Abstract
An X-ray diffraction technique has been utilized to determine the second phase content and average composition of the primary phase in aluminum-copper and aluminum-silicon alloys solidified at a cooling rate in the range of 0.06 to l05 K/s. For the Al-Cu samples, the normalized Θ phase content (ratio of the 6 content to the value predicted by the Scheil model) was found to be 0.71 at 0.1 K/s (solidification rate = 0.001 cm/s) and to increase with increasing cooling rate to 0.96 at about 180 K/s (1 cm/s). Beyond this cooling rate, it decreased with increasing the cooling rate to 0.44 at about 3.7 x lO4 K/s. The same trend was observed in the Al-Si samples, except that the normalized silicon content was much lower. Also, for both systems the normalized average composition of the primary phase was found to decrease progressively with increasing the solidification rate until it reached a minimum at 1 cm/s, beyond which it increased with higher solidification rates. The results are discussed with respect to the prevailing segregation models that include back-diffusion in the solid, dendrite tip undercooling, and the eutectic temperature depression. An equation which combines these effects at all cooling rates is given.
Similar content being viewed by others
References
M. C. Flemings:Solidification Processing, McGraw-Hill, New York, NY, 1974, pp. 31–32.
H. D. Brody and M. C. Flemings:Trans. AIME, 1966, vol. 236, pp. 615–24.
H. S. Cairnie: M.S. Thesis, Massachusetts Institute of Technology, 1980.
L.H. Hoang: M.S. Thesis, University Laval-Quebec, 1979.
A. B. Michael and M. B. Beaver:Trans. AIME, J. Metals, 1954, vol. 200, pp. 47–56.
M. L. Putman: M. S. Thesis, Massachusetts Institute of Technology, 1981.
H.S. Cairnie: Abex Corporation Research Center, Mahwah, NJ 97430; G. J. Abbaschian, Professor and Acting Chairman, Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611, and M.C. Flemings, Chairman, Materials Science and Engineering Department, MIT, Cambridge, MA 02139, private communications, 1984.
T. W. Clyne and W. Kurz:Metall. Trans. A, 1981, vol. 12A, pp. 965–71.
M. Cohen, B. H. Kear, and R. Mehrabian: Proc. Int'l. Conf. on Rapid Solidification Processing, Claitor's, Baton Rouge, LA, 1980, pp. 21-23.
J. G. Baker and J. W. Cahn:Acta Metall, 1969, vol. 17, pp. 575–78.
S.D. Peteves, J. Alvarez, and G. J. Abbaschian:Proc. of Symposium on Rapidly Solidified Metastable Materials, North-Holland, New York, NY, 1984, pp. 15–19.
M. H. Burden and J. D. Hunt:J. Crystal Growth, 1974, vol. 22, pp. 99–108.
M. H. Burden and J. D. Hunt:J. Crystal Growth, 1974, vol. 22, pp. 109–16.
M. Solari and H. Biloni:J. Crystal Growth, 1980, vol. 49, pp. 451–57.
K.A. Jackson and J. D. Hunt:Trans. AIME, 1966, vol. 236, pp. 1129–42.
J. D. Hunt and J. P. Chilton:J. Inst. Metals, 1963–64, vol. 92, pp. 21–25.
B.D. Cullity:Elements of X-ray Diffraction, Addison-Wesley, London, 1967.
M.J. Dickson:J. Appl. Cryst., 1969, vol. 2, pp. 176–80.
B.L. Averbach, M. F. Comerford, and M.B. Beaver:Trans. AIME, 1959, vol. 215, pp. 682–85.
R. L. Miller:Trans. ASM, 1964, vol. 57, pp. 892–99.
R. Gullberg and R. Langeborg:Trans. AIME, 1966, vol. 236, pp. 1482–85.
J. A. Patchett and G. J. Abbaschian: 1985 TMS Fall Meeting, Toronto, ON, Canada.
C. R. Hubbard and D. K. Smith:Advances in X-ray Analysis, Plenum Press, New York, NY, 1977, vol. 20, pp. 27–39.
A. Lutts:Advances in X-ray Analysis, Plenum Press, New York, NY, 1963, vol. 6, pp. 143–53.
R. W. Gould and S. R. Bates:Advances in X-ray Analysis, Plenum Press, New York, NY, 1969, vol. 12, pp. 87–96.
T.W. Clyne:J. Crystal Growth, 1980, vol. 50, pp. 684–90.
T. W. Clyne:J. Crystal Growth, 1980, vol. 50, pp. 691–700.
R. E. Spear and G. R. Gardner:Trans. Am. Foundrymen's Soc, 1963, vol. 71, pp. 209–15.
T. F. Bower, H. D. Brody, and M. C. Flemings:Trans. AIME, 1966, vol. 236, pp. 624–34.
H. Matyja, B. C. Giessen, and N. J. Grant:J. Inst. Metals, 1968, vol. 96, pp. 30–32.
J. A. Spittle and D. M. Lloyd:Proc. of Int'l. Conf. on Solidification and Casting of Metals, Metals Society, London, 1979, pp. 15–20.
J. D. Hunt:Proc. of Int'l. Conf. on Solidification and Casting of Metals, Metals Society, London, 1979, pp. 3–10.
K.P. Young and D.H. Kirkwood:Metall. Trans. A, 1975, vol. 6A, pp. 197–205.
E. A. Brandes:Smitthells Metals Ref. Book, 6th ed., Butterworths, London, 1983.
V. Laxmanan:Acta Metall., 1985, vol. 33, pp. 1037–49.
R.M. Jordan and J. D. Hunt:Metall. Trans., 1971, vol. 2, pp. 3401–10.
M. C. Flemings, Chairman: Materials Science and Engineering Department, MIT, Cambridge, MA 02139, private communication, 1986.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Sarreal, J.A., ABbaschian, G.J. The effect of solidification rate on microsegregation. Metall Trans A 17, 2063–2073 (1986). https://doi.org/10.1007/BF02645003
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02645003