A new parameter for describing the structure bifurcation in two-phase alloys containing coherent particles

Doi, Masao; Miyazaki, Tôru

doi:10.1007/bf00576274

Cited by 16 publications

(5 citation statements)

References 29 publications

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“…8,9 The cited analyses show that this inverse coarsening can result in a stabilization of particle size with a distribution that narrows and becomes more symmetric with time, and experimental observation of such stabilization has been reported for the case of certain nickel-based alloys. 10 Inverse coarsening is predicted in the case of spherical particles that are softer than the matrix, which is true for our case since the shear modulus c 44 of GaAs and hexagonal As are 59 and 23 GPa, respectively. 11 Hence, the elastic interaction between particles due to the coherency strain provides a possible mechanism for the inverse coarsening observed for small precipitates.…”

supporting

confidence: 57%

Size stabilization of arsenic precipitates in nonstoichiometric GaAs-based compounds

Hung

Harris

Marshall

et al. 1999

Applied Physics Letters

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A narrowing of the size distribution of arsenic precipitates in nonstoichiometric GaAs-based compounds is observed during annealing for precipitates in the small size regime of a few nanometers. This improvement in size uniformity is in marked contrast to what is observed for larger precipitates, which coarsen with a widening distribution similar to that of classical Ostwald ripening. Inverse coarsening caused by an elastic interaction between small precipitates due to coherency strain is a possible mechanism for this interesting and potentially useful behavior.

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supporting

confidence: 57%

Size stabilization of arsenic precipitates in nonstoichiometric GaAs-based compounds

Hung

Harris

Marshall

et al. 1999

Applied Physics Letters

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“…Johnson and Lee (1979) [157] show that two spherical inclusions in an anisotropic matrix can reduce their energy if they come close together and align themselves along the 'soft' crystal directions. Miyazaki, Doi and others [135,72,67] find in addition that inverse coarsening is possible if the particles are close together and the misfit strain and particle size are large enough. Shneck et al (1992) [79] give details of the elastic fields for one and two spherical inclusions in a cubic crystal with negative anisotropy.…”

Section: The Energy Of Several Inclusions : Anisotropic Elasticitymentioning

confidence: 97%

“…The reason why µ(c) appears with a negative sign in the second equation is that in the α phase the small parameter of the virial expansion is c α 0 − c, the concentration of B atoms, and the relative chemical potential of these atoms is −µ(c). Using (71) in (70), we obtain the approximate formulas The formula (72), reducing in the absence of elastic effects to the GibbsThomson formula, is due to Johnson and Alexander [134] (see also [127,114,63,29]), who used it (in a more accurate version) to calculate c at the surface of a spherical inclusion with isotropic elasticity.…”

Section: The Diffusion Equation and Its Boundary Conditionsmentioning

confidence: 99%

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Fratzl¹,

Penrose²,

Joel³

1999

Journal of Statistical Physics

230

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Elastic interactions arising from a difference of lattice spacing between two coherent phases can have a strong influence on the phase separation (coarsening) of alloys. If the elastic moduli are different in the two phases, the elastic interactions may accelerate, slow down or even stop the phase separation process. If * Dedicated to John W. Cahn, on the occasion of his 70th birthday 1 the material is elastically anisotropic, the precipitates can be shaped like plates or needles instead of spheres and can form regular precipitate superlattices.Tensions or compressions applied externally to the specimen may have a strong effect on the shapes and arrangement of the precipitates. In this paper, we review the main theoretical approaches that have been used to model these effects and we relate them to experimental observations. The theoretical approaches considered are (i) 'macroscopic' models treating the two phases as elastic media separated by a sharp interface (ii) 'mesoscopic' models in which the concentration varies continuously across the interface (iii) 'microscopic' models which use the positions of individual atoms.

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“…The amount of γ′ finally approached to a constant when aging finished. In the later exposure period, big size γ′ kept growing with small γ′ dissolved gradually, which was driven by interfacial energy [ 35 ]. As a result, the average size of γ′ increased while the amount decreased.…”

Section: Discussionmentioning

confidence: 99%

Effect of Nb on Microstructure and Mechanical Property of Novel Powder Metallurgy Superalloys during Long-Term Thermal Exposure

Zhou

Teng

et al. 2021

Materials

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Microstructure and mechanical properties of novel Ni-20Co-12Cr superalloys, with and without Nb addition, were systematically studied during long-term thermal exposure. With increased exposure time, the average diameter of the γ′ precipitates increased in both alloys in succession; this is more obviously observed in alloy containing 1 wt% Nb (1Nb). It is suggested that Nb increased the γ′ coarsening rate by accelerating the diffusion of Al and Nb in γ matrix. In addition, the γ′ phase fraction is increased by about 4% in 1Nb compared to the alloy without Nb (0Nb). The morphology of the γ′ phase changed from near-spherical to cuboidal shape during exposure in both alloys. Due to the increased γ/γ′ lattice misfit by Nb addition, 1Nb alloy showed an earlier tendency of shape change. Vickers hardness results revealed that the overall hardness decreased with the exposure time because the size increment of the γ′ precipitate weakened the precipitates strengthening and Orowan strengthening.

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A new parameter for describing the structure bifurcation in two-phase alloys containing coherent particles

Cited by 16 publications

References 29 publications

Size stabilization of arsenic precipitates in nonstoichiometric GaAs-based compounds

Size stabilization of arsenic precipitates in nonstoichiometric GaAs-based compounds

Untitled

Effect of Nb on Microstructure and Mechanical Property of Novel Powder Metallurgy Superalloys during Long-Term Thermal Exposure

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