Abstract
Morphological evolution of coherent precipitates is studied by means of a discrete atom method under a plane strain condition with a purely dilatational misfit. The method is predicated upon Hookean atomic interactions and Monte Carlo diffusion and makes no assumption of a specific precipitate shape. Precipitates having elastic constants different from those of the matrix phase are treated in both isotropic and anisotropic elastic systems. Shape evolution is examined under the condition of a constant precipitate size and an isotropic interfacial energy. The results show that in general, an elastically soft precipitate tends to have an equilibrium morphology of low symmetry such as a plate, whereas a hard particle tends to take up a shape of high symmetry such as a circle. Morphological evolution proceeds through dynamic activities of coherency-induced interfacial waves whose wavelength depends upon the difference in elastic constants, precipitate geometry, anisotropy, and diffusion temperature. Coherency-induced interfacial waves seem to be responsible for the protrusions often observed along elastically hard directions in γ′ particles of Ni-base superalloys and also to be a source for fresh ledges for growthvia the ledge mechanism. For a highly nonequilibrium precipitate, first splitting followed by coalescence appears to be a common feature in achieving its equilibrium morphology.
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References
G. Wulff:Z Kristallogr., 1901, vol. 34, p. 449.
J.D. Eshelby:Prog. Solid Mech., 1961, vol. 2, p. 89.
Jong K. Lee, D.M. Barnett, and H.I. Aaronson:Metall. Trans. A, 1977, vol. 8A, pp. 963–70.
T. Mura:Micromechanics of Defects in Solids, 2nd ed., Martinus Nijhoff, Dordrecht, 1987, p. 177.
A.G. Khachaturyan:Theory of Structural Transformations in Solids, Wiley and Sons, New York, NY, 1983, p. 213.
Y. Wang, L.Q. Chen, and A.G. Khachaturyan: inSolid → Solid Phase Transformations, W.C. Johnson, J.M. Howe, D.E. Laughlin, and W.A.Soffa, eds., TMS, Warrendale, PA, 1994, p. 245.
Y. Wang, L.Q. Chen, and A.G. Khachaturyan:Acta Metall., 1993, vol. 41, p. 279.
M. McCormack, A.G. Khachaturyan, and J.W. Morris:Acta Metall., 1992, vol. 40, p. 325.
M.E. Thompson, C.S. Su, and P.W. Voorhees:Acta Metall., 1994, vol. 42, p. 2107.
Z.A. Moschovidis and T. Mura:J. Appl. Mech., 1975, vol. 42, p. 847.
S. Satoh and W.C. Johnson:Metall. Trans. A, 1992, vol. 23A, pp. 2761–73.
P.H. Leo and R.F. Sekerka:Acta Metall., 1989, vol. 37, p. 3119.
J. Gayda and DJ. Srolovitz:Acta Metall., 1989, vol. 37, p. 641.
J.K. Lee:Metall. Trans. A, 1991, vol. 22A, pp. 1197–1209.
J.K. Lee:Scripta Metall., 1995, vol. 32, p. 559.
W.G. Hoover, W.T. Ashurst, and R.J. Olness:J. Chem. Phys., 1974, vol. 60, p. 4043.
R.A. Johnson:Phys. Rev. B, 1972, vol. 6, p. 2094.
J.T.M. de Hosson: inInteratomic Potentials and Crystalline Defects, J.K. Lee, ed., TMS, Warrendale, PA, 1981, p. 3.
K. Binder:Monte Carlo Methods, Springer-Verlag, New York, NY, 1979, p. 1.
J.K. Lee: Michigan Technological University, Houghton, MI, unpublished research, 1994.
W.C. Johnson and J.W. Cahn:Acta Metall., 1984, vol. 32, p. 1925.
S.J. Yeom, D.Y. Yoon, and M.F. Henry:Metall. Trans. A, 1993, vol. 24A, pp. 1975–81.
A. Maheshwai and A.J. Ardell:Scripta Metall., 1992, vol. 26, p. 347.
T. Miyazaki and M. Doi:Mater. Sci. Eng., 1989, vol. Al 10, p. 175.
Y.S. Yoo, D.Y. Yoon, and M.F. Henry:Metals and Materials, 1995, vol. 1, p. 47.
M.G. Hall and H.I. Aaronson:Metall. Trans. A, 1994, vol. 25A, 1923.
M.A. Grinfeld:J. Nonlinear Sci., 1993, vol. 3, p. 35.
D.J. Srolovitz:Acta Metall., 1989, vol. 37, p. 621.
H. Gao:J. Mech. Phys. Solids, 1991, vol. 39, p. 443.
B.J. Spencer, P.W. Voorhees, and S.H. Davis:Phys. Rev. Lett., 1991, vol. 67, p. 3696.
F.A. Nichols and W.W. Mullins:Trans. TMS-AIME, 1965, vol. 233, p. 1840.
M. Meshkinpour and A.J. Ardell:Mater. Sci. Eng., 1994, vol. A185, p. 153.
T. Miyazaki, H. Imamura, and T. Kozakai:Mater. Sci. Eng., 1982, vol. 54, p. 9.
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This article is based on a presentation made during TMS/ASM Materials Week in the symposium entitled “Atomistic Mechanisms of Nucleation and Growth in Solids,” organized in honor of H.I. Aaronson’s 70th Anniversary and given October 3–5, 1994, in Rosemont, Illinois.
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Lee, J.K. A study on coherency strain and precipitate morphologyvia a discrete atom method. Metall Mater Trans A 27, 1449–1459 (1996). https://doi.org/10.1007/BF02649806
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DOI: https://doi.org/10.1007/BF02649806