Eutectic Aluminium Silicon Alloy Research Articles

Influence of various titanium-containing additives on the modification efficiency of aluminum–silicon eutectic alloy

This study investigates the impact of titanium addition to the eutectic silumin AK12 melt, considering various methods of addition. The research results encompass the sole introduction of titanium (at a calculated amount of 0.1 wt.%) through different forms/methods, such as the Al–4%Ti ligature, TiO2 oxide, K2TiF6 salt, and Ti sponge. Additionally, the study explores the combined addition of titanium and a standard flux (comprising 62.5 % NaCl + 12.5 % KCl + 25 % NaF). The research involved qualitative and quantitative analyses of macro- and microstructures, spectral analysis data, and mechanical properties (tensile strength and relative elongation) of the alloys. The findings highlight that titanium has a positive influence on the structure of eutectic silumin, with the most effective results achieved when combined with the standard flux. However, the efficiency of silumin modification with titanium varies depending on the method of addition. Specifically, the introduction of titanium in the form of K2TiF6 fluoride salt, Al–4%Ti ligature, and titanium sponge positively affected macro grain refinement, reduced the spacing between the secondary dendrite arms of the solid solution (α-Al), and enhanced the dispersion of eutectic silicon. The most promising approach for complex silumin modification involves the joint introduction of titanium-containing substances and a sodium salt-based flux. This combination has a multifaceted impact on the silumin structure, leading to the simultaneous modification of various structural components in aluminum–silicon alloys. Depending on the type of titanium-containing substance, when processed alongside flux, the alloy achieves a relative elongation ranging from 9.7 % to 11.1 %, exceeding the same parameter for the unmodified alloy by more than 4 times and surpassing the sodium-modified alloy's relative elongation by 17–37 %. Furthermore, the ultimate strength reaches levels of 171–193 MPa, representing a 22–38 % improvement compared to the unmodified alloy and a 7–21 % increase compared to the sodium-modified alloy.

Effect of Stroke Length (50 mm and 100 mm) on the Dry Reciprocating Wear Characteristics of Refined and Unrefined A390 Alloy

The present work reports the influence of stroke lengths viz. 50 mm and 100 mm on the reciprocating wear characteristics of refined and unrefined hyper eutectic aluminium silicon alloy (A390). The refined A390 alloy was prepared through the electromagnetic stirring process along with the addition of 0.1 wt.% Al–5Ti–B grain refiner. The wear tests were performed in an indigenously developed pin on reciprocating plate tribometer conforming to ASTM G 133-05 standard. The microstructure had shown the refinement of eutectic silicon and decrease in size of polyhedral primary silicon particles due to the combined action of grain refiner addition and electromagnetic stirring. Refined and unrefined A390 alloys were heat treated under T6 condition. Hardness of the refined A390 alloy (107 BHN) was higher than that of unrefined A390 alloy (89 BHN). Reciprocating wear tests were conducted at two stroke lengths with contact loads varied from 15 N to 60 N and the linear velocity from 0.2 m/s to 1.0 m/s for a constant sliding distance of 350 m. During the wear tests it was observed that as the velocity varied from 0.2 m/s to 0.4 m/s the wear loss was found to decrease at both stroke lengths tested for refined and unrefined samples, further increase in velocity increases the wear rate. As the stroke length varied from 50 mm to 100 mm the wear loss was found to decrease for both refined and unrefined alloys. This reduction in wear loss with increase in stroke length was due to the reduced reversals of load happening at larger stroke length (100 mm) also the frequency of reciprocation is high at 50 mm stroke length compared to that at 100 mm for the similar sliding conditions tested.

Assessment of the effect of 3D printed sand mold thickness on solidification process of AlSi13 casting alloy

The present work addresses the printed sand mold thickness effect on the solidification process of a eutectic aluminum-silicon alloy (AlSi13). Several sand mold thicknesses (varying from 3 to 30 mm) are numerically studied using Quikcast® software. The study shows that the solidification time decreases when the sand thickness of mold increases. It is accelerated by more than 40% when the sand mold thickness increases from 3 to 30 mm. The numerical simulations are coupled with experiments. Indeed, the 3D sand printing process is used to fabricate molds presenting different thicknesses of 5 mm and 30 mm, respectively. In addition, the same printing parameters are applied for producing all sand molds. The comparison between both numerical and experimental results shows the same tendency according to the sand mold thickness. The results indicate that increasing the sand mold thickness from 5 to 30 mm allows to accelerate the solidification by 17% and 18.6%, respectively, in the numerical and experimental results. A finer microstructure is obtained when reducing the solidification time, which enhances the hardness of casting properties.

Study on mechanical and wear properties of hypereutectic Al-18Si-3.6Cu-0.34Ce alloy

In the present study an effort was made to find the mechanical and wear properties of a heat treatable hyper eutectic aluminium-silicon alloy. The alloy was prepared by conventional casting method in the form of ingots, and then chemical compositions of the alloy analysis are made by spectro spark emission spectrometer. The as cast alloy test samples are T6 heat treated by solutionizing at 500°C for 1h followed by water quenching and isothermal ageing treatment at 210°C for different aging time was achieved. The tensile test was carried out for as cast and cast aged conditions of different aging time of 1h, 3h, 5h and 7h. It was observed from tensile test the ultimate tensile strength of 1h (193.83Mpa) and 3h (168.68Mpa) aged (T6 treated) samples improved the UTS by 22% and 7% respectively as compared to as cast sample (158Mpa). Dry sliding Wear test was conducted at constant sliding speed of 1m/s, 2m/s, 3m/s and 4m/s. with varying load 10-40N. From the dry sliding wear study confirmed that wear rate and coefficient of friction are load dominant, In spite at higher sliding speed and load lower friction was noticed.

Reinforcing the Near Eutectic Aluminum–Silicon Alloy with Graphene: An Approach toward Self‐Lubricating Composite

Mechanical and physical properties of aluminum alloys make them suitable for automotive and other structural applications. The high silicon content in aluminum improves the hardness to a great extent but at the cost of ductility. Herein, the reinforcement of near eutectic Al–Si (ADC12) alloy with the reduced graphene oxide (rGO) is demonstrated. The ADC12 alloy and its composite with rGO are cast using the gravity stir die‐casting process. The structural, mechanical, metallurgical, and tribological characteristics are conducted to understand the role of rGO as a reinforcement phase. The 0.7 wt% rGO as a reinforcement phase to ADC12 alloy reduces the friction and wear volume by 50% and ≈90%, respectively, whereas it improves the hardness by 27%. The high‐resolution transmission electron microscopy (TEM) image reveals the wrapping of microstructural silicon by rGO, which inhibits the growth of primary silicon and improves the interfacial strengthening. The high mechanical strength and low shearing properties of rGO, uniform dispersion in the ADC12 alloy, and restrained growth of primary silicon make the ADC12 alloy‐based composites potential materials for structural and low‐frictional building blocks in a diversified range of applications.

Tribological behavior of aluminum silicon eutectic alloy based composites under dry and wet sliding for variable load and sliding distance

In most of the studies, the tribopair as well as tribo-components interfaces are lubricated using different lubricating oil or solid tribofilms. In the present study, the anti-friction and anti-wear performance of the tribopair is improved using nano-Aluminium Oxide (Al2O3) and Graphene Nano Platelets (GNP) as reinforcement for composite and additive for lubricant respectively. Composite material and nano lubricants have attracted the interest of many researchers around the globe to enhance the life, durability and to reduce the friction and wear losses of mechanical components. Hence the objective of this study is to provide an insight to friction and wear reduction behavior of n–Al2O3 and GNP from the tribological aspect. The samples are fabricated using Spark Plasma Sintering (SPS) rapid fabrication route and their tribological properties are determined against chromium-plated-chrome-steel under dry and wet conditions at room temperature using universal reciprocating tribometer. From the results, it is reported that composite samples with (PAO-4 + 0.5 wt% GNP + OA) nano-lubricant exhibit excellent tribological properties. This reduction is friction and wear is attributed to the hard phase ceramic reinforcements and nano-additive in lubricant that provides excellent tribological performance as well as Oleic Acid (OA) which help to improve the dispersion stability of the nano particles in the lubricating oil. Different surface characterization tools i.e. Optical Microscopy, Scanning Electron Microscopy, Electron Dispersion Spectroscopy, 3D surface profilometer are used in this study to understand the wear and lubrication mechanism after tribological testing.

Effect of Section Size as a Measure of Cooling Rate on the Solidified Microstructure and Mechanical Properties of Sand-Cast Al-Si Eutectic Alloy

Several factors contribute to the development of structure and properties of aluminiumalloy castings. This study investigated the singular effect of cooling rate on the as-cast structure andmechanical properties of an aluminum-silicon eutectic alloy, keeping other factors such as pouringtemperature, melt treatments, physical and thermal properties of the mould, and alloy compositionconstant. The rate of cooling was varied by employing different casting section sizes, based on thevariation of rate of heat extraction given by solidification time as predicted by the Chvorinov’s rule.Four test bars of section sizes 10, 20, 30, and 40 mm respectively were cast in sand mould using thesame gating system. Spectrometric analysis of the alloy formulated revealed that it could be specifiedapproximately as Al-12.8Si-1.0Cu alloy. The study showed that as section size decreased from 40mm to 10 mm; the solidification time reduced (i.e. the cooling rate increased), the microstructure gotfiner, the silicon flakes became more uniformly distributed, and the mechanical properties generallyimproved. The tensile strength, ductility, and hardness all increased in the order of decreasing sectionsize, i.e. increasing cooling rate. The mechanical properties were found to be linearly correlated withsection size or cooling rate. Whereas the elongations were lower than values for pure aluminium, thestrength and hardness were significantly higher than values for the pure metal. It is concluded thatthe cooling rate modifies the microstructure and improves the mechanical properties of as-cast Al–Sieutectic alloys

Effect of Section Size as a Measure of Cooling Rate on the Solidified Microstructure and Mechanical Properties of Sand-Cast Al-Si Eutectic Alloy

Several factors contribute to the development of structure and properties of aluminiumalloy castings. This study investigated the singular effect of cooling rate on the as-cast structure andmechanical properties of an aluminum-silicon eutectic alloy, keeping other factors such as pouringtemperature, melt treatments, physical and thermal properties of the mould, and alloy compositionconstant. The rate of cooling was varied by employing different casting section sizes, based on thevariation of rate of heat extraction given by solidification time as predicted by the Chvorinov’s rule.Four test bars of section sizes 10, 20, 30, and 40 mm respectively were cast in sand mould using thesame gating system. Spectrometric analysis of the alloy formulated revealed that it could be specifiedapproximately as Al-12.8Si-1.0Cu alloy. The study showed that as section size decreased from 40mm to 10 mm; the solidification time reduced (i.e. the cooling rate increased), the microstructure gotfiner, the silicon flakes became more uniformly distributed, and the mechanical properties generallyimproved. The tensile strength, ductility, and hardness all increased in the order of decreasing sectionsize, i.e. increasing cooling rate. The mechanical properties were found to be linearly correlated withsection size or cooling rate. Whereas the elongations were lower than values for pure aluminium, thestrength and hardness were significantly higher than values for the pure metal. It is concluded thatthe cooling rate modifies the microstructure and improves the mechanical properties of as-cast Al–Sieutectic alloys

Effects of Surface Roughness Parameters on Tribological Performance for Micro-textured Eutectic Aluminum–Silicon Alloy

Abstract Micro-textured samples with different depths exhibit various contact surface morphology parameters including Sa, Sq, Ssk, and Sku, and material ratio curves. In this paper, the relationship between micro-textures and roughness parameters was investigated. The effect mechanism of micro-textures on the friction and wear through the height and functional roughness parameters was elucidated. Micro-textured samples presented more negative Ssk, higher Sku, and larger Svk with the increasing dimple depth. The pin-on-disc reciprocating tribological test results indicated that the more negative Ssk, higher Sku, and larger Svk presented lower friction coefficient under the constant Sa and Sq. The wear topographies for the flat and micro-textured specimens with various dimple depths were examined by laser scanning confocal microscope. X-ray photoelectron spectroscopy was employed to describe the formation of absorbed film and tribofilm on the worn surface of flat and micro-textured samples. It was confirmed that more negative Ssk, higher Sku, and material ratio curves with their relative parameters (smaller value of Spk, Sk, Smr1, and larger value of Svk) could be used for predicting the tribological performance of micro-textured samples.

Synergetic Effect of Discontinuous Carbon Fibers and Graphite Flakes on Thermo-Mechanical Properties of Aluminum Matrix Composites Fabricated by Solid–Liquid Phase Sintering

Aluminum (Al) matrix composite materials reinforced with graphite flakes (GF) and pitch-based carbon fibers (CF) were fabricated by solid–liquid phase sintering with a small amount of Aluminum–Silicon eutectic alloy (Al-12 wt%Si). The amount of Al–Si is optimized for a carbon content of 50 vol% in order to achieve, in the plane of GF reinforcement, a higher thermal conductivity (TC) and a lower coefficient of thermal expansion (CTE) compared to identical composite material fabricated by conventional powder metallurgy route. Al/(GF + CF) composite materials were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray microscopy and X-ray tomography in order to highlight the distribution of the Al–Si liquid phase and the formation of a carbon network in the aluminum matrix. A small amount of CF allows to control the through-plane CTE without affecting significantly the in-plane TC of the Al-C composites. The (GF + CF) mixture and the solid–liquid phase sintering allow to achieve a TC of 410 W/m K (in-plane direction) and a CTE of 2.4 × 10−6/K (trough-plane direction), which is, for example, applicable for lightweight heat sink material.

Effect of boron on microstructure and mechanical properties of eutectic aluminum‐silicon alloy modified with phosphorus

AbstractIn order to understand the effect of boron on the microstructure and mechanical properties of eutectic aluminum‐silicon alloy modified with phosphorus, complex modification of eutectic aluminum‐silicon alloy by aluminum‐3phosphorus and aluminum‐3boron was conducted. The results show that the area fraction of primary α‐aluminum in eutectic aluminum‐silicon alloy modified with aluminum‐3phosphorus increased first and then decreased with increasing amounts of aluminum‐3boron. The area fraction and the size of primary silicon decreased rapidly first and then stabilized. The morphology of eutectic silicon transformed from needle‐like into fine short rods or granules after complex modification with aluminum‐3phosphorus and aluminum‐3boron. The ultimate tensile strength of the alloy modified with 0.4 wt.% aluminum‐3phosphorus and 0.2 wt.% aluminum‐3boron increased by 18 %, compared with that of the eutectic aluminum‐silicon alloy modified with aluminum‐3phosphorus, while the elongation decreased by 5 %. It was concluded that the comprehensive mechanical properties of eutectic aluminum‐silicon alloy were improved.

Surface Characterization and Tribological Performance of Anodizing Micro-Textured Aluminum-Silicon Alloys.

Eutectic aluminum-silicon alloys present high frictional coefficient and a high wear rate due to the low hardness under sliding friction conditions. In this paper, the eutectic aluminum-silicon alloy was textured firstly by micro-milling operations. Then, the micro-textured specimen was subjected to anodizing to fabricate alumina films. The surface topography, surface roughness, and bearing area ratio of micro-textured and anodizing micro-textured specimens were measured and characterized. For the anodizing micro-textured specimens, the surface roughness and superficial hardness increase compared with those for micro-textured ones. Tribological tests indicate that anodizing micro-textured samples present lower friction coefficient of 0.37 than that of flat samples of 0.43 under dry sliding conditions. However, they exhibit higher friction coefficient at 0.16 than that of flat samples of 0.13 under oil-lubricated conditions. The difference between the friction coefficient of anodizing micro-textured and flat samples under dry and oil-lubricated conditions is ascribed to the influence mechanism of surface roughness, bearing area ratio curves, and its relative parameters on the tribological performance of testing samples. The dry sliding friction coefficient has a positive correlation with bearing area ratio curves, while they present negative correlation with bearing area ratio curves under oil-lubricated conditions. The synergy method treated with micro-milling and anodizing provides an effective approach to enhance the dry sliding friction property of eutectic aluminum-silicon alloys.

Analysis of dimple structure fabricated using turning process and subsequent reduction in friction

Dimples is an important structure in the context of surface texturing due to its role in improving the heat transfer while minimizing wear and friction on sliding mechanical components. In this study, various sizes and shapes of dimple structures were fabricated on a cylindrical surface of a hyper eutectic aluminum silicon alloy (A390) using the turning process with the aid of a dynamic-assisted tooling (DATT), which was designed and fabricated in-house. The turning process was selected based on factors such as the capability of its machining process, low cost, minimum setup time, and green working environment. The dimples’ shapes fabricated in this study were short drop, long drop, and spherical, with widths of 397–920 µm, lengths of 2420–3261 µm, depths of 64–155 µm, and area ratios of 10–15.68%. The tribology test conducted on the samples confirmed that the coefficient of friction of these dimples in a hydrodynamic regime was 0.22–0.24 relative to the smooth surface's at 0.5, which is a maximum of 56% friction reduction. No microstructural changes were observed beneath the machined surface of the dimpled area and surface roughness (Ra) in the case of both dimple and non-dimpled surfaces. Dimple fabrication using the turning process is therefore recommended to the manufacturing industry if they intend to preserve material properties within friendly working environment(s).

The influence of SiO2 nanoparticles addition into electrolyte on the thermal conductivity of oxide layer formed on eutectic aluminum-silicon alloy by PEO

Oxide layers formed by plasma electrolytic oxidation with SiO2 nanoparticles addition into electrolyte on eutectic aluminum-silicon alloy were investigated by scanning electronic microscopy (SEM), energy dispersive X-ray microanalysis (EDXMA) and X-ray diffraction (XRD) analysis. The thermal conductivity of oxide layers was measured by constant heat flow method. Obtained values of the thermal conductivity of oxide layers are significantly smaller than the values of oxide layer components as bulk materials. Decreasing of thermal conductivity of oxide layer in ratio of two is observed if SiO2 nanoparticles are added into electrolyte. It is shown that the sedimentation of nanoparticles into oxide layer and decreasing of crystalline sizes are the reasons of decreasing of thermal conductivity.

The effect of removing worn particles by ultrasonic cleaning on the wear characterization of LM13 alloy

In this research, three dry sliding wear tests have been carried out with a pin-on-disk apparatus at the sliding speed of 0.17 m/s and under 30 N normal load. The eutectic aluminium-silicon alloy (LM13 alloy) and tool steel have been selected as wearing surfaces. In order to focus on the effect of worn particles, they have been removed periodically by ultrasonic cleaning during one test, while another one has been carried out without applying ultrasonic cleaning. To study the variation of the wear behavior, one more test has been running continuously. During the formation and removal of the tribolayer under the control of the wear behavior without ultrasonic cleaning, a mild wear regime and a lower wear rate have been observed. As to the severe regime, it has been observed at the removal of some parts of the tribolayer when the cleaning was applied.

Microstructure Evolution of Conventional and Semi-Solid A356 Alloy with Addition of Strontium

In this study, modification of aluminium silicon eutectic alloy by grain modifier, strontium was investigated on conventional and slope cast A356 alloy. A356 alloy with addition of 0 to 0.97 wt.% Sr was prepared by conventional and slope casting in melting furnace. The molten metal of A356 alloy was casted into steel mould. Microstructure was observed using SEM. Phase analysis was done using XRD. Microhardness was conducted using Vicker microhardness. Microstructure of conventional cast displayed dendritic structure whereas slope cast displayed globular structure. Addition of Sr refined eutectic structure in both conventional and slope cast alloy. Phase analysis revealed the presence of Al2Sr phase in conventional cast Al-6Si-0.97Sr. Microhardness of the conventional cast alloy decreased with increasing of Sr up to 0.97 wt.%.

G0400506 炭素繊維含有アルミニウム基複合材料の機械的性質と微視観察

Recently, aluminium (Al) based composites containing each carbon fibers (CF), such as carbon nanotubes (CNT), and vapor-growth carbon fibers (VGCF), are actively developed. These fibers have high thermal conductivities and high strengths. And then Al/VGCF composites fabricated using spark plasma sintering are known to have a high thermal conductivity. The composites are anticipated using for the application of heat exchangers. In this paper, an Al/CF composite are fabricated using sintering process. The relationship between microstructures and mechanical properties are considered using the sintering composites. First, an optimum sintering conditions of matrix in Al and Aluminum silicon eutectic alloy (Al-12Si) are considered, by measurement of porosity ratio, Vickers hardness test, and microscopic observation. And then, a relationship between microstructure of the composite and the hardness are considered. According to the experimental results, the composite with Al-12Si has lower porosity ratio than the composite without Al-12Si. The Vickers hardness correlates highly with the porosity ratio.

Simulation and Testing of a Latent Heat Thermal Energy Storage Unit with Metallic Phase Change Material

Latent heat thermal energy storage in metallic phase change materials offers a thermal energy storage concept that can store energy at higher temperatures than with sensible thermal energy storage. This may enable the use of high efficiency thermodynamic cycles in CSP applications, which may lead to a reduction in levelised cost of electricity. Eutectic aluminum silicon alloy, AlSi12, is an attractive phase change material because of its moderate melting temperature, high thermal conductivity, and high heat of fusion. A prototype thermal energy storage test rig has been built and tested as to better understand the behavior of latent heat thermal energy storage. A mathematical model was developed to predict the behavior of such a heat storage unit. The model was compared with the behavior of the test rig during discharge. The model proved to simulate the latent heat thermal energy storage with reasonable accuracy. It is recommended that more accurate material property data be obtained and that the thermal energy storage test rig be modified as to improve readings.

High Temperature Thermal Energy Storage Utilizing Metallic Phase Change Materials and Metallic Heat Transfer Fluids

Cost and volume savings are some of the advantages offered by the use of latent heat thermal energy storage (TES). Metallic phase change materials (PCMs) have high thermal conductivity, which relate to high charging and discharging rates in TES system, and can operate at temperatures exceeding 560 °C. In the study, a eutectic aluminium–silicon alloy, AlSi12, is identified as a good potential PCM. AlSi12 has a melting temperature of 577 °C, which is above the working temperature of regular heat transfer fluids (HTFs). The eutectic sodium–potassium alloy (NaK) is identified as an ideal HTF in a storage system that uses metallic PCMs. A concept is presented that integrates the TES-unit and steam generator into one unit. As NaK is highly reactive with water, the inherently high thermal conductivity of AlSi12 is utilized in order to create a safe concept. As a proof of concept, a steam power-generating cycle was considered that is especially suited for a TES using AlSi12 as PCM. The plant was designed to deliver 100 MW with 15 h of storage. Thermodynamic and heat transfer analysis showed that the concept is viable. The analysis indicated that the cost of the AlSi12 storage material is 14.7 US$per kWh of thermal energy storage.

Aluminum reinforcement by gas tungsten arc welding

AbstractAluminum is a light metal and is widely used in a variety of industries. Aluminum-silicon has good casting properties but does not offer any suitable tribological properties. Therefore, in this study surface composite coating was performed by the gas tungsten arc welding (GTAW) process, which increased hardness up to 34 HV, which is nearly two times compared to untreated specimens. This process is done by composite manufacturing with the silicon carbide reinforcement particles in the matrix of eutectic aluminum-silicon alloy. The mixed powder is deposited on the surface during melting by travelling the arc of GTAW. The desired optimum performance condition is achieved by arc current 75 amp, 1 g of poly vinyl alcohol (PVA) binder, 65 wt.% of aluminum powder and 15 wt.% of silicon carbide.