Spacing homogenization in lamellar eutectic arrays with anisotropic interphase boundaries

Ignacio, Maxime; Plapp, Mathis

doi:10.1103/physrevmaterials.3.113402

Cited by 2 publications

(4 citation statements)

References 28 publications

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“…This would include a more systematic exploration of the lamellar-growth dynamics and ORs in thin Al-Al 2 Cu alloy samples by varying the alloy concentrations within a range that extends to hypereutectic values, thus aiming at firmly evidencing the effect of the alloy concentration on the asymmetry of the nucleation sequence of the eutectic solid phases [50], and the selection of ORs. It could be also of great interest to focus more on the lamellar-branching dynamics near a diverging eutectic-grain boundary, and to study the large-scale dynamics in the presence of smooth spacing modulations [36,45], and to compare it to recent investigations of tilted-cell arrays during directional solidification of dilute alloys [52,53]. Numerical simulations would be needed for a more quantitative assessment of the lamellar-locking effect in a realistic alloy such as the Al-Al 2 Cu system -and not in simplified eutectic alloys as in Refs.…”

Section: Discussionmentioning

confidence: 99%

“…The lamellar tilt angle can then deviate from that of the γ minimum [23,24]. More importantly, the interphase boundary can smoothly rotate about that minimum, and a spacing diffusion process remains active [36]. Therefore, in a eutectic grain with a wellidentified OR, and of known orientation with respect to the main growth axis, semi-quantitative information on both the low-energy planes, and the shape of the γ-plot in the vicinity of those planes can be gained from the observation of the dynamics of locked and nearly locked lamellar growth patterns.…”

Section: Introductionmentioning

confidence: 99%

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Locked-lamellar eutectic growth in thin Al-Al2Cu samples: In situ directional solidification and crystal orientation analysis

Bottin-Rousseau

Medjkoune

Senninger

et al. 2021

Journal of Crystal Growth

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We investigated the directional-solidification dynamics of slightly hypoeutectic Al-Al 2 Cu alloys in thin samples. Our goal was to establish a link between the growth of locked, tilted-lamellar patterns and the crystal orientation relationship (OR) between the Al-rich solid solution α and the Al 2 Cu intermetallic θ, as well as to gain information on the OR-dependent anisotropy of the surface energy γ of the α-θ interphase boundaries. Thin Al-Al 2 Cu films of thickness of 13 ± 2 µm were prepared by plasma sputtering. During solidification at pulling velocities between 0.05 and 0.5 µms −1 , the coupled-growth front was observed in situ with a long-distance optics. The growth of millimeter-sized eutectic grains was thus followed in real time during transient and steady-state regimes. The orientation of α and θ crystals was measured ex situ by x-ray diffraction and electron backscattering diffraction. In several eutectic grains, a {123} α plane and a {100} θ plane were found to be closely parallel to each other. These coincident planes define a new family of (type-C) ORs in the Al-Al 2 Cu eutectic, which are distinct from the prevailing ORs that have been previously identified in bulk samples. Crucially, the inclination of the lamellae was systematically close to that of a {100} θ lattice plane, which therefore corresponds to a deep γ minimum in eutectic grains with a type-C OR, or a neighbor one. We initiated a discussion on the selection of the OR, the formation of "stray" eutectic grains, and the lamellar-growth dynamics at eutectic-grain boundaries.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Locked-lamellar eutectic growth in thin Al-Al2Cu samples: In situ directional solidification and crystal orientation analysis

Bottin-Rousseau

Medjkoune

Senninger

et al. 2021

Journal of Crystal Growth

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“…For that, phase-field models are needed [29,30] -and for ternary eutectics as well [31,32]. 3-It would be interesting to extend the present study to transient regimes in systems of a larger spatial extension, and investigate, in particular, the so-called spacing diffusion process in the presence of an interfacial anisotropy [33]. 4-The present numerical study could also motivate new thin-sample directional solidification experiments at low V, large G, and small λ, in hypoeutectic CBr 4 -C 2 Cl 6 samples, thus targeting conditions that would bring a better agreement with the sp-approximation.…”

Section: Discussionmentioning

confidence: 99%

“…This model represents an interesting step beyond a Jackson-Hunt, planar-front calculation (see, e.g., Ref. [33]). It is, however, limited to convex shapes of the solid-liquid interfaces, and becomes inaccurate for large values of the lamellar spacing.…”

Section: Discussionmentioning

confidence: 99%

Numerical Simulations of Locked Lamellar Eutectic Growth Patterns

Akamatsu

Bottin-Rousseau

2021

Metall Mater Trans A

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We present two-dimensional numerical simulations of tilted lamellar growth patterns during directional solidification of nonfaceted binary eutectic alloys in the presence of an anisotropy of the free energy γ of the interphase boundaries in the solid. We used a dynamic boundary-integral (BI) method. The physical parameters were those of the transparent eutectic CBr 4 -C 2 Cl 6 alloy. As in Ghosh et al. [Phys. Rev. E 91, 022407 (2015)], the anisotropy of γ was described by a model function with tunable parameters. The lamellarlocking effect in the vicinity of a deep minimum of the interfacial energy was reproduced. For a weak anisotropy, the lamellar tilt angle θ t was shown to depend on the growth conditions. We systematically studied the influence of usual control parameters (pulling velocity, temperature gradient, lamellar spacing, alloy concentration) on the tilted-lamellar pattern. We identified experimentally accessible conditions under which θ t falls close to the theoretical prediction based on the so-called symmetric-pattern approximation. We finally simulated locked and weakly locked lamellar patterns and found empirically a good morphological matching with experimental observations during directional solidification of thin CBr 4 -C 2 Cl 6 samples.

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Spacing homogenization in lamellar eutectic arrays with anisotropic interphase boundaries

Cited by 2 publications

References 28 publications

Locked-lamellar eutectic growth in thin Al-Al2Cu samples: In situ directional solidification and crystal orientation analysis

Locked-lamellar eutectic growth in thin Al-Al2Cu samples: In situ directional solidification and crystal orientation analysis

Numerical Simulations of Locked Lamellar Eutectic Growth Patterns

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