Effects of Ultrasonic (Cavitation) Melt Processing on the Structure Refinement and Property Improvement of Cast and Worked Aluminum Alloys

2002 ◽  
Vol 396-402 ◽  
pp. 77-82 ◽  
Author(s):  
G.I. Eskin ◽  
Dmitry G. Eskin
Keyword(s):  
Aluminum Alloys ◽  
Structure Refinement ◽  
Ultrasonic Cavitation ◽  
Melt Processing

scholarly journals Electric Transfer of ions of Alloying Elements in Aluminum Alloys by Magnetohydrodynamic Melt Processing

2017 ◽  
pp. 1031-1041
Author(s):  
Anatoly B. Laptev ◽  
◽  
Mikhail V. Pervukhin ◽  
Alexandr N. Afanasiev-Khodykin ◽  
Viktor N. Timofeev ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Melt Processing ◽  
Alloying Elements

scholarly journals Influence of MHD - plasma melt processing on the structure and properties of cast aluminum alloy A390

2021 ◽  
Vol 100 (4) ◽  
pp. 24-32
Author(s):  
A.V. Narivsky ◽  
◽  
O.M. Smirnov ◽  
V.E. Panarin ◽  
Yu.P. Skorobagatko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Negative Impact ◽  
Structure Refinement ◽  
Physical And Mechanical Properties ◽  
Primary Silicon ◽  
Melt Processing ◽  
Cast Aluminum Alloy ◽  
Structure And Properties ◽  
Cast Aluminum

Growth of production of cast products and the desire of enterprises to reduce the cost of manufacturing metal products led to a significant increase in requirements for the structure and properties of aluminum alloys. Increasing of physical and mechanical properties of alloys is most effectively at the stages of their preparation in liquid state. At that, it is possible to affect effectively on the quality of cast metal by external actions on alloys, deep refining from gases and harmful impurities, active modifying of alloy, reducing or eliminating the negative impact of heredity of charge materials. The main disadvantage of the processes of structure refinement of alloys by using modifiers is instability of their results, which depends on various reasons. One of the most important reasons is providing conditions for the formation and preservation of active modifier particles in the melt volume. They are assimilating by liquid alloy and acting on crystal nucleus at crystallization. It is known that only ~10% particles are active of the total number of particles added with the ligature into the melt. Other particles dissolve in the melt, take away by the crystallization front, or push back on to intergranular boundaries. The considered methods of electromagnetic, MHD and plasma actions on liquid metal allow to refine and modify alloys without use of special reagents. The paper presents studying of the structure and properties of supereutectic silumin A390 after treatment in casting magnetodynamic installation (MDI) by submerged into melt the plasma argon jet and alternating electromagnetic field & magnetohydrodynamic (MHD) effects, including simultaneous combination. There are developed the scientific and technological bases of MHD-plasma processing of liquid hypereutectic silumin A390 and original equipment for their realization. It provides dispersed structure of solidified alloy. Thus, there is a significant decreasing of sizes both particles of primary silicon and dendrites of α-solid solution of aluminium. Also, strength characteristics of alloys increased to 10%, and elongation rises up in 1.5-2 times. Keywords: plasma jet, magnetodynamic installation (MDI), aluminum alloy, mechanical properties.

scholarly journals Ultrasonic processing of aluminium alloys above the liquidus: the role of Zr

2020 ◽  
Vol 326 ◽  
pp. 06002
Author(s):  
Dmitry Eskin
Keyword(s):  
Solid Solution ◽  
Aluminium Alloys ◽  
Eutectic Reaction ◽  
Structure Refinement ◽  
Al Alloys ◽  
Melt Processing ◽  
Ultrasonic Processing ◽  
Solution Type ◽  
Primary Crystals

Ultrasonic melt processing (USP) is gaining quite an interest in recent years due to the benefits of this technology to the melt quality and structure refinement. A number of mechanisms have been identified that govern the effects of USP at different stages of melt processing. Technologically it is advantageous to apply USP to the fluid melt rather than to a mushy solidifying alloy. In this case heterogeneous nucleation on available or activated/multiplied substrates is the main mechanism. Among these substrates, primary crystals of Al3Zr phase were shown to be potent and effective. This paper gives a review of the own research into the role of Al3Zr in structure refinement in various groups of Al alloys, from solid-solution type to hypereutectic. This overview includes the evidence of a possible eutectic reaction between Al and Al3Zr in Al-rich alloys, mechanisms of Al3Zr formation and refinement under USP (that enables these primary crystals to be active substrates for Al and some other primary phases), the role of USP in facilitating primary solidification of Al3Zr in the Al-Zr system, and the additional benefits of solute Ti presence. The paper is illustrated with the data obtained over the last 15 years of research led by the author.

Physical Methods of Melt Processing at Production of Aluminum Alloys and Composites: Opportunities and Prospects of Application

2019 ◽  
Vol 946 ◽  
pp. 655-660 ◽  
Author(s):  
Vladislav Deev ◽  
Evgeny Prusov ◽  
Evgeny Rakhuba
Keyword(s):  
Aluminum Alloys ◽  
Aluminum Matrix ◽  
Physical Principle ◽  
Melt Processing ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Cast Aluminum ◽  
Physical Methods ◽  
Physical Processing ◽  
Average Size

The paper describes the advantages and prospects of using the physical methods of melts processing in the production of aluminum alloys and cast aluminum matrix composites. Classification of the physical methods of the melt processing by the state of metal during the processing period and by the physical principle of the imposed effects is proposed. The influence of physical processing of melts on the structure of aluminum matrix composites depending on the type of imposed influence and the origin of the reinforcing phases is shown. The positive effect of thermo-temporal treatment on the structure of materials was confirmed on example of in-situ composites of Al-Mg2Si system, it includes reduction in the average size of endogenous reinforcing phases and changing their morphology to a more compact.

scholarly journals A Comparison of the Effects of Ultrasonic Cavitation on the Surfaces of 45 and 40Kh Steels

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 138
Author(s):  
Dmitriy S. Fatyukhin ◽  
Ravil I. Nigmetzyanov ◽  
Vyacheslav M. Prikhodko ◽  
Aleksandr V. Sukhov ◽  
Sergey K. Sundukov
Keyword(s):  
Surface Properties ◽  
Structure Refinement ◽  
Structural Steels ◽  
Ultrasonic Cavitation ◽  
Internal Stresses ◽  
Surface Erosion ◽  
Limiting State ◽  
Geometric Properties ◽  
Third Stage ◽  
Time Required

The ultrasonic treatment of metal products in liquid is used mainly to remove various kinds of contaminants from surfaces. The effects of ultrasound not only separate and remove contaminants, they also significantly impact the physical–mechanical and geometric properties of the surfaces of products if there is enough time for treatment. The aim of this study was to compare the dynamics of ultrasonic cavitation effects on the surface properties of 45 (ASTM M1044; DIN C45; GB 45) and 40Kh (AISI 5140; DIN 41Cr4; GB 40Cr) structural steels. During the study, changes in the structure, roughness, sub-roughness, and microhardness values of these materials were observed. The results showed significant changes in the considered characteristics. It was found that the process of cavitation erosion involves at least 3 stages. In the first stage, the geometric properties of the surface slightly change with the accumulation of internal stresses and an increase in microhardness. The second stage is characterized by structure refinement, increased roughness and sub-microroughness, and the development of surface erosion. In the third stage, when a certain limiting state is reached, there are no noticeable changes in the surface properties. The lengths of these stages and the quantitative characteristics of erosion for the considered materials differ significantly. It was found that the time required to reach the limiting state was longer for carbon steel than for alloy steel. The results can be used to improve the cleaning process, as well as to form the required surface properties of structural steels.

Analytical Electron Microscopy Study of Second-Phase Particles in 7075 and 7475 Aluminum Alloys

1985 ◽  
Vol 43 ◽  
pp. 348-349
Author(s):  
M. Raghavan ◽  
J. Y. Koo ◽  
J. W. Steeds ◽  
B. K. Park
Keyword(s):  
Aluminum Alloys ◽  
Silicon Oxide ◽  
Analytical Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Partial Substitution ◽  
Second Phase ◽  
X Ray ◽  
Second Phase Particles ◽  
Almost All

X-ray microanalysis and Convergent Beam Electron Diffraction (CBD) studies were conducted to characterize the second phase particles in two commercial aluminum alloys -- 7075 and 7475. The second phase particles studied were large (approximately 2-5μm) constituent phases and relatively fine ( ∼ 0.05-1μn) dispersoid particles, Figures 1A and B. Based on the crystal structure and chemical composition analyses, the constituent phases found in these alloys were identified to be Al7Cu2Fe, (Al,Cu)6(Fe,Cu), α-Al12Fe3Si, Mg2Si, amorphous silicon oxide and the modified 6Fe compounds, in decreasing order of abundance. The results of quantitative X-ray microanalysis of all the constituent phases are listed in Table I. The data show that, in almost all the phases, partial substitution of alloying elements occurred resulting in small deviations from the published stoichiometric compositions of the binary and ternary compounds.

Quantitative structure determination of interfaces through Z-contrast imaging and electron energy loss spectroscopy

1996 ◽  
Vol 54 ◽  
pp. 104-105
Author(s):  
S. J. Pennycook ◽  
P. D. Nellist ◽  
N. D. Browning ◽  
P. A. Langjahr ◽  
M. Rühle
Keyword(s):  
Grain Boundaries ◽  
Cuprate Superconductors ◽  
Structure Refinement ◽  
3D Structure ◽  
Real Space ◽  
Contrast Imaging ◽  
Coordination Polyhedra ◽  
Burgers Vector ◽  
Z Contrast ◽  
Contrast Image

The simultaneous use of Z-contrast imaging with parallel detection EELS in the STEM provides a powerful means for determining the atomic structure of grain boundaries. The incoherent Z-contrast image of the high atomic number columns can be directly inverted to their real space arrangement, without the use of preconceived structure models. Positions and intensities may be accurately quantified through a maximum entropy analysis. Light elements that are not visible in the Z-contrast image can be studied through EELS; their coordination polyhedra determined from the spectral fine structure. It even appears feasible to contemplate 3D structure refinement through multiple scattering calculations.The power of this approach is illustrated by the recent study of a series of SrTiC>3 bicrystals, which has provided significant insight into some of the basic issues of grain boundaries in ceramics. Figure 1 shows the structural units deduced from a set of 24°, 36° and 65° symmetric boundaries, and 24° and 45° asymmetric boundaries. It can be seen that apart from unit cells and fragments from the perfect crystal, only three units are needed to construct any arbitrary tilt boundary. For symmetric boundaries, only two units are required, each having the same Burgers, vector of a<100>. Both units are pentagons, on either the Sr or Ti sublattice, and both contain two columns of the other sublattice, imaging in positions too close for the atoms in each column to be coplanar. Each column was therefore assumed to be half full, with the pair forming a single zig-zag column. For asymmetric boundaries, crystal geometry requires two types of dislocations; the additional unit was found to have a Burgers’ vector of a<110>. Such a unit is a larger source of strain, and is especially important to the transport characteristics of cuprate superconductors. These zig-zag columns avoid the problem of like-ion repulsion; they have also been seen in TiO2 and YBa2Cu3O7-x and may be a general feature of ionic materials.

Platelet Aggregation Induced in Vitro by Therapeutic Ultrasound

1977 ◽  
Vol 38 (03) ◽  
pp. 0640-0651 ◽  
Author(s):  
B. V Chater ◽  
A. R Williams
Keyword(s):  
Platelet Aggregation ◽  
Direct Action ◽  
Adenosine Diphosphate ◽  
Ultrasonic Cavitation ◽  
Related Phenomenon ◽  
Release Reaction ◽  
Physical Conditions ◽  
Platelet Aggregates ◽  
Active Substances

SummaryPlatelets were found to aggregate spontaneously when exposed to ultrasound generated by a commercial therapeutic device. At a given frequency, aggregation was found to be a dose-related phenomenon, increasing intensities of ultrasound inducing more extensive and more rapid aggregation. At any single intensity, the extent aggregation was increased as the frequency of the applied ultrasound was decreased (from 3.0 to 0.75 MHz).Ultrasound-induced platelet aggregation was found to be related to overall platelet sensitivity to adenosine diphosphate. More sensitive platelets were found to aggregate spontaneously at lower intensities of sound, and also the maximum extent of aggregation was found to be greater. Examination of ultrasound-induced platelet aggregates by electron microscopy demonstrated that the platelets had undergone the release reaction.The observation that haemoglobin was released from erythrocytes in whole blood irradiated under identical physical conditions suggests that the platelets are being distrupted by ultrasonic cavitation (violent gas/bubble oscillation).It is postulated that overall platelet aggregation is the result of two distinct effects. Firstly, the direct action of ultrasonic cavitation disrupts a small proportion of the platelet population, resulting in the liberation of active substances. These substances produce aggregation, both directly and indirectly by inducing the physiological release reaction in adjacent undamaged platelets.

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