Cooling and Crystallization of Melt Droplets of Aluminum Alloys in Water Environment
M. V. Zharov
Moscow Aviation Institute (National Research University), Moscow, Russia
Keywords: granulation technologies, cooling, crystallization, crystallization temperature, rate of heat removal, microstructure dispersion, dendritic parameter, droplet method, centrifugation method, drop speed, vapor envelope, thermal conductivity, mathematical model
Abstract
The physical processes of crystallization of melt droplets in water have been studied using the droplet granulation and melt centrifugation methods. A mathematical model has been developed that makes it possible to determine the cooling and crystallization rates and dendritic structural parameter of aluminum alloy granules from the initial data of the process, the diameter of melt droplets, and cooling conditions. Predicting the dendritic parameter of the microstructure of granules allows one to predict the level of microstructure dispersion and hence the strength properties of the granulate material. The model parameters take into account the speed of droplet motion, features of heat removal processes, and the temperature dependence of the thermophysical parameters of the media. An application program implementing the developed mathematical model has been developed. Implementation of the developed mathematical model has been carried out using the Microsoft Visual C++ programming language. The mathematical model has been tested in the granulation of highly alloyed aluminum alloys (D1 and D16 alloys of the Al-Cu-Mg system, and B95 and B96Ts alloys of the Al-Zn-Mg-Cu system) obtained by centrifugal melt spraying and the droplet methods with cooling in water. Crystallization rate in full-scale samples has been measured based on an analysis of the dendritic structural parameter of the material. Analysis of the calculated values of the dendritic parameter and its measurements for real granule samples has shown that there is good agreement between the simulation and measurement results.
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