Modeling of the alloy solidification modified by refractory nano-size particles
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Institutskaya str. 4/1, Novosibirsk 630090, Russia
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Received in final form: 10 July 2019
Published online: 11 February 2020
The authors propose a mathematical model of non-equilibrium crystallization of a binary alloy with modifying refractory nano-sized particles. The model describes heat transfer processes, as well as heterogeneous nucleation and crystallization of two components of the melt. The nucleation of the crystalline phase occurs on the surface of the nanoparticles during the supercooling of the melt. The liquidus temperature in the melt depends on the concentration of the dissolved alloying component, which is determined by the non-equilibrium lever equation. When the metal is cooled down to the eutectic temperature, the solidification of the alloy α-phase takes place, followed by solidification of β-phase if the cooling continues. The growth rate of the crystal phase is proportional to the supercooling value. The volume of the solid phase formed around the nucleus determines the size of the grain structure in the solidified alloy. The article depicts numerical simulation of aluminum melt solidification in cylindrical ingot mold, carried out by the authors. The parameters of heat exchange of the melt-mold system with the environment are available from experiments. The conditions of nucleation, crystallization rate, supercooling and solidification time prove to significantly differ within the cast. The area with the finest structure of the solidified metal is located near the wall of the mold. The calculated size of the grain structure in the casting is consistent with the experimental results. Comparing the results of numerical calculation with the data of a physical experiment on measuring the temperature during solidification of the melt and studying the properties of the cast confirm reliability of the proposed model.
© EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature, 2020