• Journal of Power System Engineering
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• v.9 no.4
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• pp.130-136
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• 2005

The effects of additional Mg content, the size and volume fraction of reinforcement phase on the mechanical properties of ceramic particle reinforced aluminium matrix composites fabricated by pressureless metal infiltration process were investigated. The hardness of $SiC_p/AC8A$ composites increased gradually with an increase in the additive Mg content, while the bending strength of $SiC_p/AC8A$ composites increased with an increase in additive Mg content up to 5%. However, this decreased when the level of additive Mg content was greater than 5% due to the formation of coarse precipitates by excessive Mg reaction and an increase in the porosity level. The hardness and strength of the composites increased with decreasing the size of SiC particle. It was found that the composites with smaller particles enhanced the interfacial bonding than those with bigger particles from fractography of the composites. The hardness of $Al_2O_{3p}/AC8A$ composites increased gradually with an increase in the volume fraction, however, the bending strength of $Al_2O_{3p}/AC8A$ composites decreased when the volume fraction of alumina particle was greater than 40% owing to the high porosity level.

• Composites Research
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• v.33 no.5
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• pp.241-246
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• 2020

In this study, aluminum (Al) alloy matrix composites in which B₄C particles were uniformly dispersed was manufactured through stir casting followed by hot rolling process. The microstructure, mechanical properties, and wear resistance properties of the prepared composites were analyzed. The composite in which the 40 ㎛ sized B₄C particles were uniformly dispersed increased the tensile strength and improved wear performance as the volume ratio of the reinforcement increased. In the case of the 20 vol.% composite, the tensile strength was 292 MPa, which was 155% higher than that of the Al6061. As a result of the wear resistance test, the wear width and depth of the 20 vol.% B₄C/Al6061 composites were 856 ㎛, and 36 ㎛, and the friction coefficient was 0.382, which were considerably superior to Al6061.

• Composites Research
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• v.20 no.4
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• pp.9-17
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• 2007

Powder metallurgy has been employed for the development of SiC particle reinforced aluminum metal matrix composites by means of hot isotropic pressing and vacuum hot pressing. A material model based on micro-mechanical approach then has been presented for the processes. Densification occurs by the inelastic flow of matrix materials during the consolidation, and consequently it depends on many process conditions such as applied pressure, temperature and volume fraction of reinforcement. The model is implemented into finite element software so that the process simulation can be performed enabling the predicted relative density to be compared with experimental data. In order to determine the performance of finished products, further tensile test has been conducted using the developed specimens. The effect of internal void of the materials on mechanical properties therefore can be investigated.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.131-134
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• 2002

Braided carbon fiber reinforced Al matrix composites were developed and characterized. Braided carbon fiber preforms with braiding angles of $30^{\circ}$, $45^{\circ}$ and $60^{\circ}$ were manufactured by using a braiding machine. The manufactured braided carbon fibers were used as reinforcement to fabricate Al matrix composites by employing a pressure infiltration casting method. In the processing of pressure infiltration casting, important processing parameters such as melting temperature, preheating temperature of preform and applied pressure were optimized. Prediction of elastic constants on composites was performed by using the volume averaging method, which utilizes the coordinate transformation and the averaging of stiffeness and compliance constants based upon the volume of each reinforcement and matrix material. The elastic moduli of composites were evaluated by using Resonant Ultrasound Spectroscopy(RUS) method and compared with the elastic moduli obtained from static tensile test method.

• Journal of Power System Engineering
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• v.3 no.2
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• pp.57-63
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• 1999

The fabrication of $Al_2O_3/Al$ composites by pressureless infiltration technique was made to investigate the effects of processing variables such as content of Mg, processing temperature and time on the infiltration behavior of molten Al and microstructure. When the pure Al was infiltrated into mixtures of Mg and $Al_2O_3$ powder, processing temperature required to spontaneous infiltration was decreased and critical processing temperature and Mg content were $700^{\circ}C$ and 3wt% respectively. The content of Mg was found the most powerful variable for infiltration of molten Al. The infiltration ratio increased with Mg content and processing temperature, however the $Al_2O_3/Al$ composites which were fabricated by high Mg content and processing temperature resulted in non uniform dispersion of $Al_2O_3$ particles by excessive interfacial reaction. XRD pattern indicated that $MgAl_2O_4$ and AIN was observed at the interface of $Al_2O_3$ particles and in the Al matrix as reaction products.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.2
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• pp.475-485
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• 1995

In this study, statistical analysis of fatigue data which had obtained from respective 24 fatigue crack, was examined for SiC whisker reinforced aluminium 6061 composite alloy (SiC$_{w}$/A16061) and aluminium 6061 alloy. SiC volume fraction in composite alloy is 25%. The analysis results stress intensity factor range and 0.1 mm fatigue crack initiation life for SiC$_{w}$/A16061 composite & A16061 matrix are the log-normal distribution. And regression analysis by linear model, exponential model and multiplicative model were performed to find out the relationship between fatigue crack growth rate(da/dN) and stress intensity for find out the relationship between fatigue crack growth rate(da/dN) and stress intensity factor range(.DELTA.K) in the SiC$_{w}$/A16061 composite and examine the applicability of Paris' equation to SiC$_{w}$A16061 composite. Also computer simulation was performed for fatigue life prediction of SiC$_{w}$/A16061 composite using the statistical results of this study.udy.

• Composites Research
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• v.17 no.2
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• pp.34-39
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• 2004

In this paper, a modified and representative unit cell model was employed to study the tensile behaviour of closed-cell metallic foams with varying spatial density distribution as well as material imperfections. The density variation was assumed to follow a statistical probability distribution of the Gaussian type. A multiple cell finite element model, utilising the modified unit cell, was developed. The model exhibits deformation patterns similar to those observed in tensile testing. The nominal stress-strain curve obtained from quasistatic tensile of the foam was compared with experimental findings and was found to be in good agreement in the scheme of maximum strength only if the appropriate density distribution and volume fraction of internal imperfections are taken into account. Moreover, maximum tensile strength of the aluminium foam was found to be more sensitive to the volume fraction of imperfection than standard deviation of the density.

• Journal of Powder Materials
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• v.28 no.3
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• pp.253-258
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• 2021

There is increasing demand for the development of a new material with high strength, high stiffness, and good electrical conductivity that can be used for high-voltage direct current cables. In this study, we develop aluminum-based composites containing C₆₀ fullerenes, carbon nanotubes, or graphene using a powder metallurgical route and evaluate their strength, stiffness, coefficient of thermal expansion, and electrical conductivity. By optimizing the process conditions, a material with a tensile strength of 800 MPa, an elastic modulus of 90 GPa, and an electrical conductivity of 40% IACS is obtained, which may replace iron-core cables. Furthermore, by designing the type and volume fraction of the reinforcement, a material with a tensile strength of 380 MPa, elastic modulus of 80 GPa, and electrical conductivity of 54% IACS is obtained, which may compete with AA 6201 aluminum alloys for use in all-aluminum conductor cables.

• Journal of the Korean Society for Heat Treatment
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• v.5 no.4
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• pp.209-214
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• 1992

A Study on the Interface Behavior of Aluminium Alloy Matrix Composites Reinforced with W Fiber. In this study the tungsten fiber reinforced 7072 aluminium alloy martrixcomposites were fabricated using vacuum hot press. The fiber has been aligned on the aluminium alloy sheets and these sheets were bonded with diffustion at 873K and 49Mpa. The behaviors of interface layer and mechanical properites have been investigated as a function of holding time at 873K. Several compounds were formed at the interface layer. These compounds were growing in propotion to holding time. XRD analysis showed that these compounds were $WAl_{12}$ $WAl_5$. The tensile strength decreased as the heat treatment time over 10hr gradually. The ductle fractur mode was turned to brittle mode after heat treatment.

• Journal of Powder Materials
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• v.23 no.3
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• pp.195-201
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• 2016

Composite materials consisting of pure aluminum matrix reinforced with different amounts of graphite particles are successfully fabricated by mechanical ball milling and spark plasma sintering (SPS) processes. The shrinkage rates of the composite powders vary with the amount of graphite particles and the lowest shrinkage value is observed for the composite with the highest amount of graphite particles. The current slopes of time increase with increase in the amount of graphite particles whereas the current slopes of temperature show the opposite trend. The highest thermal conductivity is achieved for the composite with the least amount of graphite particles. Therefore, the thermal properties of the composite materials can be controlled by controlling the amount of the graphite particles during the SPS process.