title: Experimental observation of oscillatory cellular patterns in three-dimensional directional solidification.
abstract: We present a detailed analysis of oscillatory modes during three-dimensional cellular growth in a diffusive transport regime. We ground our analysis primarily on in situ observations of directional solidification experiments of a transparent succinonitrile 0.24wt% camphor alloy performed in microgravity conditions onboard the International Space Station. This study completes our previous reports [Bergeon et al., Phys. Rev. Lett. 110, 226102 (2013)10.1103/PhysRevLett.110.226102; Tourret et al., Phys. Rev. E 92, 042401 (2015)10.1103/PhysRevE.92.042401] from an experimental perspective, and results are supported by additional phase-field simulations. We analyze the influence of growth parameters, crystal orientation, and sample history on promoting oscillations, and on their spatiotemporal characteristics. Cellular patterns display a remarkably uniform oscillation period throughout the entire array, despite a high array disorder and a wide distribution of primary spacing. Oscillation inhibition may be associated to crystalline disorientation, which stems from polygonization and is manifested as pattern drifting. We determine a drifting velocity threshold above which oscillations are inhibited, thereby demonstrating that inhibition is due to cell drifting and not directly to disorientation, and also explaining the suppression of oscillations when the pulling velocity history favors drifting. Furthermore, we show that the array disorder prevents long-range coherence of oscillations, but not short-range coherence in localized ordered regions. For regions of a few cells exhibiting hexagonal (square) ordering, three (two) subarrays oscillate with a phase shift of approximately ±120^{∘} (180^{∘}), with square ordering occurring preferentially near subgrain boundaries.
authors.affiliation: Institut Matériaux Microélectronique Nanosciences de Provence, Aix-Marseille Université and CNRS UMR 7334, Campus Saint-Jérôme, Case 142, 13397 Marseille Cedex 20, France.
authors.forename: J
authors.initials: J
authors.lastname: Pereda
authors.affiliation: Institut Matériaux Microélectronique Nanosciences de Provence, Aix-Marseille Université and CNRS UMR 7334, Campus Saint-Jérôme, Case 142, 13397 Marseille Cedex 20, France.
authors.forename: F L
authors.initials: FL
authors.lastname: Mota
authors.affiliation: Institut Matériaux Microélectronique Nanosciences de Provence, Aix-Marseille Université and CNRS UMR 7334, Campus Saint-Jérôme, Case 142, 13397 Marseille Cedex 20, France.
authors.forename: L
authors.initials: L
authors.lastname: Chen
authors.affiliation: Institut Matériaux Microélectronique Nanosciences de Provence, Aix-Marseille Université and CNRS UMR 7334, Campus Saint-Jérôme, Case 142, 13397 Marseille Cedex 20, France.
authors.forename: B
authors.initials: B
authors.lastname: Billia
authors.affiliation: Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115, USA.
authors.forename: D
authors.initials: D
authors.lastname: Tourret
authors.affiliation: Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Song
authors.affiliation: Institut Matériaux Microélectronique Nanosciences de Provence, Aix-Marseille Université and CNRS UMR 7334, Campus Saint-Jérôme, Case 142, 13397 Marseille Cedex 20, France.
authors.forename: J-M
authors.initials: JM
authors.lastname: Debierre
authors.affiliation: Institut Matériaux Microélectronique Nanosciences de Provence, Aix-Marseille Université and CNRS UMR 7334, Campus Saint-Jérôme, Case 142, 13397 Marseille Cedex 20, France.
authors.forename: R
authors.initials: R
authors.lastname: Guérin
authors.affiliation: Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115, USA.
authors.forename: A
authors.initials: A
authors.lastname: Karma
authors.affiliation: Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50010, USA.
authors.forename: R
authors.initials: R
authors.lastname: Trivedi
authors.affiliation: Institut Matériaux Microélectronique Nanosciences de Provence, Aix-Marseille Université and CNRS UMR 7334, Campus Saint-Jérôme, Case 142, 13397 Marseille Cedex 20, France.
authors.forename: N
authors.initials: N
authors.lastname: Bergeon