Frontiers in Solidification: An MPMD Symposium Honoring Jonathan A. Dantzig: Poster Session
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
Tuesday 5:30 PM
March 21, 2023
Room: Exhibit Hall G
Location: SDCC
Session Chair: Andre Phillion, McMaster University; Michel Rappaz, EPFL; Melis Serefoglu, Marmara University; Damien Tourret, IMDEA Materials
N-11: Development of a Data Assimilation System that Integrates Phase-field Simulation and In-situ X-ray Imaging in Dendrite Growth: Ayano Yamamura1; Shinji Sakane1; Munekazu Ohno2; Hideyuki Yasuda3; Tomohiro Takaki1; 1Kyoto Institute of Technology; 2Hokkaido University; 3Kyoto University
The integration of state-of-the-art simulations and experimental techniques is a promising research direction to compensate for the shortcomings of each method and to achieve a better understanding of dendrite growth. In this study, we developed a data assimilation system to integrate the phase-field simulation and in-situ X-ray imaging in dendrite growth. We employed a local ensemble Kalman filter (LEKF) for data assimilation and parallel computing with multiple graphics processing units for adaptive mesh refinement (parallel-GPU AMR) for phase-field simulations. The LEKF reduces the number of ensemble members used in the ensemble Kalman filter, and the parallel-GPU AMR drastically reduces the computational cost of phase-field simulations. We verified the accuracy of the proposed system through numerical experiments, that is, by conducting the so-called twin experiment. In addition, we attempted to apply the developed system to real in-situ X-ray imaging.
N-12: Effect of Process Transients on Fall-in Material Behavior in Vacuum Arc Remelting: Caleb Schrad1; Matthew Krane1; 1Purdue University
Fall-in superalloy material from crown, shelf, or consumable electrode during vacuum arc remelting may lead to the formation of Dirty White Spots (DWS), which have a deleterious effect on fatigue performance and have been known to cause sudden, uncontained jet engine failures. This work seeks to explore the contribution of process transients during VAR to the occurrence of DWS. This exploration uses a fully transient, 3D, process-scale VAR model coupled with Lagrangian particle tracking to determine the path and fate of fall-in material. This model is used then to parametrically study the effect of instabilities (e.g., sudden decreases or increases in process current, and asymmetric arcs). Additionally, safe ranges for the DWS precursor parameters of initial temperature, initial diameter, fall-in location, and drop height which yield complete precursor dissolution during these transient process conditions are estimated. Finally, this work suggests some optimal VAR process conditions which could be used to mitigate the occurrence of DWS without unduly raising the risk of other defects.
N-13: Fundamental Study on Nanoparticles Enhance Fluidity of Aluminum Alloys: Guan-Cheng Chen1; Xiaochun Li1; 1University of California Los Angeles
Fluidity is crucial for high-pressure die casting. It is well-known nanoparticles (NPs) can refine grain sizes and eliminate hot cracking during solidification processing. However, nanoparticles are traditionally considered to harm fluidity due to viscosity enhancement. Little research focuses on the effect of nanoparticles on fluidity. This paper presents a fundamental study on nanoparticle effects on the fluidity of AA2024 and AA6063 by vacuum fluidity tests. We discovered that dispersed TiC nanoparticles of 0.5, 1.0, and 2.0 vol% surprisingly enhance fluidity length by 10-20% without hot-cracking. Characterization study reveals that α-Al grains push NPs to boundaries during solidification. Higher nanoparticle concentration in the liquid phase delays the latent heat release, allowing the melt to flow further. Image analysis shows that melts flow faster initially with a better wetting angle and surface finish. This novel study suggests that nanoparticles can effectively enhance the die castability of difficult-to-cast aluminum alloys for widespread applications.
Graphite Microstructures within Solidified Hypereutectic Iron and Nickel Alloys: Steven Herrera1; 1University of California, Riverside
Graphite formation was investigated after the solidification of molten metal alloys to determine the conditions required to produce flakes, spheres, and vermicular structures. The size, shape, and spacing of graphite within a solidified structure directly impacts the strength, ductility, and thermal conductivity of metals, alloys, and composites materials containing it. Electromagnetic induction (EMI) and electromagnetic levitation (EML) heating were used to process bulk molten alloys of Fe-C, Fe-C-Si, Ni-C, Ni-C-Si, and Ni-C-Mg compositions. Graphite microstructures were examined in the droplet surface and interior and it was found that graphite flakes were promoted by increasing concentration of silicon and slower cooling rates, while spherical graphite was promoted by increasing the concentration of magnesium and faster cooling rates. Vermicular graphite occurred as an intermediary between conditions required to produce flake and spherical graphite.
N-14: Modelling Three-dimensional Microstructure Solidification Incorporating Interdependent Structural Mechanisms: Peter Soar1; Andrew Kao1; Georgi Djambazov1; Koulis Pericleous1; 1University of Greenwich
The development of solidifying dendritic microstructures can be significantly altered by interdependent structural mechanisms. Many experimental results have demonstrated this phenomenon, where dendrites can bend or twist significantly, acts as a key factor in the formation of defects in cast parts such as stray grains and slivers. Despite this, mechanical effects are often neglected when modelling the microstructure solidification process, with the few attempts presented in the literature being limited to two dimensional models which by necessity must ignore a wide variety of complex deformation behaviours. A three-dimensional Finite Volume Structural Mechanics Solver has been developed which uses displacements to alter the preferential growth orientation of the dendrites, intimately coupling structural mechanics to microstructure solidification within a larger modelling framework also capable of simulating fluid flow and electromagnetism. Example simulations investigating fundamental mechanisms which lead to the formation of casting defects will be presented with reference to observed experimental results.
N-15: Peering into Peritectic Microstructures in Three Dimensions: Shanmukha Kiran Aramanda1; Geordie Lindemann1; Ashwin Shahani1; 1University of Michigan
Production of many advanced materials, such as steel, high-temperature superconductors, and rare-earth permanent magnets, involves a peritectic transition. However, due to a significant compositional dependency and variable morphology, understanding and anticipating the growth modes of peritectic alloys has proven challenging. Here, we select the Ag-Zn as a model system to investigate the mechanisms of the peritectic transition. We study how the primary intermetallic phase transforms into the peritectic phase under slow growth conditions in directional solidification. Our efforts are made possible by x-ray microtomography, which enables us to obtain detailed three-dimensional information and avoid sectioning artefacts. Based on our experimental findings, we propose an original growth mechanism for the formation of the peritectic phase from the primary phase under peritectic transition.
N-16: Physics-embedded Graph Network for Accelerating Phase-field Simulation of Microstructure Evolution in Additive Manufacturing: Zhengtao Gan1; 1Northwestern University
The phase-field (PF) method is a physics-based computational approach for simulating interfacial morphology and phase transformation of materials. However, traditional direct numerical simulation (DNS) of the PF method is computationally resource-intensive as sufficiently small mesh size and time step are necessary to capture the fine-scale interfacial evolution of grains or dendrites. Here, a physics-embedded graph network (PEGN) is proposed to leverage an elegant graph representation of the grain structure and embed the classic PF theory into the graph network. By reformulating the classic PF problem as an unsupervised machine learning task on a graph network, PEGN efficiently solves temperature field, liquid/solid phase fraction, and grain orientation variables to minimize a physics-based loss/energy function. The approach is at least 50 times faster than DNS in both CPU and GPU implementation while still capturing key physical features.
Regular Fluctuation Cooling as an Alternative Crystal Growth Route to Control the Microstructure during Peritectic Solidification: Babak Alinejad1; Amir Mostafaei1; Haruhiko Udono2; 1Illinois Institute of Technology; 2Ibaraki University
A new mechanism is developed for preventing porosity formation in the microstructure of CoSb3 phase during peritectic solidification. Peritectic solidification involves nucleation and growth of the primary phase and formation of second phase by the reaction of the remnant liquid phase with the primary phase. The dendritic growth results in trapping of liquid phase between dendritic arms, leading to a multiphase and because of contraction of liquid, the final structure has porosity. Microstructure analysis at different stages of solidification revealed that oscillated cooling could hinder spontaneous nucleation, improve homogenous nucleation, limit the number of primary grains and impose planar growth. These factors enhance melt flux during peritectic solidification and prevent porosity formation during phase transformation contraction. By utilizing this method, dense CoSb3 single phase was obtained directly from melt in one of the most complicated solidification systems (with two peritectic transformation) in single batch process without any post treatment.