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Frontiers in Solidification: An MPMD Symposium Honoring Jonathan A. Dantzig: Peritectics & Eutectics
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Functional Materials Division, TMS Light Metals Division, TMS Structural Materials Division, TMS: Aluminum Committee, TMS: Chemistry and Physics of Materials Committee, TMS: Process Technology and Modeling Committee, TMS: Solidification Committee
Program Organizers: Andre Phillion, McMaster University; Michel Rappaz, Ecole Polytechnique Fédérale De Lausanne; Melis Serefoglu, Marmara University; Damien Tourret, IMDEA Materials Institute

Monday 2:00 PM
March 20, 2023
Room: 28E
Location: SDCC

Session Chair: Julien Zollinger, University of Lorraine - IJL; Hani Henein, University of Alberta

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2:00 PM  Invited
Phase-field Simulations of Peritectic Coupled Growth: Mathis Plapp¹; ¹Ecole Polytechnique
    Contrary to eutectic coupled growth, which is the most common growth mode for the solidification of eutectic alloys close to the eutectic composition, coupled growth occurs during the directional solidification of pertectic alloys only for specific ranges in composition, growth velocity, and applied temperature gradient. Only a few specific alloy systems have been studied in detail so far, among which Fe-Ni and Cu-Sn. Phase-field simulations offer a unique opportunity to study the conditions under which peritectic coupled growth is possible. A detailed comparison between phase-field simulations of the Cu-Sn system and the Jackson-Hunt-like theory for peritectic coupled growth is presented. Furthermore, the convergence behavior of phase-field models of peritetics with decreasing interface thickness is analyzed. Differences with the sharp-interface treatment by boundary-integral methods can be linked to the phenomenon of trijunction rotation, which is much stronger in pertectic than in eutectic two-phase growth.

2:30 PM  Invited
About the Complexity of Using a ‘Simple’ Transparent Model Alloy to Study Peritectic Couple Growth in Microgravity: Andreas Ludwig¹; Johann Mogeritsch¹; ¹Montanuniversitaet Leoben
    Peritectic coupled growth (PCG) under purely diffusive conditions were investigated using the ESA's Transparent Alloy facility onboard of the International Space Station in 2021. For this purpose, the transparent metal-like solidifying organic system TRIS-NPG (TRIS: tris-(hydroxymethyl)aminomethane, NPG: neopentylglycol) known to show a peritectic invariant reaction at round 0.51 mol fraction NPG was used. It turned out that quite a large number of unexpected phenomena governed the occurrence of PCG. These are (i) grain coarsening and grain boundary migration and its implication on the establishing of the initial planar front; (ii) occurrence of a thermal bias and the resulting concentration variations within in the cartridge; (iii) unknown nucleation hindrance for the peritectic beta phase and the metastability of the properitectic alpha phase; (iv) low and constant growth velocity and an ‘initial’ transient that seems not to end. Nevertheless, we have found suitable conditions for the occurrence of PCG.

3:00 PM  
Microstructure Evolution during Solidification of Fe-C-Mn-Si Peritectic Steels: Olajide Akintayo¹; Muhammad Nabeel¹; André Phillion¹; ¹McMaster University
    Peritectic steels suffer casting defects due to volumetric shrinkage associated with peritectic transformation at the initial stage of solidification. Hence, a fundamental understanding of their solidification microstructure is required to optimize process parameters and composition. Bridgman solidification experiments were performed on Fe-C-Mn-Si peritectic steels to investigate the influence of growth velocity and alloy composition on microstructure evolution. The microstructure shows competitive growth behaviour amongst primary δ-dendrites. An interfacial transition from a planar interface to columnar dendrites was observed under increasing growth velocities of 3, 10, and 60 µm/s. A functional relationship between primary dendrite arm spacing (PDAS) and growth velocity is established. Theoretical models of Hunt-Lu, Kurz-Fisher, and Trivedi for predicting PDAS were utilized and compared with obtained experimental data. Finally, the effects of alloying elements on the dendritic morphologies are discussed.

3:20 PM Break

3:40 PM  Invited
Formation of Locked-lamellar Grains in a Slightly Hypereutectic Al-Al2Cu Alloy during Thin-sample Directional Solidification: Sabine Bottin-Rousseau¹; Silvère Akamatsu¹; Mehdi Medjkoune²; ¹Sorbonne University; ²IM2NP
    During directional solidification of many metallic alloys of near-eutectic concentration, the main morphological features of lamellar microstructures depend on the crystal orientation relationships (OR) in the two-phase solid, in addition to growth parameters and boundary conditions. This still remains partially understood. We studied experimentally the dynamics of lamellar patterns in thin Al-Al2Cu samples. This allowed us to observe the coupled-growth front in situ. Crystallographic analyses were performed ex situ. We identified a new family of ORs in hypo-eutectic samples, and the so-called Alpha-4 and Beta-6 ORs, which have been previously found in bulk Al-Al2Cu ingots, in hyper-eutectic samples. During growth, the lamellae are observed to dynamically lock on dense coincidence planes that characterize those ORs. We will highlight the crucial role of the initial solidification stages during which eutectic grains and ORs are selected.

4:10 PM  
Eutectic Growth Dynamics during Directional Solidification with Velocity Ramps: In-situ Investigations in Microgravity: Victor Witusiewicz¹; Ulrike Hecht¹; Sabine Bottin-Rousseau²; Silvere Akamatsu³; ¹Access e.V.; ²Sorbonne University; ³Cnrs
    The morphological features of coupled-growth patterns in directionally solidified eutectics not only depend on alloy characteristics and control parameters, but also on boundary conditions and the processing history. We report here on the first systematic in situ experiments in microgravity conditions, hence free of convection effects, performed in the ISS, aiming at evidencing the effect of downward and upward velocity "ramps" on rod-like eutectic growth patterns. Real-time observation was carried out by using a model transparent alloy (succinonitrile-d,camphor) with a low concentration of a third compound (neopentylglycol). The velocity was varied linearly, stepwise or in a more complex manner in time, over one order of magnitude, in the course of the experiments. Our observations show a contrasted behavior, in terms of spatial arrangement and inter-rod spacing distribution, depending on whether the velocity ramp was ascending or descending. The dynamics exhibited a marked hysteresis upon cycling.

4:30 PM  
Tomographic Analysis of Microstructure Evolution in Ternary Al-Cu-Ag Eutectic: Amber Schneeweis Genau¹; Jessica Friess¹; Philipp Rayling¹; ¹University of Alabama at Birmingham
    Despite significant study over the last fifteen years, the reasons for the varied and complex microstructures observed in ternary eutectic Al-Cu-Ag are still not fully understood. In order to better characterize the formation and evolution of the multi-phase structures which form in this system during directional solidification, samples processed under various conditions were subjected to x-ray tomography. With the help of a new machine-learning-based image analysis tool, features such as pattern evolution, alignment, transitions between two- and three-phase growth, and the movement of grain boundaries were evaluated. The 3D visualization of complex ordering phenomena as well as persistent faceted Al-Ag2Al interfaces and misaligned microstructure patterns indicate the high energy barrier to achieve well-ordered microstructures. Overall, this study provides a valuable experimental comparison for 3D phase field simulations while demonstrating the potential of this system to be tailored in a diversity of ways.

4:50 PM  
Nanoscopic View of Irregular Eutectic Solidification: Shanmukha Kiran Aramanda¹; Paul Chao¹; Ashwin Shahani¹; ¹University of Michigan
    Eutectic solidification provides compelling examples of pattern formation, making it a well studied moving boundary phenomenon. However, the formation of several complex eutectic microstructures is still poorly understood, especially in highly anisotropic systems. To investigate the emergence of complex microstructures, we investigate Al-Ge as a model system as one of the phases (Ge) is faceted (f) while the other (Al) is non-faceted (nf). To peer into the real-time growth dynamics of the two eutectic phases at high spatial resolution (20 nm), we utilize state-of-the-art characterization techniques, namely, synchrotron-based X ray nano-radiography and nano-tomography. Furthermore, we illustrate the crystallographic bias in irregular eutectic solidification through the aid of electron diffraction. These results inform a new growth model of n/nf eutectic solidification.

5:10 PM  
Microstructural Evaluation of Containerless Solidification of Al-Ce Alloys: Jonas Valloton¹; Akankshya Sahoo¹; Marcelino da Silva Dias Filho¹; Sven Vogel²; Hani Henein¹; ¹University of Alberta; ²Los Alamos National Laboratory
    Cerium containing aluminum alloys consist mainly of fcc α-Al and Al₁₁Ce₃ intermetallic and are of interest for high temperature alloys. Due to the near zero solubility of cerium in α-Al (<50 ppm at the eutectic temperature), Al₁₁Ce₃ is very stable against high temperature dissolution. Furthermore, cerium currently remains a relatively inexpensive rare-earth alloying element. Here, containerless solidification of hypoeutectic Al-5wt%Ce and hypereutectic Al-20wt%Ce is carried out using ElectroMagnetic Levitation and Impulse Atomization. The effects of rapid solidification on the microstructures are analyzed using neutron diffraction, X-ray and electron microscopy and Electron Backscattered Diffraction. In Al-5Ce, a deviation from <100> growth direction is observed in the primary α-Al. Whereas the eutectic is mostly lamellar in Al-5Ce, the morphology of eutectic Al₁₁Ce₃ changes to so-called Chinese script in Al-20Ce. Finally, in the smallest atomized Al-20Ce droplets, nucleation of primary Al₁₁Ce₃ is bypassed in favor of an α-Al-Al₁₁Ce₃ coupled zone.

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