Patent.

[10] Y. Tsunekawa, H. Suzuki, Y. Genma, Application of ultrasonic vibration to in situ MMC process by electromagnetic melt stirring, Mater. Des. 22 (2001) 467–472.

DOI: 10.1016/s0261-3069(00)00079-0