Nonequilibrium vacancy entrapment by rapid solidification

Journal Article · Tue Sep 01 04:00:00 EDT 1992 · Acta Metallurgica; (United States)

OSTI ID:6929828

VanSiclen, C D ^[1]; Wolfer, W G ^[2]

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1. Idaho National Engineering Lab., Idaho Falls, ID (United States)
2. Sandia National Labs., Livermore, CA (United States)

In this paper, a complete self-consistent theory is presented of vacancy entrapment at a rapid advancing solidification front. This consists of heat conduction equations for the solid and liquid regions, a vacancy diffusion equation for the solid region, and boundary conditions at the liquid/solid interface expressed in the form of heat and vacancy fluxes. These dynamic fluxes, which connect the two phases and provide explicit coupling between enthalpy and vacancy concentration, describe the generation of the latent heat of fusion and the creation and annihilation of vacancies at the interface. This system of equations is specialized to the case of spherical, rapidly solidifying metal droplets, and solved by two methods. Firstly, solutions are given in the form of a set of integral equations that incorporate the boundary conditions as integral kernels. Secondly, the system of equations is transformed into a set of algebraic and first-order ordinary differential equations by use of polynomial expressions for the profiles, and is solved to give the time evolution of the temperature and vacancy concentration at the moving interface.

• DOE Contract Number: AC04-76DP00789; AC07-76ID01570
• OSTI ID: 6929828
• Journal Information: Acta Metallurgica; (United States), Journal Name: Acta Metallurgica; (United States) Vol. 230:9; ISSN 0001-6160; ISSN AMETAR
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
BOUNDARY CONDITIONS
COOLING
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DIFFERENTIAL EQUATIONS
DIFFUSION
DROPLETS
ELEMENTS
ENERGY TRANSFER
ENTHALPY
EQUATIONS
EQUILIBRIUM
FLUIDS
HEAT TRANSFER
INTEGRAL EQUATIONS
LIQUIDS
METALS
NUMERICAL SOLUTION
PARTICLES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
POINT DEFECTS
SATURATION
SOLIDIFICATION
SOLIDS
SUPERSATURATION
THERMAL CONDUCTION
THERMODYNAMIC PROPERTIES
TIME DEPENDENCE
TRAPPING
VACANCIES