Advanced Solidification Processing Research Articles

16th International Conference on the Modelling of Casting, Welding, and Advanced Solidification Processes

Preface The 16th International Conference on the Modelling of Casting, Welding, and Advanced Solidification Processes (MCWASP XVI) was held from June 18 to 23, 2023, in Banff, Canada, at the Banff Centre for Arts and Creativity. Founded in 1933, the Centre in Treaty 7 Territory within Banff National Park—Canada’s first National Park—is a learning organization built upon an extraordinary legacy of excellence in artistic and creative development. The “all-inclusive” nature of the conference and the remote setting meant that participants dined, attended oral and poster presentations, and participated in social activities as a group, fostering outstanding opportunities for networking.Given that the MCWASP community had not met in person since 2015 in Japan (the 2020 edition of MCWASP was virtual owing to COVID-19), the 2023 conference provided the opportunity to renew old friendships and make new ones as well as discuss the science of solidification and related processes—all within the backdrop of the beautiful Canadian Rocky Mountains.The technical program comprised more than 70 oral and poster presentations. In addition to content related to modelling of casting, welding, and advanced solidification processes, keynotes were invited to talk about related subjects (artificial intelligence/machine learning, and permeability modelling in shale rock) as well as the rich diversity of fossils, especially dinosaurs, found in Alberta.The oral technical program was organized with as a single session (i.e., no concurrent presentations). It featured all aspects of solidification modelling, including solidification process technologies (continuous and semi-continuous casting, shape casting, additive manufacturing, and welding), coupled multi-physics simulations, defect formation, fluid flow, micro- and macro-structure formation, numerical methods, and related experimentation, especially in-situ observation of solidification.The four-day technical program was spread over five days to give participants the opportunity to explore the stunning Canadian Rocky Mountains.In these proceedings, the papers are organized by major theme. The dominant topics are Additive Manufacturing and Welding and Microstructure Formation, followed by Continuous Casting – Shape Casting, Heat Transfer and Fluid Flow, Alloy Segregation, Defects, Imaging of Solidification, Thermomechanics, and Materials Properties. In these themes, the authors report advances in numerical modelling techniques, new scientific and process developments in solidification, and related in-situ experimentation.Although significant progress has been made over these past 16 MCWASP conferences covering 43 years, it is clear that the complexity of advanced solidification phenomena as related to conventional and emerging manufacturing technologies still attracts a great deal of scientific and industrial interest to support technological innovation. André Phillion Banff, Canada, June 2023MCWASP XVI 2023List of Peer Reviewers, Sponsors, MCWASP XVI Organizers, International Scientific Committee are available in this Pdf.

Nanocrystalline Alumina-Zirconia-Based Eutectic Ceramics Fabricated with High-Energy Beams: Principle, Solidification Techniques, Microstructure and Mechanical Properties.

Nanocrystalline alumina-zirconia-based eutectic ceramics fabricated with high-energy beams and composed of ultrafine, three-dimensionally entangled, single-crystal domains are a special category of eutectic oxides that exhibit exceptionally high-temperature mechanical properties, such as strength and toughness as well as creep resistance. This paper aims to provide a comprehensive review on the basic principles, advanced solidification processes, microstructure and mechanical properties of alumina-zirconia-based eutectic ceramics, with particular attention to the status of the art on a nanocrystalline scale. Some basic principles of coupled eutectic growth are first introduced based on previously reported models, followed by concise introduction of solidification techniques and the control strategy of solidification behavior from the processing variables. Then, the microstructural formation of nanoeutectic structure is elucidated with regard to different hierarchical scales, and mechanical properties such as hardness, flexural and tensile strength, fracture toughness and wear resistance are discussed in detail for a comparative study. Nanocrystalline alumina-zirconia-based eutectic ceramics with unique microstructural and compositional characteristics have been produced with high-energy beam-based processes, and in many cases, promising improvements in mechanical performance have been reported as contrasting with conventional eutectic ceramics.

Modelling of defects in aluminium cast products

Over the last 4 decades, remarkable progress has been made in the modelling of casting processes. The development of casting models is well reflected in the proceedings of the 15 Modelling of Casting, Welding and Advanced Solidification Processes (MCWASP) conferences that have been held since 1980.Computer simulations have enabled a better understanding of the physical phenomena involved during solidification. Modelling gives the opportunity to uncouple the physical processes. Furthermore, quantities that are difficult or impossible to measure experimentally can be calculated using computer simulations e.g. flow patterns and recalescence. However, when it comes to accurately predicting casting performance and in particular, the occurrence of defects like cracks, segregation and porosity there is certainly some way to go.In this paper, the current understanding of the main mechanisms of defect formation during shape and DC casting processes will be reviewed and requirements will be discussed to give a direction to making casting models more predictive and quantitative.

Progress in modelling solidification microstructures in metals and alloys. Part II: dendrites from 2001 to 2018

ABSTRACT This is the first account of the history of modelling dendritic and cellular solidification. While Part I reviewed the progress up to the year 2000 [Kurz W, Fisher DJ, Trivedi R. Progress in modelling solidification microstructures in metals and alloys: dendrites from 1700 to 2000. Intern Mater Rev. 2019;64:311–354], Part II retraces our modelling capabilities developed during the early years of the present century. Advances in in-situ X-ray observations of solidification of metallic alloys are also presented. While the most important contributions are mentioned, the authors are aware that such a historical review must leave many worthy articles by the wayside. This overview considers dendrite tip growth and morphology, rapid solidification, melt flow, fragmentation, columnar-to-equiaxed transition, dendrite spacings, coalescence, grain competition, and cellular growth. Modelling across the length scales from nano- up to macroscopic solidification phenomena by massive phase field computations or multiscale approaches show the potential for the simulation of real processes such as additive manufacturing, single crystal casting, welding or advanced solidification processes.

Improved biodegradable magnesium alloys through advanced solidification processing

The potential of using external fields to reduce the cost of emerging magnesium alloys used for the manufacture of medical implant devices while maintaining biocompatibility and mechanical performance is explored. Zirconium (Zr) is often added to high performance magnesium alloys as a grain refiner which is expensive, and there is uncertainty about whether or not Zr is harmful to the biocompatibility of the alloy. This is a significant barrier to the adoption of alloys that contain Zr because of the need to undertake cytotoxicity and haemocompatibility testing, as well as evaluation of long-term clinical effects. An alternative approach is to investigate methods to minimise or eliminate the need for Zr addition. External fields applied during solidification of the alloy provide an opportunity to produce a refined microstructure without the addition of Mg–Zr master alloy presenting a distinct advantage both from biodegradation and biocompatibility perspectives. Preliminary work evaluates the effect of ultrasonic treatment on microstructure and mechanical properties of Mg–Zn–Ca alloys with and without Zr and then compares their in-vivo corrosion performance to that of WE43. A framework for future research is proposed along with opportunities for the development of lower cost alloys with at least equal biocompatibility, mechanical and corrosion performance.

Systematic Phase-Field Study on Microstructure Formation During Brazing of Mar-M247 with a Si-Based AMS4782 Filler

Although advanced solidification processes like high temperature brazing have gained more and more industrial importance, they still are often not well understood, and defining optimal process conditions for practical use in many cases can be achieved only by expensive experimental trial and error methods. On the other hand, the phase-field method has become more and more powerful for the simulation of solidification and phase transformations in technical alloys. This paper presents phase-field simulations for high temperature brazing of the Ni-base superalloy Mar-M247 using a Si-based AMS4782 filler. The applied phase-field model can be online-coupled to Calphad databases which deliver the thermodynamic and mobility data for this complex multicomponent multiphase alloy. Unknown or uncertain physical parameters like diffusion coefficients have been calibrated by comparing to optical micrographs and EDX element mappings obtained from laboratory braze experiments for the same material combination. By variation of the process conditions the effects of the brazing temperature, the brazing time, and the thickness of the braze gap on precipitation of brittle phases and formation of stray grains as well as changes in the microstructure of the base material itself have been systematically investigated. Results are presented and discussed.

MCWASP XIV: International Conference on Modelling of Casting, Welding and Advanced Solidification Processes

The current volume represents contributed papers of the proceedings of the 14th international conference on ‘‘Modeling of Casting, Welding and Advanced Solidification Processes (MCWASP XIV)’’, Yumebutai International Conference Center, Awaji island, Hyogo, Japan on 21 – 26 June, 2016. The first conference of the series ‘Modeling of Casting, Welding and Advanced Solidification Processes (MCWASP)’ was started up in 1980, and this is the 14th conference. The participants are more than 100 scientists from industry and academia, coming from 19 countries. In the conference, we have 5 invited, 70 oral and 31 poster presentations on different aspects of the modeling. The conference deals with various casting processes (Ingot / shape casting, continuous casting, direct chill casting and welding), fundamental phenomena (nucleation and growth, dendritic growth, eutectic growth, micro-, meso- and macrostructure formation and defect formation), coupling problems (electromagnetic interactions, application of ultrasonic wave), development of experimental / computational methods and so on. This volume presents the cutting-edge research in the modeling of casting, welding and solidification processes. I would like to thank MAGMA Giessereitechnologie GmbH, Germany and SCSK Corporation, Japan for supporting the publication of contributed papers. Hideyuki Yasuda Conference Chairman Department of Materials Science and Engineering, Kyoto University Japan

Detached Melt Nucleation during Diffusion Brazing of a Technical Ni-based Superalloy: A Phase-Field Study

Advanced solidification processes like welding, soldering, and brazing are often characterized by their specific solidification conditions. But they also may include different types of melting processes which themselves are strongly influenced by the initial microstructures and compositions of the applied materials and therefore are decisive for the final quality and mechanical properties of the joint. Such melting processes are often not well- understood because - compared to other fields of solidification science - relatively little research has been done on melting by now. Also, regarding microstructure simulation, melting has been strongly neglected in the past, although this process is substantially different from solidification due to the reversed diffusivities of the involved phases. In this paper we present phase-field simulations showing melting, solidification and precipitation of intermetallic phases during diffusion brazing of directionally solidified and heat-treated high-alloyed Ni- based gas turbine blade material using different boron containing braze alloys. Contrary to the common belief, melting of the base material is not always planar and can be further accompanied by detached nucleation and growth of a second liquid phase inside the base material leading to polycrystalline morphologies of the joint after solidification. These findings are consistent with results from brazed laboratory samples, which were characterized by EDX and optical microscopy, and can be explained in terms of specific alloy thermodynamics and inter-diffusion kinetics. Consequences of the gained new understanding for brazing of high- alloyed materials are discussed.

Meso-scale modelling of directional solidification and comparison with in situ X-ray radiographic observations made during the MASER-12 XRMON microgravity experiment

Computational modelling of advanced solidification processes has made considerable advances over the last half century, with ever increasing levels of modelling complexity. There is, therefore, an increasing need for state of the art experimental investigation to provide suitable validation for these model predictions. In situ X-ray radiography has become a powerful tool for solidification experimentation. Using either synchrotron or microfocus X-ray sources, thin samples, encased in X-ray transparent crucibles, can be directionally or isothermally solidified, allowing for direct real time observation of dynamic solidification phenomena. This paper presents the results of a meso-scale Front Tracking simulation of a directional solidification experiment, performed using an Al–20wt.% Cu alloy, carried out under microgravity conditions on board the MASER 12 sounding rocket. The sample was mounted in a Bridgman type gradient furnace and solidified using a prescribed cooling regime with a constant gradient, thus promoting directional solidification in the field of view. The actual thermal gradient in the sample was found to be lower than the nominal thermal gradient, as set/recorded by thermocouples embedded in the heater elements. The adjusted thermal data were supplied as inputs to the Front Tracking model and good agreement was then observed between the model predictions and the in situ observations. The extent and amplitude of the undercooled zone ahead of the columnar front was predicted based on analytical growth kinetics laws and the results were also compared to analytical models of columnar-to-equiaxed transition (CET) prediction.

Solidification of Silicon for Solar Cells

Silicon is the dominating material in solar cells. Monocrystalline and multicrystalline cells have approximately equal market shares and are produced from wafers, cut from single crystals produced by Czochralski (CZ) pulling or from polycrystalline ingots made by directional solidification, respectively. The present paper reviews how demands for lower cost, better yield, higher efficiency and use of less pure silicon in solar cells are addressed by advanced solidification processing. In monocrystalline solar silicon, careful growth control results in less point defects, and better efficiency. Continuous- or semi-continuous CZ growth processes are being developed for better productivity and lower cost. In multicrystalline solar silicon, extended defects such as dislocations and grain boundaries decrease efficiency, particularly in combination with new, less expensive, but more contaminated silicon feedstock. This problem is addressed by control of nucleation and growth of ingots with larger grains, preferred grain orientation and lower dislocation density.

Solidification paths of multicomponent monotectic aluminum alloys

Solidification paths of three ternary monotectic alloy systems, Al–Bi–Zn, Al–Sn–Cu and Al–Bi–Cu, are studied using thermodynamic calculations, both for the pertinent phase diagrams and also for specific details concerning the solidification of selected alloy compositions. The coupled composition variation in two different liquids is quantitatively given. Various ternary monotectic four-phase reactions are encountered during solidification, as opposed to the simple binary monotectic, L′ → L′′ + solid. These intricacies are reflected in the solidification microstructures, as demonstrated for these three aluminum alloy systems, selected in view of their distinctive features. This examination of solidification paths and microstructure formation may be relevant for advanced solidification processing of multicomponent monotectic alloys.

Numerical study on the prediction of microstructure parameters by multi-scale modeling of directional solidification of binary aluminum–silicon alloys

In order to create a model to predict microstructural quantities like grain size, primary and secondary dendrite arm spacing a multi-phase and multi-scale model based on the work of Wang and Beckermann [C. Wang, C. Beckermann, Metallurgical and Materials Transactions A 27A (1996) 2754–2764] was combined with a front tracking technique [A. Wu, A. Ludwig, in: C.-A. Gandin, M. Bellet (Eds.), Modeling of Casting, Welding, and Advanced Solidification Processes – XI, TMS, 2006, pp. 291–298], micro-models for nucleation [M. Rappaz, P. Thevoz, Acta Metallurgica 35 (7) (1987) 1487–1497], primary [J. Hunt, S.-Z. Lu, Metallurgical and Materials Transactions A 27A (1996) 611–623], secondary [W. Kurz, D. Fisher, Fundamentals of Solidification, Trans Tech Publication, 1986, ISBN 0-87849-522-3] dendrite arm spacing and a control volume based finite element solver for axial-symmetric problems. As most of the micro-models are just valid for pure diffusive conditions, the model just takes into account macroscopic diffusion in the melt and thus neglects the influence of melt flow. The new software was used for a comprehensive comparison to several test cases. The validation includes investigation of the correlation of calculated and measured grain size distributions for inoculated alloys. Experimental and numerical data for the primary and secondary dendrite arm spacing for steady state and transient directional solidification were compared in a second step. A good correlation is found for all test cases.

Advanced solidification processing of an industrial gas turbine engine component

This paper will describe the efforts of the Advanced Turbine Airfoil Manufacturing Technology Program sponsored by the U.S. Department of Energy through the Oak Ridge National Laboratory and Howmet Research Corporation. The purpose of the program is to develop single-crystal and directionally solidified casting technologies to benefit Advanced Turbine Systems (ATS) industrial and utility gas turbine engines. The focus is on defining and implementing advanced Vacuum Induction Melting (VIM) furnace enhancements that provide precise control of mold temperatures during solidification. Emphasis was placed on increasing the total magnitude of thermal gradients while minimizing the difference in maximum and minimum gradients produced during the solidification process. Advanced VIM casting techniques were applied to Solar Turbines Incorporated’s Titan 130 First Stage High Pressure Turbine Blade under the ATS program. A comparison of the advanced VIM casting process to the conventional Bridgeman casting process will be presented as it pertains to the thermal gradients achieved during solidification, microstructure, elemental partitioning characterization, and solution heat treat response.

A stabilized hybrid FE/FV method applied to fluid flow in mold filling

Modern casting processes allow the precise production of parts with complex shapes. Numerical simulation increasingly becomes an important tool aiding design and production. A finite element method using finite volume principles is described. A new adaptive stabilization based either on bubble functions or a Petrov-Galerkin method is elaborated. Then, a new stabilization scheme, named FF-VOF, is presented to describe the free surface evolution during mold filling. Finally, the developed method is applied to the mold filling benchmark defined at the 7th Conference on Modeling of Casting, Welding and Advanced Solidification Processes.

Application of an adaptive grid refinement technique to three-dimensional finite element analysis of the filling stage in the die-casting process

In order to obtain a higher resolution of the free surface configuration, an adaptive grid refinement technique is incorporated into the volume of fluid (VOF) and the marker surface methods for three-dimensional finite element analysis of the filling stage in the die-casting process. The adaptive grid is created at each time step through the grid refinement and coarsening procedures, as opposed to employing the fixed grid in the classical VOF and marker particle methods. In the adaptive grid, the elements finer than those of the internal and external regions are distributed over the surface region. The adaptive grid is used for generating the fluid region grid that better describes the shape of the predicted free surface at each time step, and for advancing the predicted free surface more precisely. To verify the efficiency of the adaptive grid refinement technique rigorously, a benchmark problem of the conference on the “Modeling of Casting, Welding and Advanced Solidification Processes VII” (MCWASP VII) has been analyzed and the numerical results are found to be in good agreement with the experimental results. A typical industrial problem of the die-casting process such as a cover of transmission case has been analyzed and it has been shown that the adaptive grid incorporated into the VOF and marker surface methods can be effectively applied to general die-casting process analysis.

Gravity and temperature effects on particle distribution in Al–Si/SiC composites

During the EuroMIR’95 space flight four hypo-eutectic Al–Si alloy matrix composites with a SiC dispersion were made molten at different thermal gradients and solidified with a different cooling rate in the TITUS (Tubular furnace with Integrated Thermal analysis Under Space conditions) tube furnace. On comparison with the ground processed reference samples, it appears that the distribution of the particles in the molten zone is much more homogeneous in the zero gravity cast specimens. Also additional tests were performed in a high gradient furnace (ASPF — advanced solidification processing facility) and in a low gradient furnace to complement the results of the space processed samples. A higher temperature gradient, where the gradient is parallel to the direction of solidification and opposite to the gravity, gives less convection. A decrease in the cooling rate leads to larger dendrites and cells, and to a decrease of the homogeneity of the SiC particle distribution. The SiC particles settle in the terrestrial experiments, but the distribution differs as a function of the thermal profile. The SiC particles form a network in the liquid state but will, during resolidification, be pushed to the last solidified zone, between the α-Al dendrites, into the Al–Si eutectic zone.

Nanocrystalline Materials Manufactured by Advanced Solidification Processing Methods

Nanocrystalline Materials Manufactured by Advanced Solidification Processing Methods

Nanocrystalline Materials Manufactured by Advanced Solidification Processing Methods

Nanocrystalline Materials Manufactured by Advanced Solidification Processing Methods

Anomaly in dendritic growth data — effect of density change upon solidification

We examine recent dendritic growth data obtained by Glicksman and co-workers [M.E. Glicksman, M.B. Koss and E.A. Winsa, Phys. Rev. Lett. 73 (1994) 573; M.E. Glicksman, M.B. Koss, L.T. Bushnell, J.C. LaCombe and E.A. Winsa, ISIJ Int. 35 (1995) 1216; MRS Fall Meeting, Symp. P, Boston, MA, 1995, in press; M.E. Glicksman, M.B. Koss, L.T. Bushnell and J.C. LaCombe, in: Modelling of Casting, Welding and Advanced Solidification Processes VII, Eds. M. Cross and J. Campbell, (The Minerals, Metals and Materials Society, 1995); private communication] in microgravity. These authors have pointed out an anomaly in the data, when compared with theoretical predictions. In particular, a systematic deviation of the growth Pe´clet number from an Ivantsov's theory was noted at the intermediate supercooling range. This work considers effects due to density change upon solidification. This requires a careful reexamination of the definition of material parameters, and an evaluation of effects due to the solidification-induced fluid flow (“Stefan wind”). A consistent application of carefully obtained material parameters clearly eliminates the discrepancy between the theory and experimental data. However, the effect of fluid flow due to the solid-melt density change is shown to be of minor importance to the particular experiment and material under consideration. We conclude by presenting an Ivantsov's theory modified for the wall proximity effect and corrected for density change upon solidification that matches the entire range of supercooling levels used in Glicksman's experiments.

Differential scanning calorimetry and the advanced solidification processing of metals and alloys

This paper describes some examples of the use of differential scanning calorimetry (DSC) in providing information for advanced solidification processing of metals and alloys. Spray forming, squeeze casting, grain refinement and crystallization of amorphous alloys are all discussed. DSC measurements are shown to be valuable for testing kinetic theories of nucleation and growth, and validating solidification process models.