198
Y. Birol / Journal of Alloys and Compounds 481 (2009) 195–198
pellets contained fine AlB2 particles dispersed inside, and KAlF4
spent salt entrapped between aluminium grains. Inoculation of a
popular aluminium foundry alloy, 357, with Al-3B pellets at a B
additionlevelof 0.005 wt%has produced fine equiaxedgrains across
the entire section of the grain refining test sample which were more
or less retained for holding times upto 15 min (Fig. 4). The macro-
graphs of the inoculated samples imply over a 4-fold refinement of
the cast grains upon inoculation. The grain refinement performance
of the Al-3B pellets at this addition level is judged to be compara-
ble with those reported for similar Al–B alloys [43,24]. It is thus
concluded that powder metallurgy processing could be employed
to manufacture Al–B alloy pellets for the grain refinement of alu-
minium foundry alloys when rapid adjustments are required to
achieve optimum grain structures.
[3] T. Sagstad, N. Dahle, et al., Proceedings of the Fifth International AFS Conference
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[
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[
[
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[11] Y. Birol, J. Alloys Compd. 420 (2006) 71.
[
12] J. Wang, S. He, B. Sun, Q. Guo, M. Nishio, J. Mater. Process. Technol. 12 (1996)
66.
7
[
13] K.V.S. Prasad, B.S. Murty, P. Pramanik, M. Chakraborty, Mater. Sci. Technol. 12
(1996) 766.
14] C.D. Mayes, D.G. McCartney, G.J. Tatlock, Mater. Sci. Technol. 9 (1993) 97.
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Metals Society, London, 1983, p. 171.
[
[
4
. Summary
[
16] A. Hardman, F.H. Hayes, Mater. Sci. Forum 217–222 (1996) 247.
[
[
17] G.P. Jones, J. Pearson, Metall. Trans. 7B (1976) 223.
18] M.S. Lee, B.S. Terry, Mater. Sci. Technol. 7 (1991) 609.
When Al/KBF4 powder blend samples prepared by mixing and
ball-milling are heated, KBF4 starts to react with aluminium at
[19] Y. Birol, J. Alloys Compd. 420 (2006) 207.
[20] Y. Birol, J. Alloys Compd. 427 (2007) 142.
◦
temperatures as low as 490 C, well below the melting point of
[
21] Y. Birol, J. Alloys Compd. 440 (2007) 108.
aluminium. KBF4 salt is first reduced by aluminium producing
AlB2 particles in aluminium grains and KAlF4 salt dispersed in
between. The former are in the form of clustered stringers marking
the counters of the original powder grains in the mixed sam-
ples. AlB2 particles are dispersed in the aluminium grains more
homogeneously in the ball-milled samples owing to the disper-
sion capacity of the high energy milling process. No evidence of
the AlB12 phase, often reported to be present in Al–B master alloys,
was available. Producing Al–B master alloy tablets with a dispersion
of AlB2 particles in aluminium grains, by heat treating compacted
[
22] Y. Birol, J. Alloys Compd. 443 (2007) 94.
[23] Y. Birol, J. Alloys Compd. 458 (2008) 271.
[24] S.A. Kori, B.S. Murty, M. Chakraborty, Mater. Sci. Eng. A283 (2000) 94.
[
[
25] G.K. Sigworth, M.M. Guzowski, AFS Trans. 93 (1985) 907.
26] J.A. Spittle, S. Sadli, Mater. Sci. Technol. 11 (1995) 533.
[
27] T. Sritharan, H. Li, J. Mater. Process. Technol. 63 (1997) 585.
[28] P.S. Mohanty, J.E. Gruzleski, Acta Mater. 44 (1996) 3749.
[29] P.S. Mohanty, F.H. Samuel, G.E. Gruzleski, Metall. Trans. B 26 (1995) 103.
[
30] H.T. Lu, L.C. Wang, S.K. Kung, J. Chin. Foundryman’s Assoc. 29 (1981) 10.
[31] P.A. Tøndel, G. Halvorsen, L. Arnberg, Light Metals, TMS Publication, 1993, p.
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[32] G.W. Halldin, Y. He, T.H. Tsai, in: J.G. Bewley, S.W. McGee (Eds.), Progress in
Powder Metallurgy, Vol.38, Metal Powder Industries Federation and American
Al/KBF powder blends well below the melting point of aluminium,
4
is judged to be quite feasible. Al–3B pellets thus produced were
shown to offer adequate grain refining efficiency for A357 alloy.
1201.
[
[
34] Y. Birol, J. Mater. Sci. 42 (2007) 5123.
35] Y. Birol, J. Alloys Compd. 455 (2008) 164.
Acknowledgement
[36] Y. Birol, J. Alloys Compd. 460 (2008) L1.
37] Y. Birol, J. Alloys Compd 478 (2009) 265–268.
[
[
[
38] Y. Birol: J. Alloys Compds., doi:10.1016/j.jallcom.2009.01.091.
39] J.B. Fogagnolo, E.M. Ruiz-Navas, M.H. Robert, J.M. Torralba, Scripta Mater. 47
(2002) 243.
It is a pleasure to thank Fahri Alageyik for his help in the exper-
imental part of the work.
[
40] C. Suryanarayana, Prog. Mater. Sci. 46 (2001) 1.
[
41] JANAF Thermochemical Tables, Supplement No. 1, J. Phys. Chem. Ref. Data 14
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