Theoretical and experimental investigations of the process of vibration treatment of liquid metals containing nanoparticles

It is known that the use of external effects, such as acoustic fields (from ultrasonic to low-frequency range), help in breaking down agglomerates, improving particle wettability, providing uniform particle distribution in the melt volume, and reducing the grain size. The fragmentation of growing crystals, de-agglomeration of particles and their mixing in liquid metal under the influence of vibration (with frequencies of 10–100 Hz) are considered in this paper. The major advantage of such a technique in comparison with high-frequency methods (sonic, ultrasonic) is the capability of processing large melt volumes proportional to the wavelength. The mechanisms of the breaking down of particle agglomerates and the mixing of particles under conditions of cavitation and turbulence during the vibration treatment of the melt are considered. Expressions linking the threshold intensity and frequency with the amplitude necessary to activate mechanisms of turbulence and cavitation were obtained. The results of vibration treatment experiments for an aluminum alloy containing diamond nanoparticles are given. This treatment makes it possible to significantly reduce the grain size and to improve the casting homogeneity and thus improve the mechanical properties of the alloy

Influence of the modifying ability of various compositions on the microstructure and properties of the AK7ch alloy

The results of experimental studies of the AK7ch Al–Si alloy before and after modifying with compositions—(i) the K2ZrF6 industrial modifier, (ii) modifying mixture based on refractory metal oxides and cryolite, and (iii) the Arsal 2120 foreign flux—are presented. It is established that modification of the AK7ch alloy leads to the uniform distribution of eutectics (α-Al + β-Si) and structural components, diminishing silicon crystals by a factor of 1.5–2.0 on average, refining, and variation in shape of Fe-containing phases. It is shown that an increase in relative elongation by a factor of 2 and more is characteristics of all modified samples, and the tensile strength, hardness, and densities of casts for all the samples are different and have an ambiguous character

Influence of the modifying ability of various compositions on the microstructure and properties of the AK7ch alloy

The results of experimental studies of the AK7ch Al–Si alloy before and after modifying with compositions—(i) the K2ZrF6 industrial modifier, (ii) modifying mixture based on refractory metal oxides and cryolite, and (iii) the Arsal 2120 foreign flux—are presented. It is established that modification of the AK7ch alloy leads to the uniform distribution of eutectics (α-Al + β-Si) and structural components, diminishing silicon crystals by a factor of 1.5–2.0 on average, refining, and variation in shape of Fe-containing phases. It is shown that an increase in relative elongation by a factor of 2 and more is characteristics of all modified samples, and the tensile strength, hardness, and densities of casts for all the samples are different and have an ambiguous character

Influence of the modifying ability of various compositions on the microstructure and properties of the AK7ch alloy

The results of experimental studies of the AK7ch Al–Si alloy before and after modifying with compositions—(i) the K2ZrF6 industrial modifier, (ii) modifying mixture based on refractory metal oxides and cryolite, and (iii) the Arsal 2120 foreign flux—are presented. It is established that modification of the AK7ch alloy leads to the uniform distribution of eutectics (α-Al + β-Si) and structural components, diminishing silicon crystals by a factor of 1.5–2.0 on average, refining, and variation in shape of Fe-containing phases. It is shown that an increase in relative elongation by a factor of 2 and more is characteristics of all modified samples, and the tensile strength, hardness, and densities of casts for all the samples are different and have an ambiguous character

Theoretical and experimental investigations of the process of vibration treatment of liquid metals containing nanoparticles

It is known that the use of external effects, such as acoustic fields (from ultrasonic to low-frequency range), help in breaking down agglomerates, improving particle wettability, providing uniform particle distribution in the melt volume, and reducing the grain size. The fragmentation of growing crystals, de-agglomeration of particles and their mixing in liquid metal under the influence of vibration (with frequencies of 10–100 Hz) are considered in this paper. The major advantage of such a technique in comparison with high-frequency methods (sonic, ultrasonic) is the capability of processing large melt volumes proportional to the wavelength. The mechanisms of the breaking down of particle agglomerates and the mixing of particles under conditions of cavitation and turbulence during the vibration treatment of the melt are considered. Expressions linking the threshold intensity and frequency with the amplitude necessary to activate mechanisms of turbulence and cavitation were obtained. The results of vibration treatment experiments for an aluminum alloy containing diamond nanoparticles are given. This treatment makes it possible to significantly reduce the grain size and to improve the casting homogeneity and thus improve the mechanical properties of the alloy

Numerical modelling of the molten metal flow in a disk agitator mixer

Numerical modelling of the molten metal flow in a crucible under the action of stirred disk agitator is carried out. The influence of the agitator rotational speed on the molten metal flow field is investigated. Dependences of the turbulent diffusivity and the power number on the agitator rotational speed are obtained. The effect of the interaction between the molten metal-air interface and agitator elements on the flow field in a crucible is shown

Numerical modelling of the molten metal flow in a disk agitator mixer

Numerical modelling of the molten metal flow in a crucible under the action of stirred disk agitator is carried out. The influence of the agitator rotational speed on the molten metal flow field is investigated. Dependences of the turbulent diffusivity and the power number on the agitator rotational speed are obtained. The effect of the interaction between the molten metal-air interface and agitator elements on the flow field in a crucible is shown