Consideration of the Timing Effect of Dendrite Pinch-Off on Dendrite Fragmentation During Directional Solidification of Superalloys | Chapter 2 | Proceedings of the 8th International Conference on Solidification and Gravity

Single-crystal superalloys play a vital role in aerospace and power generation due to their superior mechanical properties at high temperatures. However, the formation of freckles during the casting process is highly detrimental. The freckle is characterized by a trace of small misoriented spurious (equiaxed) grains with a local accumulation of eutectics. The primary source for the spurious grains is considered to be dendrite fragmentation. It is known that the interdendritic flow in the dendrite growth direction promotes dendrite remelting, creating favourable conditions for dendrite fragmentation. Therefore, a flow-driven fragmentation model was primarily proposed, assuming that the fragmentation occurs when the following criterion,\(\vec{u}_l-\vec{u}_c\cdot\nabla c_l<0\), is fulfilled. Although the above model has considered global transport phenomena and their impacts on the local thermodynamic condition for the dendrite remelting, some other microscopic events influencing the fragmentation were ignored or simplified. One such event is the timing effect of dendrite pinch-off. In this conference contribution, a modification to the previous flow-driven fragmentation model was suggested. In addition to the above flow-driven remelting criterion, a second condition, i.e., the necessary time for the remelting(t_r) of the dendrite roots to allow the pinch-off (\(\tau\)) to occur, is applied to the model. An improved simulation-experiment agreement is achieved in terms of both the distribution of the segregation channel and the formation of spurious grains. The mechanisms for the onset of segregation channels and the production of spurious grains are studied.

Author (s) Details

Haijie Zhang
Metallurgy Department, Chair of Simulation and Modelling Metallurgical Processes, Montanuniversitaet Leoben, Franz-Josef Street 18, 8700, Leoben, Austria.

 

Menghuai Wu
Metallurgy Department, Chair of Simulation and Modelling Metallurgical Processes, Montanuniversitaet Leoben, Franz-Josef Street 18, 8700, Leoben, Austria.

 

Abdellah Kharicha
Metallurgy Department, Chair of Simulation and Modelling Metallurgical Processes, Montanuniversitaet Leoben, Franz-Josef Street 18, 8700, Leoben, Austria.

 

Please see the book here:- https://doi.org/10.9734/bpi/mono/978-93-49473-95-9/CH2

Numerical Study on the Effect of Convection on Grain Growth Structure in Metallic Systems | Chapter 9 | Proceedings of the 8th International Conference on Solidification and Gravity

 The effect of convection within the droplet during the levitation experiment on the grain structure was investigated using phase-field simulation considering convection. This study aims to distinguish the effects of convection and heterogeneous nucleation on the grain structure. In binary alloy systems, convection generates a strong solute gradient near the solid-liquid interface, leading to faster solid growth.  The effect of flow velocity on the degree of grain deformation was investigated based on elliptical fitting and aspect ratio, and it was found that the shape of grown grains tends to deform with an increase in convection velocity. Under levitation experimental conditions, the aspect ratio decreased up to 0.80 times compared to the no-flow case. Small vortices are generated for the further large velocity, creating the local concentration gradient, thus resulting in the short-wavelength grain interface. In the solidification of pure metals based on heat transport, the effect of convection on grain shape was relatively small compared to the case of binary alloys because of the large thermal diffusion.

 

Author (s) Details

 

Kohei Tanimoto
Graduate School of Integrative Science and Engineering, Tokyo City University, Tokyo 158-8557, Japan.

Nagano Hideaki
Department of Mechanical Systems Engineering, Tokyo City University, Tokyo 158-8557, Japan.

Kenjiro Shimano
Department of Mechanical Systems Engineering, Tokyo City University, Tokyo 158-8557, Japan.

Suguru Shiratori
Department of Mechanical Systems Engineering, Tokyo City University, Tokyo 158-8557, Japan.

 

Please see the book here:- https://doi.org/10.9734/bpi/mono/978-93-49473-95-9/CH9

Surface Morphology Characterization of a Dendrite in Al-Ge Observed by Synchrotron Tomoscopy | Chapter 3 | | Proceedings of the 8th International Conference on Solidification and Gravity

Dendrites can exhibit a rich variety of morphologies as they grow. Based on the local surface curvature, the morphology of a dendrite can be visualized in a 2D probability plot, called interface shape distribution (ISD) map. Synchrotron tomoscopy was used to observe the solidification of aluminum-germanium samples of different compositions, as it enables high temporal and spatial resolution. The steps required to extract a dendrite from a large tomoscopy data set are demonstrated using an Al-25wt.% Ge alloy, involving noise reduction and segmentation from the liquid phase. The three-dimensional dendrite morphology of a selected dendrite in an Al-45wt.% Ge alloy was studied in detail. Special attention is paid to the creation of the dendrite surface from the voxelized data. The influence of different smoothing parameters on the ISD map is shown. The suitability of the experimental and analytical approach to quantify dendrite morphology is demonstrated and will be applied to other alloy compositions in future work. It opens up new perspectives for determining properties such as the solid-liquid interfacial energy anisotropy, which influences the morphology of dendrites.

 

Author (s) Details

N. Bellenbaum
Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Linder Höhe, 51170 Köln, Germany.

E. Sondermann
Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Linder Höhe, 51170 Köln, Germany.

 

F. Yang
Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Linder Höhe, 51170 Köln, Germany.

 

P. H. Kamm
Institute of Applied Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.

 

T. R. Neu
Institute of Applied Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.

 

F. García-Moren
Institute of Applied Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany.

 

F. Kargl
Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Linder Höhe, 51170 Köln, Germany.

 

M. Becker
Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Linder Höhe, 51170 Köln, Germany.

 

Please see the book here:- https://doi.org/10.9734/bpi/mono/978-93-49473-95-9/CH3

Advancements in Refining Techniques for Improving Liquid Metal Quality in Aluminum Alloys | Chapter 9 | Engineering Research: Perspectives on Recent Advances Vol. 4

Aluminum is a metal widely used in many industries due to its lightweight, durability, and resistance to corrosion. Its unique combination of properties, including high strength-to-weight ratio and excellent thermal and electrical conductivity, makes it a material of choice in sectors such as aerospace, automotive, construction, and packaging.

This chapter investigates the impact of refining processes on the quality of liquid metal in the production of aluminum alloys, with a particular focus on the 6060 alloys. It examines how the presence of oxide compounds during aluminum processing affects the liquid metal's quality and evaluates the effectiveness of various refining methods aimed at removing these compounds.

The study involved casting samples made from 6060 aluminum alloy, and exploring how variables such as flux amounts, cleaning times, and nitrogen gas pressure influence the quality of the liquid metal. To assess metal quality, three key metrics were analyzed: the density index (DI%), bifilm index (BI), and hydrogen level (ml/100g Al), using the solidification under vacuum (RPT) method.

Additionally, the chapter delves into microstructural analysis, considering factors such as grain size, grain number, and homogeneity ratio, with a focus on identifying optimal parameters that lead to superior liquid metal quality. The findings underscore the critical role of optimizing refining processes to enhance the quality of liquid metal, emphasizing the significance of these methods in aluminum production.

In conclusion, this chapter highlights the essential refining techniques that can lead to improved metal quality, which is crucial for the manufacturing of high-performance aluminum alloys.

 

Author (s) Details

 

Bilgehan Tunca
R&D Department, Sistem Aluminyum San. Ve Tic. A.S., Turkey.

 

Burak Ince
R&D Department, Sistem Aluminyum San. Ve Tic. A.S., Turkey.

 

Dilek Deniz
R&D Department, Sistem Aluminyum San. Ve Tic. A.S., Turkey.

 

Please see the book here:- https://doi.org/10.9734/bpi/erpra/v4/4481

Development of a New Magnetic Stirring Facility and Efficient Method for Refinement of Solidified Grain Structure | Chapter 10 | Effect of Microgravity and Magnetic Steering on the Melt Flow and the Microstructure of Solidified Alloys

This work aimed to develop an efficient stirring facility and method with magnetic induction. Because the stirring by Rotation Magnetic Field (RMF) often produces strong macrosegregation, the Traveling Magnetic Field (TMF) was chosen for the stirring. The construction of this TMF twin-inductor is significantly different from the traditional magnetic stirrers, and it has a closed magnetic circuit. Three different magnetic fields can be produced with the developed twin-inductor to investigate the stirring effect. The inductor develops strong shearing stress at the flow perpendicular to the solidification front by flowing a part of metallic-melt layers touching each other in a direction opposite. The TMF twin inductor was combined with a solidification facility for the unidirectional solidification of different alloys.

 

The effect on the grain structure of the three different magnetic fields was compared using Al-7%Si-1% and Al-10%Si-0,2%Fe alloys. It has demonstrated that the most efficient mixing occurs when the magnetic fields in the two inductors move opposite each other.

Author(s) Details:

Arnold Rónaföldi,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary and Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary.

Zsolt Veres,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary and Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary.

Mária Svéda,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary.

András Roósz,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary and Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary.

Please see the link here: https://stm.bookpi.org/EMMSMFMSA/article/view/13086

Effect of Solidification Parameters on the Amount of Eutectic and Secondary Arm Spacing of Al–7wt%Si Alloy Solidified under Microgravity: An Experimental Analysis | Chapter 4 | Effect of Microgravity and Magnetic Steering on the Melt Flow and the Microstructure of Solidified Alloys

This chapter highlights the effect of G and v on the secondary dendrite arm spacing (SDAS) in purely diffusion circumstances, analysed the thermal data of the experiments in detail, and take into account the macrosegregation caused by the diffusion of Si from the initial mushy zone during the homogenization step of experiments. During the solidification of hypoeutectic alloy (like Al-7% Si), density difference develops in the melt generated by concentration and temperature difference. On Earth, as an effect of this density difference, the melt can flow due to gravity affecting the solidified microstructure. The developing meso- and micro-structures are also significantly affected by the melt flow occurring during the solidification processes in different casting technologies. This melt flow can be eliminated in a microgravity environment, which then makes it possible to examine the solidification process under conditions of pure diffusion. In the Materials Science Lab (MSL) on board the International Space Station (ISS), four solidification experiments were conducted on grain refined and non-grain refined Al-7wt% Si alloy to investigate the effects of the solidification parameters  (solid/liquid front velocity v, temperature gradient G) on the dendritic microstructures and the grain structure. A detailed analysis of the grain structure was conducted in a few previous articles. The macrosegregation was calculated by the Finite Different Method. Because the steady-state solidification conditions were never reached, the solidification process was characterized by the average front velocity and temperature gradient. It is shown that steady-state solidification conditions are never reached. At a given sample position, the velocity of the solid/liquid S/L) and the eutectic/liquid (E/L) fronts and the temperature gradient at the two fronts are different. Then, the solidification process can be characterized by the average front velocity and average temperature gradient.

Author(s) Details:

András Roósz,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary and Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary.

Arnold Rónaföldi,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary and Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary.

Yuze Li,
School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an, 710100, China.

Nathalie Mangelinck-Noël,
Aix Marseille University, Université de Toulon, CNRS, IM2NP, 13013 Marseille, France.

Gerherd Zimmermann,
ACCESS e.V., Intzestrasse 5, Aachen, Germany.

Henri Nguyen-Thi,
Aix Marseille University, Université de Toulon, CNRS, IM2NP, 13013 Marseille, France.

Mária Svéda,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary.

Zsolt Veres,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary and Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary.

Please see the link here: https://stm.bookpi.org/EMMSMFMSA/article/view/13079

Microstructure Analysis of Al-7 wt%Si Alloy Solidified on Earth Compared to Similar Experiments in Microgravity: An Update | Chapter 3 | Effect of Microgravity and Magnetic Steering on the Melt Flow and the Microstructure of Solidified Alloys

 This chapter highlights a comparative overview of the grain structure (especial the CET) and the type of the coarsening process of the secondary dendrite arm (especially the kinetic constant n) of the samples solidified in space and the Earth to get information on the effect of buoyancy flow. During ground-based solidification, buoyancy flow can develop by the density difference in the hypoeutectic type of the alloy, such as Al-7 wt% Si alloy. Buoyancy flow can affect the thermal field, solute distribution in the melt, and the position and amount of the new grains. Under microgravity conditions, natural convection does not exist or is strongly damped due to the absence of the buoyancy force. Therefore, experiments in microgravity conditions provide unique benchmark data for pure diffusive solidification conditions. Compared to the results of the ground-based and microgravity ( µ g) experiments, it is possible to get information on the effect of gravity (buoyancy force). In the framework of the CETSOL project, four microgravity solidification experiments were performed on grain-refined (GF) and non-grain refined Al-7 wt% Si alloy onboard the International Space Station in the Materials Science Laboratory. Four ground-based (GB) experiments were performed under Earth -like conditions with the same (similar) solidification parameters in a vertical Bridgman-type furnace. A detailed analysis of the grain structure and amount of eutectic and secondary dendrite arm spacing (SDAS) for different process conditions is reported and compared with the results of the microgravity experiments. GB experiments showed that the microstructure was columnar in the samples that do not contain GF material or in case the solid/liquid (vSL front velocity was slow (0.02 mm/s)). In contrast, in the GF material sample, progressive columnar/equiaxed transition (PCET) was observed at vSL = 0.077 mm/s and GSL = 3.9 K/mm. The secondary (SDAS) dendrite arm spacing follows the well-known power law, SADS = K[ t0 ]1/3  where K is a constant, and t0 is the local solidification time for both GB and µg experiments. The experiments in microgravity conditions provide unique benchmark data for pure diffusive solidification conditions. Compared to the results of the ground-based and microgravity experiments, it is possible to get information on the effect of gravity (buoyancy force).

Author(s) Details:

András Roósz,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary and Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary.

Arnold Rónaföldi,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary and Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary.

Yuze Li,
School of Physical Science and Technology, Northwestern Polytechnical University, Xi’an, 710100, China.

Nathalie Mangelinck-Noël,
Aix Marseille University, Université de Toulon, CNRS, IM2NP, 13013 Marseille, France.

Gerhard Zimmermann,
ACCESS e.V., Intzestrasse 5, D-52072, Aachen, Germany.

Henri Nguyen-Thi,
Aix Marseille University, Université de Toulon, CNRS, IM2NP, 13013 Marseille, France.

Mária Svéda,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary.

Zsolt Veres,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary and Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary.

Please see the link here: https://stm.bookpi.org/EMMSMFMSA/article/view/13078

Application of Cleaner Technologies in the Treatment of Leachate and the Prevention of Surface and Groundwater Pollution in the Environment | Chapter 8 | Modern Advances in Geography, Environment and Earth Sciences Vol. 7

 In the northern Kosovo region, direct discharge of urban and industrial waste waters, as well as leachate (originating from unlawful landfills) into receivers without previous filtration, is unfortunately quite frequent. Furthermore, reckless and inappropriate site selection for industrial and municipal landfills, which are frequently located near or on the river's edge, contributes greatly to pollution. Direct sampling and the TCLP (Toxicity Characteristic Leashing Procedures) method were used to analyse the leachate from these sites. Possible methods for removing and reducing existing pollution were given based on the examination of physicochemical parameters of filtrated water from the sites itkovac, Grabovac, and Balaban, as well as analysis of surface water and groundwater samples from the site Grabovac. Purification of municipal and industrial waste waters, as well as leachate from illegal landfills, was recommended as a possible long-term solution. The use of a Membrane Bio Reactor (MBR) to implement remediation with a unified system for water purification, which includes the process of stabilization/solidification of residual sludge, would result in a neutral powder material that is completely safe for the environment and suitable for a variety of applications. The goal of this research is to track the impact of leachate landfill water on surface and groundwater around landfills, as well as to avoid and remediate contamination through the use of cleaner landfill water treatment technology.

Author(S) Details

Irma Dervisevic
University of Prishtina, Faculty of Technical Sciences, Kosovska Mitrovica, Serbia.

Jelena Dokic
University of Prishtina, Faculty of Technical Sciences, Kosovska Mitrovica, Serbia.

Natasa Elezovic
University of Prishtina, Faculty of Technical Sciences, Kosovska Mitrovica, Serbia.

Gordana Milentijevic
University of Prishtina, Faculty of Technical Sciences, Kosovska Mitrovica, Serbia.

Vladan Cosovic
University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Belgrade, Serbia.

Almin Dervisevic
Faculty of Technology in Novi Sad, Study Program of Pharmaceutical Engineering,Novi Sad, Serbia.

View Book:- https://stm.bookpi.org/MAGEES-V7/article/view/5097

Developing the Numerical Simulation of Multicomponent Alloy Solidification | Chapter 3 | Advanced Aspects of Engineering Research Vol. 16

 A non-equilibrium model was used to study multicomponent melt solidification, in which a Stefan problem with two borders was addressed numerically, the boundaries being between the solid phase and the two-phase transition zone, and between the two-phase transition zone and the liquid phase. The two-phase zone is represented by a porous material with varied porosity. The additional force preventing melt flow due to porosity is taken into account in the same way that Darcy's law is taken into account. Computer simulations were used to simulate the solidification of Sn-20 wt. percent Pb binary alloys via the process of downward-directed crystallisation along the gravity vector. The results of a quasi two-dimensional benchmark experiment on horizontal (i.e., perpendicular to the gravity vector) directional solidification of a binary Sn-3 wt. percent Pb alloy are presented in the publication. Two crystallisation models were used in the calculations: equilibrium and non-equilibrium crystallisation. The non-equilibrium model is proven to provide a more accurate depiction of natural convection-induced heat field evolution and solute dispersion. Solidification, binary alloy, dual-phase region, macrosegregation, convection, heat-mass transfer, modelling, comparison with experimental results, columnar-to-equiaxed transition Keywords: solidification, binary alloy, dual-phase region, macrosegregation, convection, heat-mass transfer, modelling, comparison with experimental results (CET).

Author (S) Details

V. P. Ginkin
Institute for Physics and Power Engineering (IPPE), Bondarenko sq.1, 249033 Obninsk, Russia.

S. M. Ganina
Institute for Physics and Power Engineering (IPPE), Bondarenko sq.1, 249033 Obninsk, Russia.

A. V. Kartavykh
Technological Institute for Superhard and Novel Carbon Materials (TISNCM, Moscow branch), B.Tolmachevsky per.5, 119017 Moscow, Russia.

View Book :- https://stm.bookpi.org/AAER-V16/article/view/1988

Research on the Simulation of Solidification Parameters during Zr Based Bulk Metallic Glass Matrix Composite’s (BMGMCs) Additive Manufacturing | Chapter 6 | Recent Developments in Engineering Research Vol.4

 

After a silence of three decades, bulk metallic glasses and their composites have re-emerged as a
competent engineering material owing to their excellent mechanical properties not observed in any
other engineering material known till date. However, they exhibit poor ductility and little or no
toughness which make them brittle and they fail catastrophically under tensile loading. Exact
explanation of this behaviour is difficult, and a lot of expensive experimentation is needed before
conclusive results could be drawn. In present study, a theoretical approach has been presented aimed at solving this problem. A detailed mathematical model has been developed to describe solidification phenomena in zirconium based bulk metallic glass matrix composites during additive manufacturing. It precisely models and predicts solidification parameters related to microscale solute diffusion (mass transfer) and capillary action in these rapidly solidifying sluggish slurries. Programming and simulation of model is performed in MATLAB®. Results show that the use of temperature dependent thermophysical properties yields a synergic effect for multitude improvement and refinement simulation results. Simulated values proved out to be in good agreement with prior simulated and experimental results. There is significant effect of initial metal temperature, composition, type of alloying elements,temperature gradient and thermo-physical properties on final microstructure developed as a result of heat and mass transfer phenomena.

Author (s) Details

Muhammad Musaddique Ali Rafique
Eastern Engineering Solutions LLC, Detroit, MI, USA.

View Book :- https://bp.bookpi.org/index.php/bpi/catalog/book/263

Recent Studies on Probabilistic Modelling of Microstructural Evolution in Zr Based Bulk Metallic Glass Matrix Composites during Solidification in Additive Manufacturing | Chapter 5 | Recent Developments in Engineering Research Vol.4

 The present study aims to model nucleation of primary phase ductile crystalline particles in glassy

matrix. Bulk metallic glass and their composites (BMGMCs) are a new class of materials which
possess superior mechanical properties as compared to existing conventional materials. Owing to
this, they are potential candidates for tomorrow’s structural applications. However, they suffer from
poor ductility and little or no toughness which render them brittle and they manifest catastrophic failure under applied force. Their behavior is dubious, unpredictable and requires extensive experimentation to arrive at conclusive results. A cellular automata method is described for describing nucleation and growth of primary ductile phase particles in glassy matrix in bulk metallic glass matrix composites. A probabilistic cellular automaton (CA) model is developed and described in present study by author which is used in conjunction with earlier developed deterministic model to predict microstructural evolution in Zr based BMGMCs in additive manufacturing liquid melt pool. It is elaborately described with an aim to arrive at quantitative relations which describe process and steps of operations. Results indicate that effect of incorporating all mass transfer and diffusion coefficients under transient conditions and precise determination of probability number play a vital role in refining the model and bringing it closer to a level that it could be compared to actual values. It is shown that proposed tailoring can account for microstructural evolution in metallic glasses. It is found that proper use of transport equations and calculations of random probability number play pivotal role in describing microscale solute diffusion and solid fraction evolution in solidifying alloy. Use of moderate size simulation grid (cartesian) to counter mesh anisotropy along with selection of decentered square
algorithm also helps in model refinement and optimization.

Author (s) Details

Muhammad Musaddique Ali Rafique
Eastern Engineering Solutions LLC, Detroit, MI, USA.

View Book :- https://bp.bookpi.org/index.php/bpi/catalog/book/263