Special Issue "Casting and Solidification of Light Alloys"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (31 May 2020).

Special Issue Editor

Prof. Dr. Alexander Vorozhtsov
Website
Guest Editor
Tomsk State University, Tomsk, Russia
Interests: high-energy materials; high-strength light alloys; metal matrix nanocomposites

Special Issue Information

Dear Colleagues,

The processes of casting and crystallization are defining in the formation of the final properties of light alloys, and optimization of these processes allows improving efficiency of the use and applications of light alloys. The analysis and design of such processes requires special attention. The aim of this Special Issue is to present the latest achievements in technology, including advanced and modern approaches, structure development, and properties of the light alloys.

Investigation of the effect of casting and crystallization on the structure and properties of the resulting light alloys (based on aluminum and magnesium to begin with), and in particular, research connected with detailed analysis of the microstructure of light alloys obtained using various external influences of ultrasonic, vibration, magnetic, and mechanical processing on the casting and crystallization, are welcomed. The use of modern methods of studying the properties of alloys in order to assess the effect of structure on the mechanical and functional properties of light alloys is planned for publication in the Special Issue. Research on the study of introduction of additives (modifiers, reinforcers, including nanosized ones, etc.) into the melt on the crystallization process, the technological properties of casting (fluidity, segregation, shrinkage, etc.), the structure and physicomechanical properties of light alloys are also of interest for this issue. It would be great to find papers that focus on the study of the relations of physicomechanical properties with the defective structure of light alloys and mathematical modeling of plastic deformation of dispersion-strengthening materials. We would like any articles taking both experimental and theoretical (analytical and numerical) approaches, as well as those that consider a combination of these approaches.

Prof. Dr. Alexander Vorozhtsov
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • light alloys
  • aluminum
  • magnesium
  • additives
  • mathematical modelling
  • analytical research

Published Papers (12 papers)

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Research

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Open AccessArticle
The Structural and Phase State of the TiAl System Alloyed with Rare-Earth Metals of the Controlled Composition Synthesized by the “Hydride Technology”
Metals 2020, 10(7), 859; https://doi.org/10.3390/met10070859 - 29 Jun 2020
Abstract
The structural state and the quantitative phase analysis of the TiAl system, alloyed with rare-earth metals synthesized using hydride technology, were studied in this work. Using the Rietveld method, the content of the major phases in the initial system Ti(50 at.%)–Al(50 at.%), as [...] Read more.
The structural state and the quantitative phase analysis of the TiAl system, alloyed with rare-earth metals synthesized using hydride technology, were studied in this work. Using the Rietveld method, the content of the major phases in the initial system Ti(50 at.%)–Al(50 at.%), as well as Ti(49 at.%)–Al(49 at.%), with alloying additions Ta, Y and Dy having a high accuracy was determined. The methods of scanning electron microscopy, transmission electron microscope and X-ray spectral microanalysis of the local areas of the structure for studying the distribution of alloying elements were used. The energies of lattices of separate phases were also determined after the full-profile specification. All the lattices of the identified structures (about 30) turned out to be stable. It was established that in the Ti(49 at.%)–Al(49 at.%) systems under study with alloying additions of metals Ta, Y and Dy, there were intermetallides composed of AlTi3, TiAl in the hexagonal, tetragonal and triclinic units. It is known that after microalloying alloys by Y and Dy metals, the mass fraction of TiAl phases increases significantly (>70%). Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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Open AccessArticle
Microstructure of In-Situ Friction Stir Processed Al-Cu Transition Zone
Metals 2020, 10(6), 818; https://doi.org/10.3390/met10060818 - 18 Jun 2020
Abstract
The majority of literature sources dedicated to dissimilar Al-Cu friction stir welding testifies to the formation of intermetallic compounds (IMC) according to diffusion-controlled reactions, i.e., without liquation on the Al/Cu interfaces. Fewer sources report on revealing Al-Cu eutectics, i.e., that IMCs are formed [...] Read more.
The majority of literature sources dedicated to dissimilar Al-Cu friction stir welding testifies to the formation of intermetallic compounds (IMC) according to diffusion-controlled reactions, i.e., without liquation on the Al/Cu interfaces. Fewer sources report on revealing Al-Cu eutectics, i.e., that IMCs are formed with the presence of the liquid phase. This work is an attempt to fill the gap in the results and find out the reasons behind such a difference. Structural-phase characteristics of an in-situ friction stir processed (FSP) Al-Cu zone were studied. The single-pass FSPed stir zone (SZ) was characterized by the presence of IMCs such as Al2Cu, Al2Cu3, AlCu3, Al2MgCu, whose distribution in the SZ was extremely inhomogeneous. The advancing side SZ contained large IMC particles as well as Al(Mg,Cu) solid solution (SS) dendrites and Al-Al2Cu eutectics. The retreating side SZ was composed of Al-Cu solid solution layered structures and smaller IMCs. Such a difference may be explained by different levels of heat input with respect to the SZ sides as well as by using lap FSP instead of the butt one. Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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Open AccessArticle
Microstructural Analysis of Friction Stir Butt Welded Al-Mg-Sc-Zr Alloy Heavy Gauge Sheets
Metals 2020, 10(6), 806; https://doi.org/10.3390/met10060806 - 17 Jun 2020
Abstract
Friction stir welding (FSW) on a heavy gauge sheet of a hereditary fine-grained Al-Mg-Sc-Zr alloy was carried out to study the specifics of plasticized metal flow and microstructural evolution in different sections and zones of the joint. It was found that the stir [...] Read more.
Friction stir welding (FSW) on a heavy gauge sheet of a hereditary fine-grained Al-Mg-Sc-Zr alloy was carried out to study the specifics of plasticized metal flow and microstructural evolution in different sections and zones of the joint. It was found that the stir zone (SZ) macrostructure may contain either a single or many nugget zones depending on the metal sheet thickness and the seam length. The effect of grain kinking in a thermomechanically affected zone (TMAZ) under pressure from the stir zone metal was discovered. The stir zone metal was fine-grained but had a microhardness lower than that of the base metal, which may be explained by the overaging effect of FSW on the Al3Sc precipitates. The tensile strength of the joint was almost equal to that of the base metal (BM). The grain size distributions were obtained in different sections below the sheet surface and away from the exit hole, which allowed us to suggest the specific adhesion-assisted layer-by layer metal transfer mechanism in FSW. Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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Open AccessArticle
Wear of ZhS6U Nickel Superalloy Tool in Friction Stir Processing on Commercially Pure Titanium
Metals 2020, 10(6), 799; https://doi.org/10.3390/met10060799 - 16 Jun 2020
Abstract
The use of electric arc or gas welding in the manufacture of titanium components often results in low quality welded joints due to large residual stresses and strains. A successful solution to this problem can be found in the application of friction stir [...] Read more.
The use of electric arc or gas welding in the manufacture of titanium components often results in low quality welded joints due to large residual stresses and strains. A successful solution to this problem can be found in the application of friction stir welding. However, friction stir welding (FSW) of titanium alloys is complicated by rapid tool wear under high loads and temperatures achieved in the process. This paper studies the durability of a tool made of ZhS6U Ni-based superalloy used for friction stir processing of commercially pure titanium and the effect of the tool wear on the weld quality. The total length of the titanium weld formed by the tool without failure comprised 2755 mm. The highest wear of the tool is observed at the base of the pin, which brings about the formation of macrodefects in the processed material. The tool overheating causes an increase in the dendrite element size of ZhS6U alloy. The transfer layer contains chemical elements of this alloy, indicating that the tool wear occurs by diffusion and adhesion. As a result of processing, the tensile strength of commercially pure titanium increased by 25%. Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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Open AccessArticle
Structure and Properties of Al–0.6wt.%Zr Wire Alloy Manufactured by Direct Drawing of Electromagnetically Cast Wire Rod
Metals 2020, 10(6), 769; https://doi.org/10.3390/met10060769 - 09 Jun 2020
Abstract
The method of electromagnetic casting (EMC) was used to produce the long-length rod billet (with a diameter 12 mm) of aluminum alloy containing 0.6 wt.% Zr, 0.4%Fe, and 0.4%Si. The combination of high cooling rate (≈104 K/s) during alloy solidification and high [...] Read more.
The method of electromagnetic casting (EMC) was used to produce the long-length rod billet (with a diameter 12 mm) of aluminum alloy containing 0.6 wt.% Zr, 0.4%Fe, and 0.4%Si. The combination of high cooling rate (≈104 K/s) during alloy solidification and high temperature before casting (≈830 °C) caused zirconium to dissolve almost completely in the aluminum solid solution (Al). Additions of iron and silicon were completed in the uniformly distributed eutectic Al8Fe2Si phase particles with an average size of less than 1 µm. Such fine microstructure of the experimental alloy in as-cast state provides excellent deformability during wire production using direct cold drawing of EMC rod (94% reduction). TEM study of structure evolution in the as-drawn 3 mm wire revealed the onset of Al3Zr (L12) nanoparticle formation at 300 °C and almost-complete decomposition of (Al) at 400 °C. The distribution of Zr-containing nanoparticles is quite homogeneous, with their average size not exceeding 10 nm. Experimental wire alloy had the ultimate tensile strength (UTS) and electrical conductivity (EC) (234 MPa and 55.6 IACS, respectively) meeting the AT2 type specification. At the same time, the maximum heating temperature was much higher (400 versus 230 °C) and meets the AT4 type specification. Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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Open AccessArticle
Microstructure and Hardness Evolution of Al8Zn7Ni3Mg Alloy after Casting at very Different Cooling Rates
Metals 2020, 10(6), 762; https://doi.org/10.3390/met10060762 - 07 Jun 2020
Abstract
In this study, we combined both a high strength Al-8%Zn-3%Mg aluminum matrix and a reinforcing contribution of Al3Ni intermetallics in Al8Zn7Ni3Mg hypereutectic alloy with a tuned microstructure via a variation of cooling rates from 0.1 K/s to 2.3 × 105 [...] Read more.
In this study, we combined both a high strength Al-8%Zn-3%Mg aluminum matrix and a reinforcing contribution of Al3Ni intermetallics in Al8Zn7Ni3Mg hypereutectic alloy with a tuned microstructure via a variation of cooling rates from 0.1 K/s to 2.3 × 105 K/s. Using the Thermo-Calc software, we analyzed the effect of nickel content on the phase equilibria during solidification and found out that 7%Ni provides a formation of equal fractions of primary (6.5 vol.%) and eutectic (6.3 vol.%) crystals of the Al3Ni phase. Using microstructural analysis, a refinement of intermetallics with an increase in cooling rate was observed. It is remarkable that the structure after solidification at ~103 K/s across 1 mm flake casting consists of a quasi-eutectic with 1.5 μm Al3Ni fibers, while an increase in the cooling rate to ~105 K/s after melt spinning leads to the formation of 50 nm equiaxed Al3Ni particles. Under these conditions, the alloy showed an aging response at 200 °C, resulting in hardness of 200 HV and 220 HV, respectively. After 470 °C annealing, the fibers in the 1 mm sample evolved to needles. However, in melt-spun ribbons, the particles were kept globular and small-sized. Overall, the results may greatly contribute to the development of new eutectic type composites for rapid solidification methods. Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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Open AccessArticle
Influence of Continuous Casting Speeds on Cast Microstructure and Mechanical Properties of an ADC14 Alloy
Metals 2020, 10(5), 625; https://doi.org/10.3390/met10050625 - 11 May 2020
Abstract
To improve the mechanical properties of the casting alloys, various attempts have been made to use alternative casting technologies. The Ohno continuous casting (OCC) process is a unidirectional solidification method, which leads to high-quality cast samples. In this study, the Al-Si-Cu-Mg alloy was [...] Read more.
To improve the mechanical properties of the casting alloys, various attempts have been made to use alternative casting technologies. The Ohno continuous casting (OCC) process is a unidirectional solidification method, which leads to high-quality cast samples. In this study, the Al-Si-Cu-Mg alloy was cast at casting speeds of 1 mm/s, 2 mm/s, and 3 mm/s, by the OCC process. The aim of this study is to investigate the effects of the casting process parameters, such as casting speeds and cooling conditions, on the crystallization characteristics and mechanical properties of OCC-Al-Si-Cu-Mg alloy. Particularly, secondary dendrite arms spacing of α-Al dendrites in OCC samples significantly decreases with increasing casting speed. Moreover, the mean tensile strength of the samples, produced at the highest casting speed of 4.0 mm/s, is significantly higher than that for the samples produced at a casting speed of 1.0 mm/s. Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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Open AccessArticle
Analysis of Different Solution Treatments in the Transformation of β-AlFeSi Particles into α-(FeMn)Si and Their Influence on Different Ageing Treatments in Al–Mg–Si Alloys
Metals 2020, 10(5), 620; https://doi.org/10.3390/met10050620 - 10 May 2020
Abstract
In the as-cast state, Al–Mg–Si alloys are not suitable for hot forming. They present low ductility due to the presence of intermetallic β-AlFeSi particles that form in the interdendritic regions during the solidification process. Homogenization treatments promote the transformation of these particles into [...] Read more.
In the as-cast state, Al–Mg–Si alloys are not suitable for hot forming. They present low ductility due to the presence of intermetallic β-AlFeSi particles that form in the interdendritic regions during the solidification process. Homogenization treatments promote the transformation of these particles into α-(FeMn)Si particles, which are smaller in size and more rounded in shape, thus improving the ductility of the material. This paper analyses the influence of various solution treatments on the transformation of β-AlFeSi particles into α-(FeMn)Si particles in an Al 6063 alloy. Their effect on different ageing treatments in the 150–180 °C temperature range is also studied. An increase in the solution temperature favours greater transformation of the β-AlFeSi particles into α-(FeMn)Si, dissolving a greater amount of Si, thereby having a significant effect on subsequent ageing. We found that as the dwell time at a temperature of 600 °C increases, the rate of dissolution of the Fe atoms from α-(FeMn)Si particles exceeds the rate of incorporation of Mn atoms into said particles. This seems to produce a delay in reaching the peak hardness values in ageing treatments, which warrants further research to model this behaviour. The optimal solution treatment takes place at around 600 °C and the highest obtained peak hardness value is 104 HV after a 2 h solution treatment at said temperature and ageing at 160 °C for 12 h. Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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Open AccessArticle
Simulation on the Effect of Porosity in the Elastic Modulus of SiC Particle Reinforced Al Matrix Composites
Metals 2020, 10(3), 391; https://doi.org/10.3390/met10030391 - 19 Mar 2020
Abstract
Although the porosity in Al-SiC metal matrix composites (MMC) can be diminished; its existence is unavoidable. The purpose of this work is to study the effect of porosity on Young’s modulus of SiC reinforced aluminum matrix composites. Finite element analysis is performed based [...] Read more.
Although the porosity in Al-SiC metal matrix composites (MMC) can be diminished; its existence is unavoidable. The purpose of this work is to study the effect of porosity on Young’s modulus of SiC reinforced aluminum matrix composites. Finite element analysis is performed based on the unit cell and the representative volume element approaches. The reliability of the models is validated by comparing the numerical predictions against several experimental data ranging in low- and high-volume fractions and good agreement is found. It is found that despite the stress transfer from the soft matrix to the reinforcement remains effective in the presence of pores, there is a drop in the stress gathering capability of the particles and thus, the resulting effective elastic modulus of composite decreases. The elastic property of the composite is more sensitive to pores away the reinforcement. It is confirmed, qualitatively, that the experimentally reported in the literature decrease in the elastic modulus is caused by the presence of pores. Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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Open AccessArticle
Pure Aluminum Structure and Mechanical Properties Modified by Al2O3 Nanoparticles and Ultrasonic Treatment
Metals 2019, 9(11), 1199; https://doi.org/10.3390/met9111199 - 07 Nov 2019
Abstract
This paper examines dispersion hardened alloys based on commercial-purity aluminum obtained by permanent mold casting with the addition of aluminum oxide nanoparticles. Ultrasonic treatment provides a synthesis of non-porous materials and a homogeneous distribution of strengthening particles in the bulk material, thereby increasing [...] Read more.
This paper examines dispersion hardened alloys based on commercial-purity aluminum obtained by permanent mold casting with the addition of aluminum oxide nanoparticles. Ultrasonic treatment provides a synthesis of non-porous materials and a homogeneous distribution of strengthening particles in the bulk material, thereby increasing the mechanical properties of pure aluminum. It is shown that the increase in the alloy hardness, yield stress, ultimate tensile strength, and lower plasticity depend on the average grain size and a greater amount of nanoparticles in the alloy. Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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Open AccessArticle
Influence of Titanium Diboride Particle Size on Structure and Mechanical Properties of an Al-Mg Alloy
Metals 2019, 9(10), 1030; https://doi.org/10.3390/met9101030 - 23 Sep 2019
Cited by 1
Abstract
In the present study, aluminum alloys of the Al-Mg system with titanium diboride particles of different size distribution were obtained. The introduction of particles in the alloy was carried out using master alloys obtained through self-propagating high-temperature synthesis (SHS) process. The master alloys [...] Read more.
In the present study, aluminum alloys of the Al-Mg system with titanium diboride particles of different size distribution were obtained. The introduction of particles in the alloy was carried out using master alloys obtained through self-propagating high-temperature synthesis (SHS) process. The master alloys consisted of the intermetallic matrix Al-Ti with distributed TiB2 particles. The master alloys with TiB2 particles of different size distribution were introduced in the melt with simultaneous ultrasonic treatment, which allowed the grain refining of the aluminum alloy during subsequent solidification. It was found that the introduction of micro- and nanoparticles TiB2 increased the yield strength, tensile strength, and plasticity of as-cast aluminum alloys. After pass rolling the castings and subsequent annealing, the effect of the presence of particles on the increase of strength properties is much less felt, as compared with the initial alloy. The recrystallization of the structure after pass rolling and annealing was the major contributor to hardening that minimized the effect of dispersion hardening due to the low content of nanosized titanium diboride. Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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Review

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Open AccessReview
A Review of Friction Stir Processing of Structural Metallic Materials: Process, Properties, and Methods
Metals 2020, 10(6), 772; https://doi.org/10.3390/met10060772 - 09 Jun 2020
Abstract
Friction stir processing (FSP) has attracted much attention in the last decade and contributed significantly to the creation of functionally graded materials with both gradient structure and gradient mechanical properties. Subsurface gradient structures are formed in FSPed metallic materials due to ultrafine grained [...] Read more.
Friction stir processing (FSP) has attracted much attention in the last decade and contributed significantly to the creation of functionally graded materials with both gradient structure and gradient mechanical properties. Subsurface gradient structures are formed in FSPed metallic materials due to ultrafine grained structure formation, surface modification and hardening with various reinforcing particles, fabrication of hybrid and in situ surfaces. This paper is a review of the latest achievements in FSP of non-ferrous metal alloys (aluminum, copper, titanium, and magnesium alloys). It describes the general formation mechanisms of subsurface gradient structures in metal alloys processed by FSP under various conditions. A summary of experimental data is given for the microstructure, mechanical, and tribological properties of non-ferrous metal alloys. Full article
(This article belongs to the Special Issue Casting and Solidification of Light Alloys)
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