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Marshall Space Flight Center Projects
  Dynamic Selection of Three-Dimensional Interface Patterns in Directional Solidification
   
  • DSIPUnderstanding of dendrite evolution has been dramatically increased by microgravity experiments, principally in undercooled pure materials.
  • Understand the dynamics that lead to uniform and reproducible three-dimensional pattern formation in materials, particularly alloys
  • Obtain benchmark data required for establishing the detailed dynamics of interface pattern selection during the solidification of alloys.
  • A fundamental understanding of interface dynamics is central to tailor microstructures to optimize materials properties.

pdf icon Dynamic Selection of Three-Dimensional Interface Patterns in Directional Solidification Quad Chart



Microstructure Formation in Castings of Technical Alloys under Diffusive and Magnetically-Controlled Convective Conditions (MICAST)
   
  • MICASTDefects in directionally solidified dendritic alloys result in production losses.
    Misalignment of dendrite arms and macrosegregation are produced by
    uncontrolled convection.
  • NASA’s interest is in enhancing the mathematical modeling of solidification with
    global objectives.
  • A specific objective is the simulation of solidification in castings of changing
    cross section.

 

pdf icon Microstructure Formation in Castings of Technical Alloys under Diffusive and Magnetically-Controlled Convective Conditions (MICAST) Quad Chart



Crystal Growth of Ternary Compound Semiconductors (GTS)
   
  • GTSIn crystal growth there is a need to understand the relation between processes in the fluid phase, both liquid and vapor, such as buoyancy driven convection, the incorporation of impurities, and defects in the resulting crystal.
  • Relation between fluid phase processes and the generation of defects in a grown crystal is an outstanding problem in materials growth.
  • Studies in microgravity will be compared with modeling and will be used to optimize ground-based experiments.

pdf icon Crystal Growth of Ternary Compound Semiconductors (GTS) Quad Chart



  Quasi-Crystalline Undercooled Alloys for Space Investigation (QUASI)
   
  • QUASIDetermine the influence of liquid and solid short-range order on the nucleation barrier
  • Determination the composition dependence of nucleation rate and evaluate a new coupled flux model for nucleation
  • Correlate the nucleation kinetics with the local structure of the liquids
  • Correlate the local structure with containerless measurements of thermophysical properties
  • Determine changes in the growth rate of the solid as a function of the complexity of the solid phase

pdf icon Quasi-Crystalline Undercooled Alloys for Space Investigation (QUASI) Quad Chart



Reduction of Defects in Germanium Silicon (RDGS)
   
  • RDGSPartially detached crystals can be grown on Earth
  • Test the theory that solidification free of wall contact reduces defect density
  • Evaluate competing theories for the production of critical materials by testing different growth configurations and using the space environment


 

pdf icon Reduction of Defects in Germanium Silicon (RDGS) Quad Chart



The Role of Convection and Growth Competition in Phase Selection in Microgravity (LODESTARS)
   
  • LODESTARComplex stainless steels can form a metastable dendritic ferrite phase, prior to the formation of the stable austenite phase
  • Determine governing factors behind kinetics of transformation in these commercially relevant structural materials
  • Determine the effects of fluid flow in nucleation of the second phase, within the meta-stable phase in the mushy zone
  • Correlate the local structure with containerless measurements of thermophysical properties

pdf icon The Role of Convection and Growth Competition in Phase Selection in Microgravity Quad Chart



     
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 Interntional Space Station
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Advanced Capabilities Division Research & Technology task Book  
 
 
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