Abstract
Shaping of metals by thixoforming relies on the unusual flow behavior of semisolid slurries containing nondendritic solid phase. The microstructure of an alloy stirred during freezing consists of rounded particles of solid, as opposed to the dendrites associated with conventional solidification. In the semisolid state, these slurries are thixotropic, in that their apparent viscosity is dependent on shear rate and time. Here, a technique of rapid compression testing is outlined, carried out under conditions similar to normal industrial thixoforming, to assess slurry flow behavior and to examine the correlation between feedstock production routes, microstructure, and resistance to flow. Samples are heated to the desired temperature in the semisolid state with various soaking times and rammed at constant velocity against a platen backed by a load cell. The load-displacement curves produced from the tests may show an initial peak, believed to originate from a skeletal structure which rapidly breaks down under shear. The load signal during flow decreases with increasing soaking time and with temperature, and the initial peak eventually disappears in all alloys investigated. Quantitative metallography indicates that the lower loads correspond to greater spheroidicity of the solid particles within the slurry. The curves have been analyzed to derive the viscosity as a function of average shear rate and demonstrate that the semisolid slurries exhibit pseudoplastic flow behavior which is dependent on the compression velocity and is far removed from steady-state conditions.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
D.B. Spencer, R. Mehrabian, and M.C. Flemings: Metall. Trans., 1972, vol. 3, pp. 1925–32.
P.A. Joly and R. Mehrabian: J. Mater. Sci., 1976, vol. 11, pp. 1393–418.
M.C. Flemings: Metall. Trans. A, 1991, vol. 22A, pp. 957–79.
D.H. Kirkwood: Int. Mater. Rev., 1994, vol. 39, pp. 173–89.
M.P. Kenney, J.A. Courtois, R.D. Evans, G.M. Farrior, C.P. Kyonka, A.A. Koch, and K.P. Young: Metals Handbook, 9th ed., ASM INTERNATIONAL, Metals Park, OH, 1988, vol. 15, pp. 327–38.
J.P. Gabathuler, H.J. Huber, and J. Erling: Proc. Int. Conf. on “Aluminium Alloys: New Process Technologies”, Ravenna, Italy, 1993 Publ., Associazione Italiana di Metallurgia, Milan, pp. 169–80.
K.P. Young, C.P. Kyonka, and J.A. Courtois: U.S. Patent 4-415-374, 1983.
D.H. Kirkwood, C.M. Sellars, and L.G.E. Boyed: U.S. Patent 5-133-811, 28/07/1992.
S.C. Bergsma, M.C. Tolle, E. Evangelista, M.E. Kassner, and X. Li: Proc. 5th Int. Conf. on “Semisolid Processing of Alloys and Composites,” Golden, Co, 1998, A.K. Bhasin, J.J. Moore, K.P. Young, and S. Midson, eds. Colorado School of Mines, Golden, CO, 1998, pp. 149–55.
A. Leatham, A. Ogilvy, P. Chesney, and J.V. Wood: Metall. Mater., 1989, vol. 5 (3), pp. 140–43.
M. Kiuchi and S. Sugiyama: Proc. 2nd Int. Conf. on “Semisolid Processing of Alloys and Composites,” Cambridge, MA, 1992, S.B. Brown and M.C. Flemings, eds. Massachusetts Institute of Technology Press, Cambridge, MA, 1992, pp. 47–56.
T. Haga and S. Suzuki: Proc. 6th Int. Conf. on Semisolid Processing of Alloys and Composites, Turin, Italy, 2000, G.L. Chiarmetta and M. Rosso, eds., Edimet Spa, Brescia, Italy, 2000, pp. 735–40.
European Patent Specification FP 0-745-694-Al, UBE Industries Ltd., Japan.
K. Hall, H. Kaufmann, and A. Mundl: Proc. 6th Int. Conf. on Semisolid Processing of Alloys and Composites, Turin, Italy, 2000, G.L. Chiarmetta and M. Rosso, eds. Edimet Spa, Brescia, Italy, 2000, pp. 23–28.
P. Kapranos: Proc. 4th Int. Conf. on Semisolid Processing of Alloys and Composites, Sheffield, United Kingdom, 1996, D.H. Kirkwood and P. Kapranos, eds. Univerity of Sheffield, Sheffield, UK, 1996, pp. 360–62.
D.H. Kirkwood and P. Kapranos: Met. Mater., 1989, vol. 5, pp. 16–19.
P. Kapranos, D.H. Kirkwood, and M.R. Barhudarov: Proc. 5th Int. Conf. on Semisolid Processing of Alloys and Composites, Golden, CO, 1998, A.K. Bhasin, J.J. Moore, K.P. Young, and S. Midson, eds. Colorado School of Mines, Golden, CO, 1998, pp. 11–19.
P. Kapranos, T.Y. Liu, H.V. Atkinson, and D.H. Kirkwood: J. Mater. Processing Technol., 2001, vol. 111, pp. 31–36.
V. Laxmanan and M.C. Flemings: Metall. Trans. A, 1980, vol. 11A, pp. 1927–36.
W.R. Loué, M. Suéry, and J.L. Querbes: Proc. 2nd Int. Conf. on Semisolid Processing of Alloys and Composites, Cambridge, MA 1992, S.B. Brown and M.C. Flemings, eds., Massachusetts, pp. 266–75.
G.J. Dienes and H.F. Klemm: J. Appl. Phys., 1946, vol. 17, pp. 485–511.
T. Witulski, U. Morjan, I. Niedick, and G. Hirt: Proc. 5th Int. Conf. on Semisolid Processing of Alloys and Composites, Golden, CO, 1998, A.K. Bhasin, J.J. Moore, K.P. Young, and S. Midson, eds., Colorado School of Mines, Golden, CO, 1998, pp. 353–60.
W.R. Loué and M. Suéry: Mater. Sci. Eng. A, 1995, vol. 203, pp. 1–13.
C.J. Quaak: Ph.D. Thesis, Technische Universiteit Delft, Delft, The Netherlands, 1996.
T.Y. Liu, P.J. Ward, D.H. Kirkwood, and H.V. Atkinson: XIIIth Int. Congr. on Rheology, Cambridge, United Kingdom, 2000, D.M. Binding, N.E. Hudson, J. Mewis, J.-M. Piau, C.J.S. Petrie, P. Townsend, M.H. Wagner, and K. Walters, eds., British Society of Rheology, Glasgow, United Kingdom, 2000, vol. 4, pp. 61–63.
T.Y. Liu, H.V. Atkinson, P.J. Ward, and D.H. Kirkwood: Metall. Mater. Trans. A, 2003, vol. 34A, pp. 409–17.
J.A. Yurko and M.C. Flemings: Metall. Mater. Trans. A, 2002, vol. 33A, pp. 2737–46.
E. Tzimas and A. Zavaliangos: J. Mater. Sci., 2000, vol. 35, pp. 5319–29.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Liu, T.Y., Atkinson, H.V., Kapranos, P. et al. Rapid compression of aluminum alloys and its relationship to thixoformability. Metall Mater Trans A 34, 1545–1554 (2003). https://doi.org/10.1007/s11661-003-0266-y
Received:
Issue Date:
DOI: https://doi.org/10.1007/s11661-003-0266-y