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Project Title:  Pore-Mushy Zone Interaction during Directional Solidification of Alloys: Three Dimensional Simulation and Comparison with Experiments Reduce
Images: icon  Fiscal Year: FY 2019 
Division: Physical Sciences 
Research Discipline/Element:
MATERIALS SCIENCE--Materials science 
Start Date: 09/16/2016  
End Date: 09/15/2019  
Task Last Updated: 12/11/2019 
Download report in PDF pdf
Principal Investigator/Affiliation:   Eshraghi, Mohsen  Ph.D. / California State University, Los Angeles 
Address:  Department of Mechanical Engineering 
5151 State University Dr 
Los Angeles , CA 90032-4226 
Email: meshrag@calstatela.edu 
Phone: 323-343-5218  
Congressional District: 34 
Web:  
Organization Type: UNIVERSITY 
Organization Name: California State University, Los Angeles 
Comments:  
Co-Investigator(s)
Affiliation: 
Tewari, Surendra  Ph.D. Cleveland State University 
Felicelli, Sergio  Ph.D. University of Akron 
Project Information: Grant/Contract No. NNX16AT75G 
Responsible Center: NASA MSFC 
Grant Monitor: Strutzenberg, Louise  
Center Contact: (256) 544-0946 
louise.s@nasa.gov 
Solicitation: 2015 Physical Sciences NNH15ZTT001N-15PSI-B: Use of the NASA Physical Sciences Informatics System – Appendix B 
Grant/Contract No.: NNX16AT75G 
Project Type: GROUND 
TechPort: No 
No. of Post Docs:  
No. of PhD Candidates:
No. of Master's Candidates:  
No. of Bachelor's Candidates:  
No. of PhD Degrees:
No. of Master's Degrees:
No. of Bachelor's Degrees:  
Program--Element: MATERIALS SCIENCE--Materials science 
Flight Assignment/Project Notes: NOTE: Extended to 9/15/2019 per NSSC information (Ed., 9/12/18)

 

Task Description: Formation of shrinkage porosity and bubbles during solidification disturbs the dendritic array network and seriously degrades the mechanical properties of castings, whether these are large commercial castings of aluminum or steel alloys or a small directionally solidification single crystal turbine blade. Since in-situ observation of the interaction of pores/bubbles with the primary dendrite array in the mushy zone is not feasible in opaque metal alloys, transparent organic alloys solidifying in narrow gapped rectangular cross-section glass crucibles have been extensively used for such studies. However, all these observations are essentially between bubble and a two-dimensional (2D) array of primary dendrites and are affected by the wall effects. Analytical and numerical modeling of pore formation and migration in mushy zone have also been 2D. Contrary to earlier belief, it is now recognized that the basic premise of such experiments, i.e., 2D dendrites represent morphology of a three-dimensional (3D) array, is false. Understanding pore-mushy zone interaction in real castings requires both the experimental observations and also the theoretical/numerical modeling with 3D array of dendrites.

Pore Formation and Mobility Investigation (PFMI) experiments were conducted in the microgravity environment aboard the Space Station with the intent of better understanding the role entrained porosity/bubbles play on microstructure during controlled directional solidification (DS). Although, the PFMI investigators have qualitatively described some of their observed interactions between the pore and mushy zone, no attempt has been made to analytically or numerically model these observed mushy zone disturbances caused by the presence of bubbles during directional solidification. Purpose of this research is to develop a numerical 3D model which can simulate the pore-mushy zone interaction during directional solidification of Succinonitrile-Water alloys in microgravity and test the simulation results against the PFMI microstructural observations, quantitatively and qualitatively. Several sets of time-temperature-interface-bubble interaction data will be extracted and analyzed from the PFMI videos for this purpose.

In order to achieve this goal, we exploited forefront methods in microscale solidification. We used a methodology based on cellular automaton (CA) and phase field (PF) to determine the interface between phases and lattice Boltzmann (LB) to solve the transport equations and simulate pore formation and its motion during directional solidification. The outcome of the proposed research was an unprecedented tool to numerically simulate the pore-mushy zone interaction during directional solidification in a 3D domain, providing critical information on microstructure response to process parameters. This can impact the design of improved mushy zone models based on the microstructure information obtained from the direct simulation. The developed knowledge advanced the state of understanding of solidification phenomena in the microscale, contributed to improved numerical predictions of porosity formation, and advanced the state of the art in LB methods for simulating transport phenomena. PFMI is the only 3D spatial/temporal observation of pore-mushy zone interactions available to make qualitative/quantitative comparisons with our simulation results as a unique model for large scale simulations of pore-mushy zone interactions with a micro-scale resolution.

 

Research Impact/Earth Benefits: This investigation helped to explain fundamental aspects of the mechanisms that regulate the formation of microporosities. The formation of these defects depends on microstructure features that cannot be properly captured by current meso- and macro-scale models based on averaging techniques. The direct numerical simulation of bubble dynamics in a dendritic network can provide a relation between macroscopically observable variables like cooling rate or temperature gradient and difficult to measure dynamic microscopic features like microporosity distribution, interdendritic permeability, solute redistribution, and dendrite arm spacing. This research not only provided valuable contribution to the understanding of pore-mushy zone interaction during solidification in the absence of gravity, which would be helpful for future in-space fabrication processes involving solidification, but it was a first step to quantitatively simulate such 3D interactions during terrestrial directional solidification in realistic size sample domains. Although much observation has been done in pictures of static microstructures at different stages of solidification, it has never been possible to capture the dynamic response of these features in an evolving mushy zone. This information is critical to assess, validate, and improve macroscale mushy zone models used in current casting and welding codes.

 

Task Progress & Bibliography Information FY2019 
Task Progress: We investigated various enhancements available for the multiphase Lattice Boltzmann (LB) models in order to come up with a reliable scheme to simulate motion and interaction of bubbles during dendritic solidification in binary alloys. The Shan-Chen model, which is the most popular multiphase LB model, was investigated. First, the original Shan-Chen model was studied. A phase separation problem and a contact angle problem were modeled and validated. The interaction of existing bubbles and a dendrite during solidification of a binary alloy was simulated. Although this model can predict the shape of the bubble contacting the solid, it generates a large spurious current. In addition, all of the bubbles tend to merge in an unrealistic manner. Due to the order of magnitude of the spurious current, this model cannot be used to simulate Marangoni effect and natural convection. A realistic equation of state (EOS), middle-range repulsive force, and Exact Difference Method (EDM) force scheme were mixed and implemented to overcome the above-mentioned problems. Although the mixed model reduced the spurious current significantly, the artificial current was still in the same order of magnitude as Marangoni convection. Moreover, the model was unable to reproduce the bubble-dendrite interactions in a meaningful way. By implementing a Phase-Field (PF)-Lattice Boltzmann (LB) model, we eliminated such problems and reduced the spurious current to about 1e-6, which is acceptable. Using the PF-LB model, we simulated bubble-dendrite interactions during directional solidification under Marangoni convection. The results showed that the Marangoni effect tends to remove bubbles from between the dendrites, which favors the growth of more secondary arms as well as a faster growth of the primary arms. Due to the temperature difference at the interface of the bubble and surrounding fluid, Marangoni convection causes fluid flow during solidification. Most of previous works on simulation of bubble-dendrite interactions ignore the Marangoni effect while it can have a significant effect especially in microgravity conditions where natural convection is absent.

The Pore Formation and Mobility Investigation (PFMI) experiments at International Space Station (ISS) have shown that pores and bubbles adhered to the ampoule walls can change the morphology of dendrites and affect the growth kinetics. We used our numerical models to simulate the Marangoni effect and bubble-dendrite interactions during solidification of binary alloys. Effect of Marangoni convection on dendrite growth and bubble-dendrite interactions under microgravity and terrestrial conditions were studied.

A Phase Filed (PF)-Lattice Boltzmann (LB) model was developed to simulate bubble-dendrite interactions. Using the developed model, interaction of growing dendrites with a big bubble attached to a wall was simulated. The bubble diameter was about two times as big as the primary dendrite arm spacing, similar to what is observed in PFMI-15 experiment. The simulation considered Marangoni convection in the absence of gravity. The results showed that the dendrite branch in vicinity of the bubble grow slower compared to the dendrites far from the bubble. Also side branching is enhanced in the vicinity of the bubble.

The thermocapillary flow field associated with a bubble in PFMI-15 experiment was investigated. The flow path was tracked by following miniature dendrite branches that made circular routes from the interface, through the bulk liquid, and back, and showed that a flow field that extended 4.5 mm into the melt had average velocity of ~0.1 mm/s and another one that extended 2.5 mm averaged ~0.4 mm/s. We followed similar tracer dendrite branches as they enter from the melt into the mushy-zone and after traversing certain distance in the mush come back out into the melt. An interesting observation from the PFMI videos was that the tracer dendrite branches invariably accelerated as they approached the solid-liquid interface,

We performed large-scale three-dimensional (3D) simulations of dendrite growth using our LB code and generated the geometries of the dendrites. Then, the results were imported into COMSOL (commercial Finite Element Analysis software) to study the effect of Marangoni convection and formation of flow streams in the presence of bubble. Our simulation results show that, in the presence of the bubble, convection near the S/L interface is stronger and the maximum flow velocity is observed near the bubble/liquid interface. The same trends can be seen in PFMI videos as well. The tracer dendrite branches slow down as they distance from the interface and accelerate on their return. The results also showed that the velocity magnitude is larger in front of the bubble in the case when only Marangoni convection is responsible for convection (micro-gravity conditions). We also performed simulations for terrestrial conditions in which free convection due to gravity was the main factor controlling the flow velocity, while Marangoni effect was not significant.

The fluid velocities simulated in COMSOL were imported back to our 3D LBM model for dendritic growth to investigate the effect of induced Marangoni convection on the morphology of dendrites. We observed that the induced Marangoni convection changes the temperature field. The temperature profile was not linear ahead of dendrite tip; the melt near the bubble had a higher temperature. The Marangoni convection is responsible for the relatively higher temperature near the bubble. Also, the growth rate decreases in the dendrites closer to the bubble.

A 3D Cellular Automaton-Lattice Boltzmann (CA-LB) model was developed to directly investigate the effect of thermocapillary convection induced by bubbles on microstructural evolution during solidification through direct simulations. The large-scale simulations performed with the developed model provided quantitative results about the effects of Marangoni convection on fluid flow, temperature and concentration profiles, growth speed, and orientation of the dendritic microstructure. PFMI experiment and simulation results confirmed that when a large bubble and the solid front are close enough, the induced Marangoni convection can spoil the expected quiescent environment under the microgravity conditions, altering the microstructure. Effect of bubble size was investigated through large-scale simulations of dendrite growth. While no apparent effect on the microstructure was observed for small bubbles, the large bubbles altered the growth rate and tilted the dendrites in the direction of the fluid flow. The simulations provided quantitative information about the effects of Marangoni convection on the microstructure. The results shed light to unexplained observations in the PFMI experiments such as deviation of dendritic array from its original growth direction in the absence of terrestrial convection.

 

Bibliography Type: Description: (Last Updated: 12/24/2019)  Show Cumulative Bibliography Listing
 
Abstracts for Journals and Proceedings Nabavizadeh SA, Eshraghi M, Felicelli SD. "Three-Dimensional Modeling of Bubble-Dendrite Interactions under Microgravity and Terrestrial Conditions." Presented at TMS 2019. 148th Annual Meeting, The Minerals, Metals and Materials Society, San Antonio, TX, March 10-14, 2019.

TMS 2019. 148th Annual Meeting, The Minerals, Metals and Materials Society, San Antonio, TX, March 10-14, 2019. , Mar-2019

Abstracts for Journals and Proceedings Dorari E, Eshraghi M, Felicelli SD. "Buoyancy-Induced Flow Pattern During Dendritic Solidification." Presented at TMS 2019. 148th Annual Meeting, The Minerals, Metals and Materials Society, San Antonio, TX, March 10-14, 2019.

TMS 2019. 148th Annual Meeting, The Minerals, Metals and Materials Society, San Antonio, TX, March 10-14, 2019. , Mar-2019

Abstracts for Journals and Proceedings Nabavizadeh SA, Eshraghi M, Felicelli SD. "Modeling the Effects of Bubble Dynamics on Dendrite Growth During Solidification of Binary Alloys." Presented at the MS&T (Materials Science & Technology Conference & Exhibition) Conference 2018, October 14-18, 2018. .

MS&T (Materials Science & Technology Conference & Exhibition) Conference 2018, October 14-18, 2018. , Oct-2018

Articles in Peer-reviewed Journals Lenart R, Eshraghi M. "Modeling columnar to equiaxed transition in directional solidification of Inconel 718 alloy." Computational Materials Science. 2020 Feb 1;172:109374. https://doi.org/10.1016/j.commatsci.2019.109374 , Feb-2020
Articles in Peer-reviewed Journals Nabavizadeh SA, Eshraghi M, Felicelli SD. "A comparative study of multiphase lattice Boltzmann methods for bubble-dendrite interaction during solidification of alloys." Applied Sciences. 2019;9(1):57. Published: 24 December 2018. https://doi.org/10.3390/app9010057 , Jan-2019
Articles in Peer-reviewed Journals Nabavizadeh SA, Eshraghi M, Felicelli SD, Tewari SN, Grugel RN. "Effect of bubble-induced Marangoni convection on dendritic solidification." International Journal of Multiphase Flow. 2019 Jul;116:137-52. https://doi.org/10.1016/j.ijmultiphaseflow.2019.04.018 , Jul-2019
Articles in Peer-reviewed Journals Nabavizadeh SA, Eshraghi M, Felicelli SD, Tewari SN, Grugel RN. "The Marangoni convection effects on directional dendritic solidification." Heat and Mass Transfer. First online 09 December 2019. https://doi.org/10.1007/s00231-019-02799-4 , Dec-2019
Books/Book Chapters Eshraghi M, Felicelli, SD. "Advances in Understanding the Kinetics of Solidification: Modeling Microstructural Evolution." in "Manufacturing Techniques for Materials: Engineering and Engineered, Advances, and Applications." Ed. T.S. Srivatsan, T.S. Sudarshan, K. Manigandan. Boca Raton, FL: CRC Press, 2018. ISBN 9781315104133, Apr-2018
Dissertations and Theses Dorari E. "Modeling Dendritic Solidification Under Melt Convection Using Lattice Boltzmann and Cellular Automaton Methods." Ph.D Dissertation, The University of Akron, July 2019. , Jul-2019
Dissertations and Theses Lenart R. "A Phase Field - Lattice Boltzmann Model for Predicting Solidification Microstructure." Master’s Thesis, California State University, Los Angeles, June 2019. , Jun-2019
Dissertations and Theses Nabavizadeh SA. "Modeling Bubble-Dendrite Interactions During Alloy Solidification." Ph.D. Dissertation, The University of Akron, to be completed in 2020. , Dec-2020
Project Title:  Pore-Mushy Zone Interaction during Directional Solidification of Alloys: Three Dimensional Simulation and Comparison with Experiments Reduce
Images: icon  Fiscal Year: FY 2018 
Division: Physical Sciences 
Research Discipline/Element:
MATERIALS SCIENCE--Materials science 
Start Date: 09/16/2016  
End Date: 09/15/2019  
Task Last Updated: 09/05/2018 
Download report in PDF pdf
Principal Investigator/Affiliation:   Eshraghi, Mohsen  Ph.D. / California State University, Los Angeles 
Address:  Department of Mechanical Engineering 
5151 State University Dr 
Los Angeles , CA 90032-4226 
Email: meshrag@calstatela.edu 
Phone: 323-343-5218  
Congressional District: 34 
Web:  
Organization Type: UNIVERSITY 
Organization Name: California State University, Los Angeles 
Comments:  
Co-Investigator(s)
Affiliation: 
Tewari, Surendra  Ph.D. Cleveland State University 
Felicelli, Sergio  Ph.D. University of Akron 
Project Information: Grant/Contract No. NNX16AT75G 
Responsible Center: NASA MSFC 
Grant Monitor: Rogers, Jan  
Center Contact: 256.544.1081 
jan.r.rogers@nasa.gov 
Solicitation: 2015 Physical Sciences NNH15ZTT001N-15PSI-B: Use of the NASA Physical Sciences Informatics System – Appendix B 
Grant/Contract No.: NNX16AT75G 
Project Type: GROUND 
TechPort: No 
No. of Post Docs:  
No. of PhD Candidates:
No. of Master's Candidates:
No. of Bachelor's Candidates:
No. of PhD Degrees:  
No. of Master's Degrees:
No. of Bachelor's Degrees:
Program--Element: MATERIALS SCIENCE--Materials science 
Flight Assignment/Project Notes: NOTE: Extended to 9/15/2019 per NSSC information (Ed., 9/12/18)

 

Task Description: Formation of shrinkage porosity and bubbles during solidification disturbs the dendritic array network and seriously degrades the mechanical properties of castings, whether these are large commercial castings of aluminum or steel alloys or a small directionally solidification single crystal turbine blade. Since in-situ observation of the interaction of pores/bubbles with the primary dendrite array in the mushy zone is not feasible in opaque metal alloys, transparent organic alloys solidifying in narrow gapped rectangular cross-section glass crucibles have been extensively used for such studies. However, all these observations are essentially between bubble and a two-dimensional (2D) array of primary dendrites and are affected by the wall effects. Analytical and numerical modeling of pore formation and migration in mushy zone have also been 2D. Contrary to earlier belief, it is now recognized that the basic premise of such experiments, i.e., 2D dendrites represent morphology of a three-dimensional (3D) array, is false. Understanding pore-mushy zone interaction in real castings requires both the experimental observations and also the theoretical/numerical modeling with 3D array of dendrites.

Pore Formation and Mobility Investigation (PFMI) experiments were conducted in the microgravity environment aboard the Space Station with the intent of better understanding the role entrained porosity/bubbles play on microstructure during controlled directional solidification (DS). Although, the PFMI investigators have qualitatively described some of their observed interactions between the pore and mushy zone, no attempt has been made to analytically or numerically model these observed mushy zone disturbances caused by the presence of bubbles during directional solidification.

Purpose of this research is to develop a numerical 3D model which can simulate the pore-mushy zone interaction during directional solidification of Succinonitrile-Water alloys in microgravity and test the simulation results against the PFMI microstructural observations, quantitatively and qualitatively. Several sets of time-temperature-interface-bubble interaction data will be extracted and analyzed from the PFMI videos for this purpose.

In order to achieve this goal, we will exploit forefront methods in microscale solidification. We propose a methodology based on cellular automaton (CA) to track the interface and Lattice Boltzmann (LB) to solve the transport equations and simulate pore formation and its motion during directional solidification. The outcome of the proposed research will be an unprecedented tool to numerically simulate the pore-mushy zone interaction during directional solidification in a 3D domain, providing critical information on microstructure response to process parameters. This will have a huge impact on the design of improved mushy zone models based on the microstructure information obtained from the direct simulation. The developed knowledge will advance the state of understanding of solidification phenomena in the microscale, will contribute to improved numerical predictions of porosity formation, and will advance the state of the art in LB methods for simulating transport phenomena. PFMI is the only 3D spatial/temporal observation of pore-mushy zone interactions available to make qualitative/quantitative comparisons with our 3D LB-CA results as a unique model for large scale simulations of pore-mushy zone interactions with a micro-scale resolution.

 

Research Impact/Earth Benefits: This investigation will help explain fundamental aspects of the mechanisms that regulate the formation of microporosities. The formation of these defects depends on microstructure features that cannot be properly captured by current meso- and macro-scale models based on averaging techniques. The direct numerical simulation of bubble dynamics in a dendritic network will provide a relation between macroscopically observable variables like cooling rate or temperature gradient and difficult to measure dynamic microscopic features like microporosity distribution, interdendritic permeability, solute redistribution, and dendrite arm spacing. It is expected that this research will not only provide valuable contribution to the understanding of pore-mushy zone interaction during solidification in the absence of gravity, which would be helpful for future in-space fabrication processes involving solidification, but it will be a crucial first step to quantitatively simulate such 3D interactions during terrestrial directional solidification in realistic size sample domains. Although much observation has been done in pictures of static microstructures at different stages of solidification, it has never been possible to capture the dynamic response of these features in an evolving mushy zone. This information is critical to assess, validate, and improve macroscale mushy zone models used in current casting and welding codes.

 

Task Progress & Bibliography Information FY2018 
Task Progress: Due to the temperature difference at the interface of the bubble and surrounding fluid, Marangoni convection causes fluid flow during solidification. Most of previous works on simulation of bubble-dendrite interactions ignore the Marangoni effect while it can have a significant effect especially in microgravity conditions where natural convection is absent. The Pore Formation and Mobility Investigation (PFMI) experiments at International Space Station (ISS) have shown that pores and bubbles adhered to the ampoule walls can change the morphology of dendrites and affect the growth kinetics. We used our numerical models to simulate the Marangoni effect and bubble-dendrite interactions during solidification of binary alloys. Effect of Marangoni convection on dendrite growth and bubble-dendrite interactions under microgravity and terrestrial conditions were studied.

A Phase Filed (PF)-Lattice Boltzmann (LB) model was developed to simulate in bubble-dendrite interactions. Using the developed model, interaction of growing dendrites with a big bubble attached to a wall was simulated. The bubble diameter was about two times as big as the primary dendrite arm spacing, similar to what is observed in PFMI-15 experiment. The simulation considered Marangoni convection in the absence of gravity. The results showed that the dendrite branch in vicinity of the bubble grow slower compared to the dendrites far from the bubble. Also side branching is enhanced in the vicinity of the bubble.

Two dimensional (2D) models are usually unable to capture all features of microstructures that are determinative in many materials properties, especially when fluid flow is involved. It is known that melt flow can significantly alter the growth kinetics by affecting solutal gradient around the dendrites, and moving the bubbles. While melt convection is blocked by dendrite arms in 2D simulations, flow can go around the 3D arms which results in a different bubble distribution and dendritic morphology. Studies have shown that the growth of dendrites in 3D is considerably different from 2D. Therefore, in order to obtain correct physical results, it is necessary to perform the simulations in 3D.

The thermocapillary flow field associated with a bubble in PFMI-15 experiment was investigated. The flow path was tracked by following miniature detached dendrite branches that made circular routes from the interface, through the bulk liquid, and back, and showed that a flow field which extended 4.5 mm into the melt had average velocity of ~0.1 mm/s and another one that extended 2.5 mm averaged ~0.4 mm/s. We followed similar tracer dendrite branches as they enter from the melt into the mushy-zone and after traversing certain distance in the mush come back out into the melt. This observation showed that the flow speed in the mushy region is higher than that in the bulk melt, which was puzzling and was considered for our numerical simulations. Another interesting observation from the PFMI videos was that the tracer dendrite branches invariably accelerated as they approached the solid/liquid (S/L) interface.

We performed large-scale three-dimensional (3D) simulations of dendrite growth using our LB code and generates the geometries of the dendrites. Then, the results were imported into COMSOL (commercial Finite Element Analysis software) to study the effect of Marangoni convection and formation of flow streams in the presence of bubble. Our simulation results show that, in the presence of the bubble, convection near the S/L interface is stronger and the maximum flow velocity is observed near the bubble/liquid interface. The same trends can be seen in PFMI videos as well. The tracer dendrite branches slow down as they distance from the interface and accelerate on their return. The results also showed that the velocity magnitude is larger in front of the bubble in the case when only Marangoni convection is responsible for convection (micro-gravity conditions). We also performed simulations for terrestrial conditions in which free convection due to gravity was the main factor controlling the flow velocity, while Marangoni effect was not significant.

The fluid velocities simulated in COMSOL were imported back to our 3D LBM model for dendritic growth to investigate the effect of induced Marangoni convection on the morphology of dendrites. We observed that the induced Marangoni convection changes the temperature field. The temperature profile was not linear ahead of dendrite tip; the melt near the bubble had a higher temperature. The Marangoni convection is responsible for the relatively higher temperature near the bubble. Also, the growth rate decreases in the dendrites closer to the bubble.

 

Bibliography Type: Description: (Last Updated: 12/24/2019)  Show Cumulative Bibliography Listing
 
Abstracts for Journals and Proceedings Lenart R, Eshraghi M, Felicelli SD. "Modeling Dendritic Solidification in Microgravity and Terrestrial Conditions." TMS 2018. 147th Annual Meeting,The Minerals, Metals and Materials Society, Phoenix, AZ, March 11-15, 2018.

TMS 2018. 147th Annual Meeting, The Minerals, Metals and Materials Society, Phoenix, AZ, March 11-15, 2018. http://www.programmaster.org/PM/PM.nsf/ApprovedAbstracts/2227C45F068F04B58525814F0069B533?OpenDocument ; accesed 9/12/18. , Mar-2018

Abstracts for Journals and Proceedings Dorari E, Eshraghi M, Felicelli SD. "A Lattice Boltzmann Model with Multiple Grids and Time Steps for Dendritic Solidification." TMS 2018. 147th Annual Meeting,The Minerals, Metals and Materials Society, Phoenix, AZ, March 11-15, 2018.

TMS 2018. 147th Annual Meeting,The Minerals, Metals and Materials Society, Phoenix, AZ, March 11-15, 2018. http://www.programmaster.org/PM/PM.nsf/ApprovedAbstracts/7B273D2B32519A748525814D007BBB36?OpenDocument ; accessed 9/12/18. , Mar-2018

Abstracts for Journals and Proceedings Dorari E, Eshraghi M, Felicelli SD. "Simulation of Dendritic Solidification Using Multiple-Grid Lattice Boltzmann Model." Presentation at ASME 2017 International Mechanical Engineering Congress and Exposition, Tampa, Florida, November 3–9, 2017.

ASME 2017 International Mechanical Engineering Congress and Exposition, Tampa, Florida, November 3–9, 2017. , Nov-2017

Abstracts for Journals and Proceedings Nabavizadeh SA, Eshraghi M, Felicelli SD, Tewari SN. "Marangoni Effects on Bubble-Dendrite Interactions Under Microgravity and Terrestrial Conditions." 33rd Annual Meeting of the American Society for Gravitational and Space Research, Seattle, WA, October 25-28, 2017.

33rd Annual Meeting of the American Society for Gravitational and Space Research, Seattle, WA, October 25-28, 2017. , Oct-2017

Abstracts for Journals and Proceedings Nabavizadeh SA, Eshraghi M, Felicelli SD. "A Phase-Field Lattice Boltzmann Model for Bubble-Dendrite Interaction During Solidification of Binary Alloys." TMS 2018. 147th Annual Meeting, The Minerals, Metals and Materials Society, Phoenix, AZ, March 11-15, 2018.

TMS 2018. 147th Annual Meeting, The Minerals, Metals and Materials Society, Phoenix, AZ, March 11-15, 2018. http://www.programmaster.org/PM/PM.nsf/ApprovedAbstracts/9F686A7810F5FFBF8525814F000C07A4?OpenDocument ; accessed 9/12/18. , Mar-2018

Articles in Peer-reviewed Journals Dorari E, Eshraghi M, Felicelli SD. "A multiple-grid-time-step lattice Boltzmann method for transport phenomena with dissimilar time scales: Application in dendritic solidification." Applied Mathematical Modelling. 2018 Oct;62:580-94. https://doi.org/10.1016/j.apm.2018.06.023 , Oct-2018
Dissertations and Theses Upadhyay SR. (Supriya R. Upadhyay) "Spurious Grain Formation during Directional Solidification in Microgravity." Master’s Thesis, Cleveland State University, May 2018. , May-2018
Papers from Meeting Proceedings Nabavizadeh SA, Eshraghi M, Felicelli SD. "Feasibility Study of Different Pseudopotential Multiphase Lattice Boltzmann Methods for Dendritic Solidification." ASME 2017 International Mechanical Engineering Congress and Exposition, Tampa, Florida, November 3–9, 2017.

In: ASME 2017 International Mechanical Engineering Congress and Exposition. Volume 14: Emerging Technologies; Materials: Genetics to Structures; Safety Engineering and Risk Analysis, Tampa, Florida, USA, November 3–9, 2017. Paper No. IMECE2017-71019, V014T11A033; 7 pages. https://doi.org/10.1115/IMECE2017-71019 , Nov-2017

Project Title:  Pore-Mushy Zone Interaction during Directional Solidification of Alloys: Three Dimensional Simulation and Comparison with Experiments Reduce
Images: icon  Fiscal Year: FY 2017 
Division: Physical Sciences 
Research Discipline/Element:
MATERIALS SCIENCE--Materials science 
Start Date: 09/16/2016  
End Date: 09/15/2018  
Task Last Updated: 07/18/2017 
Download report in PDF pdf
Principal Investigator/Affiliation:   Eshraghi, Mohsen  Ph.D. / California State University, Los Angeles 
Address:  Department of Mechanical Engineering 
5151 State University Dr 
Los Angeles , CA 90032-4226 
Email: meshrag@calstatela.edu 
Phone: 323-343-5218  
Congressional District: 34 
Web:  
Organization Type: UNIVERSITY 
Organization Name: California State University, Los Angeles 
Comments:  
Co-Investigator(s)
Affiliation: 
Tewari, Surendra  Ph.D. Cleveland State University 
Felicelli, Sergio  Ph.D. University of Akron 
Project Information: Grant/Contract No. NNX16AT75G 
Responsible Center: NASA MSFC 
Grant Monitor: Rogers, Jan  
Center Contact: 256.544.1081 
jan.r.rogers@nasa.gov 
Solicitation: 2015 Physical Sciences NNH15ZTT001N-15PSI-B: Use of the NASA Physical Sciences Informatics System – Appendix B 
Grant/Contract No.: NNX16AT75G 
Project Type: GROUND 
TechPort: No 
No. of Post Docs:  
No. of PhD Candidates:
No. of Master's Candidates:
No. of Bachelor's Candidates:
No. of PhD Degrees:  
No. of Master's Degrees:  
No. of Bachelor's Degrees:
Program--Element: MATERIALS SCIENCE--Materials science 
Task Description: Formation of shrinkage porosity and bubbles during solidification disturbs the dendritic array network and seriously degrades the mechanical properties of castings, whether these are large commercial castings of aluminum or steel alloys or a small directionally solidification single crystal turbine blade. Since in-situ observation of the interaction of pores/bubbles with the primary dendrite array in the mushy zone is not feasible in opaque metal alloys, transparent organic alloys solidifying in narrow gapped rectangular cross-section glass crucibles have been extensively used for such studies. However, all these observations are essentially between bubble and a two-dimensional (2D) array of primary dendrites and are affected by the wall effects. Analytical and numerical modeling of pore formation and migration in mushy zone have also been 2D. Contrary to earlier belief, it is now recognized that the basic premise of such experiments, i.e., 2D dendrites represent morphology of a three-dimensional (3D) array, is false. Understanding pore-mushy zone interaction in real castings requires both the experimental observations and also the theoretical/numerical modeling with 3D array of dendrites.

Pore Formation and Mobility Investigation (PFMI) experiments were conducted in the microgravity environment aboard the Space Station with the intent of better understanding the role entrained porosity/bubbles play on microstructure during controlled directional solidification (DS). Although, the PFMI investigators have qualitatively described some of their observed interactions between the pore and mushy zone, no attempt has been made to analytically or numerically model these observed mushy zone disturbances caused by the presence of bubbles during directional solidification.

Purpose of this research is to develop a numerical 3D model which can simulate the pore-mushy zone interaction during directional solidification of Succinonitrile-Water alloys in microgravity and test the simulation results against the PFMI microstructural observations, quantitatively and qualitatively. Several sets of time-temperature-interface-bubble interaction data will be extracted and analyzed from the PFMI videos for this purpose.

In order to achieve this goal, we will exploit forefront methods in microscale solidification. We propose a methodology based on cellular automaton (CA) to track the interface and Lattice Boltzmann (LB) to solve the transport equations and simulate pore formation and its motion during directional solidification. The outcome of the proposed research will be an unprecedented tool to numerically simulate the pore-mushy zone interaction during directional solidification in a 3D domain, providing critical information on microstructure response to process parameters. This will have a huge impact on the design of improved mushy zone models based on the microstructure information obtained from the direct simulation. The developed knowledge will advance the state of understanding of solidification phenomena in the microscale, will contribute to improved numerical predictions of porosity formation, and will advance the state of the art in LB methods for simulating transport phenomena. PFMI is the only 3D spatial/temporal observation of pore-mushy zone interactions available to make qualitative/quantitative comparisons with our 3D LB-CA results as a unique model for large scale simulations of pore-mushy zone interactions with a micro-scale resolution.

 

Research Impact/Earth Benefits: This investigation will help explain fundamental aspects of the mechanisms that regulate the formation of microporosities. The formation of these defects depends on microstructure features that cannot be properly captured by current meso- and macro-scale models based on averaging techniques. The direct numerical simulation of bubble dynamics in a dendritic network will provide a relation between macroscopically observable variables like cooling rate or temperature gradient and difficult to measure dynamic microscopic features like microporosity distribution, interdendritic permeability, solute redistribution, and dendrite arm spacing. It is expected that this research will not only provide valuable contribution to the understanding of pore-mushy zone interaction during solidification in the absence of gravity, which would be helpful for future in-space fabrication processes involving solidification, but it will be a crucial first step to quantitatively simulate such 3D interactions during terrestrial directional solidification in realistic size sample domains. Although much observation has been done in pictures of static microstructures at different stages of solidification, it has never been possible to capture the dynamic response of these features in an evolving mushy zone. This information is critical to assess, validate, and improve macroscale mushy zone models used in current casting and welding codes.

 

Task Progress & Bibliography Information FY2017 
Task Progress: We investigated various enhancements available for the multiphase Lattice Boltzmann (LB) models in order to come up with a reliable scheme to simulate motion and interaction of bubbles during dendritic solidification in binary alloys. The Shan-Chen model, which is the most popular multiphase LB model, was investigated. First, the original Shan-Chen model was studied. A phase separation problem and a contact angle problem were modeled and validated. The interaction of existing bubbles and a dendrite during solidification of a binary alloy was simulated. Although this model can predict the shape of the bubble contacting the solid, it generates a large spurious current. In addition, all of the bubbles tend to merge in an unrealistic manner. Due to the order of magnitude of the spurious current, this model cannot be used to simulate Marangoni effect and natural convection.

A realistic equation of state (EOS), middle-range repulsive force, and Exact Difference Method (EDM) force scheme were mixed and implemented to overcome the above-mentioned problems. Although the mixed model reduced the spurious current significantly, the artificial current was still in the same order of magnitude as Marangoni convection. Moreover, the model was unable to reproduce the bubble-dendrite interactions in a meaningful way.

By implementing a Phase-Field (PF)-Lattice Boltzmann (LB) model we eliminated such problems and reduced the spurious current to about 1e-6, which is acceptable. Using the PF-LB model, we simulated bubble-dendrite interactions during directional solidification under Marangoni convection. The results showed that the Marangoni effect tends to remove bubbles from between the dendrites, which favors the growth of more secondary arms as well as a faster growth of the primary arms.

In order to provide a stable and computationally efficient approach, we are developing multiple-time-step and multiple-grid LB techniques to model the transport phenomena during solidification. To validate our basic dendrite growth model, we measured the dendrite tip growth speed from the PFMI15 test results. The results will be used to verify if our simulation results are in reasonable agreement with the observed behavior.

 

Bibliography Type: Description: (Last Updated: 12/24/2019)  Show Cumulative Bibliography Listing
 
 None in FY 2017
Project Title:  Pore-Mushy Zone Interaction during Directional Solidification of Alloys: Three Dimensional Simulation and Comparison with Experiments Reduce
Images: icon  Fiscal Year: FY 2016 
Division: Physical Sciences 
Research Discipline/Element:
MATERIALS SCIENCE--Materials science 
Start Date: 09/16/2016  
End Date: 09/15/2018  
Task Last Updated: 10/19/2016 
Download report in PDF pdf
Principal Investigator/Affiliation:   Eshraghi, Mohsen  Ph.D. / California State University, Los Angeles 
Address:  Department of Mechanical Engineering 
5151 State University Dr 
Los Angeles , CA 90032-4226 
Email: meshrag@calstatela.edu 
Phone: 323-343-5218  
Congressional District: 34 
Web:  
Organization Type: UNIVERSITY 
Organization Name: California State University, Los Angeles 
Comments:  
Co-Investigator(s)
Affiliation: 
Tewari, Surendra  Ph.D. Cleveland State University 
Felicelli, Sergio  Ph.D. University of Akron 
Project Information: Grant/Contract No. NNX16AT75G 
Responsible Center: NASA MSFC 
Grant Monitor: Rogers, Jan  
Center Contact: 256.544.1081 
jan.r.rogers@nasa.gov 
Solicitation: 2015 Physical Sciences NNH15ZTT001N-15PSI-B: Use of the NASA Physical Sciences Informatics System – Appendix B 
Grant/Contract No.: NNX16AT75G 
Project Type: GROUND 
TechPort: No 
No. of Post Docs:  
No. of PhD Candidates:  
No. of Master's Candidates:  
No. of Bachelor's Candidates:  
No. of PhD Degrees:  
No. of Master's Degrees:  
No. of Bachelor's Degrees:  
Program--Element: MATERIALS SCIENCE--Materials science 
Task Description: Formation of shrinkage porosity and bubbles during solidification disturbs the dendritic array network and seriously degrades the mechanical properties of castings, whether these are large commercial castings of aluminum or steel alloys or a small directionally solidification single crystal turbine blade. Since in-situ observation of the interaction of pores/bubbles with the primary dendrite array in the mushy zone is not feasible in opaque metal alloys, transparent organic alloys solidifying in narrow gapped rectangular cross-section glass crucibles have been extensively used for such studies. However, all these observations are essentially between bubble and a two-dimensional (2D) array of primary dendrites and are affected by the wall effects. Analytical and numerical modeling of pore formation and migration in mushy zone have also been 2D. Contrary to earlier belief, it is now recognized that the basic premise of such experiments, i.e., 2D dendrites represent morphology of a three-dimensional (3D) array, is false. Understanding pore-mushy zone interaction in real castings requires both the experimental observations and also the theoretical/numerical modeling with 3D array of dendrites.

Pore Formation and Mobility Investigation (PFMI) experiments were conducted in the microgravity environment aboard the Space Station with the intent of better understanding the role entrained porosity/bubbles play on microstructure during controlled directional solidification (DS). Although, the PFMI investigators have qualitatively described some of their observed interactions between the pore and mushy zone, no attempt has been made to analytically or numerically model these observed mushy zone disturbances caused by the presence of bubbles during directional solidification.

Purpose of this research is to develop a numerical 3D model which can simulate the pore-mushy zone interaction during directional solidification of Succinonitrile-Water alloys in microgravity and test the simulation results against the PFMI microstructural observations, quantitatively and qualitatively. Several sets of time-temperature-interface-bubble interaction data will be extracted and analyzed from the PFMI videos for this purpose.

In order to achieve this goal, we will exploit forefront methods in microscale solidification. We propose a methodology based on cellular automaton (CA) to track the interface and Lattice Boltzmann (LB) to solve the transport equations and simulate pore formation and its motion during directional solidification. The outcome of the proposed research will be an unprecedented tool to numerically simulate the pore-mushy zone interaction during directional solidification in a 3D domain, providing critical information on microstructure response to process parameters. This will have a huge impact on the design of improved mushy zone models based on the microstructure information obtained from the direct simulation. The developed knowledge will advance the state of understanding of solidification phenomena in the microscale, will contribute to improved numerical predictions of porosity formation, and will advance the state of the art in LB methods for simulating transport phenomena. PFMI is the only 3D spatial/temporal observation of pore-mushy zone interactions available to make qualitative/quantitative comparisons with our 3D LB-CA results as a unique model for large scale simulations of pore-mushy zone interactions with a micro-scale resolution.

It is expected that this research will not only provide valuable contribution to the understanding of pore-mushy zone interaction during solidification in the absence of gravity, which would be helpful for future in-space fabrication processes involving solidification, but it will be a crucial first step to quantitatively simulate such 3D interactions during terrestrial DS in realistic size sample domains.

 

Research Impact/Earth Benefits: It is expected that this research will not only provide valuable contribution to the understanding of pore-mushy zone interaction during solidification in the absence of gravity, which would be helpful for future in-space fabrication processes involving solidification, but it will be a crucial first step to quantitatively simulate such 3D interactions during terrestrial DS in realistic size sample domains.

 

Task Progress & Bibliography Information FY2016 
Task Progress: New project for FY2016.

 

Bibliography Type: Description: (Last Updated: 12/24/2019)  Show Cumulative Bibliography Listing
 
 None in FY 2016