scholarly journals PROSPECTS FOR IMPROVING THE PROPERTIES OF SECONDARY FOUNDRY ALLOYS OF THE AL-SI SYSTEM USING THE MODIFICATION PROCESS

2021 ◽  
pp. 28-33
Author(s):  
Yuri Dotsenko ◽  
Vadim Seliverstov ◽  
Denis Nasonov ◽  
Nikita Nasonov
Keyword(s):  
Eutectic Silicon ◽  
Primary Crystallization ◽  
Structure Characteristic ◽  
Secondary Aluminum ◽  
Modification Process ◽  
Foundry Alloys ◽  
Cast Alloys ◽  
Alloys Of The Al ◽  
Short Range Structure ◽  
Physical And Mechanical Characteristics

The results of analytical studies of the use of modern modifiers for secondary aluminum alloys, which affect the structure of the metal of castings and allow to obtain the necessary physical and mechanical characteristics. It is shown that modifiers influencing the size of the primary grain and the shape of eutectic silicon inclusions are of the greatest interest for the production of castings from secondary silumins. It is shown that according to modern ideas the structure of the metal melt is not homogeneous. In some temperature range, complete mixing of atoms does not occur, and microregions with a short-range structure characteristic of the crystalline phase appear. These formations are called differently: atomic groups, clusters, clots, islands, complexes of atoms, clusters, etc. In the last decade, ultrafine powders of chemical compounds (nanopowders), which act as additional crystallization centers during primary crystallization, have become increasingly used as modifiers of cast alloys.

Effect of Aging and Annealing Treatments on the Microstructural Behavior of Some Al-Si Based Alloys

2015 ◽  
Vol 775 ◽  
pp. 152-159
Author(s):  
Zakia Sersour ◽  
Lynda Amirouche
Keyword(s):  
Automotive Industry ◽  
Isothermal Annealing ◽  
Eutectic Silicon ◽  
Solution Treatment ◽  
Heat Treatments ◽  
Microstructural Characteristics ◽  
Present Contribution ◽  
Foundry Alloys ◽  
Microstructural Behavior ◽  
Good Flow

Al-Si foundry Alloys, of eutectic and hypo-eutectic compositions, are largely employed in the automotive industry because of their enhanced mechanical properties, their good flow and their relatively low melting points. We investigate in the present contribution, two different groups of alloys namely the AS13 (Al-13%Si in weight) and the AS10G (Al-10%Si-0.35%Mg in weight). Our study comprises two main parts in which, two types of heat treatments have been carried out: (i) Industrial heat treatments and (ii) isothermal annealing at 400°C and 500°C. The samples were characterized by optical microscopy, scanning electron microscopy and micro-hardness measurements. The microstructural characteristics of these alloys are mainly determined by their concentration in additives such as Mg. The AS13 alloys microstructure is characterized by the distribution and form of the eutectic silicon particles, whereas the AS10G alloys one is essentially marked by the presence of dendrites, Mg2Si precipitates and some other intermetallic compounds. Most of these compounds and precipitates are formed after heat treatments. It was observed that some other compounds such as the iron-based intermetallics, which already form during solidification, where impossible to dissolve with solution treatment. These compounds were observed to prohibit Mg2Si precipitates formation due to Mg solute trapping.

New Developments with the SEED Technology

2012 ◽  
Vol 192-193 ◽  
pp. 373-378 ◽  
Author(s):  
Pascal Côté ◽  
Marie Eve Larouche ◽  
X. Grant Chen
Keyword(s):  
Alloy Development ◽  
New Developments ◽  
Seed Technology ◽  
Optimization Of Process Parameters ◽  
Process Reliability ◽  
Foundry Alloys ◽  
Cast Alloys ◽  
Semi Solid ◽  
Industry Needs

The SEED technology, a rheocasting process based on the slurry-on-demand approach, is an emerging technology that was developed in the mid-2000s. Many publications with regard to the process and to alloy development using this technology were made since, and several industrial units are operated worldwide. Moreover, the process is still actively developed and is fully supported by a team of scientists, engineers and technicians. With a global objective of addressing the user requirements and the industry needs, works were conducted toward optimization of the process and equipment. At first, the focus was on developing a simplified version of the SEED process to eliminate the so-called “drainage” phase while preserving the prime quality of the slurry produced. Improvement of some system components and integration of new features were also targeted to secure the overall equipment efficiency (OEE) and increase the process reliability. This work, backed with the optimization of process parameters and comprehensive techniques adapted for semi solid casting, led to the consolidation and even improvement of the properties of the parts produced for the common foundry alloys 356/357 and 319. Furthermore, the non-drained SEED version was applied to the validation of the process capabilities for uncommon cast alloys with works on 6061 wrought alloy, Duralcan metal matrix composite, and others. The results confirmed that the SEED process can efficiently be used in non-drained mode and achieve the same quality of slurry as the drained version originally developed. It is now proven in the industrial scale and actually integrated in the updated industrial equipment. Moreover, the capabilities of the process for special alloys and applications are still the subject of active development works.

Analysis of the Antimony and Strontium Cross-Effects in Al-Si Foundry Alloys

2014 ◽  
Vol 790-791 ◽  
pp. 464-469
Author(s):  
Monika Tokár ◽  
György Fegyverneki ◽  
Valéria Mertinger
Keyword(s):  
Thermal Analysis ◽  
Image Analysis ◽  
Eutectic Temperature ◽  
Eutectic Silicon ◽  
Research Work ◽  
Cooling Curves ◽  
Computer Image Analysis ◽  
Unmodified Alloy ◽  
Foundry Alloys ◽  
Modification Rate

In this work we show the effect of various concentrations of strontium and antimony on the level of modification in the Al-Si alloy. The scale of the modification rate was determined in two ways: thermal analysis was performed and the images of the samples. The eutectic temperature registered during the analysis were compared to the eutectic temperature of the unmodified alloy and on the basis of them was determined which samples are registered as modified, which are not. On the basis of the results of the cooling curves the partially modified category was introduced, if the ΔT value is less than 9°C and more than 7.5°C. The samples made of the alloys were examined with a computer image analysis and the samples were grouped on the basis of the size of the eutectic silicon phases. The aim of our research work was the examination of cross-effects of strontium and antimony.

Effects of Bismuth on the Microstructure and Mechanical Properties of AlSi9Cu3(Fe) Die Casting Alloys

2013 ◽  
Vol 765 ◽  
pp. 59-63 ◽  
Author(s):  
Stefano Ferraro ◽  
Giulio Timelli ◽  
Alberto Fabrizi
Keyword(s):  
Mechanical Properties ◽  
Trace Element ◽  
Die Casting ◽  
Eutectic Structure ◽  
Al Alloys ◽  
Casting Alloys ◽  
Microstructure And Mechanical Properties ◽  
Die Cast ◽  
Foundry Alloys ◽  
Cast Alloys

In secondary die cast Al alloys, Bismuth is generally considered an impurity element and present as a trace element in commercial foundry alloys. In the present work, the influence of different Bi content on the microstructure and mechanical properties of a commercial die cast AlSi9Cu3(Fe) alloy is investigated. The Bi level ranges between 0.015 and 0.3 wt.%. The results show that the presence of Bi seems to not produce significant changes in the microstructure and mechanical properties. Fine Bi-rich compounds are observed in the die cast alloys and they are mainly distributed in the interdendritic regions and along grain boundaries. TEM investigations revealed a complex Bi-Bi2Mg3eutectic structure, which presents mainly rod-type and blocky morphology.

scholarly journals Applications of Rare Earth Metals in Al-Si Cast Alloys

2021 ◽  
Author(s):  
Mohamed Gamal Mahmoud ◽  
Yasser Zedan ◽  
Agnes-Marie Samuel ◽  
Victor Songmene ◽  
Herebert W. Doty ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Rare Earth ◽  
High Purity ◽  
Eutectic Silicon ◽  
Rare Earth Metals ◽  
Grain Refining ◽  
Cast Alloys ◽  
Noticeable Reduction ◽  
The Cost

The present article reviews a large number of research publications on the effect of mischmetal (MM), rare earth metals (RE), La or Ce, and combinations of La + Ce on the performance of Al-Si cast alloys mainly 319, 356, 380, 413, and 390 alloys. Most of these articles focused on the use of rare earth metals as a substitute for strontium (Sr) as a eutectic silicon (Si) modifier if added in low percentage (< 1 wt.%) to avoid precipitation of a significant amount of insoluble intermetallics and hence poor mechanical properties. Other points that were considered were the affinity of RE to react with Sr., reducing its effectiveness as modifier, as well as the grain refining efficiency of the added RE in any form. None of these articles mentioned the exact composition of the RE used and percentage of tramp elements inherited from the parent ore. Using high purity La or Ce proved to have no effect on the Si shape, size or distribution, in particular at low solidification rates (thick sections). However, regardless the source of the RE, its addition to Sr-modified alloys reduced the modification effect. As for grain refining, apparently a high percentage of RE (> 1 wt.%) is required to achieve a noticeable reduction in grain size, however at the cost of alloy brittleness.

scholarly journals Solutions of the scientific problem of modifying of foundry alloys

2019 ◽  
pp. 15-18
Author(s):  
E. I. Marukovich ◽  
V. Yu. Stetsenko
Keyword(s):  
Gas Bubbles ◽  
Gas Generation ◽  
Metal Melt ◽  
Scientific Problem ◽  
Active Elements ◽  
Foundry Alloys ◽  
Cast Alloys ◽  
Surface Active

For a solution of the problem of modification of a microstructure of cast alloys it is necessary to accept admission that crystallization centers of crystals of phases are the crystalline buildups consisting of nanocrystals of phases. The role of modifiers comes down to lower concentration in a metal melt of the dissolved surface-active elements and gases and (or) to formate of the moistened substrates on which process of gas generation and deleting gas bubbles will be most preferable.

Effect of Heat Treatment on the Microstructure of Gravity Cast and Squeeze Cast Al-Si-Mg Alloy

2015 ◽  
Vol 830-831 ◽  
pp. 164-167
Author(s):  
Arjun Bala Krishnan ◽  
Kavin Selvaraj ◽  
Akhil Madhusoodhanan Geethakumari ◽  
Ravi Manickam
Keyword(s):  
Heat Treatment ◽  
Squeeze Casting ◽  
Cast Alloy ◽  
Eutectic Silicon ◽  
Solution Treatment ◽  
A356 Alloy ◽  
Sand Cast ◽  
Squeeze Cast ◽  
Cast Alloys ◽  
Gravity Cast

The present work deals with the effect of solutionising heat treatment on the features of Al-7Si-0.3Mg (A356) alloy in terms of microstructural modifications and hardness. The microstructure of sand cast and gravity cast alloys are coarse which results in lower strength compared to the alloys cast using modern casting techniques such as squeeze casting which is used for the fabrication of near-net-shaped castings. The influence of enhanced cooling rate on the hardness and microstructure of the squeeze casting technique has been exploited in the present study. In order to optimise the heat treatment process, the microstructure of the gravity and squeeze cast alloys were compared after solution treatment. The quantitative analysis of the microstructure was carried out using an image analyser attached to the optical microscope. The aspect ratio, particle count and circularity of eutectic silicon and SDAS are measured. The squeeze cast alloy is found to have finer microstructure with enhanced properties compared to the gravity cast alloy.

Effect of Ultrasonic Melt-Treatment on the Eutectic Silicon and Iron Intermetallic Phases in Al-Si Cast Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 431-436 ◽  
Author(s):  
W. Khalifa ◽  
Yoshiki Tsunekawa ◽  
Masahiro Okumiya
Keyword(s):  
Eutectic Reaction ◽  
Eutectic Silicon ◽  
Intermetallic Phases ◽  
The Other ◽  
Ultrasonic Vibrations ◽  
Limited Effect ◽  
Melt Treatment ◽  
Cast Alloys ◽  
Iron Intermetallic ◽  
Ultrasonic Melt Treatment

The ultrasonic melt treatment is highly efficient in controlling the size and morphology of the alpha-aluminum phase in the Al-Si cast alloys. However, the influence of this treatment on the other phases, namely: the eutectic Si and the Fe-intermetallic phases, has not been thoroughly investigated. This study was undertaken to investigate the effect of ultrasonic melt treatment on the morphology and size of these phases. Four Al-Si cast alloys, 384, 380, 356 and 356 (with 0.8% Fe), were considered in this study. The treatment temperatures were varied from about 100oC above the liquidus temperatures down to the Al-Si eutectic temperature, for different treatment times (4 to 54 s). The results showed that the Si particles are only affected by the ultrasonic vibrations when the eutectic reaction takes place under the ultrasonic field, where more compacted and large Si particles are formed. This limited effect was observed only near to the ultrasonic horn. For other investigated conditions, including treatment in the liquid and semisolid states, the Si particles were obviously unaffected by the ultrasonic treatment. On the other hand, the iron intermetallic phases changed their morphology from large plate-like particles to a more compacted globular form, by the application of ultrasonic vibrations at temperatures up to 10oC above liquidus. Treatments at higher temperatures have limited effect on the morphology of the Fe-intermetallic phases. These observations are general and apply to all the studied alloys.

scholarly journals Effect of Alloying Elements on the Sr Modification of Al-Si Cast Alloys

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 342
Author(s):  
Elisa Fracchia ◽  
Federico Simone Gobber ◽  
Mario Rosso
Keyword(s):  
Eutectic Silicon ◽  
Alloying Elements ◽  
Spherical Form ◽  
Beneficial Effects ◽  
Sr Modification ◽  
Casting Alloys ◽  
Cast Alloys ◽  
Modifying Effect ◽  
Dendritic Arm Spacing ◽  
Si Content

Strontium-based modifier alloys are commonly adopted to modify the eutectic silicon in aluminum-silicon casting alloys by changing the silicon shape from an acicular to a spherical form. Usually, the modifier alloy necessary to properly change the silicon shape depends on the silicon content, but the alloying elements’ content may have an influence. The AlSr10 master alloy’s modifying effect was studied on four Al-Si alloys through the characterization of microstructural and mechanical properties (micro-hardness and impact tests). The experimental results obtained on gravity cast samples highlighted the interdependence in the modification of silicon between the Si content and the alloying elements. After modification, a higher microstructural homogeneity characterized by a reduction of up to 22.8% in the size of intermetallics was observed, with a generalized reduction in secondary dendritic arm spacing. The presence of iron-based polygonal-shaped intermetallics negatively affects Sr modification; coarser silicon particles tend to grow close to α-Fe. The presence of casting defects such as bifilm reduces Sr modification’s beneficial effects, and little increase in absorbed impact energy is observed in this work.

scholarly journals Influence of magnesium on high-temperature structural-phase stability of Al-Ni-La system alloys

2021 ◽  
Vol 98 (2) ◽  
pp. 38-46
Author(s):  
M. M. Voron ◽  
Keyword(s):  
Elevated Temperatures ◽  
Structural Phase ◽  
Nickel Content ◽  
Magnesium Content ◽  
Cast State ◽  
Lanthanum Content ◽  
Cast Alloys ◽  
Cast Condition ◽  
Alloys Of The Al ◽  
Eutectic Component

The paper considers a relevance of the Al-Ni-La system cast alloys development as promising materials for application at elevated temperatures. The influence of magnesium on the structural-phase characteristics of alloys-representatives with a nickel content of about 2% wt. and lanthanum - about 5,5 and 11,5% wt. were studied in the cast condition and after annealing at 425 ° C for 5 hours. It is shown, that the addition of magnesium in the amount of 0,6 wt%. to alloys with a lanthanum content of 5,5 % wt. helps to increase the size of the lanthanum-containing eutectic component in the cast state, but stimulates its grinding after annealing. Since doubling the lanthanum content, magnesium has almost no effect on the structure of the eutectic in the cast state, but intensifies the process of changing its structure during annealing. In this case, the size of the eutectic components is almost unchanged and can be compared with an undoped alloy. Increasing the magnesium content twice to 1,2% wt. in the alloy with a lanthanum content of 11% wt. leads to a noticeable enlargement of Al11La3 intermetallics. After annealing, this structural component retains the characteristics of a fibrous structure and at the same time increases in size by about half. The magnesium content in the eutectic zones and in the solid solution hardly changes after annealing. The obtained data indicate the possibility of using magnesium as an additional alloying element of cast heat-resistant alloys of the Al-Ni-La system, which is able to simultaneously contribute to their strengthening both under normal conditions and at elevated temperatures. In this case, magnesium, in the amount of about 0,6% wt., also helps to preserve the fine structure of the eutectic components at high temperatures. Keywords: Al-Ni-La, Al-Ni-La-Mg, alloying, structural stability, heat resistance.

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