Application of alloy solidification theory to cellular automata modeling of near-rapid constrained solidification

M. R. Rolchigo, R. LeSar

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

To utilize the full potential of additive manufacturing routes for metallic part production, understanding how microstructure and texture develop as functions of alloying additions and process conditions is critical. Use of cellular automata (CA) with alloy solidification theory can provide a useful augmentation to experimental microstructure observations, as it can accurately and efficiently reproduce nucleation and growth of cubic crystal structures common to binary and ternary alloy solidification. We apply CA to model constrained solidification under thermal gradient magnitudes and solidification velocities representative of those commonly encountered along the melt pool boundary in Laser Engineered Net Shaping (LENS®), a specific alloy-based additive process. Various sets of alloying elements, quantities, and nucleation parameters are used to show the model's ability to predict realistic trends in nucleation and growth of single phase β-Ti alloys. 2D and 3D model implementations are qualitatively and quantitatively compared, and alloy composition (element and quantity) is shown to play a critical role on the columnar to equiaxed transition (CET) through changes to the interfacial response function. Simulation results are further used to define a parameter that correlates with the CET over a range of imposed conditions, linking alloy solidification theory to the CA prediction of microstructure. This CA model can serve as a useful tool when designing sets of alloying additions that would produce given microstructures, while coupled application of this CA to process scale simulations of additive process temperature fields will facilitate design of both specific alloy compositions and sets of process conditions for microstructure control.

Original languageEnglish
Pages (from-to)148-161
Number of pages14
JournalComputational Materials Science
Volume163
DOIs
StatePublished - Jun 1 2019
Externally publishedYes

Funding

The authors gratefully acknowledge the support of the National Science Foundation for this collaborative DMREF program (DMREF-1434462), in which an MGI strategy is adopted. The authors also acknowledge the engagement of industrial partners through the Center for Advanced Non-Ferrous Structural Alloys (CANFSA), an NSF Industry/University Cooperative Research Center (I/UCRC) between Iowa State University and the Colorado School of Mines. MRR would also like to thank James Belak and associated colleagues at Lawrence Livermore National Lab for productive discussion regarding solidification modeling and the opportunity to participate in the lab’s summer internship program. The authors gratefully acknowledge the support of the National Science Foundation for this collaborative DMREF program (DMREF-1434462), in which an MGI strategy is adopted. The authors also acknowledge the engagement of industrial partners through the Center for Advanced Non-Ferrous Structural Alloys (CANFSA), an NSF Industry/University Cooperative Research Center (I/UCRC) between Iowa State University and the Colorado School of Mines. MRR would also like to thank James Belak and associated colleagues at Lawrence Livermore National Lab for productive discussion regarding solidification modeling and the opportunity to participate in the lab's summer internship program.

FundersFunder number
NSF Industry/University Cooperative Research Center
National Science FoundationDMREF-1434462
Colorado School of Mines
Iowa State University
National Science Foundation

    Keywords

    • Additive manufacturing
    • Alloy design
    • Alloy solidification
    • Cellular automata
    • Grain growth
    • Nucleation

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