Abstract
The early stage coarsening behaviour of δ′ (Al3Li) precipitates and composite precipitates, consisting of β′ (Al3Zr) core enveloped by a δ′ shell, in an Al-2.5% Li-0.15% Zr alloy has been studied at 443, 473 and 503 K by conventional transmission electron microscopy using superlattice dark-field images. Coarsening kinetics of δ′ precipitates was found to exhibit considerable deviation from the t 1/3 law corresponding to diffusion control at 473 and 503 K. This deviation may be explained either by the operation of a surface-reaction controlled coarsening mechanism represented by t 1/2 law, or by the presence of a slower precoarsening stage preceding diffusion-controlled coarsening. The particle-size distributions of δ′ precipitates were not in accordance with either the earlier theoretical predictions or the normal distribution. They were symmetrical or slightly skewed to the left, and particle sizes twice the average were observed. The coarsening kinetics of composite precipitates, was found to be rather different from that of δ′; a diffusion model which yields t 1/n law with n changing from 1/4 to 1/6 as the coarsening progresses, was predicted. The composite precipitates have exhibited quite a narrow and rather symmetrical size distribution.
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A. G. Khachaturyan, T. F. Lindsey and J. W. Morris Jr, Metall. Trans. 19A (1988) 249.
V. Radmilovic, A. G. Fox and G. Thomas, Acta Metall. 37 (1989) 2385.
M. K. Aydinol and A. S. Bor, in “ Proceedings of EMAG'91 Conference ”, Bristol, England, September, 1991, edited by F. J. Humphreys (IOP Publishing Ltd., Bristol, 1991) p. 253.
B. Noble and G. E. Thompson, Met. Sci. J. 5 (1971) 114.
D. B. Williams and J. W. Eddington, ibid. 9 (1975) 529.
B. P. Gu, G. L. Liedl, J. H. Kulwicki and T. H. Sanders Jr, Mater Sci. Eng. 70 (1985) 217.
B. P. Gu, G. L. Liedl, T. H. Sanders Jr and K. Welpmann, ibid. 76 (1985) 147.
K. Mahalingam, B. P. Gu, G. L. Liedl and T. H. Sanders Jr, Acta Metall. 35 (1987) 483.
P. L. Makin and B. Ralph, J. Mater. Sci 19 (1984) 3835.
O. Jensrud and N. Ryum, Mater. Sci. Eng. 64 (1984) 229.
I. M. Lifshitz and V. V. Slyozov. J. Phys. Chem. Solids 19 (1961) 35.
C. Wagner, Z. Elektrochem. 65 (1961) 581.
A. J. Ardell, Acta Metall. 20 (1972) 61.
A. D. Brailsford and P. Wynblatt, ibid. 27 (1979) 489.
K. Tsumuraya and Y. Miyata, ibid. 31 (1983) 437.
P. W. Voorhees and M. E. Glicksman, ibid. 32 (1984) 2001.
Idem, ibid. 32 (1984) 2013.
C. K. L. Davies, P. Nash and R. N. Stevens, ibid. 28 (1980) 179.
G. J. Shiflet, H. I. Aaronson and T. H. Courtney, ibid. 27 (1979) 377.
Y. Tomokiyo, K. Yahiro, S. Matsumura, K. Oki and T. Eguchi, in “Proceedings of the International Symposium on Dynamics of Ordering Processes in Condensed Matter”, Kyoto, Japan, August 1987, edited by S. Komura and H. Furukawa (Plenum Press, New York, 1987) p. 233.
M. R. Spiegel, in “Schaum's Outline Series: Statistics” (McGraw Hill, New York, 1972) p. 201.
L. P. Costas, USAEC Rep. DP-813 (1963) US Atomic Energy Commission.
S. F. Bauman and D. B. Williams, Acta Metall. 33 (1985) 1069.
M. Furukawa, Y. Miura and M. Nemoto, Trans. Jpn. Inst. Metals 26 (1985) 230.
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Aydinol, M.K., Bor, A.S. Coarsening of δ′ (Al3Li) and composite precipitates in an Al-2.5% Li-0.15% Zr alloy. JOURNAL OF MATERIALS SCIENCE 29, 15–25 (1994). https://doi.org/10.1007/BF00356567
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DOI: https://doi.org/10.1007/BF00356567