Vacancy supersaturation in rapidly solidified metal droplets

Journal Article · Wed May 15 04:00:00 EDT 1991 · Physical Review, A; (USA)

DOI:https://doi.org/10.1103/PhysRevA.43.5344· OSTI ID:5461961

Van Siclen, C D ^[1]; Wolfer, W G ^[2]

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1. Idaho National Engineering Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415 (USA)
2. Sandia National Laboratories, P.O. Box 969, Livermore, California 94550 (USA)

A self-consistent theory for vacancy entrapment in rapidly solidified metal droplets is presented. Supersaturation occurs when excess (nonequilibrium) vacancies created at the solidification front by the liquid-solid density difference are unable to diffuse back to the interface before the droplet solidifies. The model consists of heat-conduction equations for the liquid and solid phases, a vacancy-diffusion equation, and boundary conditions at the internal and external surfaces that provide coupling between regions and generate the interface dynamics and vacancy entrapment. Solutions to this system of equations are derived in the form of a set of integral equations that incorporate the boundary conditions as integral kernels. These are evaluated numerically to produce temperature and vacancy-concentration profiles for rapidly solidified droplets of various sizes, initial undercoolings, and convective cooling rates. For undercooled, micrometer-sized metal droplets, the model gives vacancy concentrations at solidification far in excess of equilibrium values.

• DOE Contract Number: AC04-76DP00789; AC07-76ID01570
• OSTI ID: 5461961
• Journal Information: Physical Review, A; (USA), Journal Name: Physical Review, A; (USA) Vol. 43:10; ISSN 1050-2947; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

656002* -- Condensed Matter Physics-- General Techniques in Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
BOUNDARY CONDITIONS
ELEMENTS
FLUIDS
KINETICS
LIQUID METALS
LIQUIDS
METALS
PHASE TRANSFORMATIONS
SATURATION
SOLIDIFICATION
SUPERSATURATION
TRAPPING
VOIDS