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Packing of sedimenting equiaxed dendrites
Antonio Olmedilla1, Miha Založnik1, Bernard Rouat1
1Institut Jean Lamour, CNRS, Université de Lorraine, Nancy, France.
Physical Review. E
|February 17, 2018
Summary
Crystal grain packing during solidification impacts material structure. This study uses simulations and experiments to link grain shape and hydrodynamics to packing fraction in metal alloys.
Area of Science:
- Materials Science
- Physics
- Fluid Dynamics
Background:
- Grain packing during solidification significantly influences phase-change, material structure, and defect formation.
- Dendritic grain morphology and low inertia (due to small solid-liquid density differences) affect packing fraction.
- Experimental investigation of grain packing during metal alloy solidification is challenging due to coupled phenomena.
Purpose of the Study:
- To investigate the packing of equiaxed dendrites in a model system.
- To understand the influence of grain morphology and hydrodynamic conditions on packing fraction.
- To establish a relationship between packing fraction and key parameters in a system mimicking metal alloy solidification.
Main Methods:
- Utilized a model system of fixed-shape, nonconvex particles undergoing sedimentation.
- Employed numerical simulations using a discrete-element model.
- Conducted experiments using transparent liquids in a sedimentation column.
- Matched hydrodynamic conditions to those in solidifying metals using particle Stokes number.
Main Results:
- Determined the packing fraction of model dendrites.
- Quantified the impact of grain morphology (shape parameter) on packing fraction.
- Quantified the impact of hydrodynamic conditions (Stokes number) on packing fraction.
- Established a combined relationship between packing fraction, morphology, and hydrodynamics.
Conclusions:
- The packing fraction of equiaxed dendrites is controllable by grain morphology and hydrodynamic conditions.
- The model system effectively replicates key aspects of metal alloy solidification packing.
- This combined experimental and simulation approach provides a viable method for studying complex solidification phenomena.
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