Properties Of Al-Si Alloys Research Articles

Effects of melt thermal treatment on cast Al-Si alloys: A review

The shape and size of primary phases (α-Al and primary Si in hypoeutectic and hypereutectic alloys, respectively), and that of eutectic Si phase significantly affect the mechanical properties of cast Al-Si alloys. The Al-Si alloys prepared by the conventional casting method have large-sized primary phases and needle-shaped eutectic Si phases along with their uneven distribution in the microstructure. This leads to poor mechanical properties in those alloys. This paper presents a review on a modified casting process known as melt thermal treatment, which has the potential to positively change the shape and size of primary and eutectic phases in Al-Si alloy without any foreign additives. Various researches that have been carried out to study the effect of melt thermal treatment on microstructure and different properties of Al-Si alloys are discussed here.

Use of artificial neural network for prediction of mechanical properties of Al-Si alloys synthesized by stir casting

Mechanical testing plays an important role in evaluating the fundamental properties of engineering materials as well as, in developing new materials. The use of conventional mathematical models in analytical calculating of the mechanical properties in most materials is very complex. In the current study Al-Si alloys were synthesized using the stir casting method. The mechanical properties as the tensile strength, Brinell hardness and wear property for the produced Al-Si alloys were investigated. Then, the obtained experimental results were used to train the artificial neural network (ANN). The neural network model is used to predict the effect of silicon content on the tensile strength, the hardness test, and wear loss for the prepared Al-Si alloys. Three neural networks were used in this study and the percent of silicon content variable was used as the ANN's input for each. Tensile test is used as ANN's output and the training function used is (traincgp) in first neural network. Also, hardness test is used as ANN's output and the training function used is (traincgf) in second neural network and wear loss test is used as ANN's output and the training function used is (traincgf) in third neural network. The obtained outcomes showed that predictions data in the applied neural networks were closer to the experimental results. The optimum mean square error (MSE) for ANNs during the tensile test, the hardness test and the wear loss test equal to 0.0335, 0.0023, 0.014 respectively and these results were satisfactory.

Microstructure, Texture and Mechanical Properties of Al Alloy A380 Prepared by Directional Solidification Method

The mechanical properties of Al-Si alloys are affected by several microstructural features such as secondary dendrite arm spacing (SDAS), size and shape of eutectic Si-particles, presence of intermetallics as well as by porosity. In the current study, Al-Si-Cu alloy A380 was prepared by a unique directional solidification method to produce samples with two different SDAS of 9 μm and 27 μm. The lower solidification rate resulted in larger SDAS, larger grain size, larger eutectic Si and larger intermetallics including Fe-rich β phase. The microstructure with higher solidification rate was found to be finer and more homogeneous with smaller eutectic Si and intermetallics. The specimen with larger SDAS exhibited stronger texture than the one with smaller SDAS. The specimen with smaller SDAS showed improved mechanical properties including YS, UTS and ductility.

Microstructure and properties of Al-Si alloys under intermediate frequency electromagnetic field

The intermediate frequency electromagnetic (IFEM) field was applied to treat Al-1%Si (high-purity) and Al-8%Si alloys during direct chill (DC) casting process. The ingot was studied by means of metallographic examination and mechanical tests. The results showed that compared to the conventional casting, both Al-1%Si and Al-8%Si alloys processed under IFEM field exhibited superior refinement as well as an enhancement in the mechanical properties, especially the elongation. Si element segregation of high purity Al-1%Si alloy had effectively improved under IFEM field. Numerical simulation was used to better understand the role of IFEM field, that showed the inducing forced convection and the subsequent achievement of a uniform temperature field of IFEM field during the solidification could be accounted for the experimental observations.

Effect of Mg and Cu Additions on Microstructure and Mechanical Properties of Squeeze Casting Al-Si-Cu-Mg Alloy

The effects of Mg and Cu additions with different contents on the mechanical properties of Al-Si alloy prepared by indirect squeeze casting have been experimentally investigated. The microstructure and mechanical properties of as-cast and T6-treated Al-Si-Cu-Mg alloys were tested by OM, SEM, DSC and tensile measurement, where the samples were produced by artificial aging at 180°C for 8 h after solution treatment at 540°C for 4 h. It has been found that for the as-cast alloys, with increasing contents of Mg and Cu the tensile strength (UTS) and yield strength (YS) increased, while the percentage elongation (El) decreased. And the optimal mechanical properties of Al-Si-Cu-Mg alloys were obtained under the content ratio of Cu/Mg within 4, where the UTS and El reached 426 MPa and 6.3% after T6 treated, respectively.

Effect of combined grain refinement and modification on microstructure and mechanical properties of hypoeutectic, eutectic and hypereutectic Al-Si alloys

The effect of melt treatment owing to the combined addition of grain refiner and modifier on the microstructure and mechanical properties of Al-Si alloys having 7% (hypoeutectic), 12% (eutectic) and 15% silicon (hypereutectic) is studied. 1 wt. % of Al-1Ti-3B Master alloy was used as grain refiner. For modification of eutectic Si, 0.2 wt. % of Al-10Sr Master alloy was added to hypoeutectic alloy and 0.4 wt. % is added to eutectic alloy as well as hypereutectic alloy. Furthermore, refinement of primary Si in hypereutectic alloy was achieved by addition of 0.04 wt. % of phosphorus. The goal of this investigation is to determine the influence of combined addition of grain refiner and modifier on mechanical properties and qualitatively correlate with the microstructural changes.

New High Strength and Heat Resistance Aluminum Alloy Material for Engine Cylinder Head

The effect of Cu、Ni、Fe、Mn on the mechanical properties of Al-Si alloy by orthogonal experiment method was investigated in this paper. By tensile testing and microstructure analysis, the content Ni element is 1% under the condition of Cu. The addition of Fe can improve high temperature strengthening of the alloy. However, we need to control the ratio of Fe and Mn to prevent the appearance of β phase, and reduce herringbone Fe phase. The best content of Cu、Ni、Fe、Mn is 1%,0.7%,0.9% and 0.5%. Thus the alloy’s room temperature and high temperaturetensile strength reaches 249MPa and 212MPa, fully meet the requirements of high-temperature load of the cylinder head.

An Investigation of the Effect of Surface Refining on the Hardness and the Wear Properties of Al-Si Alloy

Surface refining of Al–Si alloy was carried out using the GTA heat source. It was observed that the microstructure contains a globular shaped eutectic – Si distribution within the α–Al matrix. The hardness is found to increase and the wear is found to decrease upon surface refining. The precipitation hardening treatment was effective in increasing the hardness of the modified layer. The GTA heat source has been successfully applied to the surface refining of the Al–Si alloy. The result of this study is comparable to those of previous studies.

Effect of B Refinement on Structure and Fracture Morphology of Al-7 wt.% Si Alloy

Using optical microscope, electronic tensile testing machine, scanning electron microscopy methods, such as detailed treatment of the B hypoeutectic Al-Si alloy microstructure, mechanical properties and fracture morphology were studied. The results showed that after treatment by the B refinement, α-Al dendrite phase was refined, resulting in mechanical properties of Al-Si alloy significantly improved. Which, B content 0.036wt.%, the alloy the best, the σb, δ, respectively, than the non-thinning increased 67.8% and 15.2%. From the fracture surface, the fracture morphology of the specimen showed a quasi-cleavage fracture. Which, B content 0.036wt.% at the time of fracture is more deep dimples, and a good plastic toughness.

Effect of Cobalt content on mechanical properties of Al-Si alloy

This work encompasses studying the effect of different contents of Co on Al-Si alloy with Sb modification prepared by stir casting method. The content of Co is varying from 0 to 1.2wt%, The effect of Cobalt on microstructure, micro hardness, tensile strength and wear rate were studied extensively. The results show that the intermetallic compounds was increased with the increasing of Cobalt content .The Co-bearing compounds presented as small block shape at first and gradually turned into dendrite or fish bone shape. The addition of Co has appositive effect on tensile strength of the Al-Si alloys that used in the current research, the maximum tensile strength was (177MPa) when Co content was 0.9%Co at room temperature as well as wear rate were studied in this paper and noticed that the addition at 0.9%Co had the better effect at low and high load(5N),(10N).

Effect of Pulse Magnetic Field on Primary Silicon in Al-20Si Alloy

Due to its good wear resistance, Al-20Si is widely used as piston. But coarse primary silicon greatly undermines the mechanical properties of Al-Si alloy. The primary silicon could be refined in pulse magnetic field with suitable magnetic flux density and magnetic field frequency. In this work, the microstructure of Al-20Si alloy with and without pulse magnetic field treatments was observed, and the influence mechanism of weak pulse magnetic on the microstructure of the alloy was investigated. The results showed that the grain size of primary silicon fluctuated with increasing magnetic flux density at 1Hz. The smallest grain size of primary silicon is obtained at 94mT. The grain size of the primary silicon decreased with increasing magnetic field frequency under the magnetic flux density of 94mT.

Preparation of Density Ceramic and Fiber Joining Materials

The joining materials of density ceramics and the fibre would be potential value as sealing materials for high-temperature seal field. Zirconia toughened mullite ceramics (ZTM) were chosen the density ceramics due to excellent high temperature mechanical properties. Aluminum silica ceramic fibre was attractive because of favorable elasticity properties. Combining the two materials, the high-temperature resistance elasticity seal materials would be prepared by microwave joining technique. Using the absorber-microwaves properties of Al-Si alloy, interlayer compositions of the joining materials were designed. The ZTM ceramics and fibers materials were joining by microwave hybrid heating method and the mechanism of microwave joining was discussed.

Effects of Grain Refining and Modification on Mechanical Properties and Microstructures of Multielement Al-7.5Si Cast Alloy

With orthogonal tests the effects of grain refiners and modifiers, Al-10Sr, rare earth (RE) and Al-Ti-5B, on the mechanical properties of Al-Si alloy for automobile cylinder blocks were studied. The best result occurred when the proportion of refiners and modifiers was Al-10Sr = 0.1wt%, RE = 0.3wt%, Al-5Ti-B = 0.8wt%. With SEM and EDS the as-cast microstructures of materials after grain refining and modification were observed and analyzed. Tiny branch-shaped AlSi phase, thin-striped AlCu phase, new small bone-shaped AlSiMn phase, new leaf-shaped or feathered B(AlCuCe) phase as well as the phases of other metal compounds made the as-cast microstructures more complicated and more compact after grain refining and modification. Some brittle phases reduced in size obviously and distributed in the grain boundaries of plastic α-phase in network, which acted as intercrystalline strengthening to certain degree. During the tensile deformation these brittle phases could reduce the stress concentration, impeded dislocation movement, and then strengthened the alloy matrix. In addition after grain refining and modification the porosity was significantly reduced.

A Novel Material Preparation of Density Ceramics and Fibre Joining

The joining materials of density ceramics and woven fibres would be potential value as sealing parts for thermal protection system application in aerospace field. Based on ZrO2-Al2O3-SiO2 phase diagram, the ceramics matrix and interlayer compositions were designed. Using the absorber-microwaves properties of Al-Si alloy, the joining of ZTM ceramics and fibre materials with interlayer was achieved by microwave hybrid heating method. The experiment results indicated that the interlayer ingredients were mullite, zirconia and alumina after microwave sintering. The strength of joint specimens was related with the interlayer compositions and the specimen preserved elasticity property according to the test result of universal testing machine. The joint mechanism of interlayer by microwave sintering was discussed in this paper.

Effects of High Density Ultrasonic Field Coupling on the Microstructures and Properties of Al-Si Alloy

The effects of high density ultrasonic field coupling on the microstructures and properties of Al-12Si alloy were investigated. It is shown that when the melt undergoes ultrasonic coupling processing prior to solidification, the nucleation rate of liquid phase can be raised to make α(Al) dendrite transform towards near equiaxed grains, the growth of Si phase is restrained and eutectic Si microstructure is refined due to acoustic streaming effect and thermal mechanism; When the melt undergoes ultrasonic coupling processing during the melt solidification, large degree of supercooling is produced in the liquid phase in the solidification interface front edge to reduce the critical radius of crystal nucleus and critical work of nucleation and break up, rupture by melting and refine the Si phase to improve obviously the strength of Al-12Si alloy due to its cavitation effect, acoustic streaming action and heat undulation; The crushing effect of ultrasonic coupling on Si phase occurs mainly during the crystallizing solidification and threshold sound intensity exists.

The Interlayer Designation for ZTM Ceramics and Fibre Joining

The joining materials of density ceramics and the fibre would be potential application value as seal materials at high temperature condition or in aerospace field. According to chemical composition consistent principle of ceramics/interfaces/fibre, the interlayer of mullite ingredient was designed which based on the ZTM ceramics composition. Using the absorber-microwaves properties of Al-Si alloy, the joining of ZTM ceramics and fibre materials with interlayer was achieved by microwave hybrid heating method. The experiment results indicated that the volume expansion of interlayer was about 4.8% when the content of Al-Si was 24 wt % in the compositions. The interlayer ingredients were mullite, zirconia and alumina after sintering. The fibres were better joint with interlayer by microwave sintering than by traditional method.

Structure and physicomechanical properties of Al-Si alloys

Al-Si alloy samples with a silicon content of 8–15 wt % are grown by the Stepanov method at a solidification rate of 102 and 103 μm/s. The microstructure of the samples is examined, and the stress-strain curves obtained during tension and bending at a strain rate of 10−4 s−1 are studied. The behavior of Young’s modulus, the modulus defect, and ultrasonic attenuation is investigated. The silicon content in a eutectic structure is found to increase with the solidification rate. The yield strength and the ultimate tensile strength increase with the silicon content up to a eutectic composition. The quality index (which characterizes the strength and plasticity of the material) of Stepanov-grown samples is higher than the quality indices of traditional modified ingots.

Influence of Magnesium on Structure and Properties of Al-Si Alloy

Aluminium-silicon alloys have low density, high electrical and thermal conductivity and high resistance to corrosion at ambient temperature. However, these alloys usually contain numerous alloying and impurity elements, which consist essentially of a fairly ductile matrix of alpha aluminium solid solution with a variety of non-ductile particles of silicon and various intermetallic compounds. The shape and distribution of these constituents largely control the deformation behaviour of the alloy. The addition of magnesium makes the alloys lighter and harder, but its hardening effect is fully responsive only after proper heat treatment. Therefore, in the present study, microstructures and properties of the alloys have been evaluated on the as-cast and heattreated conditions. Results show that the addition of magnesium to aluminium-silicon eutectic base alloy refines microstructure up to certain level and increases the strength and hardness at the expense of ductility.

1604 Al-Si合金の曲げ特性に及ぼす切削加工の影響(S79-2 先端材料と加工(2),S79 先端材料と加工)

1604 Al-Si合金の曲げ特性に及ぼす切削加工の影響(S79-2 先端材料と加工(2),S79 先端材料と加工)

TEM Investigation of Spherical Primary Si Particles in As-Quenched Al60Si40 Ribbons

Al-Si alloys with high Si content are attractive in engineering application, especially in automobile industry. Their mechanical properties and machinability are quite sensitive to the morphology of the primary Si phase. In order to improve the mechanical properties of Al-Si alloys, optimizing the shape and distribution of the primary Si are quite important. In this paper, the microstructure of the primary Si in the Al 60 Si 40 alloys prepared by rapid solidification method has been studied used the transmission electron microscope (TEM).