Effect of Free Ti on Grain Refinment of Aluminium Inoculated with Potent TiB₂ Particles

Abstract:

Growth restriction plays an important role in grain refinement and is often linked with as-cast grain size of Al-Alloys. It has been suggested that Ti is the most powerful solute element for growth restriction among all the commonly used alloying elements. In this work, the growth restriction effect of Ti on the grain refinement of high purity Al (HP-Al, 99.99%) and commercial purity Al (CP-Al, 99.7%) has been investigated using the Alcan TP-1 tests. Grain refining tests were conducted with the same inoculation of potent TiB₂ at a fixed level and free Titanium addition. The results showed that, when the TiB₂ inoculation was fixed to be equivalent to the particle number density of 0.2% Al-5Ti-1B addition, CP-Al has a fully equiaxed grain structure with only 46 ppm solute Ti, while HP-Al has a fully equiaxed grain structure with much higher Ti addition (960 ppm).

• Periodical: Materials Science Forum (Volumes 790-791)
• Pages: 155-160
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.790-791.155
• Online since: May 2014
• Authors: Li Zhou*, Zhong Yun Fan
• Keywords: Grain Refinement, Growth Restriction, Pure Aluminium, Titanium

References

[1] T.E. Quested, Understanding mechanisms of grain refinement of aluminium alloys by inoculation, Mater. Sci. Tech., 20 (2004) 1357-1369.

DOI: 10.1179/026708304225022359

[2] A.M. Bunn, P. Schumacher, M.A. Kearns, C.B. Boothroyd, A.L. Greer, Grain refinement by Al-Ti-B alloys in aluminium melts: A study of the mechanisms of poisoning by zirconium, Mater. Sci. Tech., 15 (1999) 1115-1123.

DOI: 10.1179/026708399101505158

[3] P.S. Mohanty, J.E. Gruzleski, Mechanism of Grain-Refinement in Aluminum, Acta. Metall. Mater, 43 (1995) 2001-(2012).

[4] P. Schumacher, A.L. Greer, J. Worth, P.V. Evans, M.A. Kearns, P. Fisher, A.H. Green, New studies of nucleation mechanisms in aluminium alloys: Implications for grain refinement practice, Mater. Sci. Tech., 14 (1998) 394-404.

DOI: 10.1179/mst.1998.14.5.394

[5] M. Easton, D. StJohn, Grain refinement of aluminum alloys: Part II. Confirmation of, and a mechanism for, the solute paradigm, Metall. Mater. Trans. A: Physical Metallurgy and Materials Science, 30 (1999) 1625-1633.

DOI: 10.1007/s11661-999-0099-4

[6] G.P. Jones, J. Pearson, Factors affecting the grain-refinement of aluminum using titanium and boron additives, Metallurgical Transactions B, 7 (1976) 223-234.

DOI: 10.1007/bf02654921

[7] J.A. Spittle, S. Sadli, Effect of alloy variables on grain refinement of binary aluminium alloys with Al-Ti-B, Mater. Sci. T, 11 (1995) 533-537.

DOI: 10.1179/mst.1995.11.6.533

[8] M. Easton, D. St John, the effect of alloy content on the grain refinement of aluminium alloys, light metal, 2001, pp.927-933.

[9] C.A. Tarshis, J.L. Walker, J.W. Rutter, Metall. Trans, 2(1971) 2589.

[10] I. Maxwell, A. Hellawell, A simple model for grain refinement during solidification, Acta Metall, 23 (1975) 229-237.

DOI: 10.1016/0001-6160(75)90188-1

[11] P. Desnain, Y. Fautrelle, J.L. Meyer, J.P. Riquet, F. Durand, Prediction of equiaxed grain density in multicomponent alloys, stirred electromagnetically, Acta. Metall. Mater, 38 (1990) 1513-1523.

DOI: 10.1016/0956-7151(90)90119-2

[12] M. Easton, D. St John, An analysis of the relationship between grain size, solute content, and the potency and number density of nucleant particles, Metall. Mater. Trans. A: Physical Metallurgy and Materials Science, 36 (2005) 1911-(1920).

DOI: 10.1007/s11661-005-0054-y

[13] Z. Fan, Epitaxial Nucleation and Grain Refinement, Proceedings of the John Hunt International Symposium, UK, 2011, pp.29-44.

[14] Z. Fan, An Epitaxial Model for Heterogeneous Nucleation on Potent Substrates, Metall. Mater. Trans A, 44 (2012) 1409-1418.

DOI: 10.1007/s11661-012-1495-8

[15] Standard test procedure for alumnium grain reifners: TP-1. The alumnium association, Washington, DC, (1987).