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On The Transition From Diffusion-Limited To Kinetic-Limited Regimes Of Alloy Solidification, Sergey Sobolev
On The Transition From Diffusion-Limited To Kinetic-Limited Regimes Of Alloy Solidification, Sergey Sobolev
Sergey Sobolev
An abrupt transition from diffusion-limited solidification to diffusionless, kinetic-limited solidification with complete solute trapping is explained as a critical phenomenon which arises due to local non-equilibrium diffusion effects in the bulk liquid. The transition occurs when the interface velocityVpasses through the critical pointV=VD, where V=VDis the bulk liquid diffusive velocity. Analytical expressions are developed for velocity–temperature and velocity–undercooling functions, using local non-equilibrium partition coeffi-cient based on the Jackson et al. kinetic model and the local non-equilibrium diffusion model of Sobolev. The calculated functions dem-onstrate a sharp break in the velocity–undercooling and velocity–temperature relationships at the critical pointV=VD. At this point …
Local Nonequilibrium Solute Trapping Model For Non-Planar Interface, Sergey Sobolev
Local Nonequilibrium Solute Trapping Model For Non-Planar Interface, Sergey Sobolev
Sergey Sobolev
A generalized solute trapping model was proposed incorporating the dependency on interfacial normal velocity along the dendrite side, as an extension of the continuous growth model modified by Sobolev with the local nonequilibrium diffusion model (LNDM). The present model predicts that the transition to diffusionless solidification is not sharp, but occurs in a range of velocities. Analysis indicates that for local nonequilibrium solute diffusion in bulk liquid the effect of the interfacial normal velocity dependency on solute partitioning is considerable.