A new mathematical model of supercooled melt crystallization based on the variational principles of thermodynamics has been developed. The model takes into account the crystal formation and diffusion growth regularities, as well as the diffusionless crystal growth with the deviation from the local equilibrium at the surface. The model also takes into account the growing crystals mutual influence on the components concentration in the melt. The calculations for the supercooled eutectic melt Fe83B17 showed that the nucleation and growth of the phases Fe and Fe2B with a metastable phase Fe3B occure in the melt. The local equilibrium on the surface of the growing Fe3B crystals with the melt probably does not maintained. The regularities of the nucleation and mutual influence of the growing crystals of the phases are studied. The nucleation and growth rate of the Fe3B nuclei differs from the growth of Fe and Fe2B nuclei due to the diffusionless capture of boron atoms by the growing Fe3B crystals surface. The model will help to calculate the melt cooling technology mode for producing amorphous ribbons on a copper rotating drum.The calculation made it possible to analyze changes in the temperature and the crystallization degree in the various ribbon layers. The calculation results have been verified experimentally by X-ray diffraction and calorimetric studies of the obtained ribbons. The correspondence of the calculation and the experimental results confirms the effectiveness developed methodology for studying the regularities of crystal growth in supercooled melts.
The new crystallization theory for overcooled metastable melt is developed; it is based on variational mechanical principles and takes into account regularities of forming and diffusion growth of equilibrium crystals as well as diffusion-free growth of metastable crystals. Calculations for the melt Fe 83 B 17 were conducted on the model; they displayed that simultaneous nucleation and growth of Fe and Fe 2 B with metastable phase Fe 3 B are observed in overcooled melt, and growth speed of near-critical dimensional crystals of Fe 3 B exceeds crystal growth speed of Fe and Fe 2 B. The effect of diffusion-free growth is observed for Fe 3 B crystals, when quickly growing Fe 3 B crystal surface catches boron atoms. Quasi-equilibrium phase diagram for overcooled Fe-B melt was built on the base of the developed theory; it takes into account both equilibrium crystal growth and metastable phase growth. The obtained diagram allows to predict the values of components concentration near the surface of growing crystals both for Fe and Fe 2 B crystals meeting the requirements of local equi-librium condition on their surface and for Fe 3 B metastable crystals which are characterized by diffusion-free growth stipulated by high motion speed of crystal surface.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.